AFCEC-TR-77-12

NBSIR 77-1238

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TECHNICAL GUIDELINES

FOR ENERGY CONSERVATION

CENTER FOR BUILDING TECHNOLOGY

INSTITUTE FOR APPLIED TECHNOLOGY

NATIONAL BUREAU OF STANDARDS

WASHINGTON D.C. 20234

MTL4--

^OTL

JUNE 1977

Final Report For Period December 1975 to March 1977

Approved for Public Release; Distribution Unlimited

AIR FORCE CIVIL ENGINEERING CENTER

TYNDALL AIR rORCE BASE

FLORIDA 32403

SB

1

AFCEC-TR-77-1 2

NBSIR 77-1238

TECHNICAL GUIDELINES FOR ENERGY CONSERVATION

Center for Building Technology

Institute for Applied Technology

National Bureau of Standards

Washington, D.C. 20234

June 1977

Final Report for Period December 1975 to March 1977

U S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Dr. Sidney Harman, Under Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director
UNCLASSIFIED

SECURITY CLASSIFICATION OF THIS PAGE (When Date Entered) REPORT DOCUMENTATION PAGE READ INSTRUCTIONS

BEFORE COMPLETING FORM

1. REPORT NUMBER

AFCEC-TR-77-12

2. GOVT ACCESSION NO. 3. RECIPIENT’S CATALOG NUMBER

4. TITLE (and Subtitle) Technical Guidelines for Energy

Conservation

5. TYPE OF REPORT & PERIOD COVERED

Final Report, December

1975 to March 1977

6. PERFORMING ORG. REPORT NUMBER

NBS IR 77 1238

7. AUTHORfsJ Building Environment Division

of

National Bureau of Standards

8. CONTRACT OR GRANT NUMBERfsJ

9. PERFORMING ORGANIZATION NAME AND ADDRESS National Bureau of Standards

Department of Commerce

Washington, DC 20234

10. PROGRAM ELEMENT. PROJECT, TASK AREA & WORK UNIT NUMBERS

Investigational Engineering IEDE 4017

11. CONTROLLING OFFICE NAME AND ADDRESS Air Force Civil Engineering Center (DE)

Air Force Systems Command

Tyndall Air Force Base, Florida 32403

12. REPORT date

June 1977

13. number of pages

too

14. MONITORING AGENCY NAME 6 ADDRESS^// different from Controlling Office) 15. SECURITY CLASS, (of this report) UNCLASSIFIED

15a. DECLASSI FI CATION/ DOWN GRADING SCHEDULE

16. DISTRIBUTION STATEMENT (of this Report) Approved for public release; distribution unlimited.

17.

DISTRIBUTION STATEMENT (of the abstract entered In Block 20, if different from Report)

18.

SUPPLEMENTARY NOTES Available in DDC

19.

KEY WORDS ( Continue on reverse side if necessary and identify by block number) Air Force facilities; building energy conservation; energy management; evaluation and monitoring; survey of buildings.

20. ABSTRACT (Continue on reverse side if necessary and identify bv block number) This report provides detailed technical material on various energy conservation

actions for existing Air Force facilities and utility systems. It is specifically tailored to serve as a working document for Base engineers and technical

personnel. The report covers energy conservation for Air Force facilities, including the equipment for providing hot water, space heating and cooling, lighting, and humidification. It also covers central plant systems and underground

' distribution systems (hot water, steam, and chilled water). It does not cover

[ energy conservation measures for tactical or mission-related equipment such as

V gro und ve hicles or fig hter aircraft. j DD 1 j a N 73

'1 473 EDITION OF 1 NOV 65 IS OBSOLETE UNCLASSIFIED

SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered)
PREFACE

This report is the technical portion of a two-report Energy Conservation

effort prepared by the Staff of the Center for Building Technology of the

National Bureau of Standards (NBS) for the Air Force Civil Engineering

Center (AFCEC) , Tyndall AFB, Florida.

AFCEC-TR-77-11 is designed for use by managers to enhance their understanding of energy conservation measures and to assist them in developing a comprehensive energy program. This report provides the necessary engineering information for Staff engineers to evaluate and implement appropriate

energy conservation measures.

This report, the results of research performed during the period December

1975 to March 1977, was submitted by NBS to AFCEC in March 1977. The NBS

Program Manager was Clinton W. Phillips, Office of Housing and Building

Technology, and the NBS project leader and coordinator was Douglas M. Burch,

Thermal Engineering Section, Building Environment Division.

VOLUME II. TECHNICAL GUIDELINES FOR ENERGY CONSERVATION. Separate chapters were prepared and reviewed by staff with particular expertise in each

area, as indicated:

CHAPTER 1. INTRODUCTION. Robert Jones and D. Burch, reviewed by

C. W. Phillips.

CHAPTER 2. ENERGY CONSERVATION MEASURES FOR EXTERIOR BUILDING ENVELOPES.

D. M. Burch and R. Baumgardner*, reviewed by F. J. Powell.

CHAPTER 3. MODIFYING MECHANICAL SYSTEMS AND OPERATING PRACTICES FOR

ENERGY CONSERVATION. D. M. Burch and ENVIRO-MANAGEMENT & RESEARCH,

INC.**, in consultation with R. Beausoliel, A. Camacho, J. B. Coble,

D. Garbern, J. Kao, M. McNeil, and S. Treado , reviewed by R. Jones.

CHAPTER 4. CONDUCTING THE BUILDING SURVEY. R. Baumgardner*, reviewed by

F. J. Powell.

CHAPTER 5. MEASUREMENTS FOR IDENTIFYING ENERGY CONSERVATION POTENTIAL.

D. M. Burch, reviewed by T. Kusuda.

CHAPTER 6. THE ECONOMIC ANALYSIS. Stephen Petersen, reviewed by

H. E. Marshall.

APPENDICES

A. HEAT TRANSFER FUNDAMENTALS, B , A . Peavy, reviewed by J. Hill,

* Rollin Baumgardner, Consultant, Rollin, Inc., P.0. Box 308,

Stroudsburg, PA 18360

** ENVIRO-MANAGEMENT & RESEARCH, INC., 901 8th St., N.W.,

Washington, D.C.

i
B. SOLAR ENERGY SYSTEMS FOR AIR FORCE APPLICATIONS. James Hill,

reviewed by T. Kusuda.

C. HEAT AND CHILLED WATER DISTRIBUTION SYSTEMS. T. Kusuda,

reviewed by D . M. Burch.

D. SURVEY OF COMPUTER PROGRAMS FOR EVALUATING BUILDING AND SYSTEM

PERFORMANCE. William Carroll, reviewed by F. J. Powell.

E. BIBLIOGRAPHY OF ENERGY CONSERVATION DOCUMENTS. Mary Reppert

Valuable assistance was given for field measurements by Walter Ellis and

James Allen, and for editing by M. Reppert, and for typing and copying, by

S. Baile, R. Schmeit, S. Wyand , G. Linton, D. Dawson, and Sara Gill.

The AFCEC Project Officer was Captain Larry W. Strother.

This report has been reviewed by the Information Office (01) and is releasable

to the National Technical Information Service (NTIS) . At NTIS it will be

available to the general public, including foreign nations.

This report has been reviewed and is approved for publication.

Technical Director Commander

ii
TECHNICAL GUIDELINES FOR ENERGY CONSERVATION

CONTENTS

PAGE

PREFACE i

Chapter 1. Introduction 1-1

Chapter 2. Energy Conservation Measures for Exterior

Building Surfaces 2-1

Chapter 3. Modifying Mechanical Systems and Operating

Practices for Energy Conservation 3-1

Chapter 4. Conducting the Building Survey 4-1

Chapter 5. Measurements for Identifying Energy

Conservation Potentials 5-1

Chapter 6. Economic Analysis 6-1

Appendix A. Heat Transfer Fundamentals A-l

Appendix B. Solar Energy Systems for Air Force Applications B-l

Appendix C. Heat and Chilled Water Distribution Systems C-l

Appendix D. A Survey of Computer Programs for Evaluating

Building and System Performance D-l

Appendix E. Bibliography on Energy Conservation E-l

SI Conversion Table

i ii
.
TECHNICAL GUIDELINES FOR ENERGY CONSERVATION

CHAPTER 1. INTRODUCTION

1. 1 Purpose

This report provides detailed technical material on various energy

conservation actions for existing Air Force facilities and utility

systems. It is specifically tailored to serve as a working document for

base engineers and technical personnel.

1. 2 Scope

This report covers energy conservation for Air Force facilities and

family housing, including the equipment for providing hot water, space

heating and cooling, lighting, and humidification. It also covers central plant systems and underground distribution systems for hot

water, steam, and chilled water. It does not cover energy conservation

measures for tactical or mission-related equipment such as ground vehicles or fighter planes. Whereas this report addresses the retrofit of

existing buildings and systems, its use is also encouraged in the design

of new buildings, and extensions or remodeling of existing buildings and

systems

1. 3 Background on the Energy Problem

It has been estimated that between 1971 and 2001, the United States

will consume more energy than it has in its entire history. By 2001 the

annual U. S. demand for energy in all forms is expected to double, and

the annual worldwide demand will probably triple.*

Because the great increase in energy consumption in the past century has taken place chiefly in the advanced countries, it is instructive to examine the trends in the U.S. The annual consumption of all

forms of energy in the United States has increased seventeen-fold in the

past century, with a corresponding population increase of a little more

than five-fold. During this period, fuel sources have shifted steadily

(see figure 1-1). Wood was the dominant fuel energy source in 1850;

* Energy and Power , Scientific American, Inc., W. H. Freeman and Company,

600 Market Street, San Francisco, California, 1974.

1-1
Figure 1-1. U. S. energy consumption. (From Energy and Power , Scientific American, Inc., 1974.)

1-2
consumption and wood had declined to some 10 percent. In the 50 years

between 1910 and 1960, coal lost its leading position to natural gas and

oil. Today nuclear power is emerging as a national energy source. Escalating world energy consumption has resulted in spiraling Air

Force energy costs. A graphic example of this is given in table 1-1.

TABLE 1-1. AIR FORCE ENERGY CONSUMPTION

Fiscal Year Total A.F. Energy Consumption

12

10 Btu

Energy Costs

10^ Dollars

1973 242

1974 209

1975 204

1976 197

163

185

311

355

Note that Air Force energy conservation programs have resulted in

approximately a 19-percent reduction in energy consumption. However,

due to increased energy costs, Air Force energy costs have risen by

a factor of over 2.0.

1. 4 Motivation

The effective use of this report depends upon BCE personnel, their

knowledge, experience, and motivation. The operating and maintenance

personnel must be called upon to examine mechanical and electrical

systems to increase their energy efficiency. Operating procedures long

considered standard are being questioned. Even the requirements of

codes and regulations are being subjected to reevaluation. In the

process, operating engineers and designers are finding out that their

systems can be improved considerably, while still providing adequate

performance.

In order to assure that all potential measures are identified and

that the most cost-effective and energy-efficient measures are selected,

responsible BCE personnel should follow the procedures described in

this report for audit, identification, and analysis. The experience of

successful programs to implement energy conservation measures indicates

that the key can be a thorough and systematic investigation of all

1-3
installations, all systems, and all equipment. Nothing can be excused or overlooked, and each must be evaluated against the respective performance

criteria contained in this report. In this way, the wealth of information

assembled in the report can be used to complement the experience of BCE

personnel.

1. 5 Use of this Technical Report

It will be helpful for the user <pf this report to familiarize himself

with the Table of Contents and the general content of each of the chapters. However, each of the chapters is designed to be self-contained, so the user need not read the entire report for treatment of each topic.

AFCEC-TR-77-12 consists of six chapters, including this introduction, and

five appendices.

Chapter 2 provides technical information on energy conservation

measures for exterior building envelopes.

Chapter 3 provides technical information in modifying mechanical

equipment and utility systems for energy conservation.

Chapter 4 explains how to conduct a physical reconnaissance of a building to identify potential target areas for energy conservation.

Chapter 5 describes key measurements which can be performed for

identifying energy conservation potentials.

Chapter 6 presents a methodology for determining how to allocate

a given energy conservation budget to optimize the dollar return

(energy savings) for a particular dollar investment.

In the appendices, some special information is developed, which

will be of particular interest to those who would like to go into

greater detail on the following items:

A. Heat Transfer Fundamentals

B. Solar Energy Systems

C. Heat and Chilled Water Distribution Systems

D. Computer Programs for Evaluating Buildings and System

Performance.

Finally, appendix E provides a bibliography of energy conservation

documents.

1-4
The expected result of using AFCEC-TR-77-11 and AFCEC-TR-77-12 is

the planning and development of comprehensive energy conservation programs, which will identify in a consistent manner throughout Air Force

installations energy-efficient and economically feasible retrofit measures

for implementation. In this way, not only will the national need to conserve resources be addressed, but also the burden of rising utility

costs at United States Air Force Bases will be reduced.

1-5-

«*

CHAPTER 2. ENERGY CONSERVATION MEASURES

FOR EXTERIOR BUILDING ENVELOPES

CONTENTS

2.1 Assessing the Problem 2-2

2.2 Fenestration 2-4

2.2.1 Reducing Heat Conduction through

Windows 2-4

2.2.2 Solar Shading 2-7

2.3 Reducing Air Infiltration 2-10

2.4 Retrofitting Building Surfaces for

Energy Conservation 2-14

2.4.1 Minimum Requirements for an Insulation to be Eligible for Use

by the Air Force 2-16

2.4.2 Thermal Resistances of Insulation

Materials 2-16

2.4.3 Energy Conservation Measures for

Exterior Building Envelopes 2-18

2.5 Figuring an Economically Optimum Allocation in

Energy Conservation Resources for Building

Envelopes 2-19

References 2-24

2-1
CHAPTER 2. ENERGY CONSERVATION MEASURES

FOR EXTERIOR BUILDING ENVELOPES

2. 1 Assessing the Problem

Before deriving a detailed energy conservation plan for modifying

the exterior envelope of a building, it is a good practice to assess whether the building has predominantly a heating or cooling problem or possibly both. The treatment of these two types of problems is usually

quite different. The following general guidelines are provided.

Buildings located on Air Force Bases having more than 6000 heating

degree days* will usually consume much more energy for space heating

than for space cooling (see figure 2-1). In such instances, more significant reductions in annual energy consumption can usually be obtained

by treating the heating problem than the cooling problem. In treating

the heating problem, emphasis should be placed on reducing heat loss due

to air infiltration and reducing conduction losses through the exterior

building envelope. The latter is conventionally accomplished through

the installation of storm windows and thermal insulation to the exterior

walls, ceilings, and floors of a building.

On the other hand, buildings located on Air Force Bases having less

than 3000 heating degree days will often consume much more energy for

space cooling than for space heating. In treating such a building,

emphasis should be placed on reducing internal heat gains from equipment

and lighting, reducing solar radiation through windows (through the use

of shading devices), and reducing heat gains due to air infiltration.

Buildings located on Air Force Bases having heating degree days

between 3000 to 6000 will often have both heating and cooling problems

which should be treated.

A degree day is a unit based upon temperature difference and time

used in estimating fuel consumption and specifying nominal heating

load of a building in winter. For any one day, when the mean temperature is less than 65° F, there exist as many degree days as there are Fahrenheit degrees difference in temperature between the

mean temperature for the day and 65° F.

2-2
USAF

ACTIVE

MAJOR

INSTALLATIONS

2-3

Figure 2

1.

Heating

degree

day

map

of

United

States

showing

the

location

of

major

Air

Force

installations.
A map of the United States showing the location of active major Air

Force installations is given in figure 2-1. Lines of constant heating

degree days have been superimposed on this map. By locating the particular Air Force Base on this map, one can determine whether the buildings

on the Base have predominantly a heating or cooling problem, or possibly

both. Once the type of problem has been identified, a more appropriate

treatment program to reduce energy consumption may be devised.

2 . 2 Fenestration

A heating problem may be alleviated by reducing the thermal transmittance of the exterior building envelope of a building by using storm

windows or insulating glass units, by installing storm doors, and by

reducing air infiltration through cracks around windows and doors. On

the other hand, cooling problems are treated most effectively by reducing

solar radiation transmitted through glass by using shading devices and

by reducing air infiltration through cracks around windows and doors.

2.2.1 Reducing Heat Conduction through Windows

The heat conduction through an existing single-pane window may be

reduced by simply adding another pane, forming an air space between the

two panes. Another retrofit option is to replace an existing singlepane window system with a double-pane insulating-glass system which

consists of a hermetically sealed two-pane system with an air space

between the panes. The coefficient of transmission (U) for various

window systems is given in table 2-1.

TABLE 2-1. COEFFICIENT OF TRANSMISSION (U)

FOR VARIOUS WINDOW SYSTEMS Btu/h-ft 2 -°F [1]*

Description Winter Summer

Flat glass, single pane 1.13 1.06

Insulating glass-double pane

3/16-inch air space .69 .64

1/4- inch air space . 65 .61

1/2-inch air space . 58 .56

Insulating glass-triple pane

1/4-inch air space .47 .45

1/2-inch air space .36 .35

Storm windows

1 to 4-inch air space . 56 . 54

Numbers placed in brackets denote literature references cited at the

end of the chapter.

2-4

1
The heat-loss rate (q) through a window is governed by the relation:

q = U-A-(T. - T ) (1)

1 o

where U = coefficient of transmission

A = area of the window

T_^ - T

q

= inside-to-outside temperature difference.

Reductions in thermal transmittance (U) are seen to be directly proportional to the heat-loss rate. Note that the coefficient of transmission

for double-pane window systems is only slightly improved by increasing

the thickness of the air space. As a general rule, the addition of a second pane reduces the heat conduction by approximately one-half.

The installation of storm windows provides reductions in heating

energy requirement not only by reducing heat loss from a building, but

also by reducing the number of heating hours. When the thermal transmittance of the building envelope is reduced, the heat from the lighting

equipment and people can provide a larger proportion of the needed heat

supply

When reductions in heating energy requirements obtained from having

storm windows installed are considered for buildings having only moderate internal heat release rates (family-housing units and dormitories)

payback period as a function of energy price is plotted for various

heating degree days in figure 2-2. Here the term "energy price" is

defined as the dollar cost per 100,000 Btu (therm) of heating energy

delivered to the conditioned space. Note that the payback period for

storm windows decreases as the energy price increases and as the number

of heating degree days increases.

It should be pointed out that the addition of storm windows may not

always save energy. One such case is a building for which doors remain

open during periods when the building is heated (such as a guard-gate

building or some warehouses). For such buildings, heat is readily

transferred due to massive air leakage, and often the indoor temperature

may actually approach the outdoor temperature. Since the temperature

difference across the windows in this instance is small, the heat

2-5
o

cvi

CQ

Q

Q

O

o

o_

cvT

QQ

O

o

o.

2-6

Figure

2-2.

Payback

periods

for

storm

windows

[2].
transfer through the window is small and the benefit derived from the

installation of storm windows is negligible. The addition of a storm

window to a building may actually increase the annual energy requirements in the case of a building having cooling requirements during

periods when the outdoor temperature is lower than the indoor temperature. This condition occurs in a building having a large internal

equipment load (such as a computer facility, a laundry facility, or a plant shop). The condition also occurs for buildings at geographic

locations having hot summer days and cool nights during which natural

cooling of the structure may occur. In these instances, the effect of

installing a storm window may be to trap internal heat inside the

structure and reduce the effect of natural cooling when there is no provision for introducing outside make-up air. A complete analysis of

the annual benefit to be derived from storm windows is best accomplished

with a computer simulation (see Appendix D)

2.2.2 Solar Shading

Solar shading devices can reduce the solar radiation transmitted

through windows and thereby reduce the cooling loads for a building.

The following energy conservation measures will provide reductions in

transmitted solar radiation:

Interior shading devices

° draperies

° Venetian blinds

° pull shades

Exterior shading devices

° awnings

° trees

Others

° heat-absorbing glass

° solar films and reflective coatings

° solar screens. In evaluating a solar-shading device, the shading coefficient,

defined as the fraction of solar radiation that is transmitted through

a window system with a particular solar-shading device installed, may be

used as a criterion. Shading coefficients for various shading devices

are presented in reference [1]. Another factor which should be con- sidered is the reduction of natural light that occurs when solar-shading

devices are installed.

2-7
If designed properly, exterior shading devices are generally more

effective than interior shading devices. The use of deciduous trees and

shrubbery as a solar shading device for south-facing windows has the

additional advantage that in the winter solar radiation is transmitted

and will provide a free source of heat.

Internal shading devices such as blinds, curtains, and solar films

present a somewhat less effective way of reducing solar radiation.

The American Society of Heating, Refrigerating, and Air-Conditioning

Engineers (ASHRAE) [1] , gives the reduction in solar heat gain that can

be expected for a single plate-glass window when using internal shading

devices as follows:

VENETIAN BLINDS ROLLER SHADE

Opaque Translucent

Medium Light Dark White Light

36% 45% 41% 75% 61%

Similar results are given by ASHRAE for closed draperies, showing that

they can reduce solar gain by as much as 65 percent. These internal

shading devices are relatively inexpensive and yet can be very effective. Of course they must be used properly; that is, shades and drapes

should be closed during the cooling season on sunlit surfaces and opened

when needed during the heating season. Solar shading devices should be installed only for those window

systems that are exposed to solar radiation. Since windows on the north

side of a building are seldom exposed to solar radiation, shading devices

need not be installed on north windows. However, interior shading

devices such as insulated draperies will reduce the heat transfer due to

air-to-air temperature difference.

Solar transmission through a window system may be substantially re- duced by applying a reflective coating or film to one side. For instance,

installing a storm window with a reflective coating in front of an

existing single-pane window can reduce the overall daytime heat transmission through the window by a factor of 4 [5].

2-8
Other types of glass available for energy conservation applications

are tinted glass and heat-absorbing glass. Tinted glass reduces light

levels and glare. However, it absorbs solar energy, making it a hot

radiant-heating panel when it is exposed to the sun. This may be

desirable under certain climatic conditions. Reflective and heatabsorbing glass rejects solar energy and does not become hot. It re- flects up to 80 percent of the radiant energy, which is very helpful

for cooling in summer, but results in a loss of useful heat in winter.

Natural light is lost when tinted or reflective glass is used. The

effects on yearly consumption should be considered before a choice is

made.

Summary of Energy-Conservation Measures for Fenestration

Minimal Expenses

0 Inspect condition of indoor shading devices such as draperies

and blinds which can reduce heat gain by as much as 50 percent.

Keep indoor shading devices clean and in good repair.

During the heating season, close all interior shading devices

to reduce nighttime heat losses.

0 Use opaque or translucent insulating materials to block off and

thermally seal all unused windows.

Significant Expense

° Consider adding reflective and/or heat-absorbing film to glazing

to reduce solar heat gains by as much as 80 percent. Be aware that

such films will substantially reduce the benefits of natural

lighting. Investigate their predicted years of durability.

° Consider adding reflective materials to the window side of

draperies to reflect solar heat when draperies are drawn.

° Install indoor shading devices to reduce the transmission of

solar radiation in the summer. They should be light-colored

and opaque. In order to retard winter heat loss, draperies

should be insulated or lined.

° Consider installation of outdoor shading devices, such as sun- shades, awnings, balconies, and trees, which intercept solar heat

before it has a chance to enter the building, and which dissipate

2-9
heat outdoors rather than indoors. Adjustable sunshades permit

solar radiation to enter during the heating season.

° Consider installation of storm windows if practical.

° If storm windows are not practical, consider reglazing with

double- or triple-glazing, or with heat absorbing and/or reflective

glazing materials. In selecting a replacement, choose a window

system that has a low heat transmission coefficient.

° Consider the installation of solar screens.

° Use operable thermal shutters which decrease the composite "U"

value to 0.1.

° Allow direct sun on windows from November through March. Shade

windows from direct sun from April through October.

° Plant deciduous trees for summer and winter sunshading and windbreak effects.

2 . 3 Reducing Air Infiltration

The purpose of this section is to present background material and

specific energy conservation measures for reducing air infiltration in

buildings

Air infiltration is the exchange of indoor air of a building with

the outdoor air caused by indoor-to-outdoor temperature difference and

wind forces. When the indoor air of a building is warmer than the

outdoor air, it will be lighter than the outdoor air and will tend to

rise and leak out of the top levels of a building while colder outdoor

air enters the building at the lower levels. This driving force is

called the stack effect. When an exterior surface of a building decelerates moving outdoor air, an inside-to-outside pressure difference

is developed across the building surface which in turn causes air

infiltration on one side and air exfiltration on the lee side.

In treating a building for air infiltration, one needs to establish

priorities for energy conservation measures. Defects in the construction

should be given first priority. This category includes items such as broken windows, holes in walls, large louvered ventilation exhaust

openings frozen in an open position, window systems which have become

warped to such an extent that they can no longer be closed, etc.

2-10
Of second priority are the less obvious cracks and small openings

such as around windows, doors, etc. Such items are usually treated by

applying caulking and weatherstripping.

An important point that should be made is that the use of conventional measures to reduce air infiltration on a building that is of

tight original construction may not be effective in reducing air infil

tration. National Bureau of Standards studies [3,4] have shown that

conventional measures to reduce the obvious leaks and cracks in woodframe residences were only able to reduce the air infiltration rate to one half air change per hour.

Energy conservation measures for reducing air infiltration in

buildings are summarized in the following:

Windows and Skylights

Minimal Expense

° Replace broken or cracked window panes.

° Replace worn or broken weatherstripping around operable windows

If possible, install weatherstripping where none was installed

previously

0 Weatherstrip operable sash if crack is evident.

° Caulk around window frames (exterior and interior) if cracks

are evident.

° Rehang misaligned windows.

° Be certain that all operable windows have sealing gaskets and cam latches that are in proper working order.

° Consider posting a small sign next to each operable window

instructing occupants not to open window while the building is

being heated or cooled.

Exterior Surfaces

Minimal Expense

° Caulk, gasket or otherwise weatherstrip all exterior joints,

such as those between wall and foundation or wall and roof, and

between wall panels.

2-11
Caulk, gasket or otherwise weatherstrip all openings, such as those provided for entrance of electrical conduits, piping,

through-the-wall cooling and other units, outside air louvers, etc.

° When window and through-the-wall air conditioning units permit

outdoor air to enter the building cover them when not in use. Specifically designed covers can be obtained at relatively low

cost.

Elevator Shafts

Minimal Expense

° Seal elevator shafts around cabs at floor stations.

Windbreaks

Minimal Expense

° If open space is available, consider planting trees or large

shrubs to act as windbreaks on the windward side of the building.

The windbreak can have positive value on reducing wind impact,

at least on lower floors. Trees and shrubs also can be used to

reduce solar penetration.

Fireplace Damper

Minimal Expense

° Close the fireplace damper when not in use.

° Repair fireplace damper if it does not seal properly.

Doors

Minimal Expense

Replace any worn or broken weatherstripping. Install weatherstripping where appropriate.

° Rehang misaligned doors.

° Caulk around door frames.

° Inspect all automatic door closers to ensure they are functioning

properly. Consider adjustment for faster closing.

Inspect gasketing on garage and other overhead doors. Repair,

replace, or install as necessary.

2-12
Consider placing a small sign next to each door leading to the

exterior or unconditioned spaces advising occupants to keep door

closed at all times when not in use.

° Consider installing signs on exterior walls near delivery doors

providing instructions to delivery personnel on operation of doors.

Establish rules for all building personnel regarding opening

and closing of doors, directing them to keep them closed whenever

possible.

Consider installing automatic door closers on all doors from

conditioned spaces leading to outdoor environment.

Significant Expense

If the building has a garage, but does not have a garage door,

consider installing one, preferably motorized to enable easier

opening and closing.

° Consider use of a card-, key-, or radio frequency-operated

garage door which stays closed at all times except when in use.

° Consider making delivery entrances smaller. The larger the

opening, the more air that infiltrates when doors are open.

° Consider using an expandable enclosure for delivery ports. It

reduces infiltration when in use because it can be adjusted to

meet the back of a truck, reducing substantially the amount of air

which otherwise would infiltrate.

° Consider installation of an air curtain, especially in delivery

areas. The device prevents penetration of unconditioned air by

forcing a layer of air of predetermined thickness and velocity over the entire entrance opening. (An expert in the field should be

consulted before obtaining such a device, especially when highrise

structures are involved. The degree of stack effect, among other

things, determines its usability.)

0 Consider installation of a vestibule for the entrances of a building, where practical. It should be fitted with self-closing

weather stripped doors.

2-13
° Consider utilizing revolving doors for the entrances. Studies

have shown that such devices allow far less air to infiltrate with

each entrance or exit. Use of revolving doors in both elements of

a vestibule is even more effective. If high-peak traffic is involved, swinging doors can be used to supplement revolving doors.

Ventilation Exhaust Openings

Minimal Expense

Permanently close off ventilation exhaust openings that are not

essential or never used.

Close off ventilation exhaust openings when not in use. Check spring-activated ventilation exhaust devices to make sure

that they are in proper operating condition.

Significant Expense

° Consider replacing existing ventilation exhaust devices with

spring-activated ventilation exhaust devices.

2 . 4 Retrofitting Building Surfaces for Energy Conservation

Often the most significant reductions in the energy requirement for

space heating can be obtained by installing insulation into existing

walls, ceilings, and floors of buildings. However, such energy conservation measures are not always cost effective due to the high initial cost

required for the modification.

Energy conservation measures which increase the thermal resistance

of the exterior envelope of a building envelope reduce the heating energy

requirement by the following two mechanisms:

° reduction of heat-loss rate;

° reduction of heating hours.

When thermal insulation and storm windows are added to a building, there

will exist a larger number of hours during periods of moderately cold

weather for which space heating can be entirely provided by the lights,

people, and equipment instead of the heating plant. The number of

heating hours is thereby reduced. This latter phenomenon provides

substantial reduction in the heating energy requirement which is often

not considered in evaluating the cost effectiveness of energy conservation measures.

2-14
The addition of thermal insulation may not always provide reduction

in the energy requirement for space cooling. In geographic locations

having a large number of cooling days for which the nighttime outdoor

air temperature falls below the indoor temperature of the building, wall

insulation may not be effective in reducing the energy requirement for

space cooling. An explanation is given in the following:

Wall insulation unquestionably reduces heat gain through the wall

during the day. However, the insulation may eliminate a previous benefit

of natural cooling during nighttime periods. When this occurs, the

internal heat from lighting, equipment, people, and residual stored

solar heat from the previous day must be removed by the air conditioning

equipment. Before the insulation had been installed, a major portion of

these internal gains could have been removed by heat loss through the

walls to the cool outdoor air. In many instances the reduction of

natural cooling during the night can actually offset the reduction in

heat gains during the day.

Another effect of adding thermal insulation in the walls is to

increase the number of cooling hours. For every building there is an outdoor temperature at which no energy is required for space cooling.

At this condition, the heat loss through the building envelope is

sufficient to remove the internal heat gains from lighting, equipment,

people, and transmitted solar radiation. This outdoor air temperature

is called the "outdoor balance temperature". When insulation is added

to the walls of a building, the heat-loss rate from the building is

reduced, and the outdoor temperature must reach a lower level before

natural cooling is sufficient to remove the internal heat gains. Under

such conditions, the number of hours for space cooling (by the airconditioning equipment) is essentially increased.

The foregoing situation generally occurs at geographic locations

having moderate summer energy requirements. For locations having ex- tremely hot summers, for which the nighttime outdoor temperatures are usually hotter than the indoor temperatures of the buildings, wall

insulation may produce reductions in the energy requirement for space

cooling

2-15
Additional topics on retrofitting of building envelopes are discussed in the following sections.

2.4.1 Minimum Requirements for an Insulating Material to be Eligible

for Use by the Air Force

Insulating materials eligible for use by the Air Force must meet

the appropriate Federal Specification and American Society for Testing

Materials (ASTM) Tests for the particular material. Federal Specifications and ASTM designations for various insulation materials are sum- marized in table 2-2. If an insulation material does not have a Federal

Specification and/or an ASTM test, a special waiver for its use should

be obtained from the appropriate Major Command Headquarters for the

Base.

In addition to the foregoing, every thermal insulation used in an Air Force building must have a flame-spread rating less than 25 when

tested according to ASTM E 84-70 flame-spread test method, and it must

have a smoke-development rating not over 30, except when the insulation

is isolated from the interior of the building by masonry walls, in which

case it may have a flame-spread rating up to 100, and no smoke-development

limitation is required.

2.4.2 Thermal Resistance of Insulation Materials

2 The heat transfer rate (q/A) in Btu/h*ft through a wall, ceiling,

or floor is customarily expressed by the relation:

q/A = AT/R (2)

where AT = air-to-air temperature difference, °F

2 R = thermal resistance, h*ft ,0 F/Btu

Note that increasing the thermal resistance decreases the heat-transfer

rate.

In selecting an insulating material, it is desirable to minimize

the heat-transfer rate by using an insulation material with the largest

R-value. Thermal-resistance values (R-values) per inch thickness for

various insulation materials are given in table 3 of chapter 20 of the

ASHRAE Handbook on Fundamentals. To find the total R-value for a particular thickness of insulation, multiply the R-value for the

material by the thickness of the specimen.

2-16
TABLE 2-2. FEDERAL SPECIFICATIONS AND ASTM TEST

DESIGNATIONS FOR VARIOUS INSULATIONS

Type of

Insulation Number

Federal Specification

Title

ASTM

Designation

Mineral

Fiber

HH-I-521E

HH-I-526C

Insulation Blankets, Thermal (Mineral

Fiber, for Ambient Temperatures)

Insulation Board, Thermal (Mineral

Fiber)

C665-70

C612-70

C726-72

HH-I-545B Insulation, Thermal and Acoustical

(Mineral Fiber, Duct Material) —

HH-I-1030B Insulation, Thermal (Mineral Fiber

for Pneumatic or Poured Application)

C764-73

HH -I-529B Insulation Board, Thermal (Mineral

Aggregate) —

Mineral

Cellular

HH-I-551E Insulation, Block and Board, Thermal

(Cellular Glass)

C552-73

HH-I-574A ’Insulation, Thermal (Perlite) C549-73

HH-I-585B Insulation, Thermal (Vermiculite) C516-67

Organic

Fiber

HH-I-515C Insulation Blanket, Thermal; and

Insulation, Thermal (Loose-fill

for Pneumatic or Poured Application) Cellulose, Vegetable and

Wood Fiber

C739-73

HH-I-528B Insulation Batts and Blankets,

Thermal (Vegetable Fiber) —

LLL-I-535A Insulation Board, Thermal and

Insulation Block, Thermal

C208-72

Organic

Cellular

HH-I-524B

HH-I-530A

Insulation Board, Thermal

(Polystyrene)

Insulation Board, Thermal

C578-69

C591-69

HH-I-573B Insulation, Thermal (Flexible

Unicellular Sheet and Pipe

Covering)

C534-70

Air

Spaces

HH-I-1252A Insulation, Thermal, Reflective

(Aluminum Foil) —

2-17
For example, find the R-value for 6 inches of cellulose. From reference [1], the R-value per inch is found to be 3.7. For 6 inches the

total thermal resistance is (3.7) (6) = 22.2.

2.4.3 Energy Conservation Measures for Exterior Building Envelopes

Some measures for reducing heat transmission through walls, roofs,

and floors are given below:

Minimal Expense

° When exterior surfaces of a building are repainted, select a light color paint to provide small absorptance for solar radiation.

° When a new exterior roof surface is installed, select a lightcolored exterior roof surface to provide small absorptance for

solar radiation.

° Plant trees around structure to serve as a windbreak and provide natural shading of building surfaces from solar radiation.

° Repair major cracks and openings through exterior surfaces.

Significant Expense

° Where roof insulation is not practical, consider insulating the

top floor ceiling. This can be done easily with blown insulation.

In most cases, ceiling insulation also will require a vapor

barrier placed on the warm side of the ceiling—if not integral

with the insulation—to prevent structural damage caused by rot,

corrosion or expansion of freezing water.*

° Consider blowing more insulation into cavity walls.

° Consider installing thermal insulation in the floor over unconditioned spaces (such as crawl spaces, unheated basements,

and unheated garages)

° Consider installing thermal insulation around the perimeter

edges of slab floors placed on grade.

° Consider insulating non-cavity walls.

* Caution: The installation of ceiling insulation may cause a reduction in attic temperatures and thereby increase the likelihood for

pipes located above the insulation to freeze.

2-18
2. 5 Figuring an Economically Optimum Allocation of Energy Conservation

Resources for Building Envelopes

In determining the economically optimum level for a particular

energy conservation investment (e.g., how much ceiling insulation to

be installed) , the methodology should be based on an incremental analysis. The energy savings and cost for each additional increment of investment should be calculated. Increments of investment should be added

until the incremental cost of the investment exceeds the incremental

saving in energy (expressed in dollars). This procedure is outlined in

detail in chapter 6.

Based on the foregoing technique, a procedure was developed for

estimating the economically optimum level of investment for various

energy conservation actions for the exterior envelopes of family-housing

units and dormitories . This procedure was specifically developed for

these two types of buildings and in many cases will not be applicable to

other types of buildings. The procedure is given in the following:

(a) Locate your Air Force Base on the heating zone map given in

figure 2-3.

(b) Locate your Air Force Base on the cooling zone map given in

figure 2-4. If your Air Force Base is on the borderline of

two zones, select the zone in which the climate is more typical

of your area.

(c) Locate the heating index from table 2-3 by finding the number

at the intersection of your heating zone row and the heating

fuel cost column (to the nearest cost shown)

(d) If the building being considered is air conditioned, locate the

cooling index for attics from table 2-4 by finding the cooling

zone and cooling costs to the nearest cost shown.

(e) If the building being considered is air conditioned, locate the

cooling index for walls from table 2-5 by finding the cooling

zone and cooling costs to the nearest cost shown in the table.

(f) Find the sum of the heating and cooling index for attics.

(g) Find the sum of the heating index and cooling index for walls.

(h) Find the resistance value of insulation recommended for the

attic and around attic ducts from table 2-6.

2-19
(i) Find the recommended level of insulation for floors over unheated areas from table 2-7. Using table 2-7, check to see whether storm doors are economical for the building.

Storm doors listed as optional may be economical if the

doorway is heavily used during the heating season.

(j) Find the recommended level of insulation for the walls and

ducts in unheated areas from table 2-8. Table 2-8 also shows

the minimum economical storm window size in square feet for

triple-track storm windows.

EXAMPLE

Consider an example house located on the maps of figures 2-3

and 2-4. It is located in heating zone III (figure 2-3) and in

cooling zone B (figure 2-4). This house currently uses fuel oil at

a cost of 34c a gallon to heat. It uses electricity at 4c a kilowatt hour to cool.

(a) From figure 2-3, the example house is located in heating

zone III.

(b) From figure 2-4, the example house is located in cooling zone B.

(c) From table 2-3, heating index is found to be 20.

(d) From table 2-4, cooling index for attics is 5.

(e) From table 2-5, cooling index for walls is found to be 2.

(f) The sum of the heating index and cooling index for attics is 25.

(g) The sum of the heating index and cooling index for walls is 22.

(h) From table 2-6, the recommended resistance value is R-30 for

the ceiling and R-16 for ducts.

(i) From table 2-7, the recommended resistance for a floor over an unheated space should be R-19. A storm door is seen to be

optional.

(j) From table 2-8, the example house should have full wall

insulation if none existed previously, and R-16 around ducts

located in unheated regions other than the attic.

2-20

1
Figure 2-4. Summer cooling zones.
TABLE 2-3 HEATING INDEX

Type of fuel: Gas (therm)

Oil (gallon)

Electric (kWh)

90

130

120

170

150

210

Heat pump (kWh) H 1.30 1.70

H 1 2 2 3

E II 5 6 8

A Z

T O

1 N

N E

III 8 10 13

IV 11 14 18

V 14 18 23

G VI 22 28 36

TABLE/ 2-4

Type of

air conditioner:

.COOLING INDEX FOR

Cost per unit*

ATTICS

Gas (therm) 9C 12c 15c 18c 24 c 30c 36c

Electric (kWh) 1.5c 2c 2.5c 3 c 4 c 5 c 6 c C A 0 Z „

0 0 0 0 0 0 0 o o B 2 2 3 4 5 6 7 L N C 3 5 6 7 9 1

13

1 E D 5 6 8 9 12 15 18 N E G

7 9 114 18 23 27

Cost per unit*

180 240 300 360 540 720 900

250 340 420 500 750 $1.00 $1.25

10 1.30 1.60 20 30 40 50

20 2.60 3.30 40 60 80 100

3 4 5 6 9 12 15

9 12 15 18 27 36 45

15 20 25 30 45 60 75

21 28 35 42 63 84 105

27 36 45 54 81 108 135

42 56 70 84 126 168 210

TABLE 2-5. COOLING INDEX FOR WALLS

Type of

air conditioner: Cost per unit*

Gas (therm) 9c 12c 15c 18c 24c 30c 36 c Electric (kWh) 1.5c 2 c 2.5c 3c 4 c 5c 6 c C A 0 2

R O 0

3

0 0 0 0 0 0 0

1 1 2 2 2 3 4

L N C 2 2 3 4 5 6 7

1 E D 3 3 4 5 7 8 10 8

E 4 5 6 8 10 13 15

TABLE 2-6. ATTIC FLOOR INSULATION AND ATTIC DUCT INSULATION

INDEX ATTIC INSULATION DUCT INSULATION*

Heating Index Approximate Thickness

Plus Cooling Mineral Fiber Mineral Fiber Cellulose Approximate

Index (or Attics R Value Batl'Blanket Loose-Fill*

Loose-Fill** R Value Thickness

1 3 R 0 0" 0" 0" R 8 2"

4 9 R 11 4" 4 6" 2- 4" R 8 2"

10 IS R 19 6" 8 10" 4 6" R 8

' 2"

16 27 R -30* ** 10" 13 15" 7 9" R 16 4"

28 35 R 33 11" 14 16" 8 10" R 16 4"

36 45 R 38 12" 17 19” 9 11" R 24 6" 46 60 R 44 14" 19 21" 11 13" R 24 6"

61 85 R 49 16" 22 24" 12 14" R 32 8" 86 105 R 57 18" 25 27" 14 16" R 32 8"

106 130 R 60 19" 27 29" 15 17" R 32 8"

131 — R 66 2i" 29 31" 17 19" R 40 10-

* Use Heating Index only it ducts are not used for air conditioning •* High levels of loose-fill insulation

in many attics *’ "Assumes that |Oists are covered: otherwise use R 22. may not be feasible

2-22
TABLE2-7 ..INSULATION UNDER FLOORS

AND STORM DOORS

INDEX INSULATION UNDER FLOORS - STORM DOORS

Heating Index Mineral Fiber Only RValue Bait Thickness

0-7 O'* 0"* • None

8 15 IT* 4

Norte

16 30 19 6 Optional

31-65 22 7” Optional 66

22 7“ On all doors

If your furnace and hot water heater are located in an otherwise unheated basement, cut your Heating Index in hall to find the level of floor insulation

In Zone I and II R 1 1 insulation is usually economical under floors over open crawlspaces and over garages in Zdne I insulation is not usually economical if crawlspace is closed off

TABLE 2-8. WALL INSULATION, DUCT INSULATION, AND STORM WINDOWS

INSULATION AROUND DUCTS

INDEX WALL

INSULATION

IN CRAWLSPACES AND IN OTHER

UNHEATED AREAS (EXCEPT ATTICS)’ STORM WINDOWS

Heating Index Plus Resistance and (Triple-Track) Minimum

Cooling Index for Walls (blown-in) Approximate Thickness Economical Window Size 0-10 None R 8 (2") none

11-12 / R 8 (2") 20 sq ft 13 15 I

R 16(4") 1 5 sq. ft. 16 19 1 Full- R 16(4") 1 2 sq ft 20 28 / Wall R 16(4") 9 sq ft 29 35 \ Insulation R 16(4") 6 sq ft 36 45 1 Approximately R 24(6") 4 sq ft 46 65 f R-14 R-24(6") All windows’ * 66— V R 32(8") All windows’

* Use Healing Index only if ducts are not used for air conditioning 1 ' Windows too small for triple track windows can be

fitted with one piece windows

2-23
REFERENCES

1. ASHRAE Handbook of Fundamentals , American Society of Heating,

Refrigeration, and Air Conditioning Engineers, 1972.

2. Retrofitting Existing Housing for Energy Conservation: An

Economic Analysis, S. R. Petersen, Building Science Series 64,

National Bureau of Standards, Dec. 1974.

3. Retrofitting an Existing Wood-Frame Residence for Energy

Conservation—An Experimental Study, D. M. Burch and C. M. Hunt,

Building Science Series (in review Jan. 1977), National Bureau

of Standards.

4. Comparison of Measured and Computer -Predicted Thermal Performance

of a Four-Bedroom Wood-Frame Townhouse, B. A. Peavy, D. M. Burch,

and F. J. Powell, Building Science Series 57, National Bureau of

Standards, April 1975.

5. Technical Options for Energy Conservation in Buildings, NBS

Technical Note 789, National Bureau of Standards, July 1973.

2-24
CHAPTER 3. MODIFYING MECHANICAL SYSTEMS AND OPERATING

PRACTICES FOR ENERGY CONSERVATION

CONTENTS

PAGE

3.1 Modifying Building Operation 3-3

3.1.1 Night Temperature Setback 3-3

3.1.2 Reducing Indoor Temperature 3-5

3.1.3 Economizer Cycles 3-6

3.1.4 Modifying Humidity Control of Mechanical Equipment 3-6

3.1.5 Ventilation Air 3-10

3.2 HVAC Equipment in Large Buildings 3-12

3.2.1 Reduce Energy Consumption for Fans 3-12

3.2.2 Reduce Energy Consumption for Pumps 3-17

3.2.3 Reduce Distribution System Heat Losses 3-17

3.2.4 Eliminate Steam Leaks 3-20

3.2.5 Assess Energy Use for Humidification Processes 3-20

3.2.6 Flash Condensate to Low-Pressure Steam 3-20

3.2.7 Increase Condensate Return to Boilers 3-21

3.3 HVAC Equipment in Family Housing 3-22

3.3.1 Heating Plants 3-22

3.3.2 Central Air Conditioning Equipment 3-23

3.3.3 Summary of Energy Conservation Measures for HVAC

Equipment in Family Housing 3-24

3.4 Domestic Hot Water 3-25

3.4.1 Background 3-25

3.4.2 Reduce the Temperature of Domestic Hot Water

Supplied to Taps 3-27

3.4.3 Reduce the Quantity of% Domestic Hot Water Used 3-31

3.4.4 Improve the Efficiency of the Storage and

Distribution Systems 3-31

3.4.5 Generate Hot Water More Efficiently 3-32

3.4.6 Replace Central Systems by Local Heating Units 3-32

3.4.7 Install Temperature Boosters 3-33

3.4.8 Install Separate. Boilers for Summer Generation

of Domestic Hot Water 3-33

3.4.9 Waste-Heat Recovery for Hot-Water Heating 3-33

3.5 Lighting 3-36

3.5.1 Background 3-36

3.5.2 Conserve Energy by Turning Off Lights 3-37

3.5.3 Improve the Effectiveness of Existing Lighting

Installations 3-37

3.5.4 Use Daylight for Illumination 3-41

3.5.5 Add Switching and Timers to Shut Off Lights 3-42

3-1
3.5.6 Remove Unnecessary Lamps 3-42

3.5.7 Reduce Lighting Loads by Relamping 3-44

3.5.8 Reduce Illumination Levels 3-46

3.6 Central Plants 3-47

3.6.1 Steam and HTW Generating Plants 3-49

3. 6. 1.1 Limit Flue-Gas Losses 3-49

3. 6.1.2 Limit Combustion Losses 3-53

3. 6.1. 3 Preheat Oil to Increase Efficiency 3-53

3. 6. 1.4 Reduce Blowdown Losses 3-55

3. 6.1. 5 Isolate Off-Line Boilers 3-55

3.6.1. 6 Replace Boilers At or Near End of

Useful Life 3-57

3. 6. 1.7 Replace Existing Boilers with Modular

(Multiple) Boilers 3-57

3. 6.1.8 Convert from Steam Atomizing Burners to

Air-Atomizing Burners 3-57

3.6.2 Chilled Water Plants 3-60

3.7 Electrical Load Management 3-61

3.7.1 General 3-61

3.7.2 Selection of Interruptable Loads 3-61

3.7.3 Major Loads that Can be Deferred without Consumer

Dissatisfaction 3-62

3.7.4 Load Management Control Techniques 3-62

3.8 Energy Monitoring Control Systems 3-63

3.8.1 Background 3-63

3.8.2 Description of Typical System 3-64

3.8.3 Consideration for Procurement of EMCS 3-64

3.8.4 Select and Train an Operator 3-67

3.8.5 Communication Lines 3-68

3.8.6 Back-up Equipment 3-69

3.8.7 Service/Maintenance Contracts 3-70

3.8.8 EMCS Manning 3-70

3.9 Energy Recovery through Waste POL Utilization 3-71

3.10 Power-Factor Adjustments 3-73

3.10.1 Background 3-73

3.10.2 Power-Factor Fundamentals 3-75

3.10.3 Analysis of Power-Factor Problems 3-77

3.10.4 Selection of the Most Suitable Location for

Power-Factor-Correction Capacitors 3-81

3.11 Waste-Heat-Reclamation Systems 3-83

3.11.1 Prime Targets for Waste-Heat Recovery 3-83

3.11.2 Waste-Heat Recovery Devices 3-83

References 3-93

3-2
CHAPTER 3. MODIFYING MECHANICAL SYSTEMS AND OPERATING

PRACTICES FOR ENERGY CONSERVATION

3. 1 Modifying Building Operation

3.1.1 Night Temperature Setback

Energy requirements for space heating of family-housing units and

dormitories may be reduced 5 to 15% by setting back the indoor temperature 10° F during an 8-hour night-time period. Night temperature setback

will also produce substantial saving in other types of Air Force buildings. Clock thermostats are commercially available and range in price

from $50 to $100*. The fuel savings for the first couple of years will

usually pay for the initial cost of the clock thermostat; fuel savings

after this short payback period will represent money in the bank. The

heat loss from buildings is proportional to the difference in temperature

between the indoor and outdoor air. Night-time reduction of indoor air

temperature will provide significant reductions in the night-time fuel

consumption. However, when the indoor temperature is set up in the

morning, the heating plant must run a long time to reheat the building.

Thus, some of the night-time fuel savings are offset by increased fuel

consumption in the morning to reheat the building.

Recently Nelson of Honeywell conducted a research study [1]** to

investigate the heating energy savings for residential buildings achieved

by night temperature setback of the indoor air temperature. The Nelson

data is plotted to show fuel savings versus annual heating degree days

in figure 3-1. The top line gives the fuel savings for a 10° F, 8-hour

setback, whereas the bottom line gives the fuel savings for a 5° F,

8-hour setback.

Notice that increasing the amount of setback significantly increases

the fuel savings. Also, the percent fuel savings becomes greater as the

annual heating degree days decrease. A surprising finding of the Nelson

study [1] was that the percent fuel savings resulting from night

* 1976 prices.

** See references cited at end of chapter.

3-3
oo

3-4

if) 5-<Q

LlI

LlI tr




LlI QO

J-<

LUX ]

Figure

3-1.

Fuel

savings

achieved

by

night

temperature

setback.
temperature setback was practically independent of the degree of insulation of the building. Thus, the percent fuel savings would be

the same for a poorly insulated building as for a well insulated

building

The data from Ref. [l],in the strict sense, are applicable to residential buildings and, in most cases, may be applied to dormitories. Night

temperature setback for other types of Air Force buildings will usually

provide substantial energy savings. However, the amount of savings for

these other-type buildings will depend on the amount of internal loads

and the characteristics of the heating plant.

3.1.2 Reducing Indoor Temperature

For space heating applications, the energy savings that may be

achieved by reducing the indoor temperature from one level to another

may be estimated from the relation:

„ 0 . Al\

% Savings = 1 ...

T* _ T* \ / B o

where AT^ = reduction in indoor temperature, °F

T = outdoor balance temperature, °F

£> T

q = winter average outdoor temperature, °F.

The outdoor balance temperature is the outdoor temperature for which no space heating energy from the heating plant is required (usually 60° F to

65° F) . At this condition the internal heat from lights, equipment,

occupants, and transmitted solar radiation is sufficient to heat the

building. Winter average outdoor temperatures for a wide range of geographic locations are given in table 1 of chapter 43 of the 1973 ASHRAE

Systems Volume [2],

Example

The indoor temperature of a dormitory located in Washington, D.C.

is reduced by 4° F. Calculate the reduction in the heating

energy requirement.

3-5
The outdoor balance temperature for the dormitory is taken

as 65° F, and the winter average temperature for Washington,

D.C. is 45.7° F. Thus,

% savings 4 65-45.7 20.7%

Caution: For interior spaces and for spaces having large internal loads

(due to lights, environment, people, etc.), a lowering of the thermostat

can have a negative effect on energy consumption; in this situation,

know your system before making adjustments.

For space cooling applications, raising thermostat settings to

80° F and humidistat settings to 60% RH could reduce the space-cooling

energy requirement by an estimated 15% compared with operation at 75° F

and 50% RH. (Note: in some reheat systems internal operating temperatures must also be raised along with thermostat settings, to effect the

desired energy savings.)

3.1.3 Economizer Cycles

The economizer cycle provides for the introduction of outdoor air

into a conditioned space of a building in order to reduce the number of

operating hours of the refrigeration equipment. When the temperature

and relative humidity of the outdoor air are within prescribed limits,

and the thermostat is calling for cooling, the economizer cycle can introduce outdoor air into the building instead of providing space

cooling with air conditioning equipment. Use of an economizer cycle in

residential buildings can make a considerable reduction in compressor

operating time, according to an analog computer study recently completed

by Honeywell [3]. Figure 3-2 gives the calculated savings when the

economizer cycle is used on a residential building.

3.1.4 Modifying Humidity Control of Mechanical Equipment

Perhaps the most definitive experimental study on thermal comfort

is one conducted on over 1600 college students at Kansas State University over the past several years [4]. The students were exposed

3-6
I

Montana

3-7

Figure

3-2.

Percent

savings

with

air

economizer

used

in

a

residential

building

[3J.
(over a 3-hour period) to uniformly heated or cooled environment (wall

temperatures identical to the air temperature) with moderate air velocities, and asked to vote on a scale from 1 to 7 which ranged from

cold to hot

1 . cold 5. slightly warm

2. cool 6. warm

3. slightly cool 7. hot

4. comfortable

All subjects, male and female alike, were clothed in cotton twill

shirts and trousers (shirts worn outside of the trousers) , and cotton

sweat socks without shoes. The net insulating value of the clothing

ensemble, as computed by means of an electrically heated copper manikin, was 0.6 clo*, which has been generally accepted as the standard clothing

for thermal clothing studies.

Even though the results are available for men and women separately

and also for the votes taken at each half-hour interval for the entire 3

hours of exposure, the data shown in figure 3-3 is an average for the

votes of men and women taken together at the end of the 3 hours. One

should note the very slight dependence of comfort on relative humidity.

Studies such as these have led to the conclusion that temperature is far

more important than relative humidity at comfort conditions. It is

interesting to note that at the comfort condition (KSU=4) , a relative

humidity change of 13% is equivalent to a dry-bulb temperature change of

1° F. In specifying the comfortable operating conditions for a building,

one approach is to select bounds for the relative humidity (say between

20 and 60%) and KSU upper and lower bounds (say 3j£KSU< 5) . The cross- hatched region of figure 3-3 includes all the combinations of dry-bulb

temperatures and relative humidities that produce the above-defined

* clo represents a measured resistance to heat transfer of the

clothing ensemble of 0.88 ft^'h* F/Btu or equivalent of

an overall heat-transfer coefficient = 1.13 Btu/h* f tp- • °F.

3-8

1
o

CVJ

til a:3

£EW

CLs

111

CD

_J3

CD>

orQ

3-9

Figure

3

3.

Various

comfort

levels

shown

on

psychrometric

chart.
comfort conditions. The mechanical systems of some buildings presently

in use are designed to provide indoor humidity control within a rather

narrow range. Such systems expend considerable amounts of energy for

humidification and dehumidification processes. In many instances, these

mechanical systems can be modified so as to maintain indoor conditions

within the comfort range and at the same time reduce unnecessary humidification and dehumidification, thereby reducing heating and cooling

energy requirements.

3.1.5 Ventilation Air

Air circulation systems are provided in buildings to supply or remove

heat from a space, to provide outside air to remove odors and contaminants,

and to provide oxygen for occupants and combustion. It has been common practice to determine required air quantities for heating and cooling

spaces from the equation:

Q

= H/ (1 . 08 • AT) (2)

3 where Q

= air quantity, ft /min

H = heat removed (or added) to the space, Btu/h

AT = temperature difference between supply air and space air, °F.

The quantity of outside air introduced frequently has been based on

2 regulations that state requirements in cfm/ft , cfm/person, or air changes

per hour. Many of the regulations call for generous air quantities that

result in extravagant use of energy; some systems employ even more

excessive outside air quantities due to poor design, faulty installation,

or inattentive operation.

Significant energy savings can often be achieved by reducing outside

air quantities to recommended Air Force criteria levels given in

table 3-1. Also, large savings can be achieved by shutting down systems

completely when building is unoccupied. It must be noted that the interaction of related (and frequently interconnected) supply, return, makeup, and exhaust systems must be considered when systems are shut down

or dampers are closed or adjusted.
TABLE 3-1. OUTSIDE AIR VENTILATION STANDARDS [5].

Auditorium, Theater

Automotive Shop, Garages

Bowling Alleys (Personnel occupied space

only)

Chapel

Chapel Annex (Classroom)

Classrooms

Conference and Briefing Rms Cocktail Lounge

Data Processing and Electronic Equipment Room

Dining Hall, Messes, Clubs, Restaurant,

and Snack Bar

Dormitory, Officers Quarters

Flight Control Center Gymnasium

ACND Areas

Kitchens (Dining Hall and Hospital)

Medical Facilities Mechanical Equip Rm

Offices, Drafting Rm, Library

Ozalid Room

Paint Finishing Rm Paint Hangar, Paint Spray Booth

Parachute Wrapping and Storing

Security and Switchboard Rms

Shops, Aircraft Maintenance

Shops, Civil Engineering

Toilets and Locker Rooms

Shower Rooms

AIR COND MECH VENT

cfm/sf cfm

person Summercfm/sf

Winter cfm

person

5 6-12 5

15 5-10 15 NONE NONE 6

0.25 5-10 5

5 5-10 5

25 5-10 25

25

0.25 5-10

5 3-6

25

6 5

15

3

5 3 10'

3

2

5 3

5 4 103

5 6-12 5 6-12

2.0

2.5

REMARKS

See para 6-63 and 6-69

See chapter 20

See atch 12

See paras 6-65 and 6-82h

See section J

Total air supply to limit rm temp rise to 10° max

depending on satis equip

operation

Interior rooms only 1

Exhaust duct connected2

to equip, summer and

winter

See section H

Interior rooms only3

Required year-round

Required year-round

3-11
3.2 HVAC Equipment in Large Buildings

Energy consumption by HVAC equipment in large buildings can be

lowered by the following measures:

reducing energy consumption for fans;

reducing energy consumption for pumps;

reducing distribution system heat losses;

eliminating steam leaks;

eliminating unnecessary reheat;

flashing condensate into low-pressure steam;

increasing condensate return to boilers;

These measures are discussed in the following sections.

3.2.1 Reduce Energy Consumption for Fans

Implementing energy conservation methods which reduce heating

and/or cooling loads permits reduction of air volume handled by the

central HVAC system. Whenever the volume of air is reduced, the re- sistance to air flow in that section of the system is also reduced.

This occurs because the resistance of any system depends upon the

quantity of air circulated in the system as well as the characteristics

of the various portions of the system including:

intake and discharge louvers;

heating and cooling coils;

filters;

° apparatus casings;

ductwork system; and

registers, grilles, and diffusers.

The total resistance to air flow is the sum of the resistance of

the individual parts. Although straight lengths of duct generally offer

little or no opportunity for resistance reductions, the potential of

other items is substantial.

The resistance to air flow through filters is a function of filter

construction, type of media, area of media per unit volume (proportional

to actual velocity through the media, not face velocity) and the dirt

load at any given time. In general, resistance to air flow increases

with filter efficiency, although there are some high efficiency filters

which also have low resistance. To determine the "dirty" resistance

3-12
limit, contact the manufacturer of the particular filter. Consider installing a manometer across each filter bank to indicate when the filters

should be changed. If the building contains many air systems, consider the use of an alarm system to report filter conditions at a central point.

Many filters impose high resistance due to their inherent characteristics and/or because they exceed required filtration standards. Determine filtration requirements in terms of the ambient air conditions and

space air quality requirements. One of the current accepted methods for

determining air filtration efficiency is the ASHRAE Atmospheric Dust Spot

Efficiency Test Method [6], Check present filter installation to determine if an alternative type of filter will meet building needs at operating

costs sufficiently reduced to provide an economic payback.

Resistance to air flow through coils depends largely upon the number

of rows or depth required for adequate heat transfer. Cooling coils are usually many rows deep because of the small temperature differences between coil and air, and consequently offer a high resistance to air flow.

Heating coils which have a higher temperature difference are usually

fewer rows deep than cooling coils and impose less resistance to air

flow.

In some air handling systems the coils are placed in series and impose

combined resistance year-round, even though only one coil may be used at

any given time. Where the cooling medium is chilled water and the heating

medium is hot water, it may be possible to remove the heating coil and

repipe the cooling coil to provide both heating and cooling (though not

simultaneously). Eliminating the heating coil will reduce the system

resistance and thereby achieve reductions in fan horsepower. A side

benefit of using the cooling coil for both heating and cooling is that

the extra heat-transfer surface of the cooling coil provides opportunities to lower the hot-water temperatures and use low-grade waste

heat

3-13
In other installations, it may be possible to arrange the coils for

parallel flow. However, in all instances, consideration must be given

to the function of the coils, their operating limits and the danger of

freeze-up

Resistance to air flow caused by duct fittings on the inlet and

discharge side of fans can be reduced and fan performance significantly

increased by modifying the shape of the fittings (see Re f. [7] for

recommendations). Where space permits, modify abrupt chanaes in sections

of duct work where velocities exceed 2000 ft/min to lone taper-f ittines

and install turning vanes in square bends.

Supply and exhaust fans must operate at a pressure sufficient to

overcome the resistance to air flow through the ducts serving the outlet

farthest from the fan (index outlet) . When the index outlet is remote

from other parts of the system and is served by a long run of duct, it

imposes a power consumption penalty on the whole system. It is often

worthwhile to replace this section of duct with one of larger cross section and lower resistance.

To achieve correct volumes at each grille or register, dampers in

low resistance branches are adjusted until all branches are of resistance equal to the index run. Many systems when initially started have

dampers that are closed more than they need be, adding unnecessary

resistance. Also, it is common practice to reduce fan volume by closing

down dampers on the fan inlet or outlet rather than by reducing fan

speed.

Check whether these situations occur in the building and, if necessary, rebalance the system by first opening fully any dampers which are not used to proportion air flow between branches or outlets (main dampers

close to fan) . Identify the index outlet and fully open any dampers between this outlet and the fan. Measure the volume at the index outlet

and adjust branch dampers successively (starting with the next longest

run) until proportional volumes are achieved at each outlet. Each

damper adjustment will affect flow rates in branches already adjusted,

but two or three successive adjustments of the whole system will give

good balance.

3-14
Reducing the resistance to air flow in an existing system results

in an increase of air delivery which, in turn, permits a reduction in

fan speed to bring air volume down to the original level. In the case

of centrifugal fans (the type most commonly used) , the power input

varies directly with the cube of the speed. As such, any reduction in

speed, which is proportional to air volume, results in a substantial

decrease in power input.

The basic fan laws for centrifugal fans are:

volume varies directly with speed;

pressure varies directly with square of speed;

power input varies directly with cube of speed; and

volume varies directly with the square of pressure.

Reductions in the volume of air flow will provide three-fold reductions

in fan brake horsepower (BHP). Accordingly, if the volume of air in a system is reduced by 10% the reduction in fan BHP will be about 30%:

In summary, to reduce energy consumption of fans:

: reduce heating and cooling loads;

: reduce resistance to air flow, as is feasible, in each of the areas listed above;

: measure the resulting new air volume and determine the new air

volume required to meet new loads;

reduce fan speed as appropriate. Where motor sheave is adjustable, open the "v" to reduce its effective diameter and

adjust motor position or change belts to maintain proper

tension. If no further adjustment is possible, change motor

sheave. If the full load on the motor is less than 60% of

the nameplate rating, consider changing the motor to the next

smaller size.

When installing new motors:

match the phase and frequency with electrical distribution

system characteristics;

when motors cannot exactly match system voltage, use the

following criteria: — For motor loaded to under 75% of its capacity, select one having a voltage rating slightly more than system voltage.

3-15
— For motor loaded to more than 75% of its capacity,

select one having a voltage rating slightly under the

system voltage. Problems may arise if nameplate rating

of motor selected were to be in excess of system voltage

by more than 5%—a likely situation in these days of

brownout and voltage cutbacks.

Ascertain that motor has sufficient starting torque for the

fan. This caution applies to fans with large wheels having

considerable inertia.

Other measures to consider for reducing energy consumption of fans

include

Determine the tradeoff between raising supply air temperatures

during the cooling season to reduce refrigeration power and

lowering the temperature to decrease the volume of air to re- duce fan energy.

Reduce air volume and horsepower of existing variable air

volume systems; convert other systems to variable volume.

Seal off unused portions of exhaust hoods in kitchens and

cafeterias to reduce air volume and fan energy where it is

difficult or uneconomic to change fan speeds.

Eliminate preheat coils whenever possible without increasing

freezeup possibilities.

When the same system is used for both heating and cooling,

consider installing a control to reduce total air volume

during the heating season. More air is required during the

cooling cycle because of lower temperature differentials.

In large buildings where steam is available, consider turbinedriven fans with variable speed control.

In high-bay buildings, consider distribution systems that can reduce stratification. Stratification is undesirable, since

it increases heat loss from top portions of the zones of the

building during the winter.

3-16
3.2.2 Reduce Energy Consumption for Pumps

Pumps used to circulate hot water, chilled water and condenser

water are governed by basic laws similar to those for fans. Therefore,

a reduction in flow rate or in system resistance to flow results in

reduction in pumping power.

However, since water in hydronic systems is moved through closed

circuits, and the flow rate through the various elements may be varied

by means of throttling, mixing or by-pass valves, these systems are not

subject to the same balancing techniques as are air systems. Furthermore, most pumps for these systems are direct-driven by constant speed

motors. Therefore, one's ability to make adjustments for pumps, as can be done for fans, is sharply reduced.

But in view of the high potential for energy savings due to the

number of operating hours and to the frequency of overdesign to provide

safety margins, it is well worth while to consider a complete engineering analysis to determine if modifications to the system will pay off in

energy savings. One measure that can be tried in installations having

parallel pump systems is to reduce the number of pumps in operation at one time; even this operation demands careful analysis of its effect on

the performance of the system and its components.

3.2.3 Reduce Distribution System Heat Losses

Heat losses from boilers, steam and hot water piping can comprise

a sizable portion of the total energy consumed in a building.

In the case of exposed piping, examine insulation carefully.

Repair or replace damaged insulation and consider adding insulation to

that which already exists as well as installing it on pipes which cur- rently are bare. Table 3-2 indicates heat losses in pipes without

insulation and with varying amounts of insulation. Table 3-3 indicates

minimum recommended insulation for various different types of piping

systems

In the case of buried pipe, addition of insulation is a costly

procedure., even if possible. Usually it will be necessary to replace the

underground piping system. Heat loss can best be determined by measuring flow and temperature at inlet and outlet of buried runs. Grass

3-17
that is different in color along underground runs, or runs where snow

melts more quickly than in adjacent areas, often indicate underground

distribution systems with failing pipe insulation. Where there is a

considerable amount of buried pipe, the use of aerial surveys using

an infrared camera is an effective technique (see Chapter 5)

TABLE 3-2. HEAT LOSS FROM BARE AND INSULATED PIPE*

conditions: 250° F pipe temperature, 80° F ambient temperature,

calcium-silicate insulation

Pipe Bare Insulated pipe, Btu/ft«hr

Size pipe, __ Thickness of insulation. In

in Btu/ f

t • hr 1 2 3 4 5 6

1 262 35 26 27 19 17 17

2 456 53 36 29 25 23 21

3 657 72 46 36 32 28 26

4 833 87 55 43 36 32 29

6 1,202 125 75 56 46 40 35

8 1,543 158 92 69 55 48 43

10 1,902 192 108 80 66 56 50

12 2,246 215 125 93 75 64 57

*"The 1975 Energy Management Guidebook" published by Editors of

Power Magazine, McGraw Hill Inc., N.Y. , N.Y.1975.

3-18

1
TABLE 3-3. MINIMUM RECOMMENDED INSULATION FOR

VARIOUS PIPING SYSTEMS*

Types of Temperature Insulation thickness

In

piping systems range. Pipe :sizes, in.

°F Up tc> 2 2 1/2 to 4 Over 4

Heating systems

H-P steam'*' 306-400 3 4 4 1/2

2 M-P steam 251-305 2 3 3 1/2

3

L-P steam Up to 250 1 1/2 2 2 1/2

4 Condensate 190-220 1 1/2 2 2 1/2

Hot water Up to 200 1 1 1/2 2

Hot water Over 200 1 1/2 2 2 1/2

Cooling systems

Chilled water 40-60 1 1 1

Refrg. brine Below 32 1 1/2 1 1/2 1 1/2

1. High pressure

2. Medium pressure

3. Low pressure

4. For feed water

*"The 1975 Energy Management Guidebook" published by Editors of

Power Magazine, McGraw Hill Inc., N.Y. , N.Y.1975.

3-19
3.2.4

Eliminate Steam Leaks

As shown in table 3-4, steam leaks can be very costly. The entire

system should be inspected to determine if there are leaks. Malfunctioning steam traps are also a common source of losses.

TABLE 3-4. THE COST OF STEAM LEAKS IN A 125 psi SYSTEM AT $4/1,000 lb [8]

Size of Orifice

Steam Wasted

Per Month, lb

Total Cost

(Per Month)

Total Cost

(7 Months)

1/2 inch 708,750 $2,040 $14,280

3/4 inch 400,000 1,600 11,200

1/4 inch 178,000 712 5,000

1/8 inch 44,200 176 1,232

1/16 inch 11,200 45 315

1/32 inch 3,000 12 84

Note: For steam at 50 lb pressure, the waste is about

75% of the figures given; at 20 lb it is about

50%, and at 5 lb, the loss is about 25%.

Identify the location of a leaking trap by testing the temperature

of return lines with a surface pyrometer and measuring temperature drop across the suspected trap. Lack of drop indicates steam blow-through.

Excessive drop indicates the trap is holding back condensate. Repair

or replace all faulty traps.

3.2.5 Assess Energy Use for Humidification Processes

The mechanical systems of some buildings are designed to provide

indoor humidity control within a rather narrow range through the use

of reheat. Such systems expend considerable amounts of energy for

humdif ication and dehumidification processes. In many instances, adjustment of controls can be made to reduce reheat load without degrading the

indoor environment of the building. (Sec. 3.1.4)

3.2.6 Flash Condensate to Low-Pressure Steam

Where medium- and high-pressure condensate is vented to the atmosphere or discharged, a significant portion of its heat content can be

3-20
reclaimed by flashing that condensate so as to provide a source of lowpressure steam to be used for space heating or heating of domestic hot

water. The quantity of 15 psig steam that can be produced by a condensate flashing system is shown in figure 3-4. In addition to saving heat,

the flashing of condensate may reduce makeup boiler feed water.

0

l L !_

0 50 100 150 200

Inlet Condensate Pressure - psig

Figure 3-4. Flashing steam condensate (calculated

from steam tables)

3.2.7 Increase Condensate Return to Boilers

Loss of condensate represents a waste of heat and of valuable high

purity water. Identify all sources of condensate and evaluate economic

feasibility of installing pump and insulated piping to return condensate

to boiler feedwater tank. If condensate is contaminated, evaluate

possible clean-up. Repair leaking condensate return systems.

3-21
3.3 HVAC Equipment in Family Housing

3.3.1 Heating Plants

The portion of the input energy of a combustion heating plant that

is not delivered to the occupied space of a family housing unit is lost

through one of the following mechanisms:

jacket losses from the heating plant

° duct losses (or pipe losses)

° flue losses.

In the case of a forced-air electric furnace, losses occur by

way of jacket and duct losses. Energy conservation measures for improving the performance of heating plants should be aimed at reducing the

foregoing loss mechanisms.

Duct losses occur by way of air leakage at the seams where duct

sections are joined and by heat conduction through the ducts themselves.

Leaks in warm-air supply ducts may permit as much as 10% of the heating

energy to escape. Duct leaks may also cause the occupied space of residential buildings to be under either negative or positive pressure,

thereby substantially increasing the rate of air infiltration when the

furnace operates. The conductive heat-loss rate through uninsulated

O ducts located in unheated crawl spaces may be as much as 120 Btu/h’ft . 2 At this rate every 2.8 ft of duct surface would lose heat at a rate

equivalent to that for a 100-watt light bulb.

Air leaks from ducts are easily corrected by the application of a suitable duct sealant and/or duct tape at the seams where the duct

sections are joined. Conductive heat-losses from ducts located in un- heated spaces may be substantially reduced by installing thermal insulation around the ducts. Similarly, the heat loss from pipes located

in unheated spaces may be reduced by installing pipe insulation.

Losses up the flue or chimney may be reduced by lowering the mean

temperature of the stack gases and by improving the combustion efficiency

that occurs in the combustion chamber. A burner tune-up will frequently

improve combustion efficiency. When the heat output rate of the furnace

is too large for the heating load of the living space, the burner and fan

3-22
will cycle on-off quite frequently. During the off portion of the fan

cycle, heat stored in the heat exchanger is lost up the flue. This loss

may be reduced by reducing the firing rate of the burner and adjusting

the fan controls to cut in and cut out at lower temperatures. In addition,

an automatic damper may be installed in the chimney which closes when the

burner is not operating, thereby reducing the stack losses substantially.

3.3.2 Central Air Conditioning Equipment

Energy waste occurs when a central air-conditioning system is installed on an existing furnace system which has insufficient blower

capacity. An evaporator coil introduces a considerable pressure drop

and may substantially reduce the air-delivery rate of an existing

furnace blower. Furthermore, the evaporator requires a certain air flow

rate passing through it in order to obtain proper air-side convective

heat transfer. Measure the delivered air quantity and compare with that

required for the evaporator that is installed (usually 350-400 cfm/ ton

for unitary residential equipment). For belt-driven blowers, it may be

possible to increase the air-delivery rate by installing a larger pulley

on the motor shaft. For such modification, it is very important to

monitor the current supplied to the blower motor to make sure that it

remains below the maximum rated value for the motor. If increasing the

pulley size is unable to produce a sufficient air-delivery rate, then a larger size blower/motor system should be installed.

Low air conditioning performance can also be caused by improper

installation of the evaporator. It should be installed so that all the

air is forced to pass through the evaporator. If it has small gaps

around its perimeter, significant quantities of air may leak around the

evaporator instead of passing through it. This situation would result

in low suction temperature of the refrigerant line leaving the evaporator.

With regard to the outdoor condenser units, make sure that the airflow passages of the unit are not obstructed (by vegetation or inadvertently placed objects) or improperly enclosed. Also, note whether solar

radiation strikes the outdoor unit during a significant portion of the

day. Some improvement in air conditioning performance can often be

achieved by simply shading the outdoor unit.

3-23
Also, note the location of the indoor thermostat. A thermostat

placed at an unusually hot location of a building may cause overcooling

of other parts of the building, which will cause energy waste.

Another way in which energy waste may occur is for an air-conditioning system to be installed so that it uses a part of the building as a return plenum. In such instances, significant energy waste will occur

if the return plenum communicates through leaks to hot spaces such as attics, crawl spaces, and the outdoors. Warm air drawn from such spaces

not only introduces sensible heat, but also introduces moisture-laden air

which represents an increased latent load for the air-conditioning system.

After the installation of an air-conditioning equipment has been

examined, inspect the ducts for air leaks. Duct leaks may represent a significant energy waste. Serious duct leaks can usually be detected by

feeling with the fingers around the seams where duct sections are joined

together. These duct leaks can readily be eliminated by the application

of a suitable duct sealant and/or duct tape.

Consideration should also be given to insulating ducts, particularly

if the supply ducts pass through hot attic spaces. Procedures for estimating the optimum amounts of insulation for ducts located in attics and

other unheated spaces (such as crawl spaces) is presented in Chapter 2.

Routine preventive maintenance should be established, with the

following items included as part of the maintenance program, performed

prior to the air-conditioning season:

clean air filters

check the refrigerant charge of the system

oil all moving parts

check the overall operating condition of the system.

3.3.3 Summary of Energy Conservation Measures for HVAC Equipment in

Family Housing

Heating Plants

(1) Seal duct leaks with a suitable duct sealant and/or duct tape

and insulate supply air ducts that pass through unheated spaces.

(2) If the heating plant is located within the living unit, con- sider providing outdoor makeup air for combustion-air and draft-diverterair requirements.

3-24

1
(3) Consider installing a clock thermostat for reducing indoor

temperature at night.

(4) If an oversized furnace was originally installed or if the

implementation of energy conservation measures has caused the maximum

heating load to be considerably reduced, consider reducing the firing

rate of the fuel burner.

(5) Implement a pre-heating season preventive maintenance schedule

which includes: a burner tune-up and cleaning and replacement of air

filters.

(6) Make sure the thermostat and controls are operating properly

to preclude overheating.

(7) If a part of the building serves as a return plenum for the

heating plant, make sure that cold air from unheated spaces is not inadvertently drawn into the air return.

Cooling Plants

(1) Correct improper installations such as Evaporator which permits air to flow around the eva- porator instead of through it.

Under-capacity blower that cannot provide sufficient air

volume through the evaporator.

(2) Take corrective action to free inadvertently obstructed air

passages of the condenser unit.

(3) Consider shading the condenser unit to reduce solar heat gain.

(4) Turn off air-conditioning system when the building is unoccupied.

(5) Seal duct leaks with a suitable duct sealant and/or duct tape.

(6) Insulate supply air ducts located in the attic.

3 . 4 Domestic Hot Water*

3.4.1 Background

Average Usage

Hot water utilization factors (expressed in gallons of hot water consumed per person per day) for various type buildings are given in

table 3-5.

* Much of this material of this section was taken from "Guidelines for

Saving Energy in Existing Buildings," ECM 1 [8].

3-25
TABLE 3-5. HOT WATER UTILIZATION FACTORS (F) [8]

Office Buildings

(Without kitchen or cafeteria services). . . . 2 to 3 gallons per capita per day for

hand washing and minor cleaning (based

on an average permanent occupancy which

includes daily visitors)

Base Exchanges

(Without kitchen or cafeteria services). . . .1 gallon per customer per day

Food Serving Facilities

Dishwashing, rinsing

and hand washing 3 gallons per meal plus 3 gallons/

employee/ day

Schools

Boarding 25 gallons per capita per day

Day 3 gallons per capita per day (Does not

include cafeteria or athletic facilities)

Dormitories and VOQ’s. . .20 to 30 gallons per capita per day

Hospitals 30 to 50 gallons per capita per day

Average Temperature

The usual temperature at which hot water is supplied varies from

120° F to 150° F. It usually is too hot to be used directly and must be

mixed with cold water at the tap. For dishwashing and sterilization

the delivery temperature is generally 160° F or higher. Often hot water

supplied to all faucets is at temperature required for the kitchen. Hot

water, generated and stored in tanks at 150° to 160° F, loses heat by

conduction and radiation from the tank and piping, even before the

delivery

When hot water is supplied by a tankless heater, it may be within

5° or 6° F of the boiler water (or steam) temperature maintained to heat

the building. A mixing valve is often used to control the delivery temperature, but frequently the temperature at which it is set is excessive.

3-26
Energy Conservation Measures

The opportunities to conserve energy for heating domestic hot

water can be summarized as follows:

(1) Reduce the load

decrease the quantity of domestic hot water used

lower the temperature of the domestic hot water

(2) Reduce the system losses

repair leaks and insulate piping and tanks

reduce recirculating pump operating time

(3) Decrease the losses from domestic hot water generators

(4) Utilize waste heat to temper the cold water supply to heaters

and, where feasible, to generate hot water.

3.4.2 Reduce the Temperature of Domestic Hot Water Supplied to Taps

Lowering the temperature of hot water can reduce both the domestic

hot water load, and the distribution losses. The annual domestic hot

water load (Q) , not including distribution losses, is given by the

relation:

Q

= 8.3-F-N -N *C • (T -T ) (3) o d p s g

pounds of water per gallon

water utilization factor, gal per person per day (see

table 3-5)

number of building occupants

number of days per year that the building is occupied

specific heat of water, Btu/lb*°F; use 1 . 00

temperature at which water is supplied to the tap, °p

temperature at which water is supplied to water heater

(approximately equal to annual average ground water

temperature) , °F.

A chart for estimating annual hot water heating load is given in

figure 3-5. In this chart annual hot water heating load per capita

(Q/N^) is plotted as a function of water utilization factor (F) for

wher e 8.3

F

N =

o N

d -

C =

P T =

T =

3-27
ANNUAL

HOT

WATER

HEATING

LOAD,

10

Btu/person-year

HOT WATER UTILIZATION FACTOR, gal /person -day

Figure 3-5. Chart for estimating annual hot water heating load.

3-28

1
various temperature heating increments (T - T ) . To find the annual

s g

hot water heating load, find the appropriate utilization factor (F)

(from table 3-5) on the horizontal axis. Draw a line vertically upward

until it intercepts the appropriate temperature heating increment

(T - T ) curve. The annual hot water heating load per capita (Q/N ) s g o is found by reading horizontally across to the vertical axis.

From equation (3) the percentage reduction in the hot water heating

load (AQ/Q) achieved by lowering the hot water supply temperature is seen to be

AQ/Q = AT / (T - T ) (4)

s s g

Here AT^ is the reduction in the hot-water supply temperature. The

foregoing technique for calculating reductions in hot water heating

load is conservative, since it does not include the reduction in distribution losses that also occur when the hot-water supply temperature is

reduced. However, it is also subject to some over estimation since for some usages (baths, showers, etc.) the user will tend to draw more hot

water in order to obtain desired temperature.

The annual energy consumed by a fuel-fired hot-water heating device

is equal to the annual hot-water heating load divided by the efficiency

of the hot-water heater. Efficiency factors for several hot-water heating

plants are given in table 3-6.

3-29
TABLE 3-6. EFFICIENCIES FOR SEVERAL HOT-WATER HEATING PLANTS [8]

Oil-fired heating boilers used year round, but with

domestic hot water as the only summer load. .45

Oil-fired heating boilers used year round, but with a summer load such as absorption cooling in addition to

domestic hot water. .70

Gas-fired heating boilers used year round, but with

domestic hot water as the only summer load. .50

Gas-fired heating boilers used year round, but with a summer load such as absorption cooling in addition

to domestic hot water. .75

Separate oil-fired domestic water heaters. .70

Separate gas-fired homestic water heaters. .75

Separate electric water heaters. . 95

Separate coal-fired water heaters. .45

Consider the following examples:

An office building has 500 occupants for 250 days per year. The

hot-water supply temperature is 130° F and enters the heater at 60° F

(an average for the year) . Domestic hot water is used year round with

domestic hot water as the only summer load. The fuel is #2 oil, which

has a heating value of 138,000 Btu's per gallon. Find the gallons of

fuel oil saved by reducing the hot-water supply temperature to 100° F.

(1) From table 3-5, the hot-water utilization factor (F) ranges

between 2 and 3 gallons per person per day. For this example, take it

to be 3 gallons per person per day.

(2) From figure 3-5, the annual hot-water heating load for 3 gallons of hot-water supplied at 130° F (or T^ - T^ = 70° F) is

430,000 Btu per occupant per year. For 500 occupants, the annual hotwater heating load is 215,000,000 Btu per year. The required quantity

of fuel oil is

215,000,000 Btu

(0.45) (138,000 Btu/ gal)

where 0.45 is water heater efficiency.

3,500 gallons

3-30
(3) Repeating the procedure of (2) for a hot-water supply temperature of 100° F, the required quantity of fuel oil is found to be 2,000

gallons.

(4) The savings in fuel oil is seen to be 1,500 gallons. At $.36

per gallon, this fuel saving represents $540 per year.

3.4.3 Reduce the Quantity of Domestic Hot Water Used

From equation ( 3) » it is seen that the percentage reduction in

hot-water heating load (AQ/Q) due to reduced consumption is given by

the relation:

AQ/Q = AF/F (4)

Here AF is the reduction in the hot-water utilization factor. A

secondary benefit is that less water need be handled in the watersupply treatment and sewage-treatment plants, whether on-Base or off-Base.

For the preceding example, calculate the reduction in hot-water

heating energy achieved by installing flow-reducing devices only in

the lavatory faucets to reduce the water -utilizat ion factor (F) from

3 to 2 gallons per person per day. The percent reduction in hotwater heating energy is

AQ/Q = AF/F = 1/3 = 0.33

The reduction in hot-water-heating energy is found by multiplying

the original hot-water-heating energy requirement by the foregoing

reduction factor (AQ/Q), or

Fuel oil saved = (3,500) (0.33) = 1,170 gallons

3.4.4 Improve the Efficiency of the Storage and Distribution Systems

Repair or replace damaged insulation to reduce heat loss. Heat

losses from uninsulated hot water distribution systems can be substantially dependent upon the temperature differential between pipe and

ambient air and the amount of exposed piping.

3-31
Exposed piping in basements and equipment rooms is relatively

simple to insulate. Piping in ceiling spaces may also be accessible

by removing ceiling panels. Preferably, the entire piping system

should be insulated, but inaccessible portions may be left bare providing they are a small percentage of the total.

The loss of heat from storage type heaters, storage tanks, and

external heaters must be offset by the addition of heat to maintain a ready supply of hot water. This heat loss occurs 24 hours a day whether

the building is occupied or not. Storage tanks and external heaters

should be covered with a minimum of 3 inches of insulation (thermal

resistance, R = 10). Insulate bare tanks and apply additional insulation to tanks having less than 3 inches. Storage type heaters with

factory insulated jackets can be covered with an additional layer of

insulation. This insulation may consist of ordinary insulating blanket

material, or insulation jackets ready-cut and available from material

suppliers; in any event, it is likely to pay out in a few years.

3.4.5 Generate Hot Water More Efficiently

All of the measures for improving combustion units for space heating apply equally well to hot-water heaters. Keep in mind that when

more than one heater is installed on a project, it is more efficient to

operate a single unit for the total load (if it can carry it), rather

than to operate more than one unit at partial loads. When existing

water heating equipment is replaced, consider the use of modular units.

3.4.6 Replace Central Systems by Local Heating Units

Commercial hot-water systems frequently require hot water for short

periods of heavy use at various locations within the building. It is

often more efficient to provide water heaters close to the usage points

instead of using central units having long runs of hot-water piping.

Analyze the hot water use within the building to determine the

patterns of demand to determine whether installation of local units

is advantageous. Estimate the energy losses of the existing system

and calculate the savings derived by installing local units.

3-32
3.4.7 Install Temperature Boosters

When multiple temperature requirements are met by a central domestic

hot-water system, the generation temperature is determined by the maximum usage temperature. Lower temperatures for other usages are attained

by mixing hot water with cold water at the tap. Where most of the hot

water usage is at the lower temperatures and only a few specific locations require high temperature hot water, consider installing booster

heaters in the hot-water lines serving these locations.

3.4.8 Install Separate Boilers for Summer Generation of Domestic Hot Water

In many buildings, the space heating system boilers also provide

heat for the domestic hot water system. While this is satisfactory during

the heating season when the boiler is firing at high-efficiency, demand

for boiler heat in summer may be limited to hot-water generation only.

Operating large boilers at low part-loads results in low boiler

ef f iciency

To reduce energy losses due to low boiler efficiency in summer,

install a separate hot-water heater or boiler, sized for the hot-water

demand. Shut down the space heating boiler in the summer and generate

hot water at improved efficiency.

3.4.9 Waste-Heat Recovery for Hot-Water Heating

(1) Hot-Gas Heat Exchanger

A typical refrigeration machine with a water-cooled condenser

rejects approximately 15,000 Btu/h for each 12,000 Btu/h of refrigeration. An air-cooled condenser rejects up to 17,000 Btu/h. Up to one third of the heat rejected from either system can be recaptured.

To recover heat of compression, install a heat exchanger in the hot-gas

line between the compressor and condenser of the chiller. Such a waste-heat recovery system would be applicable to most Base commissary

facilities. A typical arrangement in conjunction with a domestic hotwater system is shown in figure 3-6. Hot-gas temperature depends on head pressure but is usually on the order of 120° to 130° F.

3-33
DOMESTIC HOT WATER

PUMP

Figure 3-6. Schematic of hot-gas heat exchanger heat-recovery system.

(2) Hot-Drain Heat Exchanger

Buildings with kitchens, laundries, and other service facilities

which utilize large quantities of hot water, in many cases discharge hot

waste water to drains. By installing a heat exchanger, heat can be

recaptured for use to preheat domestic hot water. One type of heat

reclamation system is shown schematically in figure 3-7.

In general, special equipment to preheat water from 50° F to

105° F will often be cost effective. The hot water at 105° F can then

be fed into the domestic hot-water tank for further heating to utilization

temperature, if required. The heat-reclamation system saves the heat

required to heat water from 50° F to 105° F which otherwise would have

been provided by other heat sources. For example, in a laundromat, the average daily wash load is

2,000 lbs/day. Water usage is 2.5 gallons of 170° F water and 1.0

gallon of 50° F water per lb of wash load. The waste water discharged

to drain is 3.5 gallons of 136° F water per lb of wash load.

3-34
Assuming that the laundromat operates 365 days/yr and that domestic

hot water is generated by an electric hot-water heater, the yearly

saving is 833 x 10 Btu. At 90% efficiency and $.03 kWh, this represents $8,130 cost saving/year.

Heat Recovered

Heat

Exchanger

Figure 3-7. Schematic of laundry and kitchen hot-water

heat-recovery system.

(3) Hot-Condensate Heat Exchanger

The condensate return portion of many steam systems exhausts large

quantities of heat in the form of flash steam when the hot condensate

is reduced to atmospheric pressure in the condensate receiver. Recover

waste heat by installing a heat exchanger in the condensate-return main

ahead of the receiver to reduce condensate temperature to approximately

180° F. Use the heat recovered to preheat water as required.

Figure 3-8 shows the schematic installation of a condensate heat

exchanger

The quantity of heat recovered depends on the quantity and temperature of the condensate. Consider the following example:

Example

Condensate return volume is equal to 6 gpm at 260° F. A heat ex- changer is installed to reduce the condensate temperature from

260° F to 180° F and the quantity of heat recovered is:

Q

= 6.(260 - 180). 500 = 240,000 Btu/h

where 500 converts gpm to pounds per hour.

3-35
In each case, the feasibility of a waste heat recovery system depends upon being able to use the recovered heat; i.e., there must be a need for the domestic hot water that is generated.

DOMESTIC HOT WATER

Figure 3-8. Waste-heat recovery using a hot-condensate heat exchanger.

3 . 5 Lighting* 3.5.1 Background

Electrical energy used for lighting accounts for a significant

portion of the total energy usage in Air Force buildings. When lights

are left on in areas which are unoccupied or unused for lengthy periods

of the week (i.e., religious buildings and outdoor parking lots), the

inadvertent waste of energy often approaches or exceeds the amount of

energy used by other building systems during the week; the cost of this

waste for one year may equal the initial cost of installing automatic

controls to eliminate it.

* Much of this material was taken from "Guidelines for Saving Energy

in Existing Buildings," Building Owners and Operators Manual, ECM 1

[ 8 ].

3-36
Electric lighting is also the major contributor to internal heat

gain in Base exchanges and commissaries, and core areas of office

buildings. Since it increases the cooling load, electric lighting

causes additional energy expenditure to operate the refrigeration

system; it would not be unusual for an air conditioning system to expend up to 2 kWh of electrical power to remove the heat resulting from

3 kWh of electric lighting.

Significant reductions in energy consumption for lighting can be

attained from the following measures:

Conserve energy by turning off lights;

Improve the effectiveness of existing lighting installations;

Use daylight for illumination;

Add switches and timers to shut off lights;

Remove unnecessary lamps;

Reduce lighting loads by relamping;

Reduce illumination levels.

These items are discussed in the following sections.

3.5.2 Conserve Energy by Turning Off Lights

Letting a light burn rather than turning it off does not save electrical energy. When electric lighting is not required, it should be

switched off. Figure 3-9 illustrates the energy savings achieved by

turning off lights during unoccupied periods for an office lighting

system of 1,000 fluorescent luminaires.

The full- system uses 92 kW. The upper graph shows typical usage

when lights are permitted to burn continuously from about 8:30 a.m. to

7:30 p.m. The lower graph shows efficient use of the same system

leaving lights on only when used. The energy saving amounts to 267.5

kWh daily or 5,875 kWh per month. At $.03 per kWh, this figure corresponds to a savings of $176 per month.

3.5.3 Improve the Effectiveness of Existing Lighting Installations

Increase the effectiveness of the present lighting system, then re- duce the number or wattage of lamps required to produce the required

illumination. In order to reduce the number and/or wattage of lamps,

consider the following measures to increase the maintained foot-candles

provided by existing lamps and fixtures:

3-37
12

time of day

lights left on

lights turned

off when not

required

normal working

hours end

office opens

Figure 3-9. Demonstration of energy saving achieved by

turning off light during unoccupied periods [8],

3-38
Improve the lumens of output by regularly cleaning fixtures and

lamps and instituting a relamping program. Clean fixtures at least

every time they are relamped. (When relamping and cleaning are

combined, the additional labor is very small.) In extremely dirty

atmospheres, clean fixtures between lamp replacements, as well.

Clean the lenses and interior housings. Use an anti-static compound

to reduce electrostatic dirt collection.

A group relamping program will produce a higher level of maintained

foot-candles, because lamp lumens will not depreciate to low levels

at the end of their lives. The effect of dirt on the output lumens

as a function of time is shown in figure 3-10.

When there are not critical reading or writing tasks, and where

some glare from exposed lamps is acceptable, illumination levels may be

increased by removing louvers or lenses from fixtures. Consider this

suggestion, for instance, in corridors, storage areas, spaces with

high ceilings, equipment rooms, and snack bars. In many instances,

this may permit a reduction in the number of lamps used.

Increase the reflectance of ceilings, walls, and floors by

cleaning or by painting with colors of higher reflectances: more illumination on tasks, with the same lumen output, will result.

Increasing the reflectivity of the interior surfaces may open the

possibility of reducing the number of lamps and luminaires while

maintaining recommended lighting levels. Greater reflectances

enhance the performance of natural daylight as well as artificial

lighting. For example, a 25 x 25-foot room with a 9-foot ceiling and

a ceiling reflectance of 80%, wall reflectance of 70%, and floor

reflectance of 30% will provide 35% more foot-candles (with no increase

in power consumption) than the same room with a ceiling reflectance

of 50%, wall reflectances of 30%, and floor reflectance of 10%.

Caution: High gloss finishes may reduce visual comfort by increasing

glare. Discretion should be used when redecorating.

3-39
months

Figure 3-10. The effect of dirt on output lumens as a function of time [8].

3-40
3.5.4 Use Daylight for Illumination

Use windows effectively as a primary source of illumination in

perimeter spaces. The amount of available daylight in a building is a function of operating hours, latitude, weather, time of year, air

quality, window size and location, shading and glazing details, re- flectivity of interior surfaces and furnishings. Control of natural

light, for effective use and integration with artificial light, is

important, because the amount of natural light available varies.

Control may be manual or automatic. Often blinds or drapes, which

should be closed only for short periods of excessive sunshine or glare, remain closed all day with the electric lights turned on, when

daylight could be used. Emphasis should be placed on proper control

of daylight; otherwise the heat gain imposed on the cooling system

may outweigh savings in energy for lighting. Indirect daylighting,

however, generates less heat per lumen of light than electrical lighting.

The luminous efficiency (lumens per watt) of various light sources

as compared to daylight is shown below (no allowance for ballast of

luminaires)

Low Pressure Sodium 183 lumens/watt

Natural Light 120 lumens/watt (varies)

High Pressure Sodium 105-120 lumens/watt

Metal Halide 85-100 lumens/watt

Fluorescent 67-91 lumens/watt

Mercury vapor 56-63 lumens/watt

Incandescent 17-22 lumens/watt

3-41
3.5.5 Add Switching and Timers to Shut Off Lights

If there are insufficient switches for unwanted lights to be

turned off, consider installing additional switches.

There are many types of surface-mounted flat ribbon conductors

available for installation in existing spaces; they can be installed

with the minimum dislocation of existing wiring or damage to interior

decorations. Locate new switches near doors or where they are most

convenient for use: switches in inconvenient locations will not be

used. If switches are group-mounted, label each one to indicate the

area it controls.

Provide time switches for areas which are commonly used for short

times, and in which lighting is inadvertently but frequently left on

(i.e., reference rooms and stock rooms). At a pre-determined time

after the switch has been turned on, it will automatically shut off; if

the area is to be used for a long period of time, the switch can be

manually overridden.

To ensure the success of any switching program, instruct all

occupants in the use of available switching.

3.5.6 Remove Unnecessary Lamps

Remove unnecessary lamps when those remaining can provide the

desired level of illumination. When removing fluorescent or highintensity-discharge lamps, also remove the ballast (or disconnect it

in place). If it is left connected to the power source, it will

continue to consume energy even though it serves no useful purpose.

When two-lamp fluorescent fixtures are mounted in a row, remove lamps

in alternate fixtures of the rows (rather than removing one entire

row) to derive higher quality lighting. In order to maintain the

recommended lighting level it may be necessary, after removing some

lamps, to use increased output lamps in place of some of the remaining

lamps. Even so, the measure should result in net savings of energy.

In many cases it will be possible to relamp the remaining fixtures

with more efficient lamps to provide more lumens per watt. Refer

to figure 3-11 to determine resulting foot-candle output with some common lamp replacements.
3-43
Lamp efficiencies vary between lamps consuming the same number of

watts and lamps of the same type. Different colors, shapes, gaseous

fills, cathode construction and internal coatings cause those variations. For example, a fluorescent 40-watt, T-12 lamp, rated 430

milliamperes, can have a rating from around 53 lumens to around 92

lumens per watt. Or, for example, a natural white fluorescent lamp at

2100 lumens (53 lumens/watt) provides 1/3 less foot-candles than cool

white fluorescent lamps at 3200 lumens (80 lumens/watt). In some cases,

it may be desirable to relamp with lower wattage lamps instead of

removing lamps.

An example of energy and money saved by removing two lamps from

every other fixture (and disconnecting ballasts) is given below:

ExampleBuilding Type - Base Exchange

Number and type of fixtures (4-40W) 2' x 4’

Floor area

Illumination level before change

Hours of operation per year

Watts saved by the change = 80W x

375

375

24.000 ft

2

100 FC

3720 hours

15.000 W

55,800 kWh „ ,/ 15,000W , Energy saved/year = y

x 3720 hours =

At an electricity cost of 4c/kWh, dollar savings =55,800 x .04

=$2,232

Additional savings in energy for cooling, due to reduced heat gain

from lighting, will compensate for loss of heat from lighting which

occurs in the winter.

3.5.7 Reduce Lighting Loads by Relamping

Efficiency of lamps is measured in lumens or usable light produced

per watt input. Selecting lamps with higher lumens per watt could permit the removal of some lamps, providing the lumens produce the required

foot- candles . More efficient lamps also impose smaller heat loads on

the air-conditioning system. In winter, any heat loss by the reduction

in wattage can generally be supplied more efficiently by the heating

system itself.

3-44
For certain type installations where the type of fixture and the

usage is identical, it is desirable to adopt a group relamping program,

so that when a majority of the fluorescent tubes reach the point of only

70% of their rated output they will be replaced. Labor costs are generally less for group relamping than for individual relamping throughout the year.

When relamping, it is important to select replacement lamps which

produce illumination suitable for the space. For instance, using high

intensity discharge lamps in an office space with a low ceiling may

produce glare and shadow which will cause eyestrain. Recommended

applications for various types of lamps are given in table 3-7.

TABLE 3-7. ENERGY CONSERVING LAMP APPLICATIONS [8].

Lamp Type Applications

Incandescent 1 . Short time uses such as decorative

display lighting or out-of-doors

(Christmas trees)

2. Religious worship halls.

3. In projection lamps for illuminating work

closets or other very confined spaces.

4. Stage spotlighting.

5. Where small light source are required to

light the task.

Fluorescent 1 . Offices and other relatively low ceiling

applications.

2. Flashing advertising signs.

3. Service islands at service stations.

4. Display cases in stores.

5. Desk lamps.

6. Classrooms or training centers.

7. Cafeterias (with color correction)

High Intensity 1 . Stores and other relatively high ceiling

Discharge applications

2. Auditoriums

3. Outdoor area lighting.

4. Outdoor floor lighting.

5. Outdoor building security lighting.

6. Marking of obstructions.

7. High bay work areas.

8. Hangars

3-45
High- intensity discharge (HID) lamps are more efficient (i.e. , they

produce more illumination per watt input) than many other types of lamps.

Therefore, substantial reductions in lighting energy can often be achieved

by converting existing lighting systems to HID systems.

There are three types of HID lamps available: mercury vapor, metal

halide and high-pressure sodium lamps. For each type there are several

sizes, wattages and bulb shapes available.

The HID lamps provide satisfactory and efficient illumination

systems for various applications such as industrial facilities (shops),

auditoriums, street lighting, gymnasiums, warehouses and some commercial

interiors. Recent information indicates lighting fixture manufacturers

have developed high-pressure sodium lamp luminaires for administrative

and classroom areas. For this type installation, detailed information on luminaire efficiency, light distribution and visual comfort index

is still under study.

Selection of a satisfactory HID lighting system for a particular

application depends on the characteristics of each type of lamp, such

as wattage, size, color quality and the light utilization of the luminaire specified. The design of the lighting systems should conform to

the recommended standards for quality of illumination, light distribution, shadows, source brightness and visual comfort of the Illuminating

Engineering Society.

Caution: HID lighting systems which are not properly designed may

produce shadow and glare, particularly for low-ceiling applications.

3.5.8 Reduce Illumination Levels

Energy consumption for lighting may sometimes be lowered by reducing

illumination levels to the following Air Force criteria values:

Illumination level,

Description of Space Foot-candles

work stations 50

work areas 30

non-working areas 10

3-46
If several tasks requiring different levels of illumination occur within the same space, first consider their visual requirements and then

modify maintenance procedures, redecorate the area, and implement changes

to the lighting system while reducing illumination levels to the appropriate level for each task. A uniform modular lighting pattern of general

illumination, throwing light equally on all areas regardless of task,

may waste up to 50% of the energy used for lighting in the building.

Orient lighting to suit the tasks to be performed or rearrange work

areas (furniture, etc.) to best utilize the lighting system in place.

Lighting in existing administrative open -space offices usually consists of long rows of fluorescent fixtures which provide a uniform lighting pattern in the building. This system of lighting is often inefficient since it provides over-illumination of some areas and insufficient

light in others. One solution to this situation is "task lighting."

The "Federal Design Matters" Pamphlet, Issue No. 5, October 1975, reported

that "task lighting" reduces the total energy requirement for lighting

and air-conditioning by 30 percent. Additionally, the pamphlet reports

"task lighting" speeds and lowers the cost of construction, alterations

and maintenance, as well as improving acoustics and fire protection, and

helps staff members to focus on their work.

Light levels in standard foot-candles can be determined with a illumination meter such as a photovoltaic cell connected to a meter

calibrated in foot-candles (i.e., foot-candle meter). These instruments

may be of an inexpensive type, portable, easy to use and suitable to

provide information for preliminary assessment of illumination levels.

Further information on energy conservation techniques relating to

lighting may be found in ref er ences [ 8 , 9 ]

3 . 6 Central Plants

The purpose of this section is to provide technical information

on ways of improving the efficiency of central steam, high-temperature

water (HTW) , and chilled-water generating plants.

3-47
In reviewing the material of this section, recognize that not all

modifications are applicable to all systems. In addition, many of

these modifications involve substantial expense and the possibility of

service interruptions. Accordingly, feasibility studies should be

conducted as necessary to consider the following factors:

effect of modification on other components of the system and on other systems;

impact on environmental conditions and related impact on comfort, productivity, safety, and health;

existing restrictions in terms of environment, zoning, building/

fire requirements;

cost of removing existing system or components, modifying space,

design, installation (including equipment, materials and labor),

salvage value of components removed;

energy consumption and cost without modification;

problems to be expected during installation and start-up.

Although the costs of these modifications generally are high, the amount

of energy and energy dollars to be conserved also will be high, thereby

making modifications justified in many cases. Recognize too that some substantial savings can be obtained with very little investment.

It also should be noted that no substantial modification should be

made before the operating and maintenance practices associated with

existing equipment are optimized to their fullest extent. To evaluate

a system based on poor operating and maintenance practices does not

provide an accurate base for determining its true efficiency. In fact,

the importance of proper operating and maintenance practices cannot be

overemphasized. Not only do they help ensure maximum energy efficiency,

but they also serve to ensure optimum system performance and response

to environmental and related needs, reduced breakdowns and associated

problems, and longer life for all equipment.

3-48
3.6.1 Steam and HTW Generating Plants

Boiler plants at U.S. Air Force installations include, among

others, high-pressure steam plants; high-pressure and low-pressure steam

heating plants, and high-temperature hot-water (HTW) plants.

In many steam and HTW generating plants, inefficient equipment design and non-optimal operating practice cause substantial energy waste.

Fortunately, some types of energy waste can be easily detected and

corrected by improved operation and minimum investment. Various energy

conservation measures for improving the efficiency of central heat

plants are discussed in the sections below.

3. 6. 1.1 Limit Flue-Gas Losses

High flue-gas temperature in central heat plants is one of the major

indicators of fuel waste. When natural gas is the fuel, the loss with a

3 flue gas temperature of 1000° F is equivalent to 179 ft of gas for

3 each 1000 ft of gas burned. If the flue-gas temperature is reduced

3 3

to 500° F, 81 ft of gas are saved for each 1000 ft of gas burned.

Substantial energy saving can be realized by reclaiming a portion of

the heat content of the flue gases for pre-heating combustion air and

"boiler feed water.

A boiler stack economizer, as shown in figure 3-12, consists of a heat exchanger placed inside the exhaust stack for the purpose of

preheating boiler feed water. Heat captured from the exhaust gases

increases the temperature of the feed water which is returned to the

boiler. In past years this technique was limited to systems using

low or nonsulphur content fuels to avoid build-up caused when the

economizer cooled the exhaust gases to the sulphur dew point. This

problem can be overcome by controlling the volume of feed water passing through the transfer coils. As a general rule, when an economizer

is installed to preheat boiler feed water, every 10 to 11° F increase

in feed-water temperature produces approximately a 1% increase in

boiler efficiency.

Preheating primary and secondary air also increases boiler efficiency by reducing the cooling effect when the air enters the combustion

chamber, As shown in figure 3-13, a 100° F increase in the temperature

3-49
A sensor constantly monitors the downstream stack temperature.

This data is relayed to the controller which activates a 3-way valve to regulate water flow through the heat

Figure 3-12. Schematic of a boiler stack economizer with

stack temperature controls.

3-50
GROSS

HEATING

VALUE

SAVED,

PERCENT

-2000

0 250 5 00 7 50 1000

TEMPERATURE OF PREHEATED AIR

ENTERING FURNACE, F

250

Figure 3-13. Fuel savings resulting from use of

preheated combustion air [10].

3-51

FURNACE

OPERATING

TEMPERATURE,

F
of the combustion air entering the boiler produces approximately a 2% reduction in boiler loss for natural gas and light oil.

Combustion air can be preheated up to 350° F for stoker-fired coal

oil, and gas. The maximum temperature permissible is determined by the

type of construction involved and the materials of the firing equipment

Manufacturer's recommendations should be followed in all cases. There are several sources of heat to perform the preheating function. As an example, ambient air in most boiler rooms is heated incidently by boiler and pipe surfaces and tends to collect below the ceiling. This air can be utilized directly as preheated combustion air by

ducting it down to the firing level and directing it into the primary

and secondary air intakes. Other methods available, discussed in

section 3-11, involve recovering waste heat from boiler stacks, from

condensate, and from blowdown hot wells, among other sources. One word of caution concerning waste-heat recovery from combustion

gases should be made. If the temperature of the flue gases is reduced

too much, sulfur trioxide (SO^) will combine with moisture in the flue

gas to produce sulfuric-acid mists. The temperature at which this

happens is called the acid dew point temperature. When sulfuric acid

mist occurs, it will adhere to cooler surfaces (such as recuperator

tubes) , entrap fly carbon and other particles in the flue gas, and

initiate low-temperature corrosion. Minimum stack temperatures for

trouble-free operation when burning oil are given in table 3-8.

TABLE 3.8. MINIMUM STACK TEMPERATURES FOR TROUBLE-FREE OPERATION

Sulfur Minimum Stack Temperature

Fuel % °C °F

Diesel type 1.0 138 280

Heavy oil 2.5 155 310

Heavy oil 3.5 160 320

3-52
In most cases, however, the corrosion problem will not be serious

if the temperature of the metal is kept above 240° F. Exposed metal

ductwork can be protected through insulation. A metal stack can be

protected by an aluminum outer shroud which provides an air space, or

it can be left bare and replaced as necessary. Masonry stacks also are

exposed to such corrosive action and may be protected by a glazed tile

1 iner

3.6.1. 2 Limit Combustion Losses

The loss of total heat input as a function of the percent (by

weight) of excess air for a natural-gas-fired boiler is given in

figure 3-14. Note that good burner performance occurs when the percent excess air is between 0 and 6% (by weight) . Excess air in the

amount of 30% increases the loss of total heat input by approximately

2%. This shows the need for measurement and adjustment of primary and

secondary air to burners.

3. 6.1. 3 Preheat Oil to Increase Efficiency

In the case of oil-fired boilers, preheating oil can increase the

efficiency of the boiler by as much as 3%, depending on the particular

constituents of the oil involved. Table 3-9 gives the minimum preheating temperatures for various grades of oil to attain complete

atomization.

TABLE 3-9. MINIMUM OIL PREHEATING TEMPERATURES REQUIRED

FOR COMPLETE ATOMIZATION

Grade Oil Temperature, °F

No. 4 135° F

No . 5 185° F

No. 6 210° F

Fuel oils must be preheated to give optimum viscosity at the burner.

Heating oil beyond the temperatures indicated will increase efficiency

even more, but is not generally recommended as it can result in vapor

locking and flame-out.

3-53
% 'lfldNI 1V3H 1V101 dO SSOlI

3-54

0

2

IN

FLUE

GAS,

%

(BY

WEIGHT)

Figure

3-14.

Combustion

loss

variations

as

a

function

of

excess

air

for

natural-gas-f

iced

boiler.
3. 6. 1.4 Reduce Blowdown Losses

The purpose of blowing down a boiler is:

to maintain a low concentration of dissolved and sus- pended solids in the boiler water, and

to remove sludge in the boiler.

The two principal types of blowdown are intermittent manual blowdown and continuous blowdown. Manual blowdown (or sludge blowdown) is

necessary whether or not continuous blowdown equipment is installed. The

frequency of manual blowdown depends on the amount of solids in the boiler

makeup water and the type of water treatment used. Continuous blowdown

results in a steady energy drain because makeup water must be heated.

Blowdown energy losses can be minimized by the use of automatic

blowdown controls that monitor the conductivity or PH of the boiler water

periodically and blowdown the boiler only when required to maintain

acceptable water quality. Further savings can be realized if the blowdown water is piped through a heat exchanger or a flash tank with a heat exchanger. In this way, heat from the boiler-blowdown flash tank can be used for preheating feed water.

3. 6. 1.5 Isolate Off-Line Boilers

Small heating loads on a multiple boiler installation are often met

by one boiler on line, with the remaining boilers idling on stand-by.

Idling boilers consume energy to meet stand-by losses. In many cases these losses are increased by a continuous induced flow of air through

the idling boilers and up the stack. Unless a boiler is about to be

used to meet an expected increase in load, it should be secured and

isolated from the heating system (by closing valves) and from- the stack

(by closing dampers)

A large boiler can be fitted with a by-pass valve or a regulating

orifice (see figure 3-15) to allow the minimum flow required to keep it warm and avoid thermal stress when it is brought on-line again. When

boiler waterside is isolated, it is important to prevent air flow through

the stack. It is possible for a back flow of cold air to freeze the

boiler

3-55
BOILER

SUPPLY

DC

UJ

Q_

u_i

DC LU

CD —

DC

DC

CD

DO

3-56

Figure

3-15.

Techniques

to

isolate

an

off-line

boiler.
3.6.1. 6 Replace Boilers at or Near End of Useful Life

Boilers which are at or near the end of their useful life should be

replaced by modern boilers which are matched to the current and projected

needs of the installation involved. In most cases 80% efficiency can be

obtained with new boilers on the market. Increased efficiency can be

gained by specifying multiple boilers with high efficiency burners.

Replacement burners should be selected on the basis of lif e-cycle, cost

rather than first cost. Increased cost of fuel, labor and materials

should be considered in developing life-cycle-cost projections. Also

consider installation of a dual-fuel system to reduce problems related

to shortages or curtailments.

3. 6.1.7 Replace Existing Boilers with Modular (Multiple) Boilers

Most boilers achieve maximum efficiency only when running at their

rated output. In most cases, however, full boiler capacity is seldom

required because heat load is 60% or less than full load 90% of the

time (see figure 3-16). Given this situation, large capacity boilers

in single units operate intermittently for the major part of the heating

season. Although high-low firing capabilities may reduce cycling, the

boilers can reach their design efficiency only for short periods, resulting in low seasonal efficiencies (see figure 3-17).

A modular (multiple) boiler system comprised of two or more boiler

units will increase seasonal efficiency. Each boiler is fired near its

capacity as much as possible. As the heating load increases, the separate boilers are brought on line in sequence until the load is satisfied.

In a typical installation, replacement of a single-unit, large-capacity,

boiler with modular (multiple) boilers may improve the seasonal efficiency by 5 to 10%. A good time to consider making this replacement is

when the existing boiler system is at or near the end of its useful

life.

3. 6.1. 8 Convert from Steam Atomizing Burners to Air-Atomizing Burners

Steam-atomizing burners consume at least 1. 5% of the total boiler

capacity to atomize the fuel oil. By contrast, air-atomizing burners

rely on an air compressor, which costs far less to operate. Accordingly, when an existing steam-atomizing burner is at or near the end of

3-57
PERCENT

FULL

LOAD

Figure 3-l6 . Typical heating load distribution (250-day season

in 6000 degree-day zone).

3-58
BOILER

EFFICIENCY

Figure 3-17- Effect of cycling to meet part loads.

3-59
its useful life, an air-atomizing replacement should be considered. In

certain cases the savings to be obtained from an air-atomizing burner

will warrant its installation prior to the scheduled replacement of the

existing system.

3.6.2 Chilled-Water Plants

For both absorption and vapor-compression systems, the parameter

characterizing the operating efficiency of the refrigeration system is

the coefficient of performance (COP), which is defined by the relation:

t

l

COP = _ - (5)

H L

where T = absolute temperature of evaporator

J-j and T = absolute temperature of condenser.

A chilled water plant can be made to operate more efficiently by

increasing its COP. This may be accomplished by decreasing the condenser

temperature (T ) which in turn may be achieved by reducing the outlet water

temperature of the cooling tower. The cooling tower is usually sized to

give the required capacity at the maximum outside design wet-bulb temperature for the location involved. This maximum wet-bulb temperature is

seldom reached, and a majority of the time it is possible to operate

the condenser water system at lower temperatures.

The COP may also be increased by increasing the evaporator temperature (T ). This may be accomplished by simply elevating the temperature

J_j of chilled water supplied to the chilled water distribution system. Most

building equipment for providing space cooling is designed for the hottest

day of the year, so that the equipment is able to operate satisfactorily

using chilled water at elevated temperature on many days without any loss

of human comfort.

Energy conservation measures for chilled-water plants are summarized

below:

° Consider the use of lower condenser water temperatures to reduce

the electric energy consumption for refrigeration equipment;

° Select and operate chillers so as to maximize the operating time

at full-load conditions. Many types of refrigeration systems

3-60
operate at maximum efficiency at full load. When the load decreases, a reduction in efficiency occurs;

° Utilize elevated chilled-water temperatures during times when

humidity conditions permit;

° Consider using heat exchangers to recover heat from condenser water.

3 . 7 Electrical Load Management

3.7.1 General

There are two key areas where the control of electrical utilization

can provide energy savings. They are:

Load curtailment (end-use conservation);

Load management (shifting of usage patterns).

Load curtailment involves actual reduction in consumption by users

of electricity through several means including reducing lighting, reducing temperature, controlling equipment usage and using more efficient

electric appliances and equipment. These methods have the joint benefit

of reducing generating requirements, and also reducing the consumption

of fossil fuels needed to generate the electricity.

Load management is directed mainly at reducing peak generating

capacity requirements. Users of electricity are encouraged to shift

the times when they use electricity from peak-usage periods to off-peak

periods, resulting in a flattened electrical daily-load-profile curve. In this way, the generating capacity requirement (which are determined

by generating requirements at peak time) can be reduced and demand

charges, employed by the utility company, can be reduced.

3.7.2 Selection of Interruptable Loads

Loads essential to the Base buildings operations, as for example,

ventilation in hazardous areas, should not be deferred to other times.

Most loads that may be considered for control fall into one of the

following categories:

(1) Inhibited loads - loads which are not used constantly and may

be scheduled to be supplied at certain times of the day, such as battery

charging banks;

(2) Switchable loads - loads which are locally controlled such as furnace in response to a thermostat control;

3-61
(3) Cyclic loads - loads that turn on-off at intervals throughout

the day, such as refrigeration compressors.

Loads most commonly selected for interruption include:

3.7.3 Major Loads that can be Deferred without Consumer Dissatisfaction

In the United States, at present, the only consumer load segment

having a substantial energy storage capacity is electric water heaters.

The volume of a typical water heater tank is about 50 gallons, which

is sufficient to avoid any great inconvenience to the customer under

normal usage, if the heater is disconnected from the electrical supply

for only a few hours. Since the average diversified demand of a water

heater during peak hours is about 1 kilowatt, an Air Force Base with

300 water heaters under control could thus reduce its load by about

300 kilowatts during the peak hours.

3.7.4 Load Management Control Techniques

Three different load-management techniques are currently employed:

(1) Time Control

The simplest load-management device is a clock-activated switch at

each individual load unit to be shed. It is the least expensive.

To make a change in the on-off times of the controlled load is a time-consuming and costly process, depending on the number of such units

on the Base. On the other hand, the main advantage of systems using

clocks is their simplicity, which is reflected in the relatively low

cost of the hardware.

A more complex time-control system is a demand controller. It is

the most common device used to defer loads. A demand controller basically

is a comparator. It is an electronic load-programming unit that monitors

the rate of energy consumption and compares this rate against a preset

desired rate of energy use. The unit can control many electrical

circuits, depending on its complexity. Input to the controller is

Water heaters Non-essential lighting

Large pumps

Ventilating fans

Clothes dryers

Washing machines

Air conditioners

Electric heaters

Furnaces

Boilers
derived by an electrical connection to both the kilowatt-hour meter and

the demand meter. The demand meter provides the controller with an end-of-interval signal derived from either a built-in timer or an external clock. Some of the limitations on the use of this equipment are physical requirements, accessibility of utility-metering equipment for

making connections, and number and strength of pulses.

(2) Radio Control

The principle of radio control is simple. Radio transmitters are

placed in suitable locations to cover the Base with a sufficiently strong

signal. The transmitted waves are modulated by a code containing an address for selecting the desired receiving group, as well as the control

message itself. At the load under control, a radio receiver detects and

decodes the message and switches on and off the load.

(3) Ripple Control

In this method of load control, a coded narrow-band audio frequency

signal is introduced into the power grid. This signal conveys switching

commands to receivers placed at the controlled load.

The ripple control system is more expensive than the radio control

system. At present, there are no United States manufacturers producing

this hardware system commercially.

3 . 8 Energy Monitoring Control Systems * 3.8.1 Background

Energy Monitoring Control Systems (EMCS) currently represent a sizable investment in Air Force dollars. If the capabilities of these

systems are properly understood and applied at Base level, the EMCS

concept can be a tremendous benefit in saving money and manhours. If

they are misunderstood or improperly used, these savings are lost. An

EMCS can be an automated watchdog to conserve energy for the Base Civil

Engineer (BCE) and permits more work to be accomplished with less re- sources. EMCS have proven their worth in both civilian and military applications by reducing the operating costs of heating, ventilating and air

* Much of this material was extracted from reference [11].

3-63
conditioning (HVAC) equipment; by improving reliability; and by reducing manhours in accomplishing work. Documented utility savings at Luke

AFB for only one month (July 1975) amounted to over $12,000 (which does

not include savings from peak demand charges) [11].

The Air Force has begun to develop the potential reductions in energy

consumption on its Bases. Automatic load shedding, night setback, GN/OFF

control programs, and reduced ventilation rates in buildings are some

of the major EMCS areas that can yield up to a 30 percent total annual

energy savings per Base.

3.8.2 Description of Typical System

A typical EMCS is shown in figure 3-18. The main components of the

system are:

(1) transducers: These devices monitor the environmental conditions

within a building and the operating conditions of its HVAC,

hot water heating, and other type equipment.

(2) remote building terminals: These units receive signals from

the vario.us transducers and process these signals for transmission to the central-processing terminal.

(3) transmission cable: This part of the system carries processed

signals from the remote building terminals to the centralprocessing terminal.

(4) central-processing terminal: This part of the system contains

either a computer for converting processed-signal data into

engineering units (or electronic hardware for performing this

function) and input/output devices such as teletype printers,

cathode-ray-tube displays, and a line printer.

3.8.3 Considerations for Procurement of EMCS

An Air Force guide specification is now available for the procurement of an EMCS. Before purchasing an EMCS, it is necessary that a detailed input/output summary be carefully developed at the Base level by

the EMCS project engineers who are familiar with both the electrical and

mechanical systems of the Base (see figure 3-19). The I/O summary should

identify (by priority of economic payback) which pieces of equipment and

what environmental conditions will be monitored/controlled by the EMCS.

This is an important step in the planning process and must be carefully

3-64
REMOTE

BUILDING

TERMINALS

3-65

Figure

3-18.

Typical

energy

monitoring

control

system.
REMARKS

Diff.

Pressure

Across

Filters

.

Specify

zones f

Control

VdO uo vjo

aoj qoBqpaax uoxpxsoq O O O —

(33°) rav sod jaduiea o _

(vdo) rav id

poaxuoo X3S0H O O

XoxauoQ uiBxSoxq < <

snxuas

snxnas =9 doxs/l-^lS < < O

Alarm

aouBuaxuxBtx Oti

C\J

SoqBuy 00 OQ OQ O

^X°^fu°°) X F 1T§TCI < < OQ a

Analog

Indication AxxpxmnH oaxxbxoh

axnssexq Q

axnaBxadmax GO OQ OQ o a

uoT^nas uiooaa^ui X

oxqdBxg

IO 9PTXS OTXBUIUlBiSBTQ X i

I

SUPPLY

SYSTEM

SUPPLY

FAN

RETURN

FAN

RETURN

AIR

TEMP.

MIXED

AIR

TEMP.

DISCHARGE

AIR

FILTER

LOW

TEMP.

ALARM

(Freeze)

ZONE

TEMP.

INDI

MINIMUM

0

. A.

REHEAT [return

air

r.m.

RETURN

AIR

FIRE

ALARM

3-66

Figure

3-19.

Typical

input/output

summary.

A

-

high

return

on

investment.

B

-

highly

desirable

points,

able

to

monitor

system

operations.

C

-

provides

data

and

control,

capability

to

perform

manual

optimizing

functions.

D

-

points

that

allow

more

complete

picture

of

total

system

operation

[11].
done to insure maximum benefits and minimum payback period for the

initial investment. Lack of proper planning in this area can mean an inefficient system.

Often small EMCS systems are initially purchased due to funding

limitations. As more funds become available, systems are often expanded

to include more channels and increased data processing capabilities. It

is strongly recommended that in adding on to such complex systems, an attempt be made to purchase the add-on equipment from the manufacturer

of the original system, in order to avoid the following problems associated with hybrid systems:

interfacing problems between components manufactured by

different companies;

legal disputes concerning who owns maintenance problems;

loss of warranty due to system modification.

Another important consideration in procuring an EMCS is to obtain a system with the capability for future expansion. In many instances, a system having expansion capability will cost only a small percentage

more than a system without this capability. On the other hand, if this

capability is not provided for, then the expansion of the system at some future time may require the procurement of new major components at the

cost of essentially a new system.

3.8.4 Select and Train an Operator

Console operator training must not be a last minute "rush" job.

During start-up of a new EMCS, there will undoubtedly be some "teething

pains." Consequently, the operator must have enough technical knowledge

of the system to do some trouble shooting. He cannot expect to learn

the system solely through trial and error methods or on-the-job training

(OJT). It would be best if the operator were already trained by the

time the contractor starts to install the EMCS; thus, contractor personnel and the operator could work together as the system is being built

up.

3-67
The system operator must be familiar with both the electrical and

mechanical systems on Base. Preferably, he should be civilian, rather

than military, to avoid the interruptions resulting from PCS moves. To

the extent possible, initial training requirements should be included in

the original EMCS project funds with training provided by the equipment

supplier. All console operators should attend at least one commercial

training course prior to system start-up or before assuming EMCS duties.

In addition to the manufacturer's training school, an EMCS Mobile

Training Team is now available at Sheppard AFB , Texas, to assist Base

personnel and provide on-site OJT during the EMCS start-up period.

Another aspect of the EMCS training program involves general

education/orientation sessions given to BCE shop personnel and management. Shop personnel play an important part in the success of EMCS.

They must be pre-briefed and have a good working knowledge of the

system's capabilities prior to start-up. Users of the system should

also be pre-briefed on what the equipment can and cannot do. All

levels of management should be educated to insure that a positive attitude exists toward the new EMCS.

3.8.5 Communications Lines

An EMCS system requires the use of telephone lines (pairs) of

coaxial cable to communicate data between the field panels (located in

various facilities throughout the Base) , and the EMCS console which is

usually located in the BCE Control Center /Service Call Area. It is

therefore essential that the EMCS project engineer(s) closely coordinate

with the local Base communications people early in the planning stage.

Past experience has shown that serious project delays can result if the

Base communications people are left in the dark or told at the last

minute about the EMCS requirements. Communications and electronics

plans to install new telephone equipment for the EMCS can take up to 12-

18 months for approval. The telephone pairs must be high quality; the

coaxial cable must also be high quality and properly installed. Failure

to closely monitor this phase of the project will quickly jeopardize

system effectiveness.

3-68
An important consideration for an EMCS is to provide lightning

protection for above ground signal-transmission and power lines. Lightning that strikes these lines may induce transient electrical surges

which can do substantial damage to the EMCS equipment. The following

measures are recommended to protect these lines:

install signal transmission lines underground instead ,of

above ground.

install arrestor (or voltage-clipping circuits) on incoming

power lines.

when signal transmission lines are installed above ground,

utilize shielded cable with the exterior-shield grounded to

the eafth.

install lightning rods at high places where signaltransmission lines are located. The purpose of these rods

is to bleed off electrical charge, instead of accumulating

and creating a transient voltage surge on signaltransmission lines.

3.8.6 Back-up Equipment

One manufacturer has a test kit that provides a back-up capability

for the EMCS in the event of equipment failure. This suitcase-size

test kit ($3,000) may be taken anywhere on base and connected into the

EMCS. It has a control capability but does not monitor input data. If,

for some reason, a field panel is one of the Base facilities should fail,

the test kit could be taken out to the facility and connected into the

system, bypassing the faulty field panel. Likewise, if the EMCS

console should shut down, the test kit could be connected into the main

system, bypassing the console; thus, the kit provides the operator with

a control capability until the console is brought back on line. Meanwhile, the mechanical and electrical equipment tied into the EMCS will

continue to operate at the same settings that were being used prior

to the failure. Therefore, a loss of the EMCS console would not result

in the shutdown of the entire Base-wide HVAC systems.

3-69
3.8.7 Service/Maintenance Contracts

Any piece of electronic equipment will require periodic servicing

and maintenance; an EMCS is no exception. The console operator can perform a limited amount of servicing and minor maintenance on the equipment if he has been properly trained at the manufacturer's school. This

is now being done at Luke AFB, for example, with the approval of the

EMCS manufacturer. Only qualified personnel should be allowed to work

on EMCS equipment. An in-house capability for total EMCS servicing does

not generally exist at Base level; therefore the manufacturer's personnel

will be needed for most servicing requirements. Contract costs vary

considerably. As a rule of thumb, an annual service/maintenance contract will cost anywhere from 5 to 10 percent of the initial EMCS purchase price. To help reduce or avoid these annual service contract

costs, the Air Force is considering as a long-range goal, having a total in-house service repair capability (24 hours a day) for EMCS

equipment at each Base.

New EMCS's normally have a one-year warranty with the respective

manufacturer which may or may not include maintenance on the EMCS equipment. It is best to get a service contract option at the time of bidding the EMCS contract. After the initial warranty period, some type of

annual service/maintenance contract will be required. Again, this

involves advance planning and budgeting; it must not be put off until

the last minute. It is important that the warranty not be allowed to

expire without a follow-up service contract.

3.8.8 EMCS Manning

The EMCS must have adequate manning depth by qualified people to

insure stable, continuous use of the system. Current Base level EMCS

manning is frequently only one-man deep. There must be back-up manning

for the console operator position to allow for TDY, leave, sickness, or injury.

The EMCS concept is a new and efficient element of utility management. It is necessary to understand its capabilities and limitations

if we are to properly use these systems as an integral part of Base

3-70
energy conservation programs. Technical expertise is available within

the various Air Force commands for anyone wanting assistance in developing a viable EMCS program.

Motivation is a key factor in producing a successful EMCS program.

Both management and labor must collectively agree to make the system

work. Disinterest on the part of middle and top level management at

Base level will practically ensure a slow death; disinterest, mistrust,

or misunderstanding of EMCS principles by the operators and shop technicians on Base will also guarantee that the program will fail.

It is necessary to carefully and thoughtfully consider better ways

to manage our scarce resources. An EMCS provides us with innovative

ways to save energy and avoid spending utility dollars. A great

flexibility in operating and maintaining our utility systems is also

gained

3 . 9 Energy Recovery through Waste POL Utilization

One proven and practical procedure which can result in substantial

energy savings is the utilization of waste POL's (petroleum, oils,

lubricants) as supplementary heating fuel in oil- and natural-gas-fired

boilers. Under this system, waste POL's are blended with the existing

fuel type and the mixture is combusted in the existing boiler. Millions

of gallons of contaminated fuels and lubricants are generated each year

on Air Force Bases. Examples of waste POL's include:

0 waste aviation-piston-engine oil;

waste aviation- turbine lube;

simple mixtures of waste aviation-piston-engine oil, synthetic turbine oil, hydraulic fluid;

contaminated jet fuel (i.e., JP-4, JP-5) ; engine oil, synthetic turbine oil, automotive crankcase oil, and non- halogenated solvent.

These waste POL's have a Btu content approximately equivalent to that of

No. 2 or No. 5 fuel oil (18,500 Btu/lb). Therefore, their inclusion in

the fuel supply can result in a gallon-f or-gallon reduction in fuel oil

purchases or similar reductions in the demand for natural gas.

3-71
This technique has been well tested and documented, and a complete

description of the test facilities, design details, and testing results

can be found in technical report AFCEC TR-76-2 [12], Recent studies

conducted at three Air Force Bases have shown that combustion of waste

POL in standard fuel mixtures does not impair boiler performance. In

fact, it may actually increase. the boiler efficiency. In addition,

utilization of controlled percentages of waste POL's does not increase

stack emissions over federal air-quality standards.

The economic feasibility of a waste POL system at any individual

Base depends on several factors, including length of the heating season,

current price of the fuel oil or natural gas used, and the resale value

of the waste POL's. A cost analysis, comparing cost of installation versus

annual savings in fuel purchases, will determine if the waste POL system

is financially attractive. Large installations will likely find rapid

amortization of capital expenditures for installation.

The steps required for waste POL utilization are:

(1) Collection, segregation and storage of waste POL's;

(2) System modifications to provide comingling of the POL's with

the standard fuel immediately before injection into the

boiler

Required alterations to existing boilers are usually minimal (i.e., a simple tee connection for oil burners, a bit more for gas-fired boilers).

It is important that JP-4 be segregated and stored in a separate

steel tank. Therefore, in order to be assured of proper segregation during

all phases of transportation, collection, and unloading, a segregation

plan should be devised in accordance with TO 42B-1-23 to analyze and

segregate waste POL's. It is also important that halogenated-hydrocarbon components not be included with other waste POL for utilization,

since the combustion of these components results in the production of

hydrogen-chloride or hydrogen-fluoride gases which are highly corrosive

and will severely damage boiler components.

Appropriate consideration should be given to the location of piping where it enters the heating plant. Due to the volatility of JP-4,

special care is required in order to maintain a safe system free of

3-72
leaks or malfunctions. Sine, the waste POL pipelines in the vicinity

of the boilers have a tendency to elongate, poorly installed connections

could deflect or distort, resulting in extremely dangerous vapor leaks.

Techniques for minimizing the possibility of such vapor leaks are given

in reference [12].

3.10 Power-Factor Adjustments

3.10.1 Background

Electric equipment having inductive loads such as induction motors

(especially when operated at less than full loads), transformers, arc welders, rectifiers, arc furnaces, fluorescent lamps, and various types

of electronic equipment is magnetized from the electrical distribution

system causing a lagging component in their current. Energy spent in

building up the magnetic fields of these equipments flows back and forth

between the generator and the load. This out-of-phase magnetizing

current causes the total current in the line to lag behind the voltage

giving rise to the power factor (PF) in the system. Power factor is

defined as the ratio of working active current to total current (which

includes both the working active current and the magnetizing current).

Power factors for various equipment are given in table 3-10. From

the definition of the power factor, a low power fav-Lor occurs when a piece of electric equipment requires a large magnetizing current. From

table 3-10, it is seen that equipment having low power factor or high

magnetizing current includes induction motors, arc welders, arc furnaces,

and induction furnaces.

The magnetizing current drawn by inductive equipment does not contribute to the work or heat output of electric equipment, but it nonetheless does constitute a KVA load on transformers of the electrical

distribution system. Thus, magnetizing current does cause the voltage

of an electrical distribution system to be reduced. This voltage drop

will decrease the performance of other electric equipment and reduce

illumination from incandescent-light sources. This magnetizing current

must also be transported through the distribution system, and there2 fore increases copper losses (I R losses) . Since the magnetizing

current does represent a KVA load on generating equipment, it has the

effect of using up valuable generating capacity. Power companies.

3-73
therefore, often impose a demand charge for lagging power factors that are a part of the customer's load.

TABLE 3-10. TYPICALLY HIGH LEADING AND LAGGING POWER-FACTOR LOADS [13].

High loads Approximate PF

Incandescent lamps 1.0 Fluorescent lamps

(with built-in capacitors) 0.95-0.97 Resistor heaters 1.0 Synchronous motors 1.0 or leading

Rotary converters 1.0 Leading loads Synchronous motors 0.9; 0.8; etc., leading,

Synchronous condensers

depending on rating

Nearly 0, leading

Capacitors 0 Lagging loads

Induction motors (full-load) Split-phase fractional hp 0.55 to 0.75 Split-phase (1-10 hp) 0.75 to 0.85 Split-phase condenser type 0.75 to 1.0 Polyphase squirrel-cage motors

High speed (1 to 10 hp) 0.75 to 0.90 High speed (10 hp or more) 0.85 to 0.92 Low speed 0.70 to 0.85 Wound rotor 0.80 to 0.90 Groups of induction motors 0.50 to 0.85 Welders 0.50 to 0.70 Arc furnaces 0.80 to 0.90 Induction furnaces 0.60 to 0.70

The simplest and most economical method of improving power factor

at the Base level is to use capacitors. When properly applied to an electrical distribution system, a power-factor-correcting capacitor

supplies a leading reactive magnetizing current that counteracts the

lagging reactive current produced by induction equipment. This improves

the overall power factor. Power-factor-correcting capacitors, when

properly located, will release electrical system capacity (KVA), raise

the voltage level, and reduce system losses. This will in many cases permit additional loads to be added to an existing system without the

need for system capacity to be increased.

Consider the induction motor shown in figure 3-20. When the motor

is operated without power-factor correction, a magnetizing current of

60 amps must be supplied from the electrical distribution system. The

3-74
60-amp magnetizing current represents a KVA load on the electrical distribution system. It causes the voltage output of transformers in the

electrical distribution system to be reduced, thereby wasting valuable

KVA capacity of the electrical distribution system. Also, reduced

voltage may cause other equipment to operate less efficiently. Note

that the installation of a power-factor-correcting capacitor causes

the magnetizing current not to appear as a load on the electrical distribution system.

WORKING (ACTIVE) CURRENT 80 AMP /

TOTAL CURRENT

FROM LINE 100 AMP ")

MAGNETIZING (REACTIVE) CURRENT 60 AMP

80 AMP INDUCTION MOTOR LOADS

80 AMP POWER FACTOR = =0.8

100 AMP A—PARTIALLY LOADED, WITHOUT

POWER FACTOR CORRECTION

B—CAPACITOR INSTALLED NEAR SAME MOTOR TO SUPPLY

MOTOR'S MAGNETIZING CURRENT REQUIREMENT

Figure 3-20. Power factor correction for an induction motor [13].

3.10.2 Power-Factor Fundamentals

Inductive loads require two current components: the magnetizing

current (reactive current) and the power producing current (active

current) . The total current (I ) is related to these two components

by the relation:

I T

2

where I

3. active or power-producing current, amps

reactive or magnetizing current, amps .

( 6)

3-75
At a common voltage, the total power component (P ) is given by the

relation

P

T

2 (7)

where P^ = active or actual power, KW

P = reactive power, KVAR

R

The power factor (PF) is defined as the ratio of active power (P ) to

a the total power (P ) or

PF - ?a/P

x

f8)

From trigonometric considerations,

PF = cos 0 = P /P (9)

Combining equations (7) and (9), we may relate reactive power to the

real power by the relation:

P

R

( 10 )

If capacitors are used to increase the power factor from one level to

another, then the reactive power (AP ) introduced by the capacitor must

R

be equal to the difference between the reactive power levels calculated

from ( IQ ) , or

AP

R (ID

where the subscripts "i" and "f" denote the initial and final power

factors, respectively.

The additional KVA capacity (AP^) that is released by a power

factor correction is equal to:

APn

P P

—5— —5— = p. PF. PF a

l f

PF - PF.

f l

PF * PF.

f l

( 12 )

3-76
3.10.3 Analysis of Power-Factor Problems

To assist Air Force personnel in evaluating power -factor problems

several charts are presented. Table 3-11 presents KW multipliers to

determine kilovars required for power factor correction. To use this

chart, enter the left vertical column at the original power factor that

existed prior to the adjustment. Then move to the right along the row containing the original power-factor value until you reach the column

containing the desired corrected power factor. The figure in the table

at this location is the KW multiplier for determining the capacitor

kilovars required for power-factor adjustment.

Figure 3-21 may be used to find the additional system capacity that

is released as a result of power-factor correction. To find the percent

additional capacity, enter the figure at the point on the horizontal

axis coinciding with the corrected power-factor value. Proceed vertically upwards until you arrive at the curve for the original power

factor. Interpolate when necessary. Read the percent additional capacity from the vertical axis. And finally, table 3-12 gives the 1975

prices of power-factor-correction capacitors.

TABLE 3-12. COST OF POWER-FACTOR- CORRECTING CAPACITORS

(1975)

Voltage of Cost of

Capacitor Capacitor ($/KVAR)

240 20 - 30

480 - 600 10 - 15

2,400 - 13,800 5-10

Note that the dollars per kilovars is much cheaper for higher voltage

capacitors. The following example is presented to demonstrate the use

of the foregoing tables and figures:

3-77
TABLE 3-11. KW MULTIPLIERS TO DETERMINE CAPACITOR KILOVARS REQUIRED

FOR POWER FACTOR CORRECTION [13].

Orig- inal power

lactor 0.80 0.81 0.82 0.83 0.84 0.85

0.50 0.982 1.008 1.034 1.060 1 086 1.112

0.51 0.937 0.962 0.989 1.015 1.041 1.067

0.52 0.893 0.919 0.945 0.971 0.997 1.023

0.53 0.850 0.876 0.902 0.928 0.954 0.980

0.54 0.809 0.835 0.861 0.887 0.913 0.939

0.55 0 769 0.795 0.821 0.847 0.873 0.899

0.56 0.730 0.756 0.782 0.808 0.834 0.860

0.57 0 692 0.718 0 744 0.770 0.796 0.822

0.58 0.655 0.681 0.707 0.733 0.759 0.785

0.59 0.619 0.645 0.671 0.697 0.723 0.749

0.60 0.583 0.609 0.635 0.661 0.687 • 0.713

0.61 0.549 0.575 0 601 0.627 0.653 0.679

0.62 0.516 0.542 0.568 0.594 0.620 0.646

0.63 0.483 0.509 0.535 0.561 0.587 0.613

0.64 0.451 0.474 0.503 0.529 0.555 0.581 0.65 0.419 0.445 0.471 0.497 0.523 0.549

0.66 0.388 0.414 0.440 0.466 0492 0.518

0.67 0.358 0.384 0.410 0.436 0.462 0.488

0.68 0.328 0 354 0.380 0.406 0.432 0 458

0.69 0.299 0.325 0 351 0.377 0.403 0.429

0.70 0.270 0.296 0.322 0.348 0.374 0.400

0.71 0.242 0.268 0.294 0.320 0.346 0.372

0.72 0.214 0.240 0.266 0.292 0.318 0.344

0.73 0.186 0.212 0.238 0.264 0.290 0.316

0.74 0.159 0.185 0.211 0.237 0.263 0.289

0.75 0.132 0.158 0.194 0.210 0.236 0.262

0.76 0.105 0.131 0.157 0 183 0.209 0.235

0.77 0.079 0.105 0.131 0.157 0.183 0.209

0.78 0.052 0.078 0.104 0.130 0.156 0.182

0.79 0.026 0.052 0 078 0.104 0.130 0.156

0.80 0.000 0.026 0.052 0.078 0.104 0.130

0.81 0.000 0.026 0.052 0.078 0.104

0.82 0.000 0.026 0.052 0.078

0.83 0.000 0.026 0.052

0.84 0.000 0.026

0.85 0.000

0.86

0.87

0.88

0.89 0.90

0.91 0.92 0.93

0.94

0.95

0.96

0.97

0.98

0.99

Corrected power laclor

0.86 0.87 0.88 0.89 0.90 0.91 0.92 0.93

1.139 1 165 1.192 1.220 1.248 1.276 1.306 1.337

1.094 1.120 1.147 1.175 1.203 1.231 1.261 1.292

1.050 1.076 1.103 1.131 1. 1 59 1.187 1.217 1.248

1 007 1 033 1.060 1.088 1.116 1.144 1.174 1.205 0.966 0 992 1.019 1.047 1.075 1.103 1.133 1.164 0.926 0.952 0.979 1.007 1.035 1.063 1.093 1.124

0.887 0.913 0.940 0.963 0 996 1.024 1.054 1.085

0 849 0 875 0.902 0.930 0.958 0.986 1.016 1.047 0.812 0.838 0.865 0.893 0.921 0.949 0..979 1.010 0.776 0.802 0.829 0.857 0.885 0.913 1.943 0.974

0.740 0.766 0.793 0.821 0.849 0.877 0.907 0.938

0.706 0.732 0.759 0.787 0.815 0.843 0.873 0.904

0.673 0.699 0.726 0.754 0.782 0.810 0.840 0.871 0.640 0.666 0.693 0.721 0.749 0.777 0.807 0.838

0.608 0 634 0.661 0.689 0.717 0.745 0.775 0.806

0.576 0.602 0.629 0.657 0.685 0.713 0.743 0.774

0.545 0.571 0 598 0626 0.654 0.682 0.712 0.743

0.515 0.541 0.568 0.596 0.624 0.652 0.682 0.713 0.485 0 51

0.538 0.566 0.594 0.622 0.652 0.683 0.456 0 4 e2 0 509 0.537 0.565 0 593 0.623 0.654

0.427 0.453 0 480 0.508 0 536 0.564 0.594 0.625

0.399 0.425 0452 0 480 0.508 0.536 0.566 0.597

0.371 0.397 0 424 0 452 0.480 0.508 0.538 0.569

0.343 0.369 0.396 0 424 0.452 0.480 0.510 0.541 0.316 0.342 0.369 0.397 0.425 0.453 0.483 0.514

0.289 0.315 0.342 0.370 0 398 0.426 0.456 0.487

0.262 0.288 0.315 0.343 0.371 0.399 0 429 0.460

0.236 0.262 0.289 0.317 0.345 0.373 0.403 0.434 0.209 0.235 0.262 0.290 0.318 0.346 0.376 0.407

0.183 0.209 0.236 0.264 0.292 0.320 0.350 0.381 0.157 0.183 0.210 0.238 0.266 0.294 0 324 0.355

0.131 0.157 0 184 0.212 0.240 0.268 0 298 0.329

0.105 0.131 0.158 0.186 0.214 0 242 0.272 0.303

0.079 0.105 0.132 0.160 0 183 0.216 0.246 0.277

0.053 0.079 0.106 0.134 0.162 0.190 0.220 ' 0.251 0.027 0.053 0.080 0.108 0.136 0.164 0.194 0.225

0.000 0.026 0.053 0.081 0.109 0.137 0.167 0.198 0.000 0.027 0055 0.083 0.111 0.141 0.172

0.000 0.028 0.056 0.084 0.114 0.145

0.000 0.028 0.056 0.086 0.117 0000 0.028 0 058 0.089

0.000 0.030 0.061 0.000 0.031 0.000

0.94 0.95 0.96 0.97 0.98 0.99 1.0

1.369 1.403 1.440 1.481 1.529 1.589 1.732

1.324 1.358 1.395 1.436 1.484 1.544 1.687

1.280 1.314 1.351 1.392 1.440 1.500 1.643 1.237 1.271 1.308 1.349 1.397 1.457 1.600 1.196 1.230 1.267 1.308 1.356 1.416 1.559

1.156 1.190 1.227 1.268 1.316 1.376 1.519

1.117 1.151 1.188 1.229 1.277 1 . 1J 37 1.480

1.079 1.113 1.150 1.191 1.239 1.299 1.442

1.042 1.076 1.113 1.154 1.202 1.262 1.405 1.006 1.040 1.077 1.118 1.166 1.226 1.369 0.970 1.004 1 041 1.082 1.130 1.190 1.333

0.936 0.970 1.007 1.048 1.096 1.156 1.299 0.903 0.937 0.974 1.015 1.063 1.123 1.266 0.870 0.904 0.941 0.982 1.030 1.090 1.233 0.838 0.872 0.909 0.950 0.998 1.068 1.201 0806 0.840 0.877 0.918 0.966 1.026 1.169

0 775 0.809 0.846 0.387 0.935 0.995 1.138 0.745 0.779 0.816 0.857 0.905 0.965 1.108 0.715 0.749 0 786 0.927 0.875 0 935 1.078 0.686 0.720 0.757 0.793 0.846 0.906 1.049 0.657 0.691 0.728 0.769 0.817 0.877 1.020

0.629 0.663 0.700 0.741 0.789 0.849 0 992

0.601 0.635 0.672 0 713 0.761 0.821 0.964 0.573 0.607 0.644 0.665 0.733 0.793 0.936 0.546 0.580 0.617 0.658 0.706 0.766 0.909

0.519 0.553 0.590 0.631 0.679 0.739 0.882

0.492 0.526 0.563 0.604 0.652 0.712 0.855

0.466 0.500 0.537 0.578 0.626 0.685 0.829 0.439 0.473 0.510 0.551 0.599 0.659 C .802 0.413 0.447 0 484 0.525 0.573 0.633 0.776

0.387 0.421 0.458 0.499 0.547 0.609 0.750

0.361 0.395 0.432 0.473 0 521 0.581 0.724

0.335 0.369 0.406 0.447 0.495 0.555 0.698 0 309 0.343 0.380 0.421 0.469 0.529 0.672 0.283 0.317 0.354 0.395 0.443 0.503 0.646 0.257 0.291 0.328 0.369 0.417 0.477 0.620

0.230 0.264 0.301 0.342 0.390 0.450 0.593

0.204 0.238 0.275 0.316 0.364 0.424 0.567 0.177 0.211 0.248 0.289 0.337 0.397 0.540 0. 1

S 0.183 0.220 0.261 0.309 0.369 0.512

0.121 0.155 0.192 0.233 0.281 0.341 0.484

0 093 0.127 0.164 0.205 0.253 0.313 0.456

0.063 0.097 0.134 0.175 0.223 0.283 0 426

0.032 0.066 0.103 0.144 0.192 0.252 0.395 0.000 0.034 0.071 0.112 0.160 0.220 0.363

0.000 0.037 0.079 0.126 0.186 0.329

0.000 0.041 0 089 0.149 0.292 0.000 0.048 0.108 0.251 0.000 0.060 0.203 0.000 0.143 0.000

3-78
ADDITIONAL

SYSTEM

CAPACITY

(AT

ORIGINAL

PF

IN

PERCENTAGE

OF

ORIGINAL

KW)

.40 .45 .50 .55 .60 .65 .70 .75 .80 .85 .90 .95 1.00 CORRECTED POWER FACTOR OF PRESENT LOAD

REQUIRED TO RELEASE ADDITIONAL CAPACITY DESIRED

Figure 3-21. Additional system capacity after

PF correction [13]

3-79
Example : Here’s how improving the power factor can save money. Assume that

a plant’s load is 1,500 KW at 0.75 power factor and the utility has a cost-rate schedule based on $2/KVA, with a maximum billed power factor

of 0.9. The billed KVA is:

1,500 KW

0.75 PF 2,000 KVA

The utility demand charge is:

2,000 KVA x $2/KVA = $4,000 a month.

The minimum KVA on which the plant's 1,500 KW demand cost can be

based is:

1,500 KW

0.9 PF

= 1,667 KVA

The demand charge at 1,667 KVA would be $3,334 a month (1,667 KVA x $2/KVA)

This means that by improving the power factor from 0.75 to 0.9,

the demand charge will be reduced $666 a month ($4,000 - $3,334 = $666).

From table 3-11, the KW multiplier to determine capacitor kilovars

required for correcting the power factor from 0.75 to 0.9 is found to

be 0.398. The number of kilovars to achieve the required power-factor

correction is (0.398) (1500) = 597 KVARS.

From table 3-12, the cost of a 480/600 - volt static capacitor is

$10/KVAR or $5970. Therefore, a $5970 investment will produce $666

monthly savings. The payoff time is less than one year.

Using figure 3-21, the additional system capacity after the powerfactor correction is found to be (1500) (.18) = 270 KVA.

3-80
3.10.4 Selection of the Most Suitable Location for Power-FactorCorrection Capacitors

Consider the electrical distribution system diagram shown in

figure 3-22. The induction motors and the small motors shown in the

diagram introduce a lagging power factor. Power-factor-correction

capacitors may be located at the following locations:

at the motor (localized correction);

at the 480-V Bus (group correction)

at the 2.4 KV Bus (group correction);

at 13.8 KV primary side of main transformer (group correction).

One of the main advantages of locating the power-factor-correction

capacitor at either the primary side of the main transformer or at

the 2.4 KV bus is that the cost of the capacitor is 5 to 10 dollars

per kilovar, which is much less than at other locations. The cost

of the capacitor at either the induction motor location or the 480-V

bus approximately doubles.

Localized correction at the motor also has several advantages.

Additional system capacity is released for all parts of the electrical

distribution system located above the point of correction. This means

that power factor correction will permit more electrical consuming

equipment to be added to the distribution system without the need of

expanding the system capacity. However, if the power-factor correction

is achieved at the primary side of the main transformer, additional

load capacity is achieved for the generating plant of the power company,

but none is made available for the Air Force power-distribution system.

An important point is that additional system capacity is only made

available for those parts, of the distribution system located above or upstream from the power-factor-correction capacitors. However, a useful analysis of all technical and economic aspects (including load

utility-rate schedules, released load KVA, reduced losses, voltage

improvements, and prices of power-factor corrective devices) needs to be

performed to select the best location for power-factor correction.

3-81
,r POWER CO. INCOMING SUPPLY

MpowVVEn CO. McTEPlNG — Q

c,

13 S KV TRANSFORMER

2.4 KV

)

MOTOR

Figure 3-22. Possible locations of power-factor- correction

capacitors [13 ]

-

3-82
3.11 Waste-Heat-Reclamation Systems

Waste-heat reclamation is the recovery or utilization of heat

energy that would otherwise be rejected. As such, heat recovery conserves energy, reduces operating costs, and reduces peak loads. This

section describes prime targets for waste-heat recovery systems and

various waste-heat-recovery devices which are available. Due to the

high cost of waste-heat-recovery devices, it is recommended that a feasibility study be first performed to investigate the cost effectiveness of such a modification.

3.11.1 Prime Targets for Waste-Heat Recovery

In examining a characteristic facility for places to use waste

heat, there are several prime targets. First consider using hot gases

to preheat boiler-makeup water. This modification is almost always cost

effective, especially when there is a large continuous flow of makeup

water. One reason why this is so attractive is that the engineering

needed to retrofit an economizer (feed-water preheater) onto an existing

boiler is fairly straightforward. Preheating combustion air is another

alternative that can greatly reduce fuel costs, but in this case there

is generally a need not only for a great deal of ductwork but also for

re-engineering the burners. The cost of such a project is likely to be

high.

An often overlooked source of profitable waste-heat utilization in

cold or hot areas is the use of heat exchangers to heat or cool the

make-up air that is introduced into a building by the mechanical system.

This can be accomplished with any of a number of heat exchangers. Waste

heat utilization for make-up air has the advantage that neither fluid

stream contains chemically reactive components or is at a temperature

which is likely to cause material damage.

3.11.2 Waste-Heat Recovery Devices

( 1) Rotary Heat Exchanger

The rotary heat exchanger shown in figure 3-23 uses a heat- transfer medium in the form of a cylindrical drum or wheel. When rotated

slowly between the supply-air and exhausted-air streams, it absorbs

heat from the warmer air stream and rejects heat to the cooler air

3-83
EXHAUST

AIR

FILTERS HEAT

WHEEL

Figure 3-23. Rotary heat exchanger.

3-84
stream. In addition to sensible heat transfer, the wheel can be

hygroscopically treated with a desiccant for transferring water vapor

from the humid air stream to the drier stream. Nonhygroscopic wheels

transfer water vapor when the temperature of one air stream is below

the dew-point temperature of the other and there is direct condensation of water vapor. During operation at temperatures below 32° F,

freezing usually is prevented by preheating the supply air.

Rotary heat exchangers are usually economical for applications

having ventilation-air rates of 4000 cfm or more. When operated at

approximately 8 to 10 rpm with a face velocity of 550 fpm, a non- hydroscopic rotary exchanger recovers 70 to 80% of the sensible heat

and 40 to 60% of the latent heat. Hygroscopic or enthalpy exchangers

recover 70 to 80% total heat.

The location of the supply and exhaust ductwork in close proximity

to each other can be an obstacle in many applications, especially when

exhaust streams are contaminated. In these cases, purge sections must

be added to the wheel and special filtration may be necessary in the

supply air.

(2) Air-to-Air Heat Exchangers

Air-to-air exchangers transfer heat directly from one air-stream

to another through direct contact on either side of a metal heat-transfer surface. This surface may be either a plate with fins (more common

for low temperature use in HVAC system) or tube as shown in figure 3-24

(more common for boiler flue-gas heat transfer). Air-to-air heat ex- changers may be purchased as packaged units or can be custom made.

They transfer sensible heat onlv and are not designed for cooling

applications. Size is limited only by the physical dimensions of the

space available.

The efficiency of each installation and cost should be calculated

based on the particular circumstances that apply. Although efficiency

of air-to-air heat exchangers generally is below 50%, it must be recognized

that they are relatively inexpensive, have low resistance to -air flow,

require no motive power input, and are trouble-free and durable.

3-85
GAS OUTLET

Figure 3-24. Flue-gas heat exchanger.
(3) Run-Around System

A limitation associated with rotary and air-to-air heat exchangers

is that the supply and exhaust ductwork must be close together. In some applications this may be physically impossible or very costly. In

addition, cross contamination caused by leakage from exhaust to supply

streams may be unacceptable when the exhaust contains noxious or poisonous fumes, or if there is a need for cleanliness.

Both of these disadvantages can be overcome by using a run-around

system (see figure 3-25) which consists of finned-tube water coils

located in the exhaust and supply air streams, and a pump circulating

water or a water /antif reeze solution between the coils.

In this form the system is for sensible heat recovery only. It is

seasonably reversible, preheating in the winter and precooling in the

summer. As with other heat-recovery devices, the coils are subject to

corrosion, condensation and the possibility of freeze-up.

Coils and pump are normally selected to achieve sensible recovery

efficiencies of 40% to 60%. Greater efficiencies can be achieved by

adding more coils in the heat exchangers to increase their capacity.

When finned tubing is added, however, the pressure drop across the coil

increases and more fan power is required for the supply and exhaust

systems. Additional tubing also increases the pumping energy required,

so gains in efficiency will be partially offset by increased energy

requir ements

If latent recovery is necessary, the system can be modified by

replacing the water coils with a cooling-tower surface; an additional

solution pump is needed to complete the system. This provides total

heat or enthalpy transfer as the solution absorbs heat and water vapor

from the air streams, and also acts as an air washer or scrubber.

3-87
Figure 3-25. Run-around system.

3-88
(4) Heat Pipe

A heat pipe is a passive heat exchanger which involves a closed

fluid within a sealed tube. A schematic of a heat pipe apparatus is

shown in figure 3-26.

Cool air passing over one end of the tube is heated when it condenses

the fluid enclosed in the tube. The warmer air stream passing over the

other end of the tube is cooled when it evaporates the fluid contained

in the tube. The action is reversible and operates whenever there is a temperature difference between either end of the tube.

To use a heat pipe apparatus for a heat recovery application, air

intake and air exhaust ducts for a HVAC system of a building must be

located close to each other. Heat recovery is achieved by installing a group of heat pipes between the air intake and the air exhaust ducts.

HEAT OUT HEAT IN

LI < FILLED i 4,4- UUNUtlMSAI IUIM tVAKUKAIIUN I I WICK

Figure 3-26. Schematic of heat pipe apparatus.

3-89
Any range of supply air cfm can be handled by the addition of more- tubes to the heat exchanger rack. In addition, they contain no moving

parts so there is minimal leakage between air streams. Mechanical

energy is not used except in the form of increased fan energy to

overcome static pressure losses.

(5) Shell and Tube Heat Exchangers

Shell and tube heat exchangers can be used to exchange heat in the

following configurations:

liquid- to- liquid

steam-to-liquid , and

gas-to-liquid

All three configurations are commercially available in a wide range

of sizes and outputs and with reliable heat exchange data.

Particularly favorable applications are to capture energy from hot

condensate, hot refrigerant gas, condenser water, and hot drain lines

from kitchens and laundries.

The heat exchanger should be insulated to prevent unnecessary heat

loss and should be constructed of materials to suit the application.

(6) Waste-Heat Boilers

Waste-heat boilers are used in conjunction with high- temperature

heat recovery as from engine exhaust and exhaust from gas turbines used

to drive refrigeration equipment or electric generators. In the case of

the turbine, a duct, similar to a breeching, is connected directly from

the exhaust of the turbine to the boiler. After passing through the

boiler the gases are discharged to the atmosphere. Gas turbines produce

about twice as much recoverable heat as reciprocating engines of the

same size. Generally, a turbine yields 7 to 13 pounds of steam per hour

(15 psi steam) per kilowatt generated. An overall system efficiency of

slightly over 65% is possible in total energy plants,* if all the re- coverable heat is used.

* A total energy plant is a plant which utilizes recovered heat from

electrical power generators to provide a portion of the energy re- quirement for space heating, domestic hot water, and space cooling.

3-90
(7) Double Bundle Condenser System

A double-bundle condenser is constructed with two entirely separate

water circuits enclosed in the same shell (see figure 3-27). Hotrefrigerant gas from the compressor is discharged into the condenser

shell where its heat is absorbed by either one of the water circuits or by both simultaneously depending on the requirements of the system at a given time.

One of the circuits is the building-water circuit and the other,

the cooling-tower circuit. The reason for splitting the condenser into

two independent hydronic circuits is to prevent contamination of the

building-water system with cooling-tower water, which may contain dirt

and undesirable chemicals. When a double- bundle condenser is used in

conjunction with a standard refrigeration machine, the heat rejected by

the compressor is made available to the building-water circuit.

In certain heat recovery application the amount of heat that can be

reclaimed during occupied hour may exceed the daytime heating requirements of perimeter zones. This excess heat can be stored for release

during times when the building is unoccupied.

The cost of installing a . double-bundle condenser system is such

that, as a replacement, it probably will be most feasible for a system

which already is at or neat the end of its useful life.

For more extensive discussions of these topics, and for a review of

the economic basis for decision making in waste-heat recovery, the

reader is referred to the National Bureau of Standards Handbook 122,

"The Waste Heat Management Guidebook" [14]

3-91
1

I 4.

Figure 3-27. Waste-heat recovery from central chiller using

double-bundle condenser.

3-92
Ref er ences

1. Reducing Fuel Consumption with Night Setback, L. W. Nelson,

ASHRAE Journal, August, 1973.

2. ASHRAE Handbook and Product Directory , Systems Volume, American

Society of Heating, Refrigerating and Air-Conditioning Engineers,

Inc. , 1973.

3. Energy Saving in Residential Buildings, L. W. Nelson and J. R. Tobias,

ASHRAE Journal, February, 1974.

4. The Nature of Thermal Comfort for Sedentary Man, R. G. Nevins and

F. H. Rohles, ASHRAE Transactions, Volume 77, Part 1, 1971.

5. Air Force Design Manual Criteria and Standards for Air Force Construction , Air Force Manual AFM 38-15, 1975.

6. Test Methods for Air Filters, R. S. Dill, ASHVE Transactions,

Vol. 44, page 379, 1938.

7. ASHRAE Handbook and Product Directory, Equipment Volume , American

Society of Heating, Refrigerating and Air-Conditioning Engineers,

Inc. , 1975.

8. Guidelines for Saving Energy in Existing Buildings, Building Owners

and Operators Manual ECM 1, Federal Energy Administration, 1975.

9. Guidelines for Saving Energy in Existing Buildings, Engineers,

Architects, and Operators Manual ECM 2, Federal Fnergy Administrat ion , 1975.

10. Heating Fuel Conservation, R. A. Mesiter, Plant Engineering, July,

1974.

11. Energy Monitoring Control Systems, R. E. Dant, Engineering and

Services Quarterly, August, 1976.

12. Waste POL Disposal through Energy Recovery, Lt. P. T. Fink, AF Civil

Engineering Center, AF Systems Command, Tyndall AF Base, Report

//AFCEC TR-76-2, Report in printing (1977).

13. The Engineering Basics of Power Factor Improvements, Irwin Lazar,

Actual Specifying Engineer, 1975.

14. The Waste Heat Management Guidebook , K. G. Kreider and M. B. McNeil,

NBS Handbook 121, 1977.

3-93

CHAPTER 4. CONDUCTING THE BUILDING SURVEY

CONTENTS

PAGE

4.1 Introduction 4-2

4.2 Prime Targets 4-3

4.2.1 Buildings Wasting Energy by Heating and

Cooling Simultaneously 4-3

4.2.2 Buildings with Structural Defects 4-7

4.2.3 Facilities Used for Purposes Other than Originally

Designed 4-12

4.3 Identifying Condensation Problems 4-13

Appendix: Data Sheet for the Building Survey 4-20

4-1
CHAPTER 4. CONDUCTING THE BUILDING SURVEY

4. 1 Introduction

The building survey is a physical reconnaissance of a building for

the purpose of identifying defects in the building and non-energyconserving practices which when corrected or modified will bring about

cost-effective reductions in energy requirements. The building survey

must be thorough enough to accurately assess the major factors which

contribute to the consumption of energy in the building. To assist the

Base Civil Engineer in carrying-out the building survey, a data sheet is

given in the appendix at the end of this chapter.

After a Base Civil Engineer has surveyed the buildings on his Base,

he should be in a position to identify a vast number of energy conservation measures for the various buildings. An energy and economic analysis

of all the reported technical options for energy conservation would be

very tedious and time consuming. To assist the Base Civil Engineer in

quickly identifying those areas having the greatest impact on or potential for energy conservation, some major target areas*are outlined in

section 4-2.

Another important aspect of the building survey is the identification of condensation problems in roofs, walls and floors. For example,

accumulation of moisture within the sidewalls of buildings often leads

to paint failure; excessive moisture accumulation in some instances may

contribute to rotting of wood siding and in masonry construction cause

mortar to loosen or degrade caulking and weatherseals. Accumulated

moisture may also wet insulation and reduce its insulating properties.

In addition, the accumulation of moisture in wood siding may cause buckling and warping of wood siding which in turn may create cracks in the

construction through which air infiltration may occur. Before additional

insulation is installed, it is imperative that potentially serious

*Note: The Air Force has several high energy-consuming testing complexes

which consume excessive amounts of energy. A discussion of energy

conservation measures for such facilities is beyond the scope of

this report.

4-2
condensation conditions such as improper attic ventilation be identified

and corrected, since more insulation may aggravate the problem. The

identification of condensation is covered in section 4-3.

4.2 Prime Targets

Viewed from either within or without, prime targets are:

1. Buildings wasting energy by heat and cooling simultaneously.

2. Buildings with structural defects.

3. Facilities used for purposes other than originally designed.

The three targets are discussed in the following sections.

4.2.1 Buildings Wasting Energy by Heating and Cooling Simultaneously

Energy wasted. under this condition is caused by excessive heating

or cooling due to improperly regulated heating, ventilating, and air

conditioning (HVAC) equipment. Unusual occupant reactions are a clue to

this problem. The normal reaction of a human being exposed to uncomfortable temperature extremes is to "adjust" the physical conditions or move

to a more hospitable environment. Windows and doors deliberately opened

to the outside when they should be normally closed are an obvious clue

to an improperly regulated heating or cooling system. There are other

defenses erected by building occupants such as blocking ventilator

openings, by-passing controls, etc. These energy-wasting conditions may

exist in any type of Air Force building and may be confined to one or two rooms, or they may affect the complete building. Occupant reaction

varies, but if windows are opened in an attempt to regulate the heating

or cooling system, the result is usually wasted energy and an unbalanced

HVAC system. Ideally, the best time to identify the foregoing is while

temperatures are high or low. Identifying such conditions is easy; finding

the cause may not be so easy. A brief check list of probable causes

includes

A. Malfunctioning temperature or regulator controls . B . Adjustment of temperature or regulator controls by unauthorized

personnel .

C. Controls improperly influenced by the environment . The cause may be direct radiation from heat sources including

the sun, excessive air movement over the thermostat or behind the

wall in or on which the thermostat is mounted.

4-3
D. Malfunctioning heating system . The design of a heating system may be the cause of overheating

or underheating. Such a condition may be found in buildings altered

from their original function. It may occur in a system using chilled

water coils over which preheated air is passed. Control malfunction

or modification of the original design may result in a preheat cycle

not matched to the load requirements.

E. Fresh air intake dampers . Motorized controls used to regulate fresh-air intake dampers

should be periodically checked for proper operation. Dampers should

normally return to a closed position when fresh air is not required.

In certain buildings no fresh air is required for unoccupied periods.

Prior to the energy shortage, many systems were designed with first

costs in mind. As a result, energy savings controls were frequently

deleted from the design, resulting in the loss of conditioned air

due to improperly regulated dampers. There are control systems

available which will remedy this problem. They will return their

initial costs in energy savings within a few years. Control specialists are available who can provide guidance in the selection of

control system packages.

F. Building exhausting conditioned indoor air to the atmosphere . Obvious vapor plumes caused by indoor air exhausted into cold

atmospheres may be visible evidence of energy waste. Normally,

however, air exhausted from a building often is not readily detectable. The volume of indoor air exhausted to the atmosphere depends

on the building function. Dining halls require almost constant

ventilation, whereas electrical maintenance shops do not. Therefore,

each type building must be considered separately. The effect of

exhausting large amounts of air from a building is to create a negative pressure and to substantially increase the infiltration of

outside air, thereby substantially increasing the energy requirement

for space heating and space cooling. The air pressure difference in

extreme cases may make opening and closing of entry doors difficult

and dangerous. A pronounced inside-to-outside pressure difference

4 -4 .
often creates a moaning or whistling sound around doors and windows

as the air is pulled inward. This sound is a clue to investigate

further. The effect on the heating and cooling system is to create

an unbalanced condition causing erratic temperature control. Under

extreme conditions, the infiltrating air (especially if it is cold)

will cause a variety of occupant reactions. These vary from erecting artificial wind barriers to blocking distribution outlets and

returns. Controls affected by infiltrating air are often the cause

of overheating or overcooling.

G. Freight doors remaining open during loading and unloading

operations . It is obvious that a great deal of energy is wasted by attempting to provide space heating for a warehouse when one side of it may

be literally open to the outdoors during loading or unloading operations. There are, however, certain corrective alternatives available such as the use of expanded rubber dock-doors that form an air

seal to the back entrance of large trailer trucks.

Several side effects show up as a result of the freight doors

remaining open. Not only is indoor air flushed from the bay which

is served by the open door, but it may also be flushed from other areas under certain conditions as shown in figure 4-1. Due to the

extraordinary volume of air exchanged under such circumstances, dirtladen air is circulated and deposited on heating system components.

This tends to further aggravate energy waste by reducing the operating efficiency of the heating and cooling equipment.

H. Hangars

The heating or cooling of a whole hangar to comfort temperature

levels may be inconsistent with the Base energy conservation programs. There may be circumstances, however, when it is required.

Normally it is not economical to maintain comfort levels in highbay structures with loose fitting doors typical of aircraft hangars.

Hangars are obvious energy consumers. Recommended procedures are

to maintain temperature levels in the main hangar space at 55° F or lower and office space at 68° F during occupied periods in the

winter.

4-5
DOOR OPEN DOOR OPEN

Figure 4-1. Effect of multiple open doors on heated air in adjoining

bays of a warehouse.
4.2.2 Building with Structural Defects

Structural defects and the accumulation of many smaller cracks may

cause a high rate of air infiltration which in turn contributes significantly to the energy requirement for space heating and space cooling.

There is the obvious hole in the wall and the not-so-obvious hole. A

gaping 6-sq ft hole is more readily identified and repaired than are

a series of cracks through which air leaks, even though the sum of these

cracks may be equal to a 12-sq ft hole. These "little openings" tend

to be overlooked because they are cracks; however, each one is a defect

and will very likely get worse, not better, leading to further deterioration. The greater the difference between inside and outside temperatures, the more likely that small fissures will become big problems,

especially in a zone in which many freeze/thaw cycles occur during the

winter. Keep in mind that air infiltration into heated spaces will

contribute much more to the energy requirement for space heating and

space cooling than air infiltration into unheated spaces such as crawl

spaces. Structural defects resulting in significant heat loss due to

air infiltration are described below:

4.2.2. 1 Foundations and Basements

There is often a crack between the sill plate and the top of the

foundation wall of wood-frame buildings. It may not be readily seen,

but the moving air can often be detected by holding your hand in the

suspected area. Smoke from a cigar or cigarette may also be used to

identify air infiltration. Trace all water, gas, electrical conduit,

and communication equipment wiring to the respective entry points and

check for gasketing or properly installed caulking around the penetration. Other sources of infiltration are windows, coal access doors,

outside entries to the basement area, and underground trenches carrying

steam lines or communication wiring.

A check also should be made for old furnace flues now unused because

of replacement of the heating plant with a non-combustion type. These

flues should be capped at both ends. The effect of air passing over an open chimney creates a negative pressure at the base of the flue and

induces air infiltration.

4-7
If the basement is under only part of the building, look for access holes to other unheated regions such as crawl spaces. These regions may

or may not be vented. Some typical sources of heat loss in basements

are depicted in figure 4-2.

4. 2. 2. 2 Slabs on Grade

Air leaks occur where the wall has parted from the slab or where

there is a penetration through the slab. These openings may not be

visually detected from either the inside or the outside unless smoke is

used, as outlined in the section under basement air leaks. Telltale

signs of air leakage are inside traces of moisture at the wall/floor

interface. Also look for water stain marks on basement trim or on the

walls. There may be evidence of water damage to flooring materials at

the perimeter edge which is also a likely indicator of an air leak.

Caution: The lack of or defective perimeter slab insulation may also be

the cause for condensation or frost, and result in water damage along

slab perimeters. Also, under certain adverse conditions, hydraulic

water pressure may force water up through small hair-line cracks in the

slab, with obvious results.

4. 2. 2. 3 Unheated Crawl Spaces

Crawl spaces may be found under bachelor quarters, dormitories, or family housing units. Access is usually difficult and detailed inspection is a less- than-pleasant chore. The crawl space is frequently one

of the major contributors to, or direct causes of, other structural or operational problems. In freezing climates, crawl spaces should be

checked for the following:

° All plumbing, including traps on sanitary sewer lines

should be insulated to Air Force specifications for the

area

° Air infiltration may be occurring around plumbing pipes,

especially to bath tubs. Check the plumbing access panel

behind the tub to verify this condition.

° Air may also be infiltrating around chimney flues which

have their foundation beginnings in the crawl space.

4-8
I;

Finure 4-2. Typical sources of air infiltration in a basement

4-9
Holes for electric wires or conduit resulting in drafts in

interior walls may be detected by feeling around interior

wall outlets or switch plates. The worst draft conditions

(potential freeze-up) will usually be found where oversized

openings have been made to accommodate plumbing and heating

pipe runs.

4. 2. 2. 4 Structures Supported on Blocks/Posts

Buildings supported on blocks or posts are either temporary or located in environments where this is a practical building technique due

to the environment. Since the climates permitting this type of structure

are mild to tropical, the primary need is for air conditioning. The

comments under crawl space are applicable to this type construction.

4. 2. 2. 5 Walls

The search for telltale signs on walls should be conducted on the

exterior first and interior last. Walk completely around the building

noting its orientation to the points of the compass. Weathering of

various exposed sides of buildings will be repeated on wall surfaces

exposed to similar weather conditions, i.e. south and west exposures

have more surface weathering, since they face prevailing winds, rain and

sun. The north side may show indications of mold, mildew or moss due

to less intense solar exposure. Some geographic areas may produce

unique weather characteristics on building surfaces due to exposure ex- tremes such as desert sand blasts, salt air, or artic temperature.

Note structural faults, such as broken or cracked foundations and

walls. These faults may be the result of neglect or poor maintenance.

They may also indicate a more serious problem behind the facade of the

building envelope. It is important to ascertain the cause of structural

faults

A crack in a large plate glass window, dark stains on siding, calcification of masonry surfaces, and paint failure may be signs of serious problems. For instance, did the plate glass crack due to physical

impact, thermal shock, or excessive wind load; or is the foundation

settling and distorting the window frame? Are the dark stains dirt or mildew, or are they caused by water leaks which left a residue of foreign

4-10
substances? Are white stains on masonry surfaces (calcification) caused

by a water leak on the back side of the facade or because moisture

migration forced salts to the surface? Is paint failure due to poor

painting practices, or is it caused by moisture migration? Is rust

streaking the result of fastener heads oxidizing or is there a leak at

the joint where the fastener has worked loose?

The observer will certainly note the Air Force requirements for

double glazing, window and door weatherstripping, and the need to caulk

minor cracks, wherever they appear.

Accumulated ice dams on roof edges, valleys, gutters, and downspouts will force water into building sidewalls, roofs and ceilings.

External damage from these conditions is usually evidenced by water

marks, severely weathered surfaces, distorted flashing and gutters, and

curled shingles.

Air conditioning equipment should be checked for unusual noise and

abnormal accumulation of debris inside equipment cabinets. If winterizing covers are needed, they should fit snugly to the unit.

4. 2. 2. 6 Ceiling/Roofs

An important aspect of the inspection of the building interior is

the space between the finished ceiling and the roof. It may be six

inches or six feet in height, but without exception it must incorporate

two components. They are insulation and adequate ventilation. Check

AFM 88-15 for specific requirements.

A visual inspection may be difficult due to space restrictions, but

look for evidence of unvented moisture collecting on the underside of

the roof sheathing or decking. Water stains, rusty fasteners, mildew,

and wood rot are all signs of high moisture levels.

Wherever there is a penetration through the roof, look for evidence

of water leaks. Rain water that leaks through a defective roof and wets

ceiling insulation may substantially increase heat transmission through

the ceiling. In geographical areas of 7000 degree days or greater, snow

loads on roofs can exceed the rating of structural support. Broken or distorted support members are readily identified.

4-11
The roof is often the "forgotten" member of the building. "Out of

sight, out of mind" is a trite but apt expression epitomizing the

attention normally given to this important component. The "if it

doesn't leak, it must be OK" theory may be reassuring, but it is no substitute for knowing. . . especially if a leak-forming condition is

in the early stage. For shingle roofs, check the ridge lines for sagging and look for curled shingles (evidence of moisture in roof sheathing) , torn or missing shingles, arid loose flashing.

For built-up roofing systems, moisture accumulation in the insulation may substantially increase heat transmission through the roof.

Signs to look for which indicate a possible moisture problem include

standing water, plugged storm drains, imperfectly sealed expansion

joints and imperfectly sealed flashing at roof edges, parapet walls and

roof penetrations. Not easily detected are small bubbles, wrinkles, or heaving which may be caused by conditions of moisture, temperature,

stress, or other structural faults already mentioned.

4.2.3 Facilities Used for Purposes Other Than Originally Designed

When buildings are used for purposes other than originally designed, often modifications may have been performed without proper

consideration for energy conservation. For instance, office spaces in

hangars may be installed without wall and ceiling insulation. In such

instances, when the interior temperature within the hangar is maintained

at a low level and the office spaces are heated, excessive heat loss may

occur. Other typical situations in which buildings are used for purposes other than originally designed include:

A. Dormitories converted to offices

B. Warehouses converted to offices

C. Sheds converted to service shops

D. Basement rooms converted to day rooms. There are other conversions not mentioned, but the important question

is, does the conversion operate satisfactorily? Was the reason for the

conversion to meet a temporary need or was there a long range plan?

If the installation has become "permanent," examine it for structural defects as previously outlined.

4-12
4. 3 Identifying Condensation Problems

The identification of moisture problems is an important aspect of

the building survey. Moisture accumulation in wood siding may lead to

paint failure, as indicated in figure 4-3. Excessive moisture accumulation may actually lead to wood rot which may substantially shorten the

life of a building. Moisture may also accumulate in the sidewall insulation material, thereby reducing its insulating properties. In addition, the accumulation of moisture in wood siding may lead to warped

and bowed boards which in turn may create cracks in the construction

through which air infiltration can occur. Paint failure may also be caused by poor surface preparation and

poor paint systems. It is necessary to look for other symptoms before

diagnosing a moisture problem. In some frame construction, a close

examination of a newly painted surface may reveal water blisters, as shown in figure 4-4. Bowed and warped boards may also be observed, as shown in figure 4-5. If paint peeling is observed without the presence

of any of the foregoing symptoms, there is a good chance the paint

peeling is not moisture related. Moisture condensation within building

surfaces is usually not seen. It becomes obvious when sufficient moisture has accumulated to cause discoloration, rusting, or other water

damage to building components. Excessive wetting of components such as insulation, structural framing, or masonry cause these components to

function in a changed design mode. They become a means of conducting

heat. They change structurally, assume new forms, emit odors, and may

sustain permanent damage.

Winter condensation problems in attics and sidewalls tend to

become more severe as one proceeds north. Generally, winter condensation problems are considered to be significant at those locations for

which the January average temperature is 35° F or lower. A map showing

the condensation zone of the United States is given in figure 4-6.

Whenever condensate is present, it is most important to identify the

cause and take appropriate corrective action.

4-13
Figure 4-3. An example of paint failure for which moisture

may be a contributing factor.

4-14
Figure 4-4. Blistering of paint due to the outward

movement of water vapor.

4-15
V.

Figure 4-5. Bowed and warped boards which may create cracks in

construction through which air infiltration can occur.

the

4-16
Figure 4-6. Winter condensation problems occur where the average

temperature for January is 35° F or lower (taken from

"Condensation Problems: Their Prevention and Solution,"

by L. A. Anderson, U.S.D.A. Forest Service Research

Paper FPL 132, Forest Products Laboratory, Madison,

Wicsonsin, 1972)

4-17
The two principal causes of excessive sidewall condensation in most

buildings are the lack of any or an improperly installed vapor barrier,

or excessive indoor humidification. During the building survey, the

presence of indoor humidifiers should be noted. A good indication of

excessive humidification is water marks on the inside wall surface under

the windows. These marks are due to water that has condensed on the

window panes during the winter season. If signs of moisture problems

are observed during the building survey, an inspection of the affected

area should be made to determine the cause. Installing a vapor barrier in an existing building is not feasible

unless major renovation is under way. If such is the case, the best

barrier or membrane is one of 2.0 to 4,0 mil polyethylene film.

Installation should be done with great care to avoid any cracks or openings through or around the film. The air inside a building in the

winter contains a large amount of water vapor compared to the outdoor

air and tends to seek minute openings and pass through them.

If the above technique is not practical, consider the use of

vapor- impermeable paints or finishes such as waterproof paints, spar

varnishes, and aluminum paint. These products are applied only to

interior surfaces of walls exhibiting moisture problems and then covered

with a cosmetic finish.

If none of the above is practical then consider the use of an exhaust fan regulated by a humidistat. Controlling the indoor relative

humidity of a building will effectively reduce the movement of water

vapor through the building envelope.

It is essential to the energy conservation program that buildings

do not accumulate excessive amounts of moisture. The accumulation of

moisture in wall insulation may increase heat transmission through the

wall. In addition, moisture accumulation in wood siding may cause warping and bowing of the siding which in turn may create cracks in the

construction through which air infiltration can occur. During the building survey, it is important to note the status of

attic ventilation openings. In the past the attic may have been closed

off to prevent freezing of pipes or for other reasons. The addition of

4-18

1
insulation to a completely closed-off attic will often lead to serious

condensation problems. The increased amount of ceiling insulation substantially reduces attic temperatures and thereby significantly increases

the likelihood for water vapor to condense on cold surfaces. It is

extremely important that closed ventilation openings be reopened before

more insulation is installed in an attic.

In an obvious effort to improve thermal performance of roof decks,

it is customary to add additional insulation. However, before any

insulation is installed underneath or on top of an existing roof deck,

expert advice should be sought. Adding insulation without full knowledge

of the present roof condition, moisture membrane, potential temperature

difference and shifting of dew point, as well as roof loading factors,

may negate any energy savings promised by the addition of more insulation.

4-19
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4-27

CHAPTER 5. MEASUREMENTS FOR IDENTIFYING ENERGY

CONSERVATION POTENTIALS

CONTENTS

Page

5.1 Introduction 5-2

5.2 Assessing the Thermal Transmission Characteristics 5-2

5.2.1 Infrared Thermography 5-2

5.2.2 Measuring Air Leakage in Buildings 5-10

5.2.3 Energy Use Indexes 5-15

5.2.4 Detecting Moisture in Built-up Roofing Systems 5-16

5.3 Assessing the Thermal Performance of Building Equipment 5-17

5.3.1 Outside Make-up Air 5-17

5.3.2 Indoor Environment 5-20

5.3.3 Building Equipment 5-21

5.4 Energy Audit for Central Plants 5-23

5.4.1 Steam and Hot-Water Generating Plants 5-23

5.4.2 Chilled-Water Plants 5-25

References 5-28

5-1
CHAPTER 5. MEASUREMENTS FOR IDENTIFYING ENERGY

CONSERVATION POTENTIALS

5. 1 Introduction

This chapter presents several simple measurement techniques for

assessing the thermal transmission characteristics of exterior building

envelopes; the thermal performance of HVAC and hot water heating equipment; and the operating efficiency of central hot water, steam, and

chilled water generating plants—for the purpose of identifying and

evaluating their respective energy conservation potentials.

5. 2 Assessing the Thermal Transmission Characteristics

5.2.1 Infrared Thermography

Infrared (IR) thermography is a powerful techniaue for identifying

potential areas for energy conservation. In this technique, an IR

television camera is used to produce a thermal picture (or temperature

profile map) of a surface or region under study. The thermal picture is

displayed on a television screen which may be photographed for record

and documentation. Regions of high heat loss and high energy waste

stand out in marked contrast with respect to other parts of the surface

being viewed and therefore may be readily identified. Once suspected

regions of energy waste have been identified, a physical reconnaissance

of these regions is necessary to verify the extent of energy waste and

to develop recommendations for corrective actions to reduce energy con- sumption at those points.

Infrared thermography is based on the principle that all objects

radiate thermal energy (E) according to the relation:

E = e*a*T

4

(1)

where e = emissivity of the surface

a = S tef an-Boltzmann constant

T = absolute temperature

5-2
An IR television camera senses the thermal radiation emitted from a surface. When the emissivity of the surface is known, the thermal

picture produced by an IR television camera may be converted into a temperature-profile map of the surface being viewed. Regions of high

heat loss on buildings are comparatively warmer than other parts of the

buildings when viewed from the exterior and will therefore stand out in

contrast with respect to other regions

An important point is that regions may appear different in the

thermal picture due to differences in the emissivities of the surfaces

being viewed. It is fortunate that most building materials and paints

(with the exception of metallic paints) have emissivities which range

between 0.85 and 1.0. Differences due to emissivities over this range

will have a small effect on the thermal picture produced by the IR television camera. However, one must become concerned with emissivity

effects when unpainted metallic objects are viewed by an IR television

camera

5. 2. 1.1 The Infrared-Television System

Generally, an IR television system consists of an IR television

camera, a black-and-white display console, and possibly a color-display

console. These components can be housed as separate pieces of equipment or combined into a single module.

The IR television camera works very much like a studio television

camera. A surface is scanned by the IR camera by a series of horizontal

trace lines. A video signal is produced by the camera. At any instant,

the intensity of this video signal is a function of the thermal radiation

entering the IR camera. The video signal from the IR camera is processed

in the black-and-white display console where it is converted into a thermal picture in which the gray tones in the picture approximately

correspond to surface temperature.

If the system has a color monitor, the color monitor will assign

separate colors to various levels of the video signal. The resulting

picture displayed on the color television screen is a thermal picture

in which the temperature range has been subdivided into various regions,

each coded with a different color. The advantage of a system having a

5-3
color monitor is that an abrupt change in contrasts occurs upon passing

from one region to another of slightly higher or lower temperature.

In terms of 1976 prices, IR television systems range from $30,000

to $60,000. Many companies also rent equipment. There are a large

number of consulting firms which could perform infrared surveys of Air

Force facilities.

5. 2. 1.2 Applications

An aerial IR survey of the facilities of an Air Force Base will be

useful in :

° identifying defective pipe insulation and steam leaks

in underground heat-distribution systems

° locating regions of built-up roofing systems having wet

insulation.

These applications are discussed below.

A National Bureau of Standards aerial survey of the underground

heat-distribution system at Arnold Air Force Base showed that the earth

above pipes with good insulation buried 6 to 10 feet could not be distinguished in the thermal picture. On the other hand, the earth above

pipes with defective insulation stood out in marked contrast with

respect to the ground surface 15 to 20 feet away from the pipe.

In the case of built-up roofing systems, a major problem is leaks

which develop in the top membrane that permit rain water to enter the

roofing system. Since the bulk of the top membrane remains impervious

to water vapor, the escape of moisture is a very slow process. The

build-up of moisture in many instances wets the roof insulation and

significantly reduces its insulating capability, thereby permitting high

heat loss through those regions having wet insulation. Infrared

thermography has been shown to be effective in identifying regions of a built-up roofing system that have wet insulation [1]*. Once such

regions are identified, repairs can be performed selectively on those

regions having defective membranes and wet insulation underneath. This

* Numbers in brackets indicate references at the end of chapter.

This report also discusses the use of nuclear moisture meters.

5-4
is significantly less costly than installing a whole new roof system on

a large building.

Another application of IR thermography is the location of major

heat leaks in buildings. Figure 5-1 shows a conventional photograph in

the visible spectrum of a test house at the National Bureau of Standards

The same view of the test house is shown in the IR spectrum in figure

5-2. Note that the major heat leaks (the windows, chimney, and louvered

ventilation opening) stand out in marked contrast with respect to other

regions displayed in the thermal picture. Further information on the

use of IR thermography to identify heat leaks in buildings may be found

in references [2-4].

Still another area of application for IR thermography is the survey

of utility services devices such as:

° defective electrical connectors

0 defective steam traps

° aboveground pipe insulation.

As an example, figure 5-3 shows a photograph in the visible spectrum of

electrical connectors on a transformer. The same group of electrical

connectors is shown in the IR spectrum in figure 5-4. Note that the

center electrical connector, which is defective, stands out in marked

contrast with respect to the others.

When interpreting IR photographs, other factors in addition to

variation in the surface heat-loss rate may produce differences in the

thermal picture. As previously discussed, variations in surface

emissivity may also produce changes in the thermal picture. In addition

when a thermographic survey is conducted during the day, surfaces which

have different solar absorptivities will be heated to different degrees

by solar radiation. This latter effect may cause dark-colored surfaces

to be warmer than light-colored surfaces. For this reason, when information on relative heat-loss rates through various building surfaces is

sought, it is best to conduct IR surveys at night in order to eliminate

solar radiation effects.

Further information on the various measurement techniques using IR

thermography is given in reference [2].

5-5
Figure 5-1. Conventional photograph of a test house at NBS [4].

5-6
Figure 5-2. Infrared picture of the NBS test house

shown in figure 5-1 [4],

5-7
Figure 5-3. Conventional photograph of electrical connectors on

a transformer.

5-8
.

I

J

Figure 5-4. Infrared picture of electrical connectors

on the transformer shown in figure 5-3.

5-9
5.2.2 Measuring Air Leakage in Buildings

Air exchange between the indoor and outdoor air usually accounts

for a quarter to a half of the heating and cooling loads of buildings.

An important part of a measurement program for identifying energy

conservation potentials for buildings is to assess the air-leakage

characteristics of various buildings located on the Base. Those

buildings having leaky construction need to be identified, so that

retrofit actions can be implemented to reduce their air-leakage rates.

In addition, once buildings of leaky construction have been identified,

further measurements can be performed to locate major air-leakage paths.

In general, air leakage occurs through cracks around doors and

windows and through openings (such as ventilation exhaust openings).

Another path, which is often not considered, is air permeation through the

seemingly solid construction. This latter air-leakage process becomes

significant when construction materials having high permeability are used.

The driving forces which cause air leakage are the inside-tooutside temperature difference and wind velocity. In the winter, the

air inside a building is considerably warmer and therefore lighter than

the outdoor air. Since it is lighter, the indoor air tends to rise and

leak out through the top parts of a building. Cold air is drawn into

the building through cracks and openings at the lower level. When wind

strikes a building, it produces an elevation in pressure on the exposed

side and a depression in pressure on the leeward side. These induced

inside-to-outside pressure differences also cause air infiltration to occur

This section describes a few measurement techniques for assessing

the air tightness of buildings and for locating specific air-leakage

paths.

5. 2. 2.1 Measuring Natural Air-Infiltration Rates

The air-infiltration rate of a building is customarily expressed in

air changes per hour. A technique for measuring the rate of air infiltration is the tracer-gas method.

The procedure for performing such a measurement is to release a small quantity of tracer gas (such as sulfur hexafluoride or helium)

inside a building and to allow this tracer gas to become uniformly mixed

5-10
with the indoor air. This is often conveniently accomplished by injecting

the tracer gas into the return duct of the air-distribution system.

Allowing the air distribution system to run continuously will usually

provide uniform mixing of the tracer gas with the indoor air. The

concentration of the tracer gas decays as the building exchanges air

with the outdoor environment. By measuring this decay as a function

of time, the air-infiltration rate for the building may be determined.

If the air-delivery system is operated continuously, the concentration

of tracer gas in the indoor air may be conveniently measured by sampling

the air in a major supply duct.

The following factors may produce errors in tracer-gas techniques:

° non-uniform mixing of the tracer gas throughout the occupied

space of the building

° errors in the measurement of tracer-gas concentration.

A complete discussion of the foregoing factors and other error-producing

mechanisms may be found in reference [6].

An advantage of the tracer-gas technique is that it measures the

air changes per hour for a building under natural driving forces of

wind velocity and inside-to-outside temperature difference. Additional

information on the tracer-gas technique may be found in references [5,6].

5. 2. 2.

Measuring the Air-Tightness Characteristics of Buildings

An important part of an air-infiltration measurement program at a Base is to rank buildings according to their air-tightness characteristics.

It is very difficult to obtain meaningful comparative data on the airleakage characteristics of buildings using the tracer-gas technique, since

the measured air-changes per hour for every building depend significantly

on the wind velocity and indoor-to-outdoor temperature difference. It is

not practical to attempt to measure air-infiltration rates for a group of

buildings at identical wind velocities and temperature differences. A

more suitable technique for ranking the air-tightness of a group of

buildings is the pressurization technique.

The procedure for the pressurization technique is to introduce outdoor air into the interior of a building, thereby imposing an induced
air- inf ilt rat ion rate. This may be accomplished by connecting a centrifugal air blower to a building through a flexible hose, as shown in

figure 5-5. The air-delivery rate of the blower is adjusted until the

* inside-to-outside pressure difference is 0.3 inches of water column

as measured with a water manometer. For residential buildings, a recent

study [8] found the required ft /min to be between 0.08 to 0.17 ft /min

per cubic foot of indoor volume, depending on the air tightness of the

tiouse . Once this condition is attained, the air—delivery rate is measured

with a suitable flow-measuring device (see diagram of figure 5-5) and the

number of induced air changed per hour (I) is calculated from the

relation

I = W-60/V (2)

3 where W = air-delivery rate of blower, ft /min

3

V = inside volume of building, ft . A single rating figure which characterizes the air-tightness of a building is called the "air-tightness figure ", which is defined as the

number of induced air changes per hour per unit surface area of the

exterior building envelope. The air-tightness figure is obtained by

dividing the induced air changes per hour (I) by the surface area of

the exterior building envelope. Retrofit actions to reduce air leakage

should be applied first to those buildings having the highest air-tightnes

figures.

When buildings are pressurized for this technique, the principle

driving force for air infiltration is the inside-to-cutside pressure

difference. Under natural conditions, the driving forces for air

infiltration are the stack effect and wind-induced pressure gradients

across various components of the building. Under natural conditions,

the stack effect causes air to exfiltrate at the top levels of a building

and to infiltrate at lower levels. On the other hand, when a building

is pressurized, air exfiltrates at all levels. Therefore, the airinfiltration patterns are different under pressurized conditions in

contrast to natural conditions. Further information on the pressurization

technique may be found in references [7,9].

*For very large and leaky buildings such as hangars, it may be more

practical to perform measurements at a lower AP.

5-12
5-13

Figure

5-5.

Schematic

illustrating

the

pressurization

technique.
5. 2. 2. 3 Locating Specific Air-Leakage Paths

Once particular buildings have been identified as having comparatively high air-tightness figures, it may be desirable to perform

additional measurements to locate the major air-leakage paths for these

buildings. Retrofit actions may then be taken to eliminate these airleakage paths. Two measurement techniques suggested for this purpose

are infrared thermography (discussed in section 5.2.1) and the smoke

technique.

The procedure for performing the smoke technique is to release

colored pyrotechnique smoke in the various rooms (zones) of a building.

The smoke is permitted to fill uniformly the interior of the building,

after which the building is pressurized using a centrifugal blower as shown in figure 5-5. Major air-leakage paths will be dramatically

displayed by effusing smoke. A disadvantage of this method is that many

pyrotechnique smokes leave a chaulky dust layer over interior furnishings

which may require a substantial clean-up effort. Further information on the smoke technique may be found in reference [4].

The preceding techniques are effective for measuring natural air

infiltration rates and air-tightness of buildings, and for locating

specific air-leakage paths. They may be useful to determine which

buildings are the best targets for retrofit actions. However, two

additional factors should be considered in determining the energyconservation effectiveness of retrofit measures.

0 Retrofit actions to reduce air leakage may not be effective

in reducing heating and cooling energy requirements for

buildings that are of tight construction to begin with.

0 Substantial air leakage may still exist after all major airleakage paths have been eliminated, since a significant amount

of air leakage sometimes occurs as a result of air permeation

through the ceiling, walls, .and floor.

5-14
5.2.3 Energy Use Indexes

The Energy Use Index (EUI) , defined as the total annual energy (in

Btu’s) consumed by a building per gross square foot of conditioned floor

area, is a single-figure energy-consumption index which may be used to

rank buildings according to their energy consumption. Energy-use-index

data can also be used to monitor the success or failure of an energyconservation program.

The following buildings or groups of buildings are presently

individually metered on most Air Force Bases:

0 family housing, metered as a group

0 hospitals

0 Base exchanges

° commissaries

° clubs

Energy-use-index data could readily be derived for these buildings.

Other buildings on Air Force Bases are generally not individually

metered and it would be more difficult to obtain energy use indexes.

If each Air Force Base were to develop EUI data for the foregoing

building types, comparison of the energy consumption of these buildings

could be obtained throughout the Air Force. A compilation and analysis

of EUI data on these types of buildings could lead to the development of

guidelines for distinguishing between energy-efficient and energywasteful buildings. In addition, the success or failure of Base-level

energy conservation programs for these buildings could be readily monitored.

In a recent study [10], the following factors were identified as having a significant effect on the energy use indexes for buildings:

0 total building refrigeration capacity

° cooling system operating hours

0 type of HVAC system

° thermal transmittance of the gross exterior wall area

° lighting power density

0 operation of computer and data systems

computer-room operating hours.

5-15
An analysis of these factors is given in reference [10]. In a strict

sense, EUI’s should be compared for buildings which have approximately

the same seven factors.

Further information on energy use indexes may be found in references

[ 10 , 11 ].

5.2.4 Detecting Moisture in Built-up Roofing Systems

When the top membrane of a built-up roofing system cracks due to

weathering or is inadvertently punctured, rain water is able to penetrate

the roof system. Since the bulk of the top, vapor-impervious membrane

is intact, the escape of water is a very slow process. The accumulation

of moisture may wet the insulation and reduce its insulating properties,

thereby causing high heat transmission to occur through those portions

of the roof having wet insulation. If the regions having wet insulation

could be located by some means, local repairs could be made on those

defective portions instead of replacing the complete roof system.

The following methods are available for investigating the moisture

content of built-up roofing systems:

° infrared thermography (discussed in section 5.2.1)

° nuclear moisture meters

° resistivity measurements

° dielectric moisture meters.

Determining the moisture content of a built-up roofing system

using a resistivity meter is based on the principle that the resistivity

of roofing materials varies as a function of moisture content. The

measurement procedure is to drive two closely separated probes into a built-up roof. An electric potential is applied between the probes,

and the resulting electric current is measured. This technique has

the disadvantage that it does require the roof to be punctured.

The dielectric moisture meter is based on the principle that the

dielectric properties of roofing materials vary with the moisture

content of the materials.

A nuclear moisture meter contains a radioactive material (such as radium, beryllium, etc.) which emits fast-neutrons to surfaces placed

underneath the device. The operation of the device is based on the

5-16
principle that the number of hydrogen atoms present in the material

below determines the fraction of the neutrons which are reflected. The

device contains a neutron-counting detector. Since each atom of water

contains two hydrogen atoms, the fraction of neutrons that are reflected

over the surface of a built-up roof system will vary with respect to the

amount of accumulated moisture therein. It should be noted, however,

that variations in the thicknesses of hydrocarbon-based materials (such

as asphalt) will also produce changes in the instrument response.

The procedure in using a nuclear moisture meter is to set up a grid

network for the roof system. A measurement is performed at the center

of each sub-area of the grid network. Since the nuclear moisture meter

provides only a relative response which varies with respect to moisture

content of the roofing material, it is suggested that samples be cored

at locations having the highest and lowest responses. The moisture

content of these samples may be determined by an oven-drying technique

and subsequently used to calibrate the readings of the nuclear moisture

meter.

Depending on the type of radioactive isotope used, licensing by the

Nuclear Regulatory Commission in agreement States and/or registration in

aon-agreement States may or may not be required. It is suggested that

customers check with equipment suppliers or their State health department.

Insomuch as these devices contain radioactive materials, some reasonable

precautions must be observed in handling, transporting, and use to avoid

any unnecessary or excess exposure to the operator. Further information

on the use of nuclear moisture meters may be found in references [12-16].

5. 3 Assessing the Thermal Performance of Building Equipment

5.3.1 Outside Make-Up Air

Often the most significant reductions in cooling and heating energy

requirements can be achieved by reducing the volume of outside make-up

air (that is introduced into the building via the mechanical system) to

Air Force criteria values [17] which are given in table 3-1 (see Chapter 3).

5-17
The following methods may be used to measure the volume of outside

make-up air:

direct method

indirect temperature-measurement method.

For the direct method, the average flow rate through the outside

make-up-air opening (s) is measured using a flow measuring device. The

volumetric flow rate of outside air through each outside make-up air

opening is equal to the product of the mean intake velocity through the

opening and its net open area. If more than one intake opening exists

for the mechanical system, the gross volume of outside make-up air is

equal to the sum of the volumetric flow rates through the separate

openings

For some HVAC Systems, the flow rate of the mixture of the return

and outside air may conveniently be measured (see figure 5-6). In such

instances, the volume of outside makeup air may be determined by measuring

the temperatures of the return air, outside air, and the mixture. This

technique for measuring the volume of outside make-up air is called the

indirect temperature-measurement method. The volumetric flow rate (Vq)

of outside air is determined from the relation:

(3)

where V = volumetric flow of mixture of outside air and return m

air

t = temperature of mixture

m

t = temperature of return air

t = temperature of outside air.

Once the volume of outside make-up air is measured by one of the

foregoing methods, the value is adjusted to the Air Force criteria

values given in table 3-1 (see Chapter 3)

5-18
Return Air

i

i

i

j

1

i

i

j

i

)

i

i

I

s

v , t m m

! Return Air

+ Outside Air

i

i

Figure 5-6. Schematic illustrating the indirect

temperature-measurement method for

determining the volume of outside

make-up air.

5-19
5.3.2 Indoor Environment

A team from the Base Civil Engineer's Office should be established

to survey the indoor environment of the buildings located on every Air

Force Base to identify the following conditions:

non-compliance with end-use restrictions on temperature

overheating and overcooling

° excessive humidification or dehumidification.

The team should be equipped with a sling psychrometer for measuring

indoor dry-bulb temperature and relative humidity (rh)

During the winter the dry-bulb temperature should not exceed 68°F

* and the indoor rh should not exceed 30 percent. A winter indoor rh

exceeding 30 percent indicates excessive humidification. Human comfort

studies have shown that raising the indoor rh above 30 percent does not

provide much improvement in the comfort of the indoor environment.

Since energy is required to evaporate water for any humidification

process, maintaining indoor rh levels above 30 percent will cause energy

wastes. In addition, indoor rh levels above 30 percent may contribute to

moisture problems in buildings.

Perhaps some of the most blatant energy wastes on Air Force Bases

are heating buildings in the winter and cooling buildings in the summer with their windows opened. Usually this condition is a result of inadequate or malfunctioning temperature controls, which causes overheating or overcooling of work and living spaces. The occupants, unable

to perform adjustments on the heating or cooling system of their building,

have no alternative but to open windows to try to restore a comfortable

indoor condition.

During every heating and cooling season, the Base civil engineer

should conduct a survey of the buildings on the Base to identify buildings

having overheating and overcooling conditions. Elimination of these

conditions should receive top priority in the Base energy conservation

program, since they represent gross energy wastes.

*An exception to this requirement is rooms containing special purpose

electronic equipment } such as computer rooms. 5-20
During the summer, indoor temperatures of air-conditioned spaces

should not be kept below 76°F. For buildings located in humid climates,

indoor rh levels maintained below 50 percent may represent excessive

dehumidification. If the cooling equipment is maintaining these con- ditions through sensible heat addition (terminal reheat) to the conditioned air, a very wasteful situation exists. In such instances, it may

be possible to effect substantial energy savings by eliminating a part

or all of the reheating process. For buildings located in extremely

humid climates, however, one must be careful when eliminating sensible

heat addition so that excessive indoor humidity levels are not created.

If the indoor dewpoint temperature is permitted to reach the temperature

of any indoor surface, then condensation will occur at that surface.

5.3.3 Building Equipment

A few simple measurements for identifying energy conservation

actions for building equipment are summarized in table 5-1. The

equipment needed for these measurements includes :

° voltmeter .

° portable (clip-on type) ammeter f 0 bulb thermometer (or digital thermometer)

° slant gage for measuring pressure drops.

or portable

watt recorder

These measurements in most cases are easy to perform and will identify

potentials for energy conservation.

In buildings having complex HVAC systems, energy waste may exist

due to :

° excessive pumping power

° excessive humidification and dehumidification.

5-21
TABLE

5-1.

MEASUREMENTS

ON

BUILDING

EQUIPMENT

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5-22
It is quite common for many existing buildings to have their HVAC

systems altered during the years without' comprehensive plans. The

existing equipment and systems may be operating at quite different

conditions than originally designed. This frequently occurs where space

usage has been changed from that originally designed and balanced. Such

conditions may often be remedied by measuring, adjusting, and balancing

the HVAC system. This involves measuring the various operating parameters

(temperatures, air-delivery rates, etc.) of the system and comparing

these values with design values for the system. Modifications of the

system are then performed to adjust its operation to an efficient

condition which usually will be consistent with the original design.

Detailed procedures for testing, adjusting, and balancing of HVAC systems

are given in references [18, 20]. There are also many consulting firms

which specialize in balancing HVAC systems.

5. 4 Energy Audit for Central Plants

5.4.1 Steam and Hot-Water Generating Plants

For central-heating plants, there are two very important measurements

which should be performed once a month to provide an indication of the

operating performance of the plants:

° plant efficiency

° boiler efficiency.

(1) Plant efficiency

The thermal plant efficiency (q) is defined by the relation:

Btu delivered per month

Btu fuel input to generators per month

# ^

5-23
Since the plant efficiency depends somewhat on the load, it is recom- mended that monthly totals for Btu delivered and fuel-input values be

used to calculate efficiency. Most Air Force plants are equipped with

fuel-consumption meters that register the total amount of input fuel

consumed. It is important that the fuel supplied only to the steam or high-temperature-hot-water (HTW) generators be metered. For steam, the

Btu delivered per month is the product of the pounds of steam delivered

per month by the enthalphy of the steam leaving the plant. The enthalpy

of the steam leaving the plant is readily determined from the steam

tables [21]. Many Air Force Bases are not equipped with totalizing

steam- consumption meters, but it is recommended that such meters be

installed. Information on the measurement of steam is available in

references [22,23]. For HTW plants, the Btu delivered per month is the

integrated product of the flow rate and the temperature differential

between supply and return. This is usually measured with a Btu meter.

Information on the various types of Btu meters is given in reference [23].

It is suggested that monthly plant efficiencies be tabulated in a log book. A central heating plant should have an efficiency of at

least 70 percent. If a plant has an efficiency significantly lower than

this figure, a strong need exists to take a look at energy conservation

measures for the central plant, outlined in chapter 2 of this report.

A record of monthly plant efficiencies makes it possible to compare

plant performance from one year to the next. A need for improved

maintenance procedures is readily identified.

(2) Boiler Combustion Efficiency

The most important component of a thermal plant is the boiler (s)

The single factor that best characterizes the performance of a boiler is

its combustion efficiency—defined as the fraction of the Btu fuel

input which is transferred as heat to the working fluid.

In general, to determine the combustion efficiency when operating

under full-load steady-state conditions, the following parameters are measured:

CC>2 and CO content of flue gas

stack temperature.

5-24
It is important that the foregoing quantities be measured after heatrecovery devices. It is recommended that prior to performing these

measurements, the boiler be operated at full- load conditions long

enough to ensure that steady boiler operation has been achieved. Once

the foregoing quantities have been measured, the boiler efficiency may

be determined from a series of nomographs given in reference [24].

It is suggested that the boiler efficiency be determined once a month. Typical boiler efficiencies for a wide variety of boilers are given in table 5-2. Note that two values are cited in the table. The

maximum attainable value is the theoretical maximum value based on the

thermodynamic Carnot efficiency. In practice, the theoretical maximum

value can only be approached. A boiler, if it is an efficient one,

should be slightly higher than the "as found" value. When a boiler has an efficiency substantially lower than the "as found" value, examine the

energy conservation measures for the central plant outlined in chapter 2 of this report.

5.4.2 Chilled-Water Plants

The performance of a chilled-water plant can be characterized by a plant coefficient of performance (n) which is defined as:

_ Btu removed from distribution system at plant exit

^ energy input to refrigeration equipment

The energy removed from the chilled-water distribution system is

best measured by a Btu meter. Such a meter senses the increase in water

temperature observed between the return and supply chilled-water temperatures at the same time that the weight rate of water flow is measured.

The Btu meter integrates the product of the measured temperature difference

and the mass rate of flow. Since both the chilled-water flow rate and

the temperature drop may vary as a function of time, it is not recommended

that the heat removed be determined from a separate measurement of flow

rate and temperature difference. Information on Btu meters may be

found in reference [23].

5-25
TABLE

5-2

INDUSTRIAL

BOILER

EFFICIENCY

(PERCENT)

AVERAGE

"AS

FOUND"

AND

MAXIMUM

ATTAINABLE

<d

x

5-26

Based

on

typical

field

surveys.
In the case of electrically-driven refrigeration compression equipment, the energy input would be the electrical energy delivered to the

equipment over a specified period of time. The electrical energy is

conveniently measured with a watthour meter. In the case of absorptionrefrigeration equipment, the energy input would be the heating energy

supplied to the generator of the absorption machine over a specified

period of time.

It is recommended that plant coefficient of performances be determined from measurements over a 24-hour period. Once a suitable instrumentation system is installed, daily coefficient of performance could be

derived from daily readings of fuel consumption and Btu’s removed. The

daily plant coefficient of performance is dependent on the cooling load.

Unfortunately, part-load coefficient of performance data for chilledwater generating plants are not well known. However, a chilled-water

plant having vapor-compression refrigeration equipment should have a coefficient of performance of approximately 3.1; a chilled-water generating

plant using an absorption-refrigeration plant should have a coefficient

of performance of 0.6 (single effect) and 1.1 (double effect).

Measurements on thermal plants are no better than the accuracy of

the instrumentation. Measuring devices should be calibrated at least once a year. Calibration services are available on most Air Force

Bases.

5-27
REFERENCES

1. Detecting Moisture in Roof Insulation with a Hand-Held Infrared

Camera, Wayne Tobiasson and Charles Korhonen, Second International

Symposium on Cold Regions Engineering, University of Alaska,

August, 1976.

2. Thermography of Buildings, Ivar Paljak and Bertil Pettersson,

Swedish Council of Building Research, Lund Institute of Technology,

Lund, Sweden, 1972.

3. Detecting Structural Heat Losses with Mobile Infrared Thermography - Part I; Description of the Technique - Part II; Survey of Pease

Air Force Base, Portsmouth, New Hampshire - Part III; R. H. Munis,

R. H. Berger, S. J. Marshall, and M. A. Bush, Survey of USACRREL,

Research Reports 326, 338, and 348, Cold Regions Research and

Engineering Laboratory, Hanover, New Hampshire.

4. Retrofitting an Existing Wood-Frame Residence for Energy Conservation—An Experimental Study, D. M. Burch and C. M. Hunt, NBS

Building Science Series (BSS) report - in review (1977).

5. Measurement of Infiltration in Two Residences, Part I: Technique

and Measured Infiltration; Part II: Comparison of Variables Affecting

Infiltration, D. R. Bahnfleth, T. T. Moseley, and W. S. Harris,

ASHRAE Transactions, 63_, 453-476, 1957.

6. Air Infiltration Measurements in a Four-Bedroom Townhouse Using

Sulfur Hexafluoride as a Tracer Gas, C. M. Hunt and D. M. Burch,

ASHRAE Trans. 81 (1), 186-201, 1975.

7. Measurement of Air-Tightness of Houses, S. Strieker, ASHRAE Trans.

81 (1), 148-167, 1975.

8. Measurement of Air Leakage Characteristics of House Enclosures,

G. T. Tamura, ASHRAE Trans. 81, (1), 202-211, 1975.

9. The Thermal Performance of a Two-Bedroom Mobile Home, G. Teitsma

and B. Peavy, NBS Report NBSIR 76-1182, 1977.

10. Evaluation of Building Characteristics Relative to Energy Consumption

in Office Buildings. Enviro-Management and Research, Inc., FEA

Contract No. CO-04-60222-00, 1975.

11. Energy Consumption in Commercial Buildings in Philadelphia, The

National Electric Manufacturers Association, New York, New York 10017.

12. ASTM D 3017, Standard Method of Test for Moisture Content of Soil

and Soil-Aggregate in Place by Nuclear Methods, 1972.

5-28
13. Density and Moisture Content Measurements by Nuclear Methods

Interim Report, L. F. Ballard and R. P. Gardner, NCHRP Report 14,

Highway Research Board, 1965.

14. Density and Moisture Content Measurements by Nuclear Methods,

R. P. Gardner and K. F. Roberts, NCHRP Report 43, Highway Research

Board, 1967.

15. Optimization of Density and Moisture Content Measurements by Nuclear

Methods, R. P. Gardner, W. L. Dunn, F. H. McDougall, and W. J. Lippold,

NCHRP Report 125, Highway Research Board, 1971.

16. Instrumentation for Measurement of Moisture/Literature Review and

Recommended Research, L. F. Ballard, NCHRP Report 138, Highway/

Research Board, 1973.

17. Air Force Design Manual Criteria and Standards for Air Force

Construction, AFM 88-15, Department of the Air Force, 1975.

18. National Standards for Field Measurements and Instrumentation,

Total System Balance, Volume 2, No. 12173. Published by Associated

Air Balance Council (AABC) , 1973. 2146 Sunset Blvd . , Los Angeles,

Cal. 90026.

19. Procedural Standards for Testing - Balancing - Adjusting of

Environmental Systems, by National Environmental Balancing Bureau

(NEBB) , 1972. 1611 N. Kent St., Arlington, Va. 22209.

20. Chapter 40 - Testing, Adjusting, and Balancing, Systems Volume, of

ASHRAE Handbook, 1973.

21. Thermodynamic Properties of Steam, J. H. Keenan and F. G. Keyes,

John Wiley and Sons, Inc., 1936.

22. Code for Steam Metering, International District Heating Association,

5940 Baum Square, Pittsburgh, Pa. 15206. (in progress - 1977).

23. District Heating Handbook, International District Heating Association, 5940 Baum Square, Pittsburg, Pa. 15206 (in progress - 1977).

24. Fuels and Combustion Handbook, Editor Allen J. Johnson, McGraw-Hill

Book Co., Inc., New York, New York, 1951.

5-29
'

.
CHAPTER 6. ECONOMIC ANALYSIS

CONTENTS

PAGE

6.1 Introduction 6-2

6.2 Present-Worth Analysis 6-3

6.3 Benefit-Cost Analysis: Fixed-Size Projects 6-8

6.4 Benefit-Cost Analysis: Variable-Size Projects 6-11

6-1
CHAPTER 6. ECONOMIC ANALYSIS

6. 1 Introduction

Energy inputs needed to achieve required energy-related services in

Base facilities, including thermal comfort, illumination, hot water, and

other functional services, can be significantly reduced through improvements in facility design (retrofit) and in operational procedures. A

considerable amount of data is available in this handbook and elsewhere

to help identify both the potential methods for reducing energy requirements

and the potential energy savings that can be achieved through their use. In some cases, significant improvements can be made at little or no cost and are therefore immediately attractive. In general, however,

physical improvements to Base facilities which reduce energy consumption

without reducing the quality of related services are costly enough to

require some economic justification. Moreover, where some of these

improvements can be utilized at two or more distinct levels of application

(such as insulation), an analysis is required to determine which of

these utilization levels is the most economically justified.

As energy prices increase relative to the cost of energy conservation

improvements, greater levels of investment in energy conservation should

be considered to offset these higher energy costs. The purpose of this

section of the handbook is to provide a framework for making such economic

considerations on a systematic basis. This framework is generally

referred to as life-cycle benefit-cost analysis. It requires that all

benefits and costs incurred throughout the economic life of energyrelated improvements to Base facilities be compared on a consistent,

time-equivalent basis. The method used to make all these benefits and

costs consistent is explained in section 6.2.

The objective of such an analysis is to determine not only which

improvements are "worth" doing, but the extent to which they are worth

doing. In most conventional benefit-cost studies, the former is stressed.

Discussion of this conventional approach to benefit-cost analysis takes

place in section 6.3. In this handbook, however, equal weight is given to

6-2
the use of benefit-cost analysis in choosing the most economical investment level when more than one level is feasible. This is the subject of

section 6.4.

6 . 2 Present-Worth Analysis

Most physical energy conservation improvements in Base facilities

require some immediate outlay of military funds. This outlay is made in

anticipation of reduced operational expenditures over the remaining

economic life of the facility. These reduced expenditures, or savings,

are generally expected to more than pay back the initial investment.

However, there are competing uses for military funds other than

energy conservation improvements. Some of these competing uses may pay

higher "dividends" than some energy conservation improvements. Thus, in

general, energy conservation investments should be made when their

rate of return is at least as great, or greater than that for the next

best alternative investment.

DoD has suggested that the minimum acceptable rate of return (representing that next best alternative) is 10 percent. For this reason, a discount rate of 10 percent is required to transform savings accrued in some future time period to their present value in a way that implicitly

includes a 10 percent annual rate of return. For example, $1000 invested

at 10 percent will be worth $1100 at the end of one year. Thus the

present value of $1100 received one year from now is $1000 if a discount

rate of 10 percent is appropriate. Present Value is determined by the

formula:

PV = FV^ x

( 1+0)

( 1 )

where PV is the Present Value, FV, . is the Future Value in t years, and

(tj

x D is the Discount rate. In our example, PV = 1100 x = 1000 .

( 1 . 1) Benefits and costs so adjusted can then be compared on a time-equivalent

basis; i.e., adjusted for foregone investment opportunities over the

life of the facility.

6-3
At the same time that future savings are discounted to present

value, it must be recognized that these savings may gradually increase

over time. While the physical reduction in energy use may remain relatively constant from year to year, an increase in energy prices will

result in higher annual dollar-value savings. These escalating energy

prices are only partly due to general inflation. Increasing world demand

for energy resources, more costly extraction processes, greater transportation distances, and stricter environmental controls will all result in

higher energy prices unless a major breakthrough in energy production

technology is achieved. Energy conservation investments are made not

only to reduce energy expenditures today but throughout the life of the

facility. Thus the effects of increasing energy prices should be fully

incorporated in the decision analysis.

The discount rate and rate of energy price increase are both essential to the determination of present-value life-cycle savings. Equally

important is the number of years over which the savings will accrue,

i.e., the economic life of the investment. DoD generally recommends that

25 years be used as the economic life of Base buildings and utilities.

Thus this recommendation should be followed whenever the expected economic

life of an improvement to Base facilities is expected to be at least 25

years. If the estimated life of an energy conservation improvement is

less than 25 years, the lower estimate should be used.

When the discount rate (D) and the appropriate economic life (L) are

known, and the average annual rate of energy price increase (P) over the

relevant lifetime is estimated, a present-worth factor (PWF) can be

quickly calculated which can be used in estimating the present value of

life-cycle energy savings. Given that physical energy savings from an energy conservation improvement are approximately constant from year to

year, the PWF will relate the present value of savings over the entire

life of the investment to the average annual savings, estimated at current

energy prices:

Present-value life-cycle savings = average annual savings at

current prices x PWF

Table 6-1 gives present-worth factors for a range of economic lives and for

several different assumptions as to the rate of future energy price

6-4
1

TABLE 6-1. PRESENT-WORTH FACTORS

Economic Life, Years

5 10 15 20 25

4-1° 0% 3.79 6.14 7.61 8.51 9.08

CD p

cd 27

O' CD 4.01 6.76 8.64 9.93 10.82

cn

t—i d

o3 oj 47 3 M 4/0 4.24 7.44 9.86 11.69 13.07

d <-> CS G

< M 6% 4.48 8.20 11.30 13.87 16.00

a) <D M 4)

cO -H o<z

J-4 °/o 4.73 9.05 12.99 16.59 19.87

a) Ph ^ $ 10% 5.00 10.00 15.00 20.00 25.00

11 r?P4 * 12% 5.28 11.06 17.38 24.30 31.87

-- — 1 —J

6-5
increases. Each PWF is based on a discount rate of 10 percent. Alternatively, the PWF can be calculated as follows:

D 4 P ( 2 )

PWF = L D = P (3)

Example #1 . Present value of annual energy savings.

Replacement of an electric furnace in a Base housing unit with a heat pump reduces annual kWh consumption by an average of 7000 kWh.

Electricity currently costs 3q per kWh, but is expected to increase in

price by about 6 percent per year over the next 15 years, the estimated

economic life of the heat pump. What is the present value of the lifecycle savings attributable to an investment in such a heat pump system?

In example #1, energy savings are realized only during the heating

season. For many energy conservation investments in buildings, energy

savings may be accrued in both heating and cooling seasons. These

savings should both be considered in estimating life-cycle savings. In some cases, it is possible that reductions in heating energy requirements

will be partially offset by increased cooling energy requirements, or vice versa. In such cases, life-cycle savings should represent net

savings. Where heating and cooling operations require different con- version efficiencies, the differences in energy costs per unit of output

should be recognized. In addition, where estimates of energy price

increases differ by type utilized, present-value savings (or losses)

should be evaluated for each fuel type and then summed in present-value

terms

Most costs incurred as a result of energy conservation improvements

are initial costs; i.e., they represent an immediate outlay of funds. As

such, they are already expressed in present-value terms. However, some

First year savings ($. 03/kWh x 7000 k.Wh)= $210.00

Present Worth Factor (15 years; 6%)

Present-value life-cycle savings

11.3

= $2373.00

6-6
improvements may require increased operation and/or maintenance (O&M)

expenditures, recurring at regular or irregular intervals throughout

their lifetime. In order to evaluate these costs on a consistent basis

with initial costs, they must be expressed in present-value terms as well.

If similar O&M requirements are expected to occur at periodic

intervals, they can be evaluated in present-value, life-cycle terms

using the average annual O&M requirements at current costs and the PWF

appropriate for the economic life and the expected annual rate of increase

in recurring O&M costs (due primarily to inflation) over this life.

If increased O&M costs are expected to occur at non-regular intervals, or require different expenditures at different times, these must

be evaluated individually in order to reduce future costs to present

value and then summed in present-value terms. This evaluation can be

accomplished using the Present Value formula (eq. 1):

til Present value of O&M cost incurred in t year =

til O&M cost in t year x O&M cost in t th

(1+D)

year

(4)

( 1 . 1 )

where t = the number of years into the future when the cost is expected

to be incurred.

Example //

. Present value of increased O&M costs.

Replacement of an electric furnace with a heat pump, while significantly reducing annual kWh consumption for space heating, may increase

annual O&M requirements related to the heating and cooling system. For

a given installation, this increase is estimated to cost $25.00 annually

at current prices and to increase 4 percent annually over the 15-year

life of the system. In addition, after eight years a new compressor

will be needed, at an estimated future installed cost of $200.00. What

is the additional present-value, life-cycle cost of the system due to

increased 0&M costs?

6-7
Average annual O&M cost at current prices

Present Worth Factor (15 years; P=4%)

Present-value, life-cycle recurring costs

= $25.00

= 9.86

= $246.50

Present-value compressor replacement cost:

$200. 00/(l.l)

8

$93.30

Total present value increased O&M costs $339.80

We now have a systematic method for expressing life-cycle, dollarvalue energy savings and related costs on a time-equivalent basis. A

benefit-cost analysis is now required to determine the economic priority

(1) Fixed-sized projects: those which are relatively non-variable

in application—either they are utilized or they are not; e.g.,

storm doors, storm windows for a given-size window.

(2) Variable-size projects: those which can be utilized at two or more distinct levels of application; e.g., building insulation.

Although benefit-cost analysis is used in assessing the economic

priorities of both of these classifications, it is approached differently

in each case. For this reason, the following discussion of benefit-cost

analysis is divided into two sections.

6.3 Benefit-Cost Analysis: Fixed-Size Projects

Fixed-size energy conservation projects are generally considered to

be economically justified only if their total present-value, life cycle

benefits (i.e., the dollar value of reduced energy requirements) equals

or exceeds their total present-value, life-cycle costs. This economic

criterion requires that the benefit-cost ratio, the ratio of total benefits (TB) to total costs (TC) , be equal to, or greater than, one:

of the alternative energy conservation projects considered.

Energy conservation projects can be classified into two general

groups

TC - (5)

6-8
Alternatively, this same criterion can be restated to require that

the payback period be less than or equal to the economic life of the

project in question. The payback period is defined here as the time

required to pay back the investment in full, including allowances for

increasing energy costs and the required annual rate of return, as represented by the discount rate.

Note that the payback period, as used here, requires that it be

referenced with respect to the economic life of the project. For this

reason the payback period is not adequate for determining the relative

economic priority of alternative projects with different economic lives.

Arbitrarily determined payback period requirements applied to a group

of projects being considered simultaneously, all with different lives,

will usually result in the suboptimal allocation of energy conservation

funds.

Economic priorities, where funds for energy conservation projects

are limited, are best determined by the benefit-cost (B/C) ratio. Those

projects with the highest B/C ratio should be given highest priority,

and those with the lowest B/C ratio (even if greater than one) should be

given lowest priority. An exception to this allocation rule may occur when the project with a high priority B/C ratio requires more funding

than is available, in which case the next highest priority project that can be funded should be implemented. However, as more funding becomes

available, the former project should be again given highest priority.

Example #3 . Storm windows and doors are considered for installation

in housing.

Prime windows are of two basic sizes, 3’x3' and 3’x5*. Storm windows on the smaller window are estimated to save nine gallons of fuel oil

and on the larger window 15 gallons of fuel oil per year per window.

Storm windows for prime windows of both sizes cost $25.00 each, installed, and are expected to last for 15 years. The storm door is expected

to save 10 gallons of oil per year, costs $40.00 installed, and is ex- pected to last 10 years. Oil currently sells for 40q per gallon and is

expected to increase in cost at 6 percent annually . No additional

6-9
maintenance is expected. Which of these modifications are economically

justified and what priority should be given to them?

Storm Windows Storm Doors

3'x3’ 3 'x5

Annual savings at current oil cost $3.60 $6.00 $4.00

Present-Worth Factor (Table 1) 11.30 11.30 8.20

Present-value life-cycle savings $40.68 $67.80 $32.80

Total cost $25.00 $25. 00 $40.00

Benefit-cost ratio 1.63 2.71 0.82

Economically justified? YES YES NO

Priority 2 1 (3)

The payback period for any of these projects can be approximated as follows, using table 6-1. Divide the total cost by annual savings at

current energy cost. Then locate the result (as nearly as possible) in

the row of PWF's in table 6-1 appropriate to the rate of energy price

increases used. The payback period will be the economic life relative

to that PWF. Interpolation will give more accurate results.

Example #4 . What is the payback period for the storm windows and

storm door in example #3?

Storm Windows Storm Doors

3 ' x3* 3' x5

(1) Total cost $25.00 $25.00 $40.00

(2) Annual savings at current oil

cost $ 3.60 $ 6.00 $ 4.00

(3) (1) / (2) 6.94 4.17 10.00

(4) Payback in years (interpolated

from table 6-1, 6% row) 8 years 5 years 13 years

Again, it is stressed that the payback period is not adequate for

determining economic priorities if the projects considered have different

economic lives.

It should be recognized that the calculation of benefits and costs

to this point has been based on an assumption of no change in the level

of energy-related services provided. In fact, improvements to building

or equipment design, either in initial construction or by retrofit, will

often result in increased occupant comfort, and at the same time reduce

6-10
peak-load power requirements and dependence on fluctuating energy supplies. These additional benefits are somewhat intangible in that it is

difficult to assign dollar values to them. However, where the economic

justification of an energy conservation investment may appear to be a borderline case if energy savings alone are considered, these intangible

factors may assist in making the final decision.

6.4 Benefit-Cost Analysis: Variable-Size Projects

The economic evaluation of variable-sized energy conservation projects requires not only the determination of economic justification, but

the determination of the most economically justified level of utilization

of such projects.

The best example of a variable-size energy conservation project is

that of installing thermal insulation in buildings. As more and more

insulation is added to a building, annual energy requirements decrease,

but at a decreasing rate, so that each additional unit of insulation

saves less energy than the preceding unit. However, as energy prices

have increased relative to insulation prices, the present value of these

energy savings has increased and more insulation has generally become

economically justified than in the past.

This section presents a simplified approach to the determination of

how much of a variable-size energy conservation technique is economically

justified. This approach is called marginal, or incremental, analysis,

because the benefit-cost analysis is applied to successive increments of

the project rather than to the total project. The need for such an incremental approach will become clear with an inspection of table 6-2.

This table shows the total benefits and costs associated with the use of

several values of insulation resistance (R) in an attic of a Base housing

unit. Present-value life-cycle savings are based on a 25-year life and a

6 percent annual energy price escalation factor (PWF=16)

While the benefit-cost ratios of table 6-2 decrease as resistance is

increased, they remain well above 1, so that total benefits exceed total

costs at all levels of application. In addition, the payback periods are

all well below the economic life of the insulation. What then is

6-11
TABLE 6-2. REPRESENTATIVE TOTAL DOLLAR COST AND SAVINGS FOR

SEVERAL VALUES OF THERMAL RESISTANCE (R)

R-value

Total

Cost

Total

Savings

B/C

Ratio

Payback

(P=6%)

0 0 0 — —

10 $200 $3200 16.0 1 year

20 350 3610 10.3 1.5 years

30 500 3770 7.5 2.2 years

40 650 3850 5.9 3 years

50 800 3900 4.9 3.5 years

TABLE 6-3. REPRESENTATIVE INCREMENTAL DOLLAR COSTS AND

SEVERAL VALUES OF THERMAL RESISTANCE (R)

SAVINGS FOR

R-value

Incremental

Cost

Incremental

Savings

Incremental

B/C

Ratio

Incremental

Payback

Period

0 0 0 — —

10 $200 $3200 16.0 1 year

20 150 410 2.73 7 years

30 150 160 1.07 23 years

40 150 80 0.53 oo

50 150 50 0.33 oo

6-12
the most economical level of insulation resistance? The B/C ratio and

payback period criteria appear to have failed because the less insulation

is utilized, the better these criteria appear to be.

Table 6-3 will help to resolve this problem. In table 6-3, incremental costs and benefits are shown for the same resistance levels shown

in table 6-2. Incremental costs and benefits are the difference between

the total costs or total benefits of two different levels of resistance.

For example, the incremental cost between R-10 and R-20 insulation is

$350 - $200 = $150. Benefit-cost ratios and payback periods are computed

for incremental savings and costs. Using the same criteria for economic

justification as outlined in section 6.3, applied instead to the successive increments of a variable-size energy conservation project, one can now determine the extent to which a given increment is economically

justified and what its economic priority is relative to increments of

other variable projects and to fixed-size projects.

In table 6-3, the third increment of resistance, R-30 (R-10 added

to R-20) is the last increment economically justifiable. Note that at

this level total savings exceed total costs by the greatest amount

($3770 - $500 = $3270) of any of the levels considered. For this reason,

R-30 is considered to be the most economically justified level of insulation

in this example. While this third increment takes approximately 23

years to pay back, it includes a 10 percent rate of return during that

time period which is by assumption greater than the next best alternative

investment. While this entire investment pays back in only 2.2 years,

we see now that the total payback period for a variable-size investment

is irrelevant to its real economic status.

In the example shown in tables 6-2 and 6-3, increments of 10 resistance units were arbitrarily chosen for ease of presentation. In actual

practice, the levels of utilization chosen might better represent available

options (e.g., R-ll, R-19, R-22, R-30, R-38, etc.). Where the level of some energy conservation technique is continuously variable (e.g.,

blown- in attic insulation) , the most economical level can be determined

by using small increments near the most economical level (which can be

approximated using larger increments) or by using more sophisticated

mathematical techniques.

6-13
In some cases, incremental B/C ratios may fall below the economically justified level and then rise above it again. If physical conditions require that increments with lower B/C ratios be utilized before an increment with a higher B/C ratio can be utilized, the increments with

the lower B/C ratios should be combined with that of the higher B/C ratio

and evaluated as one large increment in order to determine if it is

economically justified.

When a variable-size energy conservation technique is utilized up to

the point that includes the last economically justified increment, the

most economically justified level of investment has been determined. As

in the case of fixed-size projects, when investment funds are limited so that not all projects or increments with B/C ratios greater than or equal

to one can be utilized, those with the highest B/C ratios should be

utilized first.

In determining actual energy savings attributable to the various

energy conservation projects considered in a given facility, significant

interdependence among projects must be recognized. For example, replacement of an electric furnace with a heat pump and the simultaneous installation of additional insulation in the same building are interdependent

actions. The heat pump lowers the effective cost of energy needed to

heat the building, thus reducing the savings attributable to the additional insulation. At the same time the additional insulation reduces

the heating load on the heat pump, which, in turn, reduces the energy

savings attributable to the heat pump.

In a sophisticated economic analysis, the annual energy savings

credited to one project should be based on the assumption that all other

energy conservation techniques are employed at their most economical

level. Such an analysis may require several iterations, in which each

sucessive iteration comes closer to the determination of an optimal

combination of energy conservation projects for a facility.

6-14
APPENDIX A. CALCULATION OF ENERGY REQUIREMENTS FOR SPACE HEATING

AND SPACE COOLING OF BUILDINGS

CONTENTS

1.

Introduction

PAGE

A

2.

Design Parameters A-4

2.1 Outdoor Design Conditions A-4

2.2 Indoor Design Conditions A-4

2.3 General Ventilation A

2.4 Infiltration A2.5 Heat Gains A

3. Design Heating Load A

3.1 Thermal Transmittance A3.2 Overall Thermal Transmittance A

3.3 Special Temperature Conditions A

3.4 Thermal Transmittance of Unheated Spaces A

3.5 Heat Loss from Below-Grade Walls and Floors A

3.6 Heat Loss to Crawl Space A

3.7 Heat Loss from Floor Slabs A

3.8 Infiltration Heat-Loss Rate A-10

3.9 Design Heat-Loss Rate A-10

3.10 Design Heating Load A-ll

4. Design Cooling Load A-ll

4.1 Thermal Transmittance A-ll

4.2 Heat Gain through Windows A-12

4.3 Rate of Heat Gain through Opaque Walls A-17

4.4 Rate of Heat Gain through Roof Areas A-17

4.5 Heat Gain from Occupants A-21

4.6 Heat Gain from Heat-Producing Processes A-21

4.7 Heat Gain due to Ventilation and Infiltration A-22

4.8 Design Sensible and Latent Cooling Loads A-23

5.

Energy Requirement for Space Heating

5.1 Heating Hours (T ) 5.2 Building Heat-Loss Rate (H)

5.3 Heat Generation Rate within a Building

5.4 Efficiency (E ) of Heating Plant

5.5 Correction (EJ for Nighttime Setback of Thermostat

5.6 Winter Solar Heat Gain (H ) through Windows

5.7 Heating Energy Requirement

A-25

A- 2 6

A- 2 6 A- 2 6 A-27

A-29

A- 30

A-30

A-l
PAGE

6. Energy Requirement for Space Cooling A-35

6.1 Cooling Hours (T

c

) A-35

6.2 Conduction Heat Gain (Hc ) A-35

6.3 Summer Solar Heat Gain (Hw) through Windows

and Walls A-36

6. A Solar Heat Gain (H r ) through Flat Roofs A-36

6.5 Heat Gain Due to Air Infiltration and Mechanical

Ventilation (Hv ) A-38

6.6 Internal Heat Gains (Hg) A-38

6.7 Efficiency (E) of Cooling System A-39

6.8 Cooling Energy Requirement A-39

References A-A5
APPENDIX A. CALCULATION OF ENERGY REQUIREMENTS FOR SPACE HEATING

AND SPACE COOLING OF BUILDINGS*

1. INTRODUCTION

The calculation of heating and cooling energy requirements for

buildings is necessary in order to evaluate energy savings resulting

from energy conservation modifications to existing buildings. The

calculation methodology is presented in four principle sections.

(1) Design heating load

The design heating load is the maximum heat delivery rate of a heating plant required to maintain the indoor environment at comfort

conditions, when the outdoor environment is at design (cold weather)

conditions. The calculation of design heating load makes it possible to

estimate the required capacity for the heating plant.

(2) Design cooling load

The design cooling load is the maximum rate at which heat must be

removed at the cooling coil of the air conditioning equipment of a building in order to maintain the indoor environment at comfort conditions when the outdoor environment is at design (hot weather) conditions.

(3) Energy requirement for space heating

This section presents a methodology for the calculation of the net

heating energy requirement for a building over the entire heating season. Such predictions are necessary in order to quantify the annual reduction

in heating energy requirement resulting from energy conservation modification to a building.

(4) Energy requirement for space cooling

This section presents a methodology for the calculation of seasonal

energy required by the cooling equipment to remove sensible and latent

heat gains from the occupied space of a building during the cooling

season.

* Many of the equations for this chapter were taken from reference [2].

AItems (1) and (2) are essentially based on steady-state heat transfer between indoor and outdoor design conditions and are mostly taken

from chapters 21 and 22 of the 1972 ASHRAE Handbook of Fundamentals [2]

with certain simplifications. Even with these simplifications, certain

fundamental heat-transf er concepts must be adhered to in the determination of heating and cooling loads. It is expected that those using

these calculation procedures are familiar with the fundamentals.

Items (3) and (4) above are based on the bin method which is

probably the most accurate method without the use of a computer for the

determination of seasonal energy requirements. For more accurate techniques for predicting heating and cooling energy requirements, the

reader is referred to Appendix D which presents a survey of computer

programs for evaluating building and system performance.

2. DESIGN PARAMETERS

The following design parameters shall be used in heating and cooling load determinations. (If for special cases such as hospitals,

laboratories, computer room, etc., other special indoor design con- ditions are maintained, heating and cooling load calculations shall be

based on these conditions)

2 . 1 Outdoor Design Conditions

Winter and summer outdoor design conditions shall be the 97-1/2

percent and 2-1/2 (dry bulb) and 5 (wet bulb) percent values, respectively, as given in Chapter 6, Engineering Weather Data of AFM 88-8 [1]*.

2 . 2 Indoor Design Conditions

Winter indoor design conditions shall be 70° F dry-bulb temperature

with humidification, if provided, to not more than 30 percent rh. Summer indoor design conditions shall be 78° F dry-bulb temperature, with

controlled humidification, if provided, to not less than 60 percent rh.

* Numbers in brackets indicate references cited at the end of chapter.
2.3

General Ventilation

For load design of all building types except one- and two-family

dwelling units, mechanical ventilation with outside air shall be taken

as 5 cfm (standard) outdoor air per person for occupied spaces and not

to exceed 2 air changes per hour for unoccupied spaces such as corridors, foyers, etc.

2 . 4 Infiltration

Infiltration shall be taken as 0.7 air changes per hour for oneand two-family dwellings and 0.5 air changes per hour for all other

buildings. For hangars and warehouses, it is recommended that air

infiltration rates of 1.5 air changes per hour be used for energy

calculations

2 . 5 Heat Gains

Internal heat gains from lights, people, and equipment (appliances) shall be included in the following load and energy requirement calculations. During the summer, internal heat gains represent

a sensible load which must be removed by the air-conditioning equipment. In the winter, internal heat gains actually provide some of the

required heating energy and therefore need to be included in the calculation of the heating energy requirement.

3. DESIGN HEATING LOAD

The following methodology shall be used for calculation of the

heating loads:

3.1 Thermal Transmittance

The thermal transmittance (Ik) for each of the heat-flow paths is

determined by adding the thermal resistance for all elements in the

path and then taking the reciprocal of the sum. Therefore, for each

path

U

i = R + R + R + ... + R

a b c r AResistance values for air films, air spaces, and insulation and

construction materials are found in tables 1, 2 and 3, Chapter 20 of

the ASHRAE Handbook of Fundamentals [2]. U-values for windows and

doors are found in tables 8 and 9 of reference [2]. R and U values

shall pertain to winter heating conditions.

3 .

Overall Thermal Transmittance

An overall thermal transmittance for the exterior envelope of a building or residence is obtained by the relation:

U

o

U

1A1 + U

2 A2 (a

i + A?

+ U,A, + ... + U A

3 3 n n + A_ + ... + A ) j n

( 2 )

Here A denotes the surface area of each heat-flow path, such as exterior

windows, walls, ceiling or roof, and floor above crawl spaces. The sum of the heat-transf er areas equals A^ , the total envelope area (excluding slab-on-grade floors, basements and foundations below grade).

3.Special Temperature Conditions

In cases for which certain rooms are maintained at a temperature

other than prescribed by section 2.2, the thermal transmittance (1L)

for the heat-flow path shall be adjusted by the relation:

U. = U — (3)

x t . - t 1 o

where t_^ = the design indoor air temperature

t Q = the design outdoor air temperature

t^ = temperature maintained in the room.

3.4

Thermal Transmittance of Unheated Spaces

The thermal transmittance of unheated spaces is based on heat-flow

from heated rooms to unheated rooms and to the outside. The thermal

transmittance based on the total area of unheated space exposed to the

outdoors is

1_

Un

1

E U a n n

1

Z U a

r r

C4)

A

+
where U = thermal transmittance of heat-flow paths between heated

n and unheated spaces

= thermal transmittance of heat-flow paths between unheated

space and the outdoors,

and a and a are the ratios of surface area of the individual heat-flow

n r paths to the total area of unheated space exposed to the outdoors.

3.5 Heat Loss from Below-Grade Walls and Floors

If the below-grade space is heated to a specified temperature, the

heat loss should be calculated in the usual manner, based on the proper

wall and floor coefficients and the outdoor air and ground temperatures.

Heat loss through windows and walls above grade should be based on sections 3.1 and 3.2. Heat loss through below-grade walls and floors

should be based on the floor and wall coefficients for surfaces in

contact with the soil, and on the proper ground-water temperature. The

heat loss rate for below-grade walls and floors may be calculated from

the relation H^ = F*A, /where A is the pertinent surface area. Values

of the heat loss factors (F) for various ground-water temperatures are given in table A-l.

TABLE A-l. HEAT LOSS FACTO RS

a

(F) FOR BELOW-GRADE WALLS AND FLOORS [2]

Ground-Water Basement Floor Loss^, Below-Grade Wall Loss , Temperature, °F Btu/h*f

2 Btu/h*f

2

40 3.0 6.0

50 2.0 4.0

60 1.0 2.0

These values in a strict sense apply to residential buildings, but they

may also be used for other type buildings.

^Based on below-grade space temperature of 70° F and thermal transmittance (U) of below-grade wall of 0.1 Btu/h’ft2, F.

QAssumed twice below-grade floor loss.
3 . 6 Heat Loss to Crawl Space

The temperature in crawl spaces will vary widely depending on the

number and size of the ventilation openings, the amount of hot water

piping and warm-air ducting present and the amount of pipe and duct

insulation. It is necessary, therefore, to evaluate the conditions and

to select an appropriate crawl-space temperature. Frequently this is

done by assuming that it is midway between the design indoor and outdoor

temperatures. After evaluating the thermal transmittance values for the

various heat-flow paths for the floor as indicated in section 3.1, the

relation of section 3.3 is used to determine the overall U-value for the

floor.

3 . 7 Heat Loss- from Floor Slabs

Two types of concrete slab floors are (a) the unheated slab-ongrade, relying for warmth on heat delivered above floor level by the

heating system, and (b) the heated slab-on-grade containing heated

pipes or ducts that constitute a radiant slab or portion thereof for

complete or partial heating of the house. With unheated slabs-ongrade the heat loss (H^) can be estimated by means of the equation

H

f = F.P (5)

where F = heat-loss coefficient, Btu/h (per linear foot of exposed

edge)

P = perimeter or exposed edge of floor, linear feet.

Values for the heat-loss coefficient factor (F) are given in table

A-2 for various thicknesses (R-values) of edge insulation. The insulation is considered to extend under the floor horizontally for 2 ft, or

to be located along the foundation vertical wall Extending 2 ft below

the floor level. Floors containing heating pipes or ducts are now in common use. The heat loss downward into the ground and outward through

the edges of the floor slab is called the reverse loss. Heat-loss

factors (F) for heated slabs are also found in table A-2. For heated

slabs using perimeter heating, (F) values are given in table A-3.

A-8
TABLE

A-2.

HEAT

LOSS

FACTORS

(F)

FOR

CONCRETE

FLOORS

AT

OR

NEAR

GRADE

LEVEL

PER

FOOT

OF

EXPOSED

SLAB

EDGE,

Btu/h-ft

[2]

co .Q

ro

CO -O

(D

4-> rOO)

S-o

<+- LO

r-'-

ii

s_o

CO -Q

rO

CO -o

cu +J

CO

(U -Cc

13

s-o

M-OLD

II

a;

CO

rs

-u

CU

scr

a)

s_ co

"I

+-> (C

Z3

COco

cuo

c:

(13 +-> CO

CO

ai

s_

(US

s-a>

+joc

COop-

-l-> ra

coc

s-a>

+-> a;

scuQ.

CU

scu

II

CCC (13 -Q

A- 

Slab

floors

having

heating

pipes

or

ducts

under

the

slab

shall

be

considered

as

heated

slabs.
TABLE A-3 . SLAB HEAT LOSS FACTORS (F) IN Btu/h* ft TO BE USED WHEN WARM

AIR PERIMETER HEATING DUCTS ARE EMBEDDED IN SLABS

3

[2].

Outdoor

Design

Temperature

° F

Edge Insulation

1-in Vertical

Extending Down

18 in Below

Floor Surface

1-in L-Type Extending at Least 12 in

Deep and 12 in

Under

2-in L-Type Extending at least

12 in Down and

12 in Under

-20 105 100 85

-10 95 90 75

0 85 80 65

10 75 70 55

20 62 57 45

Factors include loss downward through inner area of slab.

3.8 Infiltration Heat-Loss Rate

The formula for the heat required to warm the outdoor air which

enters a building by infiltration to the building indoor air temperature

is :

H. = 0. 016* V -I* (t.-t ) (6)

1 s 1 o

where H. = infiltration heat-loss rate, Btu/h

1

3

V = volume of air space or spaces in building, ft

s I = infiltration air-flow rate (see section 2.4), air changes/h

t. = indoor-design temperature (see section 2.2), °F

t = winter outdoor-design temperature (see section 2.1) °F

o

3. 9 Design Heat-Loss Rate

The total heat-loss rate (H ) in Btu/h for a building is given by

the relation:

H = A *U * (t.-t ) + H. + H. (7)

t O O 1 O 1 f

A- 10
where U

q = overall thermal transmittance of the building envelope

(not including slab-on-grade floors and below grade spaces)

A

q

= exterior surface area of the building envelope

t^-t = inside-to-outside temperature differences

H. = heat-loss rate due to air infiltration

1 = heat-loss rate through slab-on-grade floors or below grade

spaces

3 . 10 Design Heating Loads

The design heating load is simply equal to the differences

between the design heat-loss rate (H ) and the heat-release rate due to

occupancy, lighting, and equipment or

H , = H — H - H - H (8) Load t ps as e

where H = sensible heat-release rate from occupants

ps r H = sensible heat-release rate from equipment

cLS = heat-release rate from lighting.

Procedures for estimating the foregoing internal heat-release rates are presented in sections 4.5 and 4.6. In some buildings under design

conditions the internal heat-release rates (H , H , and H ) are

ps as e small in comparison to the design heat-loss rate for the building and

may be neglected.

4. DESIGN COOLING LOADS

The following methodology shall be used for the calculation of

cooling loads.

4.1 Thermal Transmittance

The thermal transmittance for each series heat-flow path is

determined in section 3.1, where R-values should be obtained from

tables applicable to summer cooling conditions.

A-ll
4 . 2 Heat Gains through Windows

The heat flux through each window or fenestration orientation and

configuration shall be calculated by' the relation:

Q = SC* SHFG + U * (t -t.) w w o 1

( 9 )

where Qw

SC

= rate of heat flow through window, Btu/h*ft"

= shading coefficient

SHFG = solar heat gain factor, Btu/h*ft

2 U = thermal transmittance of window, Btu/h*ft * °F w

’

Solar heat gain factors (SHFG) are given in table A-4 for various

surface orientations and latitudes. Shading coefficients (SC) for

various fenestration configurations are given in tables A-5 to A-8.

The total rate of heat gain through the windows is equal to the sum of

the products of the rate of heat flow (Q ) and window area for each of

w

the windows of the building.

TABLE A-4. COOLING LOAD SOLAR HEAT-GAIN FACTORS (SHFG), Btu/h* f

2 [2]

Surface

Orientation

LATITUDE-DEGREES NORTH

24 32 40 48

N 45 37 30 24

NW 168 167 163 156

W 190 198 204 207

SW 101 114 127 138

S 17 19 20 21

SE 17 18 19 20

E 17 18 19 20

NE 17 18 19 20

HORIZ 72 81 88 92

/ A-12
TABLE A- 5. SHADING COEFFICIENTS (SC) FOR SINGLE GLASS

AND INSULATING GLASS [2].

A. Single Glass

Type of

Glass

Nominal

Thickness

Shading

h =4.0

0

Coefficient

h =3.0

0

Regular Sheet 3/32, 1/3 1.00 1.00

Regular Plate/

Float 1/4 0.95 0.97

Grey Sheet 1/8 0. 78 0.80

1/4 0.86 0.88

Heat-Absorbing 3/16 0.72 0.75

Plate/Float 1/4 0.70 0.74

B. Insulating Glass

Type of

Glass

Nominal

Thickness

Shading

h =4.0

o

Coefficient

h =3.0

o

Regular Sheet Out,

Regular Sheet In 3/32, 1/8 0.90 0.90

Regular Plate/

Float Out,

Regular Plate/

Float In

1/4 0.83 0.83

Heat-Absorbing

Plate/Float Out,

Regular Plate/

Float In

1/4 0.56 0.58

A- 13
TABLE A- 6. SHADING COEFFICIENTS (SC) FOR SINGLE GLASS WITH INDOOR

SHADING BY VENETIAN BLINDS AND ROLLER SHADES [2]

Type of

Glass

Type of Shading

Venetian Blinds

Roller Shade

Opaque Translucent

Medium Light Dark White Light

Regular Sheet

Regular Plate/Float

Regular Pattern

Heat-Absorbing

Pattern

Grey Sheet

0.55 0.59 0.25 0.39

Heat-Absorbing Plate/

Float a Heat-Absorbing Pattern

Grey Sheet

0.57 0.53 0.45 0.30 0.36

Heat-Absorbing Plate/

Float or Pattern

Heat-Absorbing Plate/

Float

3

0.52 0.40 0.28 0.32

Heat-Absorbing Plate

or Pattern

0.42 0.40 0.36 0.28 0.31

Reflective Coated

Glass

0.30 0.25 0.23

0.40 0.33 0.29

0.50 0.42 0.38

0.60 0.50 0.44

Refers to grey, bronze, and green tinted heat-absorbing plate/float

glass

Shading Coefficient for glass with no shading device.

A- 14
TABLE A-7 . SHADING COEFFICIENTS (SC) FOR INSULATING GLASS WITH INDOOR

SHADING BY VENETIAN BLINDS AND ROLLER SHADES [2]

Type of Shading

Type of Venetian Blinds Roller Shade

Glass Opaque Translucent

Medium Light Dark White Light

Regular Sheet Out

Regular Sheet In

Regular Plate/Float

Out

Regular Plate/Float

0.57 0.51 0.60 0.25 0.37

In

Heat-Absorbing

Plate/Float° Out

Regular Plate/ 0.39 0.36 0.40 0.22 0.30

Float In

Reflective Coated

Glass

SC = 0.20 0.19 0.18

0.30 0.27 0.26

0.40 0.34 0.33

For vertical blinds with opaque white or beige louvers, tightly closed,

SC is approximately the same as for opaque white roller shades.

Refers to bronze or green tinted heat-absorbing plate/float glass.

A- 15
TABLE

A8.

SHADING

COEFFICIENTS

(SC)

FOR

DOUBLE

GLAZING

WITH

BETWEEN-GLASS

SHADING

[2]

CO

CO

oJ I—

bO

oJOi—

4-1

0) •U

03 !—

a

bOc

rlX3-1 0

CO X

031 X

03

03 X

T3

a) XaHXC

a)cu

3-i bO xa

03

03NCO

3-i X

03

!-i bOOX

CO

3-i 03

4-1 03 Pi

A-16
4. 3 Rate of Heat Gain through Opaque Walls

2 The rate of heat gain (Q ) in Btu/h*ft through opaque walls shall

be calculated from the relation:

Q = U -TETD (10)

q q

Here U is the thermal transmittance of opaque walls as calculated from

q

section 4.1 and TETD is the total equivalent temperature difference

specified in table A-9 . The procedure is to identify the wall con- struction type of table A-10 which is closest to the actual wall con- struction type. Identify the group number for the wall construction

from table A-10 and then find the total equivalent temperature difference from table A-9. The total heat gain through opaque walls is

equal to the sum of products of Q by their respective opaque wall

area for each orientation.

4.4 Rate of Heat Gain through Roof Areas

2 The rate of heat flux (Q ) in Btu/h'ft through opaque roof areas

shall be calculated from the relation:

Q

= U • ETD (11)

r r

Here U is the thermal transmittance of the roof area as calculated

r from section 4.1 and ETD is the equivalent temperature difference, as specified in table A-ll for selected type roofs. The net heat gain

through a roof is equal to H^ = -A^, where A^_ is the ceiling area below the roof.

A- 17
TABLE A- 9 . TOTAL EQUIVALENT TEMPERATURE DIFFERENCE (TETD) FOR

CALCULATING HEAT GAIN THROUGH SUNLIT WALLS* [2]

North Latitude

Wall Facing

Exterior Color of Wall—

= dark , L = light

D L D L D L D L

Group A Group B Group C Group D

NE 23 17 39 20 24 15 21 14

E 26 19 36 24 30 19 27 17

SE 26 18 37 24 39 18 25 16

S 25 18 36 24 23 15 20 13

SW 41 26 42 26 23 15 22 15

W 48 30 40 25 22 15 23 15

NW 38 25 30 20 18 12 19 13

N 21 16 22 16 15 11 14 11

*The values in the table were calculated for an inside temperature

of 75° F and an outdoor maximum temperature of 95° F with an outdoor

daily range of 21° F. The table remains approximately correct for

other maximums (93°-103° F) and the other outdoor ranges (16°-34° F)

providing the outdoor daily average temperature remains approximately

85° F. If the room temperature is different from 75° F and/or the

outdoor daily average temperature is different from 85° F, apply the

following corrections:

For room air temperatures less than 75° F, add the difference between 75° F and the room air temperature; if greater

than 75° F, subtract the difference.

For outdoor daily average temperature less than 85° F, subtract the daily average temperature; if greater than 85° F,

add the difference.

A-18
TABLE A-10. 'DESCRIPTION OF WALL CONSTRUCTIONS [2]

1 Group Components

Wt., lb

per

sq f

U-Value

Btu/h-ft

2 - °F

A 1" stucco + 4" l.w.—^ concrete block +

air space

28.6 0.267

1" stucco + air space + 2" insulation 16.3 0.106

B 4" face brick + 4" l.w. concrete block

+ 1" insulation

1" stucco + 4" h.w.— concrete + 2"

insulation

62.5 0.158

62.9 0.114

C 4" face brick + 8" clay tile + 1"

insulation

96.4 0.137

4" face brick + 8" common brick 129.6 0.280

1" stucco + 12" h.w. concrete 155.9 0.365

4" face brick + 2" insulation + 4" common brick

89.8 0.106

4" face brick + 2" insulation + 4"

h.w. concrete

96.5 0.111

4" face brick + 2" insulation + 8"

h.w. concrete block

90.6 0.102

D 4" face brick + air space + 8" clay

tile

96.2 0.200

4" face brick + 2" insulation + 8"

common brick

129.9 0.098

4" face brick + 2" insulation + 8"

h.w. concrete

143.3 0.107

1 / l.w. denotes light weight —

2 / h.w. denotes heavy weight

A- 19
TABLE A- 11. TOTAL EQUIVALENT TEMPERATURE DIFFERENTIALS

CALCULATING HEAT GAIN THROUGH FLAT ROOFS [2]

(ETD) FOR

U—va 1 up ETD

Description or Roof Wt 2 Roof iColor

Construction lb/ft Btu/h* f t

* °F Dark Light

Light Construction Roofs—Exposed to Sun

1" insulation + steel siding 7.4 0.213 78 45

2" insulation + steel siding 7.8 0.125 81 46

1" insulation + 1" wood 8.4 0.206 86 48

2" insulation + 1" wood 8.5 0.122 88 49

1" insulation + 2.5" wood 12.7 0.193 79 42

2" insulation + 2.5" wood 13.1 0.117 76 41

Medium Construction Roofs—Exposed to Sun

1" insulation + 4" wood 17.3 0.183 62 32

2" insulation + 4" wood 17.8 0.113 58 30

1" insulation + 2" h.w. concrete 28.3 0.206 81 44

2" insulation + 2" h.w. concrete 28.8 0.122 79 43

4" l.w. 1 / concrete 17.8 0.213 88 48

6" l.w. concrete 24.5 0.157 72 38

8" l.w. concrete 31.2 0.125 49 24

Heavy Construction Roofs—Exposed to Sun

1" insulation + 4" h. w. —-^concrete 51.6 0.199 61 32

2" insulation + 4" h.w. concrete 52.1 0.120 58 30

1" insulation + 6" h.w. concrete 75.0 0.193 48 25

2" insulation + 6" h.w. concrete 75.4 0.117 46 23

—

l.w. denotes light weight

2 / — h.w. denotes heavy weight

A-20
4. 5 Heat Gain from Occupants

The rates at which heat and moisture are given off by human

occupants under different states of activity are given in table A-12.

The sensible heat gain (H ) is

ps

H

ps YG

1

+ VG

2

+ VG

3 + .+ P • G n n

( 12 )

where P^ = number of persons engaged in specific activity of table A-12

= sensible heat for activity of table A-12, Btu/h per person.

The latent heat gain (H ) is:

tr -*

H 1 = P •L 1 + P -L 0 + P •

0 + ...+ P -L (13) pi 11 22 33 nn

where is the latent heat for activity of table A-12, Btu/h per person

4. 6 Heat Gain from Heat-Producing Processes

Heat gain from heat-producing processes includes heat from lighting,

electric motors and office, kitchen and cleaning appliances. Heat gains

from these sources must be released within the conditioned space in order

to be considered as heat gain to the building. Heat released to an exhaust air stream or refrigeration circuit which is in turn rejected to an outdoor environment must not be considered as heat gain. Heat gain

from electric lighting (H ) is calculated from the relation:

e

H = 3. 412 *W* M* N (14)

e

where W

M

N

total installed lighting power, watts

special allowance factor, 1.2 for fluorescent fixtures,

1.0 for incandescent

use factor

0.9 for commercial

0.8 for residential

A- 21
TABLE A- 12. RATES OF HEAT GAIN FROM OCCUPANTS OF CONDITIONED SPACES [2]

Degree of Activity Sensible Heat (G)

Btu/h

Latent Heat (L)

Btu/h

Seated at rest 225 105

Seated; very light work 245 105

Moderately active office work 245 155

Standing; light work; or walking slowly 250 200

Walking; seated

Standing; walking slowly

250 250

Sedentary work 250 275

Light bench work 275 475

Moderate dancing 305 545

Walking 3 mph; moderately heavy work 375 625

Heavy work 580 870

The heat gain from motors is given in table 30, Chapter 22 of the

1972 ASHRAE Handbook of Fundamentals [2], The heat gain from all office

appliances must be calculated in a manner similar to that for lighting,

where the use factor must be based on engineering judgment. For kitchen

appliances, both the sensible and latent heat gains must be considered.

Tables 31 and 32 of the same source contain recommended rate of heat . gain values for kitchen and miscellaneous appliances.

4 . 7 Heat Gain Due to Ventilation and Infiltration

In section 2.3, mechanical ventilation with outside air shall be

taken as 5 cfm (standard) per person for occupied spaces and not to exceed

2 air changes per hour for occupied spaces such as corridors, foyers, etc.,

for all building types except one- and two-family dwelling units. The

sensible heat gain (H ) from mechanical ventilation is: vs

H = 5.5-P* (t - 78) (15) vs od

A-22
where P = number of occupants

and t , = summer outdoor design temperature (section 2.1).

od

The latent heat gain (H ) from this source is

H , = 24, 210. P . (w - 0.012) (16)

vl od

where w , is the humidity ratio of the outdoor air at the design wet-bulb

od

and dry-bulb condition specified in Ref. [1]. If u u is less than

od

0.012, H , should be set to zero. Sensible heat gain (H. ) due to air

vl is

infiltration is:

H = 0. 0183* V* I* (t , - 78) (17)

is od

3

where V = volume of conditioned space of building, ft

and I = rate of air infiltration, air changes/h.

Latent heat gain (H ^) due to infiltration is:

H., = 80. 7* V* I* (w , - .012) (18)

ll od

If (o , is less than or equal to 0.012, H„, should be taken to be zero,

od n ll

4 . 8 Design Sensible and Latent Cooling Loads

As defined in sections 4.2 through 4.7, the design sensible

heat gain (H. ) in Btu/h is:

ds

HJ =H+H+H+H +H+H + H + H.

ds w q r ps e as vs is (19)

and the design latent heat gain (H ) is:

dl

H, = H . + H , + H . + H.-

dl pi al vl ll ( 20 )

where Hw

H

H

i H

ps

heat gain through window

heat gain through walls

heat gain through roof

sensible heat gain from occupant

A-23
= heat gain from electric lighting

H = sensible heat gain from appliances

H

vg

= sensible heat gain from mechanical ventilation

H

is = sensible heat gain from natural air infiltration

H

^ = latent heat gain from occupants

H

^

= latent heat gain from appliances

= latent load due to mechanical ventilation

H^

1 = latent load due to natural air infiltration

The sum of the heat gains and H

^ is the total instantaneous heat

gain to the building at design conditions. For the simplified calculation procedures presented herein, it is recommended that a conservative estimate for the design cooling load be taken as the instantaneous heat gain (H, + H,_). The actual cooling load for the building ds dl

will be lower than this estimated figure, because radiated heat gains

(such as solar radiation through a window that strikes a floor surface) are not instantaneously converted into cooling loads. The

storage of radiation heat gains causes some leveling off in the peak

cooling load.

A simplified method for relating the instantaneous heat gain to

instantaneous cooling load is outlined as follows:

Separate the instantaneous heat gain into convective and radiant

heat gain by the values given in Table A-13. Consider the convective

portion of the instantaneous heat gain as instantaneous cooling load.

Consider the radiant portion of the instantaneous heat gain as reduced

or averaged over a period of time by the thermal storage of the building.

For lightweight construction, consider the instantaneous cooling as an average of the radiant instantaneous heat gain over a 2- to 3-h period

up to and including the time of maximum load conditions. For heavy

construction, consider the instantaneous cooling load as an average of

the radiant instantaneous heat gain over a 6- to 8-h period up to and

including the time of maximum load conditions. The total instantaneous

cooling load is the sum of the convective portion and the time-integrated

average of the radiant portion.

A- 2 4
TABLE A-13. CONVECTIVE AND RADIANT HEAT

GAIN TO COOLING LOAD [2]

Heat Gain Source Radiant

Heat , %

Convective

Heat, %

Solar, without inside blinds 100 —

Solar, with inside blinds 58 42

Fluorescent lights 50 50

Incandescent lights 80 20

People 40 20

Transmission through walls and roof 60 40

Infiltration and ventilation — 100

Machinery or appliances* 20-80 80-20

* The load from machinery or appliances varies, depending upon the

temperature of the surface. The higher the surface temperature,

the greater the radiant heat load.

5. ENERGY REQUIREMENT FOR SPACE HEATING

A bin method is outlined in the following sections for predicting

the seasonal energy requirement for space heating. In general, steadystate heating loads for 5° F temperature increments (bins) are calculated. The cumulative energy requirement for each bin is then obtained by multiplying the heating load for the bin by the number of

heating hours for the bin. The seasonal heating energy requirement

is equal to the sum of the energy requirements for the separate bins.

All outdoor air temperatures above 65° F are considered to have no heating season energy requirements. When the calculated heat generated within the building exceeds the building heat loss and raises the

indoor temperature above 78° F, the calculation for the heating energy

requirement shall be set equal to zero.

A-25
5.1

Heating Hours (T ) Total heating hours for 5° F temperature increments below 65° F are found in sections C and D, Chapter 6 of AFM 88-8 [1]. For locations other than those given in AFM 88-8 [1], weather data should be

obtained from USAF/ETAC, Scott AFB , IL 62225. 5.2

Building Heat-Loss Rate (H)

Building heat-loss rate includes heat-loss rate through windows and

opaque walls, floors, and roofs and heat loss due to infiltration and

forced ventilation. Values for the 5° F temperature increments below

65° F are determined for the relation:

to

>

t od ) ( 21 )

H = design heat-loss rate from section 2.9, Btu/h

t^ = design indoor temperature (section 2.2), °F

t design outdoor temperature (section 2.1), °F

t = mean of temperature increment (62, 57, 52, etc.), °F

5.3

Heat Generation Rate (H ) within a Building

§

The heat generation rate within a building is due to heat release

from lights, people, office, kitchen and cleaning appliances, motors,

and heat loss from hot water heaters and piping. Since these sources

of heat release are not operated on a continuous basis, the average

heat release rate must be determined by using a diversity factor which

is multiplied by the heat generation rate of the source. Diversity

factors for deriving average heat release rates are presented below:

Lights .25

Office appliances .05

Kitchen appliances .08

Cleaning appliances .04

Hot water heaters and piping .05

Motors .1

People .33

A- 2 6
These diversity factors are presented only as guidelines. They were

not derived from measured data nor are they based on a rigorous en- gineering analysis. They should be used only when more accurate information on building operation is unavailable. The diversity factors

to be used in actual applications are for the most part a matter of

judgment and depend on the occupancy and operation of a particular

building. It is recommended that for calculating energy requirement for

space heating, an average figure for the metabolic heat-release rate of

225 Btu/h per person be used.

5.4 Efficiency of Heating Plant (e ) Approximate part-load efficiencies as a function of the part-load

fraction for a gas-fired forced-air furnace and a gas-fired boiler are given in figure A-l. Here the term "part-load fraction" is defined as the ratio of heating demand to rated heating plant output. The partload efficiency for fuel-fired heating plants is seen to become less

as the part-load fraction decreases. At low part-load fractions,

the amount of time for which the heating plant does not operate and

the number of furnace cycles increase. Both of these factors increase the amount of stored heat that is lost (to the flue) from the

heat exchanger during periods when the heating plant is not operating.*

A procedure for calculating seasonal performance factors for unitary heat pumps is discussed in the Unitary Heat Pump Specification for

Military Family Housing [6], Part-load efficiency data for other types

of heating plants are presently not available. A strong need exists to

develop this data.

* The present discussion assumes that heating plants are not equipped

with automatic flue dampers which close when the burner is not

operating.

A- 2 7
TYPICAL

GASFI

RED

HYDRONIC

BOILER

A-28

PARTLOAD

FRACTION

=

HEATING

DEMAND/RATED

HEATING

PLANT

OUTPUT

Figure

A-l.

Part-load

efficiencies

of

various

types

of

heating

plants.
5. 5 Correction (E) for Nighttime Setback of Thermostat

If the thermostat is set back from the indoor design temperature of

70° F for a period during the night, reductions in heating energy re- requirement are realized. For the various 5° F temperature increments,

correction factors (E) are given in table A-14 for the variables of

outdoor temperature, amount of setback, and duration of setback. With

no nighttime setback, E = 1.

TABLE A-14. CORRECTION FACTORS (E) FOR NIGHTTIME SETBACK*

Duration, h

AVERAGE

TEMP.

OF 5° F

6 8 10

Setback, °F Setback , °F Setback, °F

INCREMENT 5 10 5 10 5 10

62 .91 .88 .88 .85 .86 .82

57 .91 .88 .89 .85 .87 .82

52 .92 .89 .90 ,86 .88 .84

47 .93 .90 .91 .87 .89 .85

42 .93 .91 .92 .88 .90 .86

37 .94 .92 .93 .89 .91 .87

32 .95 .95 .94 .90 .92 .88

27 .96 .93 .95 .91 .92 .89

22 .96 .94 .95 .92 . 93 .90

17 .97 .95 .96 .93 .94 .91

12 .97 .96 .97 .94 .95 .92

7 .97 .96 .97 .95 .95 .93

2 .98 .96 .97 .95 .96 .94

-3 .98 .97 .98 .95 .97 .94

-8 .98 .97 .98 .97 .95

* These values may not be applicable to buildings having complex HVAC

system high internal heat generation.

A-29
5.6 Winter Solar Heat Gain (H ) through Windows

s The winter solar heat gain for each orientation is the product of

window area, shading coefficient (see section 4.2), and winter solar

heat gain factor as given in table A-15. The total solar heat gain

through windows is the sum of the computations for each orientation

multiplied by the ratio Y/1550 which is a function of geographic location.

Values for Y are given in figure A-2

2 TABLE A-15. WINTER SOLAR HEAT GAIN FACTORS, Btu/h-ft

Latitude

Orientation 24 32 40 48

N 9 8 7 6

NE 16 14 11 9

E 37 33 29 25

SE 51 51 50 46

S 55 59 62 59

SW 51 51 50 46 w 37 33 29 25

HW 16 14 11 9

Horiz 66 56 45 34

5. 7 Heating Energy Requirement

For the parameters defined in sections 5.1 through 5.4, the heating energy requirement (Q.) in Btu for a particular 5° F temperature

increment is given by the relation:

Q. = E *T * (H-H -H )/e, (22)

l h g s h

where E = correction factor for nighttime setback

T = number of heating hours for temperature increment

h

H = heat-loss rate at mean temperature of the temperature

increment

A- 30
550

CD

A-31

Figure

Ar2.

Values

ofY

[5].
H - internal heat released by lights, equipment, and occupants

§

= solar heat gain through windows

e, = efficiency of the heating plant

h

For each 5° F temperature increment, the total winter energy requirement (Q ) in Btu for a building is equal to the energy needed for space

heating plus the energy needed to operate the lighting and equipment, or

Q = Q. + (H - H ) • T (23)

o i g p h

Here H is the heat released by the occupants. To obtain the total

P energy requirement over the entire winter season, equation (23) is

evaluated for each of the 5° F temperature increments. The resulting

values are then summed to give the total winter season energy requirement. The foregoing procedure for calculating the winter energy

requirement is illustrated with the following sample problem:

Sample Problem

For a residence located in Columbus, Ohio (latitude 40°) the design

heat-loss rate at 4° F (Chapter 6 of AFM 88-8 [1]) is H = 80,000 Btu/h.

It is required to find the heating energy requirement, the energy needed

to operate lighting and appliances, and the total energy consumption by

the building during the winter heating season. The calculation is carried out in table A-lb. The 5° F temperature increments, the average temperature of the increments, and

the total heating hours for the increments for a typical winter at

Columbus, Ohio are given in columns 1, 2 and 3, respectively.

These data were obtained from Chapter 6 of AFM 88-8 [1]. Equation (21) was used to calculate the heat-loss rate for the building at the mean

outdoor air temperature for each 5° F temperature increment. These

heat-loss rates are tabulated in column 4. The sum of internal heat

generation (H ) and solar heat gain through windows (H ) is given in

g

s column 5. The net heat demands for the increments (H - H - H ) g s are tabulated in column 6. The calculation of internal heat generation

(H ) and winter solar gain through windows (H ) is carried out in

g

^ tables A-17 and A-18. The part-load fractions of the heating plant for

A-32
TABLE

A-16.

CALCULATION

OF

WINTER

ENERGY

REQUIREMENTS

CO

4-J § -S3 60 QJ 3 o 00 ON 1—

LO co LO o ON >d* ON o CM ON 00 CM

d >N VJ 4J LO oo CM LO CO ON NO CO r—rH CN 00 rH CM o •H 60 •H PQ NO CO CO LO CN oo ON LO ON ON CO CN ON o 4-J S-l d 1 d <u cjvd NO r—1 NO >—

CN LO NO CO o OJ d QJ O '—

T 1 CN] CN CO CN

33

w

H i—1 c u o o

•H <4-1 a;

S-l 4JU

O

u Bl

4-J 32 Xl O 60 4J U -H HI

O

h 2 m

60 o c C -H

ai 4-i •H cd O 0J •h te

<4-4

<4-1 <4-1 w o PM H

-O

•H

4-J O

04 10 16 22 28 34 40 46 53 59 65 71 77 83 89

CNO

ON o

LO00

S-i

dd o CO

CO

O S-I eu i-J eh

CON 4-J

ffl

G

H

CO

X

d‘ ^d

H

H o

«o

oo nOoo oo

oo

ON

co o

on

CM

ON

COOn

CO

on on

LOONlO

on lO

ON nOON

d

hioH

no

LfO NO

VO

NO

oo

nO

ooNO o CnI co LO

NO NO Ni o o X X c rd PQ LO i—

CO ON LO <—1 CO ON LO i—

co ON

•H

d 1 o t—

i—

CN CM CO 'd- LO LO NO co CO

4-»

d o d g o o NO CN 00 o NO CN 00 o NO CM 00

QJ QJ o i—«H CM CN CO LO LO NO 00 00

<r

coI CO

CD

dd H» rH i—

rHr

—

rH

HH

HHr

—

t—1 r—

H

r

—1 H

H N>/

d

u PQ

u

X

0) 4-J o '—l rH rH rHH

r

—H

H

HH

r

—

H

H

r

—H

H

4-J

d o iH rH rH rH

r

—HH

r

—H t—t—

i—

HH

HH CO c a) o o M 33 1—

QJ

H

a

*HX

33 >

QJ \ QJ 00

4-J

da rd 4-J o nO CN CO < o NO CM 00 o NO CM CO t—

00

P3 oo oo ON o o H

H CM CO CO -d- <3* LO NO oo • d 10

4-1 CO

O ON LO rH co o NO CM 00 o NO CM 00 o •H

d COO 1—

CM CM co <d- <f LO LO NO co co ON o 4-1 II QJ o O 1—

d

33 1-2 1 1 # QJ 33 60 . H

60W 0)

S3 O' S3 •H CO <4-4 W

4-J

u <! CM co o CM LO ON o 00

r

—

00 o ON CO CN co

d 3 o ON NO LO o 00 CO ON LO

r

—H ^ C

QJ o oo NO NO NO NO CM co 60

O

33 33 LOU *H

<1) 4-J d d • W S-l S3 a 0) d g CM CN O- CM CM CN CM r^. CN CO oo CO rH d

Q) a) NO LO LO co CO CN CM

r

—

H 1 1 H QJ Q) s H 0 1 rH

(3 60 O

d 03 4J

4-J 4-J 0) 0) d o QJ QJ Q) <—

H CO 33 6 ON ON ON ON <d- ON NO 1—1 • QJ nO LO LO co CO CN CM r—1 t—

ON

H 1 1 a S-l \ — S. \ \ — N 1 *"

N o o LO o LO o LO o LO o LO o LO o N o LO

ai S3 Eh NO LO LO "d- co CO CM CM

r

—

r

—

LO

HH

A-33

Total

Energy

Required

214.752 x

10

Btu

1/

Includes

heat

gains

from

lighting,

equipment,

occupants,

and

transmitted

solar

rad

2/

Does

not

include

effect

of

nighttime

setback

of

the

thermostat

which

is

taken

into
the 5° F temperature increments are tabulated in column 7. Part-load

efficiencies (e^) and correction factors (E) for nighttime setback of

the thermostat are given in columns 8 and 9, respectively. Equation (22) was used to calculate the cumulative heating energy requirements for each

5° F temperature increment. Heating energy requirement for each 5° F

temperature increment is given in column 10. And finally, the net

annual heating energy requirement is found by summing the values of

column 10.

The total energy consumed by the building during the heating

season is equal to the sum of the energy required for space heating

and the energy required for lighting and equipment (see calculation

given under the tabulated values)

TABLE A-17. CALCULATION OF INTERNAL HEAT GENERATION (H ) , Btu/h

O

1. Lights, 340 watts x 3.412 x .25 = 3275.5

2. Kitchen Appliances 6000 watts x 3.412 x .08 = 1637.8

3. Cleaning Appliances 4000 watts x 3.412 x .04 = 546.

4. Hot water Heater and Pipes 400,000 x .05 = 2000.

5. Metabolism 5 persons x 225 x .33 = 371.

7830. Btu/h

TABLE A-18. CALCULATION OF WINTER SOLAR GAIN THROUGH WINDOWS (H ) , Btu/h

Shading

Area SHGF Coefficient

N 80 7 .56 313.6

E 70 29 .59 1197.7

S 90 62 .83 4631.4 w 70 29 .59 1197.7

7340.4

From figure A-2, Y = 820

H = 7340.4 x 820/1550 = 3883.3 Btu/h

s „ H + H = 11.713 x 10 Btu/h

g s

A-34
6. ENERGY REQUIREMENT FOR SPACE COOLING

The methodology for determining the cooling season energy requirement includes the building sensible and latent heat gains, heat generated

within the building, efficiency of cooling plant, and solar heat gains

through walls, roofs and fenestration areas. Energy requirement for

space cooling will be taken to be zero, when the outdoor air temperature

O is lower than 65 F. In addition, the cooling energy requirement is

taken to be zero when .the indoor temperature falls below the design

indoor temperature level, i.e., no heating or cooling is called for in

the indoor temperature range from 71° to 77° F.

6.1 Cooling Hours (T ) Total cooling hours for 5° F temperature increments, as well as coincident wet-bulb temperatures, may be found in AFM 88-8 [1], For

locations not found in the above, weather data should be obtained from

USAF/ETAC , Scott AFB , IL 62225.

6.2 Conductive Heat Gain (H ) c Exclusive of the solar heat gains, the conductive heat gain (H ) through the exterior envelope of a building due to air-to-air temperature

difference may be determined from the relation:

H = (A -U + A -U + A *U + M*A -Uj-Ct - t ) c ww qq rr ft o l

(24)

where A = area, ft

2 U = thermal transmittance, Btu/h*ft • °F

t = mean temperature of increment, °F

ot^= indoor design temperature, °F

and subscripts w, q, r, f, denote windows, opaque walls, roof, and floor,

respectively. For floors, values for the factor (M) are given below;

slab-on-grade floors M = 0.2

floor over crawl space, M = 0.8

non-cooled basements, M = 0.3

cooled basements, M - 0.7

A-35
6.3 —Summer Solar Heat Gain through Windows and Walls — (H )

-— w

The solar heat gain through windows and walls (H^) defined for each

orientation by the relation:

H = Y* SHG* [ SC* A + 0.18 A *U ] (25)

w w q q

2 SHG = summer solar heat gain from table A-19, Btu/h’ft

SC = shading coefficient (from tables A- 5 through A-8)

Y = Y /2,400 (from figure A-3)

where A , A and U are defined in section 6.2. The total solar heat

w* q q

gain (H

g

) is the sum of the values calculated for each wall orientation

of the building.

6.4 Solar Heat Gain through Roofs (H ) The solar heat gain (H ) through roofs is defined by

H = Y ' • cos

2

(<f>) [0 . 18 *SHG -7 ]

* A *U (26)

r h r r where SHG is solar heat gain for a horizontal surface as given in

^ 1 table A-19, <p is the roof-pitch angle, Y is as defined in figure A-3,

and A and U the surface area and thermal transmittance of the roof,

r r

’ respectively.

TABLE A-19. SUMMER SOLAR HEAT GAIN (SHG) FOR VERTICAL AND HORIZONTAL

SURFACES, Btu/h* f t 2

ORIENTATION

LATITUDE

24 32 40 48 56

N" 20 18 17 17 18

NE 37 35 33 32 32

E 46 47 48 50 51

SE 33 39 45 51 56

S 17 23 31 41 51 sw 33 39 45 51 56 w 46 47 48 50 51

NW 37 35 33 32 32

HORIZ 89 89 87 84 78

A-36
1500

A-37

Figure

A3.
6.5 Heat Gain due to Air Infiltration and Mechanical Ventilation (H ) The heat gain due to air infiltration and outside air introduced by

mechanical ventilation is separated into the sensible and latent loads.

The sensible load (H ) from these sources is: vs

H = (0. 0183’ V* I + 5.5-U -P)-(t - t.) (27)

VS P O 1

3

V = volume of conditioned space of building, ft

I = rate of air infiltration, air changes/h

P = number of occupants, P = 0 if no mechanical ventilation

U = diversity factor for people (see table A- 20 of section 6.6),

P

The latent load (H , ) from these sources is

vl

H , = (80.7-V-I + 24,210’U *P)*(o> -.012) (28) vl p o

= humidity ratio at coincident wet-bulb temperature for the 5° F temperature increment (see section 6.1), lb water/lb dry air

When the humidity ratio is less than 0.012, the latent load is set equal

to zero.

6.6 Internal Heat Gains (H ) g

The heat generated within buildings is due to lights, people,

office, kitchen and cleaning appliances, motors, and from hot water

heaters and piping. The heat generated from these sources does not occur on a continuous basis. To obtain the average heat release rate

for an internal source, multiply the heat release rate for the source

by a diversity factor. Diversity factors for various sources of heat

release are given in table A-20.

A-38
TABLE A-20. DIVERSITY FACTORS (U ) P

Residential Office

People .5 .25

Lights .2 .2

Office equipment - .05

Kitchen equipment .1 .08

Cleaning equipment .06 .04

Hot water heater and piping .05 .05

Motors .02 .05

These diversity factors are approximate values based on engineering

judgment and should be used only when more accurate estimates are not

available. Diversity factors are a matter of judgment and depend

significantly on the type of occupancy and the operation of a particular building.

For calculating the energy requirement for space cooling, it is

recommended that average figures for the metabolic rates be taken as 225 Btu/h for sensible heat and 105 Btu/h for latent heat.

6.7 Efficiency of Cooling Systems (E)

The efficiency of cooling systems depends upon the coefficient of

performance (COP) of the cooling plant, the energy required to pump

working fluids, the method of temperature control to conditioned spaces

and the method of heat rejection. The efficiency of air conditioning

systems varies over a wide range and depends upon the system type, the

outdoor temperature conditions, and the way in which it is operated.

It is recommended that manufacturers’ seasonal-efficiency values be used

unless measured performance data are available.

6.8 Cooling Energy Requirement

The sensible cooling load (H ) for a particular 5° F temperature

s increment in equal to the sum of the heat gains to the occupied space,

or H=H+H+H+H + H (30)

s c w r vs gs

A-39
where = conductive heat gain through exterior building envelope due to

air-to-air temperature difference

= solar heat gain through walls and windows

= solar heat gain through roof

11^^= sensible load due to axr-exchange between indoor and outdoor

air (includes both natural air infiltration and mechanical

ventilation)

H = sensible heat release by internal sources such as lights,

occupants, and equipment.

The latent load (H^) for a particular 5° F temperature increment is equal

to the sum of the latent load due to the air exchange between indoor and

outdoor air and the latent load due to moisture release from internal

sources, orH

1

H

vl

+ H

gl (31 >

where H , = latent load due to the influx of outdoor air (includes vl

both natural air infiltration and mechanical ventilation)

H , = latent load due to moisture release from internal sources,

gl

For a particular 5° F temperature increment, the total heat gain

is equal to:

Q = T • (H + KL) (32)

c s 1

where = number of cooling hours for the temperature increment.

The total heat gain during the summer cooling season is equal to the sum

of the heat gains for the various 5° F temperature increments.

The total energy consumed by the building for space cooling during

the summer cooling season is equal to the total heat gain divided by the

seasonal efficiency (E) of the cooling plant. The total energy consumed

by the building is equal to the energy consumed by the cooling plant,

plus the energy consumed by the lights and equipment [Teg* (H - H )],

P where (H - H ) is the rate of energy consumption for lighting and

8 P

equipment and T^ is the number of cooling hours for the summer cooling

season.

A-40
Sample Problem

It is required to find the energy requirement for space cooling and

energy consumption by the lighting and equipment during the cooling

season for a three-story office building located at Robins AFB, Georgia.

The dimensions of the building are 80 ft long, 40 ft wide, and 33 ft high.

The thermal transmittances of the windows, opaque walls, roof, and floor

are 1.06, 0.15, 0.15, and 0.08 Btu/h* ft^* °F, respectively. Normal

occupancy is 100 persons. The mechanical cooling system has seasonal

•efficiency of 2.09. The calculation is carried out below.

A. From Chapter 6 of AFM 88-8 [1] , the total cooling hours for

the applicable 5° F temperature increments for Robin AFB, Ga.

were obtained and inserted in column 2 of table A-21. The

average temperature and the mean coincident wet-bulb temperatures

for the various 5° F temperature increments are given in columns

1 and 3, respectively.

B. Based on the methodology presented in section 6.3, the calculation

for solar heat gain (H ) through the various walls and windows is w

carried out below:

Area

Orientation Type ft^ SC or .18 U_ SHG Heat Gain, Btu/h

N window 660 .80

4

18 10466

wall 1980 .027

E window 132 .51 47 4672

wall 1188 .027

S window 660 .51 23 8971

wall 1980 .027

W window 132 .51 47 4672

wall 1188 .027

28,781 Btu/h

H

1800

= _ ;

-

- X; 28,781 = 21 ,586 Btu/h

w 2400

The windows on the north and south exposures were assumed to

be 25 percent of the wall area, and 10 percent of the wall area

for the east and west exposures of the building.

A-41
2OW

COO

!ZM

h4Oo

Pi

COwKH

Piw>ou

!aMQ

hJMMw

EdHOH

isM

<coHCW

EC

<iHOHOSOWH<£O

<1o

CMI Cw

CQ<H

A- 42

4746

224.803 x

10

Btu
C. Using the methodology of section 6.4, the solar heat gain (H^)

through the roof is

H

r 18002400

(.18 x 89 -7) x 3200 x .05 = 1,082 Btu/h

D. Using the methodology of section 6.2, the total conduction heat

gain through the building envelope is found to be

H = 2,864* (t - t.)

c o 1

Here 2,864 is the sum of the U*A products for the various

elements of the exterior building envelope. The total heat

transmitted (H) through the building envelope is equal to the

conduction heat gain due to air-to-air temperature difference

and solar heat gain through walls, windows, and the roof, or

H = H + H + H

c w r = 22,668 + 2,864* (t - t.)

Values for H were calculated for the various temperature increments and are tabulated in column 4 of table A-2L

E. From section 6.5, the sensible heat gain due to air exchange

between the indoor and outdoor air is given by the relation:

H = 1,053* (t - t.) VS O 1

Values are computed and entered in column 5 of table A-21.

F. The sensible heat gain (H ) from internal sources is

People 100 x .25 x 225 5,625

Lights 2.5 watts/ft^ x 889^ .2 x 3.412 15,169

Office Appliances 5000 watts x .05 x 3.412 853

Cleaning Appliances 6000 watts x .04 x 3.412 819

Hot water heat and

piping losses 80,000 x .05 4,000

26,466 Btu/h

A-43
The total sensible heat gain from internal sources is seen to

be 26,466 Btu/h. The total sensible heat gain to the occupied

space is equal to the sum of the heat gains from internal sources (26,466 Btu/h), the heat gain due to total heat transmission (column 4) , and the heat gain due to air exchange

between indoor and outdoor air (column 5) . The total sensible

heat gains for the various temperature increments are tabulated

in column 6 of table A- 21.

G. Using the psychrometric chart, the humidity ratio (to ) for the

o dry-bulb temperature (column 1) and the wet-bulb temperature

(column 3) was determined for each 5°F temperature increment.

The difference in humidity ratio (<o q -.012) was subsequently

determined and entered in column 7 of table A-21 . When the

difference (to -.012) was less than zero, a value of zero was

o entered in the table. Equation (28) was then used to calculate

the total latent load, or

H = 4.64 x 10

6

• (to -.012) + (100) • (0. 25) • (105)

L o

The first term is due to moisture entering the building by way of

air exchange between the indoor and outdoor air, whereas the

second term is due to moisture released by the occupants. Values

of total latent load for the 5° F temperature increments are entered in column 8 of table A-21. The rate of total heat gain

for each 5° F temperature increment is equal to the sum of the

rate of total sensible heat gain (column 6) and the rate of

total latent heat gain (column 8) . Values for the rate of total

heat gain are tabulated in column 9.

H. The total heat gain for each 5° F temperature increment is

obtained by multiplying the number of cooling hours (column 2)

by the rate of total heat gain (column 9). These values are tabulated in column 10. The total heat gain to the building

during the summer cooling season is obtained by summing the

values of column 10 and is found to be 224.8 x 10 Btu.

A-44
I. The total energy requirement for space cooling is

Q = 224.803 x 10

2.09

= 107.6 x 10 Btu

J. The energy consumed by internal lighting and equipment over

the summer cooling season is

T • (H - H ) = 4746 • (20,841) = 98.9 x 10

6

'-8 BTU

P

K. The total energy consumption by the building over the summer cooling season is simply equal to the sum of the energy re- quirement for space cooling and for lighting and equipment,

or 206.5 x 10 Btu. This is equivalent to 60,500 kilowatt

hours.

REFERENCES

1. Engineering Weather Data, Air Force Manual 88-8, Chapter 6,

Department of the Air Force, June 15, 1967.

2. ASHRAE Handbook of Fundamentals, American Society of Heating,

Refrigerating, and Air-Conditioning Engineers, Inc. , 1972.

3. Computer Simulation of Fossil-Fuel-Fired Hydronic Boilers,

J. Chi, Proc. 2nd ASHRAE/NBS Conference on HVAC Equipment

and Systems, Purdue University, Lafayette, Indiana, April,

1976.

4. The Thermal Performance of a Two-Bedroom Mobile Home,

G. T. Teitsma and B. A. Peavy, NBSIR 76-1182, National

Bureau of Standards, January, 1977.

5. Intermediate Minimum Property Standards for Solar Heating and

Domestic Hot Water Systems, NBSIR 77-1226, National Bureau of

Standards, 1977.

6. Unitary Heat Pump Specification for Military Family Housing,

C. W. Phillips, B. A. Peavy, and W. J. Mulroy, NBSIR 76-1029,

National Bureau of Standards, 1976.

A-45

APPENDIX B. SOLAR ENERGY SYSTEMS FOR AIR FORCE APPLICATIONS

CONTENTS

PAGE

1. Introduction B-2

2. Description B-3

2.1 Active Systems B-5

2.2 Domestic Hot Water Heating Systems B-7

2.3 Solar Collectors B-9

2.4 Thermal Storage B-ll

3. Estimate of Solar System Performance B-ll

3.1 Approximate Technique B-12

3.2 Calculation Procedures for the Systems

of Figures 1 and 2 B-13

4. Simplified Economic Analysis B-20

B-l
APPENDIX B. SOLAR ENERGY SYSTEMS FOR AIR FORCE APPLICATIONS

1. INTRODUCTION

In the previous chapters of this handbook, steps have been outlined

where more or less conventional methods can be adopted to conserve energy

in existing buildings on Air Force installations. This appendix has been

included to provide guidelines for when consideration should be given to

the use of solar energy systems in buildings.

The sun is the source of practically unlimited energy, most of which

is now wasted. For example, the total solar energy reaching the ground

in the continental 48 States averages over 500 times the present United

States energy consumption. In the early 1970's, with the emphasis on finding solutions to the nation's impending energy problems, a special

panel of experts met at the request of the President's Office of Science

and Technology and identified three broad applications for solar energy

* as most promising [1] :

a. The heating and cooling of residential and commercial buildings,

b. The generation of electricity, and

c. The chemical and biological conversion of organic materials

to liquid, solid, and gaseous fuels.

The amount of research being done on these applications is growing

at an ever increasing rate both in the public and private sectors. The

first application, the space heating and cooling of buildings including

heating of domestic hot water, is the one closest to being used on a wide scale, and the only one that should be considered at the present

time for use in and around Air Force buildings.

The principal obstacle to the use of solar energy in buildings is an economic one. There can be substantial energy and dollar savings

through the use of the kinds of systems to be described in this chapter;

however, there is also a substantial investment involved in purchasing

* Numbers in brackets indicate references listed at the end of this

append ix.

B-2
and installing the equipment. The decision to be made, then, is one of

deciding whether the savings in fuel costs over a specified lifetime

will justify the initial investment.

Another secondary obstacle to the use of solar heating and cooling

is the uncertainty associated with the durability and maintenance problems

that are likely to occur. Considerable experience has been gained over

the last several years in the construction and operation of these systems.

Reference [2] describes 220 buildings that have been built or are currently

under construction, which use some form of solar heating and/or cooling.

Most of the buildings in reference [2] have been built in the United

States and in many cases reports are available describing the operating

experience. As early as 1923, solar energy systems were used for heating

domestic hot water in Florida and southern California. Reference [3]

iescribes an analysis of the solar water heating industry in Florida

during the period 1923-1974. It includes a thorough description of the

failures and successes that occurred through the use of various kinds of

components. As a result of the vast amount of experience obtained and

documented in recent years, the design and installation practice is

developing so that it is possible to construct durable systems having a lifetime equal with the conventional systems.

The remainder of this chapter is divided into three sections. In

section 2, a description is given of the typical kinds of systems to be

considered, as well as their major components. In section 3, methods are outlined for estimating what kind of fuel savings to expect from these

systems. In section 4, a simplified method is given for performing an economic analysis and using the expected fuel savings to determine

whether or not a system is likely to be economical. If more detailed

information is required than is supplied in this chapter, it is recommended that references [4-6] be consulted.

2. DESCRIPTION OF TYPICAL SOLAR ENERGY SYSTEMS AND COMPONENTS

Systems for converting the solar energy into useful thermal energy

for space heating, cooling, or heating of domestic hot water can be

classified as either active or passive. In an active system, the flow

B-3
of thermal energy into the building is controlled through the use of

auxiliary equipment such as pumps, valves, and heat exchangers. In the

passive systems, the energy flow is automatic, requiring little or no auxiliary equipment as in the case of the active systems. In most of the

passive systems, either a south wall or a flat roof is designed so that

the structural unit (or a part of it) collects and stores the thermal

energy. Examples are a massive concrete wall, painted black and covered

with a transparent surface; or stationary roof ponds/water beds covered

with movable insulation. Experiments have been conducted on these types

of systems and similar concepts and it appears that they are the most

promising from an economical viewpoint in certain regions of the country.

However, in almost all cases, the passive system must be designed as an integral part of the building. Therefore, only the active systems will

be addressed in this document since they are in many cases easily retrofitted into existing buildings.

Figure B-l is a schematic representation of an active solar space heating

and domestic hot water system. A fluid is pumped through a solar collector

where the incident solar radiation heats the fluid, and the thermal energy

is transferred to a storage unit through a heat exchanger. In turn, the

resulting stored energy is transferred through additional heat exchangers

either to heat domestic hot water or to heat the building space. The

system can be made more complicated by the inclusion of additional equipment that would also use the thermal energy in the storage tank to provide

either space cooling or space heating by some other means than through

the heat exchangers as shown.

Methods of using the thermal energy to provide space cooling include

the use of absorption and Rankine-cycle refrigeration units. In the

absorption units, the energy from thermal storage is used as a heat source

to boil refrigerant from a solution. The refrigerant subsequently absorbs

energy from the space to be cooled. In the Rankine-cycle units, the

thermal energy is used to drive a heat engine which is coupled to a con- ventional vapor-compression-cycle refrigeration unit. Detailed information

can be obtained from references [7, 8] on these and other methods of solar

cooling. Systems for solar cooling have been put into operation, but in

B-4
general, they are even less competive with conventional equipment (on an economic basis) than either solar domestic water heating or space heating.

An alternate method of providing space heating using solar energy is

to integrate a heat pump into the system of figure B-l. This can be done

in several ways and can involve air-to-air, air-to-water , or water-to-water

vapor-compression-cycle heat pumps. If the building is heated entirely by

the heat pump and the source side of the heat pump is exclusively the thermal

storage unit, it is called a solar-boosted heat pump. If a more flexible

yet more complicated system is designed, where the heat exchanger shown in

figure B-l is used as well as the heat pump, and the source side of the

heat pump can be either the thermal storage unit or the outside air, depending upon operating conditions, the system is designated as a solarassisted heat pump. More detailed information on these as well as other

heat pump concepts is included in reference [9],

The remainder of this chapter will discuss the applicability of the

type of system in figure B-l. In general, one should find that for most

localities the heating of domestic hot water will be the most economically

competitive use of solar energy, followed by space heating. If space heating,

using the concept in figure B-l, appears to be worth considering for certain

types of buildings, and a detailed analysis is subsequently conducted, con- sideration should also be given to systems employing heat pumps.

2 . 1 Active Systems

The types of active systems commercially available today are divided

into those that use water or a water-antifreeze solution as the basic heat

transfer fluid, and those that use air.

For the systems that use water or a water-antifreeze solution, they

are configured basically as shown in figure B-l. The storage unit is

usually one or more large water tanks. The heat exchanger between the

collector and storage tank could be eliminated if the system were located

in an area where freezing would not occur, or if provisions were made to

drain the solar collector at night. There is usually a pump in each loop

of the system and the pumps are controlled depending upon the available

solar radiation and the demand for either hot water or space heating within

the building. A special case of this system is one which only heats domestic

B-5
hot water. Since this is generally the system that is most economical

and should be considered first, it will be discussed in more detail

in section 2.2.

Figure B-2 shows a schematic diagram of a system which uses air as the basic working fluid. Only one fan is used; the air flow is through

ducts, and it is controlled and directed to the various components

through the use of motorized dampers. For example, when solar energy

is available for collection and there is a space heating load, room- temperature air is drawn through the solar collectors, heated, and

returned to the building. When solar energy is available for collection

and there is no space heating load, air is drawn from the bottom of the

storage unit (which is most often a packed bed of rocks or pebble bed)

,

heated and returned to the top of the storage unit. When there is a space heating load and no solar energy can be collected, hot air is drawn

from the top of the pebble bed and blown into the house while room temperature air is returned to the bottom of the pebble bed. In contrast to

the water-system, there is no need for a heat exchanger between the

collector and the storage unit and between the storage unit and the building

space. An air-to-water heat exchanger is usually used for heating the

domestic hot water.

In both types of systems, the auxiliary energy source for both

space heating and domestic water heating would in most cases be the con- ventional equipment now installed. The components would be compatible

with almost any type of energy distribution system installed in the existing

buildings; however, depending upon the type of installed system, one might

tend to select specific types of solar components. For example, an installed

system using radiators or fan-coil units for space heating would be more

compatible with a water-type system than with one using air collectors.

The primary consideration in comparing air and liquid systems involves

their life-cycle costs. Specifically, this is the annual total cost of

owning and operating the system. The cost of ownership includes the sum

of annual depreciation of the equipment based on its total useful life and an interest charge on the undepreciated equipment value. The operating

costs include maintenance, repairs, and the cost of auxiliary energy for

both heating and cooling as well as circulating the system fluids.

B-6
Although complete information on total installed costs of liquid

and air systems are not yet definitive, there do not appear to be large

differences. Since both use only small amounts of auxiliary energy

for circulating fluids and have comparable overall thermal efficiencies,

the major differences appear to be in durability and maintenance. Since

the air system is permanently dry, no significant corrosion of the

collector absorber occurs. There is no possibility of freezing the

collector fluid, so decomposable antifreeze compounds or other organic

liquids are not required. Boiling cannot occur, so replacement of

collector fluid is never needed. Fluid leakage, although not precluded,

involves minimal corrective cost and no secondary damage. Some longterm operating experience with an air system shows that maintenance is

not a significant expense and that the equipment can be expected to have

a life comparable to that of the building itself [10].

In October of 1975, the Energy Research and Development Administration (ERDA) published the results of a survey made to determine the

availability of solar heating and cooling products [11]. The report is

simply a compilation of responses to questionnaires that were sent to

all known manufacturers of solar components. Since the publication of

reference [11], ERDA has conducted a somewhat comprehensive analysis of

the information that 85 different organizations voluntarily submitted on

130 systems. Through the analysis, 36 different systems were found

technically acceptable for use in federally-sponsored demonstration

programs [12]. The basis for the evaluation included adequacy of design,

operating experience and verification of performance, compliance with

applicable interim performance criteria, warranty, and manufacturing

capability. It is expected that this evaluation will take place periodically and that the results will be a good source of information to

be used in selecting possible components/systems.

2 . 2 Domestic Hot Water Heating Systems

The heating of domestic hot water with solar energy is the most

economically viable application and the one that should be considered for all locations within the United States. There are several

reasons for this. One is the low capital cost relative to solar space

B-7
heating or cooling systems and the others relate to the unique characteristics of domestic water heating.

The demand for hot water is relatively constant throughout the

year. This means that the collector and other parts of the system produce energy for long periods of time and consequently can result in

large savings that eventually must pay for the higher initial cost of

the system. This is in contrast to a solar space heating system which

is fully operational only during the coldest months of the heating

season.A solar water heating system can also be sized more closely o the

demand. While space heating systems have to handle extreme loads only

a few days of the year, they still have to be sized large enough (includ

ing the auxiliary back-up) to meet those extremes. A water heating

system, on the other hand, will have roughly the same load day in and

day out. Except in unusual applications, the design load (expected

maximum load) will be close to the normal daily load. By avoiding the

problems of widely fluctuating loads, the solar water heating systems

can be much more economical.

A problem common to all types of solar heating is the variable

nature of sunshine. Solar water heaters, however, can often have an additional advantage over space heating systems because the requirements

for hot water are less rigid than those for space heating. If there is an extended sunless period and the user is extremely conscious of energy

and cost savings, some uses of hot water can be temporarily postponed.

This, of course, is not possible with space heating systems.

This curtailment of hot water use is of course not necessary due to

the way the systems are normally designed. Figure B-3 shows a schematic

of a typical system [13], The collector, heat exchanger, and pumps are

used to heat water in a storage tank, which in turn is fed to the conven

tional or already existing water heater in the building. The already

existing heater only has to make up the difference between the incoming

water temperature from the solar storage tank and the constant supply

temperature to the user. The controls in such a system are very much

simpler than those required by most solar space heating systems. The

thermostat in the already existing heater controls the auxiliary energy

B-8
supply, as always. The only other controls needed are the sensor and

differential thermostat shown to turn the pumps on and off.

More will be said concerning the economics of these systems in

section 4. However, it should be noted that many manufacturers are now

offering solar water heating packages for residential buildings which

include everything shown in figure B-3, except the conventional water

heater, for approximately $1000 [14].

2.3 Solar Collectors

The cross-section of a typical flat-plate solar collector used to

heat a liquid is shown in figure B-4 [15]. It consists of a dark-painted

metal absorbing plate through which the fluid passes, one or two sheets

of some transparent material on the top through which the solar energy

passes, and several inches of insulation on the back. The transparent

covers and the insulation both serve to eliminate heat loss from the

metal absorbing plate and to maximize the amount of the energy being

carried away by the fluid. The collector is usually facing south (+ 20°)

and tilted at an angle designed to optimize the amount of solar energy

received over a complete heating season*.

Typical metal absorbing plates are made of copper, aluminum, and

steel. Generally speaking, for liquid systems copper is preferred,

because of superior corrosion resistance and durability. However, it is

expensive and usually results in a heavy collector. Aluminum has been

used a great deal over the past several years because of its relative

low cost, light weight, and ease of fabrication. However, use of aluminum absorbers in a liquid system requires special precautions to prevent

corrosion. Steel has had some limited use because of its low cost but

it is difficult to fabricate, is heavy, and like aluminum requires

corrosion protection. Plastics have been used in isolated cases for the

absorber, but usually only for relatively low temperature applications

such as heating swimming pools. Whenever air collectors are being used,

the primary criteria for material selection for the absorber is cost,

since there is no corrosion. Figure B-5 [6] shows the cross-section of

three different types of air collectors.

* This is approximately the latitude + 10°

B-9
The primary source of energy loss from the solar collector is convection and radiation heat transfer from the top of the absorber to the cover plate and subsequent heat transfer away to the environment. A variety of

techniques are used to limit this heat loss. The use of double glazing is

the most straightforward and widely used technique and can reduce the

heat loss as much as 40-50 percent when the collector is operating at a temperature as high as 190° F above the ambient and the absorber is painted

with an ordinary black paint. Other techniques include the use of a selective coating on the absorber to reduce re-radiation; a transparent

honeycomb insert between the absorber and the cover plate assembly to

limit air motion and decrease convection heat transfer; some form of

concentrator incorporated into the design to concentrate the energy onto

the absorber; evacuating the space between the absorber and the cover-plate

assembly to eliminate convection altogether; or some combination of the

above. The collectors being built today which have an evacuated space

usually are of tubular construction where the absorber is a metal or glass

tube and the cover plate is a glass cylinder surrounding the absorber.

Reference [16] should be consulted for a thorough description of the

various types of collector configurations being designed and built.

Although some very encouraging results have been obtained in the last

few years in the solar collector field, it is very difficult to economically

justify any collector other than the simple single- or double-glazed flatplate collector for domestic water heating or space heating. Most of the

new designs result in significant increases in efficiency at the high

temperatures required for air conditioning (190-240° F) ; however, the

improvement at the lower operating temperatures for domestic water heating

and space heating (120-150° F) in most cases cannot justify the additional

investment. Figure B-6 is a plot of solar collector efficiency versus the

difference in temperature between the absorber and the ambient air divided

by the incoming radiation flux for some typical collectors [6]. The

efficiency is defined as the percentage of the incoming radiation normal

to the collector surface that can be converted to thermal energy and

carried away by the heat transfer fluid. As can be seen, for operating

conditions typical of domestic water heating and space heating (At/I <_0.3),

B-10
the efficiency of all the collectors shown is of comparable magnitude.

It isn’t until the operating temperature of the collector gets significantly higher than the ambient (At/I _> 0.5) typical of air conditioning

operation that the differences become significant. Figure B-6 shows

that air collectors will generally be less efficient than water collectors

for the same operating conditions . However, air collectors operating in

conjunction with pebble-bed storage units usually operate at lower tempera

tures than liquid-type collectors in systems performing the same functions

Consequently, the systems using air and those using a liquid usually have

comparable overall efficiencies.

2 . 4 Thermal Storage

The majority of all systems built to date have used either water

tanks or pebble beds for storing of thermal energy, the water tanks being

used primarily in systems employing water-heating collectors and the

pebble beds with air collectors. The primary reasons are proven reliability, low cost, and ease of installation and maintenance. Other

methods of storing thermal energy that have been proposed and are being

used primarily in research and demonstration projects involve the use of

materials which absorb significant amounts of energy upon change of

phase and consequently result in much larger energy storage quantities

per unit volume than through the use of water or rocks. The major work

in recent years has involved the use of paraffins and eutectic mixtures

of salts and salt hydrates. The reader is referred to reference [21] for

a thorough discussion of these and other means of storing thermal energy.

The two basic materials described above (water and rock) are the only ones recommended for consideration at this time due to unproven reliability and

durability over any reasonable period of time.

3. ESTIMATE OF SOLAR SYSTEM PERFORMANCE

The techniques available for estimating the amount of energy that

could be obtained from a solar energy system range from a very approximate

and crude estimate to using a detailed computer program that allows the

B-ll
system performance to be calculated hour-by-hour for an entire year or more, using actual weather data. Fortunately, techniques are now being

developed that are based on complete system studies using the sophisticated

computer programs, yet are relatively easy to use and are quite accurate

provided the type of system being considered is similar to the one which

was simulated. The major portion of this section will be devoted to

describing such a technique for estimating the performance of the types

of systems shown in either figure B-l or figure B-2. It is recommended

that the methods outlined herein be used to determine whether or not the use of solar energy systems appears feasible. If so, and the system

deviates to any great extent from the ones shown in figures B-l and B-2

and described in more detail in section 3.2, serious consideration should

be given to having a detailed study conducted using computerized analysis

techniques such as those in reference [22].

3. 1 Approximate Technique

Perhaps the easiest way of determining what kind of performance to

expect from a solar energy system when only an estimate is required is to:

a. estimate the amount of energy that could be collected under

"average" conditions each month,

b. calculate the space heating, space cooling and/or domestic

hot water load for the building each month, and

c. if for the amount of collector assumed to be used, there is

a deficit, calculate the amount of fuel to be used in the

installed equipment in order to satisfy the deficit each month.

The error using this technique could be large since a solar energy system

operates under transient conditions at almost all times and the dynamic

interaction between the variable solar radiation and the collector, the

collector and thermal storage, and thermal storage and the building,

governs the actual performance of the system. However, this technique is

useful in determining whether or not to even consider using such a system.

In order to perform the calculations outlined above, the following

steps are required:

a. monthly energy collected

B-12
1. Estimate the monthly radiation incident on a collector of

specified area, orientation, and tilt using techniques outlined in section 3.2.

2. Using an efficiency curve such as figure B-6 for the collector being considered, estimate the amount of energy extracted

from the collector. Frequently those curves are available

from the manufacturer. In order to use a curve such as plotted in figure B-6, it will be necessary to know the

monthly average daytime ambient temperature for the location

under consideration (t ), the daily average radiation incident

3. on the tilted collector surface (I) (see section 3.2), and

the operating temperature of the collector (t^)

The operating

temperature can be assumed to be 140° F for space heating and

domestic water heating and 200° F for space cooling in

lieu of detailed knowledge of the system under consideration.

b. monthly building load

The building space heating, space cooling, and domestic water

heating load can be calculated by using conventional techniques

outlined elsewhere in this document or in publications of the

American Society of Heating, Refrigerating, and Air Conditioning

Engineers [23, 24],

c. monthly auxiliary energy required

Once the deficit between a. and b. has been determined, the amount

of energy required by the conventional system can be calculated by

a simple subtraction and then dividing the result by the efficiency

of the installed system (expressed as a decimal equivalent).

3.2 Calculation Procedure for the Systems of Figures B-l and B-2

Klein, Beckman, and Duffie [25, 26] have recently published a simplified design procedure for estimating the fraction of the space

heating and hot water load in a building that can be supplied by the

solar energy system shown in figures B-l and B-2 on a month-by-month

basis. They used the computer program TRNSYS [22] to conduct over 300

simulations where the design parameters for the system were changed to

include a variety of flat-plate collector designs, sizes, tilt angles.

B-13
building space heating demands, and building hot water demands. The

results of the simulations and subsequent analyses were presented in

the form of correlation curves shown in figures B-7 and B-8 for water

and air systems, respectively. In order to use the curves, one determines

the value of the dimensionless variables on the y and x axes on a monthby-month basis for the building and system under consideration, and f is

the fraction of the monthly space heating and hot water load that is

supplied by the solar energy system. The remaining fraction is then met

by the auxiliary or presently installed system.

The validity of the method was checked by comparing the predicted

fraction using the curves of figures B-7 and B-8 with the results of detailed half-hour by half-hour simulations of four differently sized

systems over eight-year periods in Madison, Wisonsin. In addition, the

systems were also simulated in Massachusetts, South Carolina, New Mexico,

and Colorado, and results compared. It was found in both cases, that

the standard error in the fraction of the load met by solar (expressed

as a decimal) for the entire year was less than 0.017. Significant

differences did occur for specific monthly periods (generally for months

in which the load was small relative to the yearly total load) and

consequently the procedure should only be used for predicting seasonal

performance. The results using the method were compared with experimental

results for a residential building in Massachusetts and the differences

were small.

In order to use figures B-7 and B-8, one must know how to determine

the value of the two dimensionless variables. Most of the parameters

involved are easily explained; however, one must first understand the

basic performance equation for a solar collector.

The performance of flat-plate collectors operating under steady-state

conditions can be described by the following relationship [5]

3T “ fr i(t“> - fr

u

l

(t f,i - V (1)

C

where q^

= rate of useful energy extraction from the solar collector,

Btu/h

B-14
A

c

I

(xa)

cross-sectional area, ft

solar collector heat removal factor

total solar energy incident upon the plane of the solar

2 collector per unit time per unit area, Btu/(h*ft )

transmission-absorptance product for the cover plate-absorber

combination

U

L

t

heat transfer loss coefficient for the solar collector,

Bth/(h*ft 2

*°F)

temperature of the fluid entering the solar collector,

ambient air temperature, °F

Equation (1) expresses the fact that the useful energy extracted is equal

to the amount that passes through the cover-plate assembly and is absorbed

(F I (xa)) minus what is lost by heat transfer back to the environment

(FR

U

L

(t f,i

~ t a

)) * If the efficiency of the collector can be defined as the useful

energy extracted divided by the energy incident upon the collector, then

n

c

qu/A

I

( 2 )

or

(t

’ F

B

(Ta) - F

R

U

L

“ t ) a

(3)

If a manufacturer's performance data can be plotted as vs.

as shown in figure B-9 [27], then the performance factors F (xa)

and

K

F U can be determined directly as the y intercept and slope of the curve,

R L

respectively.

The additional parameters not introduced above that appear in the two

dimensionless variables of figures B-7 and B-8 are defined as follows:

B-15
-1

I

where m

C

P

e c

(m C ) P min

R

1 +

Fn UT A (m C ) , R L c pc - 1

(m C ) £ (m C ) . P c

J c p mm

mass rate of flow of fluid through the solar

collector, -lb/h

specific heat of the fluid flowing through the

solar collector, Btu/(lb*°F)

effectiveness of the heat exchanger in the

collector-storage flow loop

the smallest value of the two m C products for

P

the two fluid streams passing through the collectorstorage flow loop heat exchanger, Btu/(h*°F)

The quantity in the braces raised to the -1 power can be considered as

a penalty factor for the use of a heat exchanger in the collectorstorage flow loop. If no heat exchanger is used such as in the air system

i of figure B-2, F

R

= F

R

.

(ta) = the average value of (xa) for the solar collector

operating throughout the entire day. It is usually

equal to 90-95 percent of the value determined at

normal incidence and obtained from a plot of. solar

collector efficiency such as figure B-9 . For collectors oriented directly towards the equator at a slope from 0 to 15° greater than the latitude, (xa)

should be assumed to be 93 percent and 91 percent

of the normal incidence value for 1 and 2 glass cover collectors, respectively.

S = monthly value of solar radiation incident on

2 the solar collector array, Btu/ (month * ft ) L = monthly building space heating and hot water load,

Btu/month

t . = 212 °F

ref

B-16
t = monthly average daytime ambient air temperature

Si AT = number of hours in the month, h

The following procedure is recommended in the use of figures B-7

and B-8

a. Calculate the monthly space heating and hot water load for the

building under consideration using conventional techniques outlined elsewhere in this document or in publications of the

American Society of Heating, Refrigerating, and Air Conditioning

Engineers [23, 24],

b. Calculate the monthly incident solar radiation on the collector

array (to be explained later in this section)

c. Determine all the component parameters necessary to evaluate

the dimensionless variables of figures B-7 and B-8. It is

suggested that the calculation be done as follows:

y axis

A F (xa) S c R

from plot of

manufacturers 1 s

[A ] x [F (xa) ] c R q

. B-9 I “ [m 1

fr

(xa) x fd L qJ R

x [S ] x

x axis

A F U (t - - t ) Ax

c R L ref a

from plot

of manufacturers’ data,

ie. , Fig. B-9 , "f

tv x [F

R V x

x [Ax] x -

R

R

x [t ref ‘a’

d. Using figure B-7 or B-8, determine the fraction of the load

each month of the season that is carried by the solar system.

e. Determine the fraction of the yearly load that is carried by the

solar system. The user is cautioned that the yearly fraction is

not simply the average of all of the monthly fractions but that

each monthly fraction must be weighted according to the fraction

of the yearly load that occurs that month.

B-17
The technique is rather simple to use and if one examines the

variables in figures B-7 and B-8, it can be seen that the performance of

the system depends upon three quantities:

a. The amount of solar radiation that is absorbed by the collector

T array over the month, A F_, (xa) S.

c R

b. The amount of heat loss that occurs from the collector array

during the month with a reference temperature as the basis,

I A F UT (t - t ) At.

c R L ref a

c. The monthly building space heating and hot water load, L.

In developing the f-chart of figures B-7 and B-8, certain assumptions

were made concerning the design of the systems in figures B-l and B-2 . For

the water system of figure B-l, the capacity of the thermal storage units

used for both the space heating and domestic hot water processes were

2 assumed to total 1.85 gallons per ft of solar collector. This is equivalent to 15 Btu of energy storage per °F temperature rise in the thermal

2 storage unit per ft of solar collector. If a different size storage unit

is chosen, the yearly fraction of the load carried by solar can be multiplied

by the correction fraction in figure B-10. As can be seen, there is marginal

improvement in the system performance if the storage unit is sized larger

than what was assumed originally; however, the system effectiveness can be

significantly affected if the storage unit is undersized.

An additional assumption used in the development of figure B-7 was that

the heat exchanger between the thermal storage unit and the building space

for heating was sized so that:

e

T (mC) . L p mm

UA

= 2

where e = effectiveness of the heat exchanger in the storage-building

flow loop

(m C ) . = the smallest value of the fluid capacitance rates for the

p mxn

two fluid streams passing through the storage-building flow

loop heat exchanger, Btu/(h*°F)

UA = heat loss factor for the building space, Btu/(h ,0 F)

B-18
If the heat exchanger is sized greatly different from this, a second

correction factor in figure B-ll can be applied the same way as in

figure B-10. Again, an undersized heat exchanger has a much more pronounced effect on the system performance than does an oversized one. The f-chart for air heating systems (figure B-8) was generated

assuming a flow rate times specific heat divided by F (capacitance rate)

2 ^

of air equal to 2.87 Btu/(h* °F) per ft of collector area. Since the

performance of air collectors can vary signficantly with flow rate, the

estimated system performance using figure B-8 should be corrected for

flow rates that differ from this value. For collector capacitance rates

2 (m C^/Fr A^) between 1.47 and 5.88 Btu/(h*ft . °F) , the system performance

should be estimated after multiplying the value of the x axis parameter by

(m C ) p c Fd a

R c 2.87

0.28

The capacity of the pebble bed used in establishing figure B-8 was

2 19.6 Btu/°F per ft of collector area. The performance of systems with

2 other storage capacities between 9.8 and 78.3 Btu/(ft ,0 F) can be determined by multiplying the x axis parameter by

V p app Cr

F„ A

R c 19.6

-0.3

where V = volume of storage, ft

3

p = apparent density of storage medium, lb/ft

app

C = specific heat of storage medium, Btu/(lb*°F)

The only remaining step to be explained in the use of the present

technique is the calculation of monthly solar radiation incident on the

solar collector array. The recommended procedure is based on the original

work of Liu and Jordan [28] which has been adopted and published most

recently by El and I Associates [29],

B-19

a
Table B-l shows the average daily extraterrestrial (outside the

earth's atmosphere) solar energy falling on a horizontal surface for the

various months of the year and as a function of latitude. Table B-2

gives the average daily terrestrial solar energy falling on a horizontal

surface for the various months of the year for a large number of weather

stations in the United States. In order to obtain the average daily

terrestrial solar energy falling -on south-facing solar collectors tilted

up at a specified angle, the following equation should be used:

I

t I

h

R (4)

where I = average daily terrestrial solar energy incident on a south-facing tilted surface, ly/day

1^ = average daily terrestrial solar energy incident on a horizontal surface from table B-2, ly/day

R = ratio of average daily terrestrial solar energy incident

on a tilted surface to that on a horizontal surface. This

ratio is determined from figures B-12 through B-18 knowing

the latitude, tilt angle of the collector, month and the

ratio of I /I

t o

I = average daily extraterrestrial solar energy incident on a horizontal surface from table B-l, ly/day.

The unit of langley (ly) is one frequently used in the recording of solar

2 radiation data and is equivalent to a gram calorie per cm . It is equal

2 to 3.687 Btu/ft . Once the average daily radiation on the tilted collector

surface has been determined using equation (4) , the monthly value required

in the use of either the approximate technique of section 3.1 or the more

accurate procedure of section 3.2 is determined by simply multiplying by

the number of days in the month

4. SIMPLIFIED ECONOMIC ANALYSIS

There are a number of ways to perform an economic analysis to determine whether or not a solar energy system is competitive with conventional

B-20
heating and whether consideration should be given to retrofitting a building

with such a system. Reference [30] gives an in-depth review and explanation

of the various ways it can be done.

The procedure recommended for use here is one where the cost of owning

a solar energy system over a specified lifetime is computed. The technique

is a slightly simplified form of an annual cost model. All costs are forecasted over the assumed lifetime of the system and then are converted into

uniform annual costs by discounting.

The basic formula to be used in computing the annual dollar savings

over the lifetime of the system is:

DS - £ £ V 1(C

c Ac + CST + CE>

(5) a

where DS

f

L

= dollar savings in using the solar system over the use of the

installed conventional system, $/year

= fraction of the building space heating and hot water load

carried by the solar system and computed by the techniques

in section 3 = yearly building space heating and domestic hot water load,

10

6

Btu

= overall efficiency of the conventional installed space heating

and/or domestic hot water heating system expressed as a decimal

= average annual costs of conventional fuels used in the presently installed system over the lifetime used in the analysis,

$/10

6

Btu

= capital recovery factor for a specified lifetime and interest

rate taken from table 3

2 = solar collector installed cost, $/ft

2 = solar collector area, ft

= installed cost of thermal storage unit, $ = installed cost of everything else associated with the

installation of the solar energy system including pumps,

piping, controls, heat exchanger, etc.

B-21
The procedure to be followed in analyzing the economic trade-offs

associated with the use of the solar energy system is to first make

estimates of the fraction of the building load that might be carried by

a system having different amounts of solar collector area using the

techniques in section 3. Then using equation (4), determine if there are likely to be any dollar savings through the use of the system.

Example Problem

Determine the relationship between the yearly savings, the initial

investment, and fuel costs for retrofitting a townhouse in the Washington,

D.C. area with a solar space heating and domestic hot water system, The

2 house has a floor area of approximately 1200 ft and a heat loss factor

of 307 Btu/(h*°F) (UA for the house). The house is now heated with a gas

furnace in a forced-air distribution system and the domestic hot water is

heated by a conventional 80-gallon electric water heater. The use of hot

water can be assumed to be approximately 90 gallons/day. Assume that the

house faces south but that due to the shape of the roof, the maximum

2 amount of solar collector that can be used is 485 ft , approximately 60 percent of it tilted at an angle of 11° from the horizon and the remainder

at 55°.

Solution

Based on heating-degree days for the Washington, D.C. area as tabulated in reference [24]

the seasonal heating load was found to be

31 x 10 Btu. Based on a daily average temperature rise of 75° F for

the hot water for the year, the yearly domestic hot water load was com- puted to be 20 x 10 Btu. The technique of section 3.2 was used to predict that approximately 75 percent of the space heating and hot water

load could be carried by using double-glazed liquid, flat-plate solar

collectors with a black-painted absorber, a correctly sized water-to-air

heat exchanger in the air distribution system for space heating, and a 1000- gallon water tank for thermal storage.

Using equation (5), the yearly savings for the system was computed

for various values of total initial investment and four different fuel

B-22
prices for both gas and electricity (competing energy sources in this

case). Assumed efficiencies of 60 percent and 100 percent were used

for the gas-fired furnace and electric water heater, respectively. A

lifetime of 15 years was assumed with an interest rate of 10 percent

(capital recovery factor of 0.13147). Figure B-19 shows the results of

the calculations. The lower curve represents the approximate cost

of natural gas and electricity in the Washington, D.C. area in early

1976. The estimate of the installed cost of the system is as follows:

1. 485 ft 2 of solar collector, not installed

2. 1000-gallon water storage tank

3. heat exchanger for collector-storage fluid loop

4. heat exchanger and extra 80-gallon tank for

heating of domestic hot water

5. piping, hoses, pumps, valves, pipe and tank

insulation, 40 gallons of antifreeze, controls,

and installation

$3 ,000LOO

1, 000. 00

200. 00

500. 00

2, 300. 00

$7, 000. 00

the next

15 years would have to be between 3 and 4 times the present price before

a decision to install such a system today could be made.

It is estimated by using the technique of section 3.1 that approxi2 mately 72 ft of solar collector could be installed along with the ex- changer, extra 80-gallon tank, pump and controls for heating 75 percent

of the domestic hot water alone at a total installed cost of $1,200.00.

The plot in figure B-20 for domestic water heating alone in this house

indicates, based on the assumptions made, that the system is economical,

even if the average electricity prices over the next 15 years remain

unchanged.

Nationwide Implications

The staff of the University of Wisconsin's Solar Energy Laboratory

has recently published the results of an economic study done for a residential building very near the size of the one in the sample above [31].

The f-chart technique was used to design an economically optimized solar

space heating and hot water system for the house and then the net annual

B-23
dollar savings was computed for the house and system in 87 locations in

North America. Figure B-21 was taken from their study and shows net annual

savings represented on a map by dots of increasing sizes for four classes

of savings, i.e. , 0-100, 100-200, 200-300, and over 300 $/year. Assumptions were made that resulted in a net savings in the 0-100 $/year class

for the mid-Atlantic region, in agreement with the above example for

average fuel prices over the next 15 years of three times present prices.

As can be seen, under the same conditions, the system would be even more

economically feasible in other parts of the country such as in the upper

midwest and Rocky Mountain States.

B-24
REFERENCES

1. An Assessment of Solar Energy as a National Energy Resource, NTIS

Report No. PB-221 659, University of Maryland, December, 1972.

2. Solar Heated Buildings, a Brief Survey, W. A. Shurcliff, 12th

edition, March 3, 1976, available from the author, 19 Appleton Street,

Cambridge, Massachusetts 02138, $9.00.

3. Demand Analysis, Solar Heating and Cooling of Buildings, Phase 1

Report, Solar Water Heating in South Florida: 1923-1974, Report

No. NSF/RA/N/ 74/190, University of Delaware, December, 1974.

4. Low Temperature Engineering Application of Solar Energy, ASHRAE,

1967, to be republished in 1976 as Applications of Solar Energy

for Heating and Cooling of Buildings.

5. Solar Energy Thermal Processes , J. A. Duffie and W. A. Beckman,

John Wiley and Sons, New York, 1974.

6. Solar Heating and Cooling—Engineering Practical Design, and Economics

J. F. Kreider and F. Kreith, McGraw-Hill, New York, 1975.

7. Proceedings of the Workshop on Solar Cooling for Buildings, Los

Angeles, February 6-8, 1974, NSF Report No. NSF/RA/N/74/063 , 1974.

8.

- Proceedings of the Second Workshop on the Use of Solar Energy for

the Cooling of Buildings, Los Angeles, California, August 4-6, 1975,

ERDA Report No. SAN/1122-76/2 , Atlas Corporation, July, 1976.

9. Proceedings of the Workshop on Solar Energy Heat Pump Systems for

Heating and Cooling of Buildings, University Park Pennsylvania,

June 12-14, 1975, ERDA Report No. COD-2560-1, Penn State University,

1976.

10. Long-Term (18 years) Performance of a Residential Solar Heating

System, J. C. Ward and G. 0. G. Lof , Solar Energy , Vol. 18, No. 4,

pp. 301-308, 1976.

11. Catalog on Solar Energy Heating and Cooling Products, ERDA Report

No. 75, October, 1975.

12. Program Opportunity Announcement, (POA) DSE-75-1 Evaluation, Executive Summary, ERDA, February, 1976.

13. Sol. R. Tech Operations Manual for the Garden Way/Sol. R. Tech Solar

Panel System, J. DeVries, Sol. R. Tech, Hartford, Vermont, 1975.

B-25
14. Solar Domestic Hot Water Systems, Solar Engineering , pg. 28,

September, 1976.

15. PPG Prototype Baseline Solar Collector, Publication No. G-483

5M84, PPG Industries, Inc., 1 Gateway Center, Pittsburgh, Pennsylvan

15222, 1974.

16. Proceedings of the Workshop on Solar Collectors for Heating and

Cooling of Buildings, New York, November 21-23, 1974, Report

No. NSF/RA/N/75/019, University of Maryland, May, 1975.

17. Solar Collector Performance Studies, N. Lior and A. P. Saunders,

Report No. NSF/RANN/SE/GI27976/TR31/1, University of Pennsylvania,

August, 1974.

18. Measured Efficiency-Test Results on the Sunsource/Miromit Model 100

Solar Collector, Technical Note 741201, Sunsource, 9606 Santa Monica

Blvd., Beverly Hills, California, 90210, 1974.

19. Solar Concentrators of a Novel Design, R. Winston, Solar Energy , Vol. 16, No. 2, pp. 89-95, 1974.

20. Comparison of Performance of Solar Collectors of the Air Heating

and Water Heating Types, G. 0. G. Lof, L. E. Shaw, and R. L. Oonk,

presented at the 1975 International Congress, Solar Use Now - A Resource for People, held in Los Angeles, California, July 26-

August 1, 1975.

21. Proceedings of the Workshop on Solar Energy Storage Subsystems for

the Heating and Cooling of Buildings, Charlottesville, Virginia,

April 16-18, 1975, NSF Report No. NSF/RA/N/75/041 , University of

Virginia, 1975.

22. TRNSYS, A Transient Simulation Program, University of Wisconsin

Engineering Experiment Station Report No. 38, January, 1976.

23. ASHRAE Handbook of Fundamentals , ASHRAE , 1972.

24. ASHRAE Handbook and Product Directory , 1973 Systems, ASHRAE, 1973.

25. A Design Procedure for Solar Heating Systems, S. A. Klein,

W. A. Beckman, and J. A. Duffie, Solar Energy , Vol. 18, No. 2,

pp. 113-126, 1976.

26. A Design Procedure for Solar Air Heating Systems, S. A. Klein,

W. A. Beckman, and J. A. Duffie, presented at the 1976 International Solar Energy Society Conference, Sharing the Sun 76,

held in Winnipeg, Manitoba, Canada, August 15-20, 1976.

B-26
27 . Collector Test Procedure and Experiments with a Solar Simulator,

F. F. Simon, NASA TM X-71658, Proceedings of the Workshop on Solar

Collectors for Heating and Cooling of Buildings , New York,

November 20-23, 1974, Report No. NSF/RA/N/75/019, University of

Maryland, May, 1975.

28. The Long-Term Average Performance of Flat-Plate Solar Energy

Collectors, B. Y. H. Liu and R. C. Jordon, Solar Energy , Vol. 7,

pp. 53, 1963.

29. Determining the Availability of Solar Energy within the Contiguous

United States, published by E. I. and I Associates, P. 0. Box 37,

Newbury Park, California 91320, $4.00, 1975.

30. Solar Heating and Cooling in Buildings: Methods of Economic

Evaluation, Rosalie T. Ruegg, NBS Report NBSIR 75-712, July, 1975.

31. Solar Heating in the United States, J. A. Duffie, W. A. Beckman,

and J. G. Dekker , ASME paper 76-WA/Sol-8, presented at the ASME

Winter Annual Meeting, New York, December, 1976.

B-27
o>

CV

cz LU

B-28

Figure

B-i

SCHEMATIC

DIAGRAM

OF

A

LIQUID

SOLAR

HEATING

AND

DOMESTIC

HOT

WATER

SYSTEM

[25]
Figure B-2- Schematic Diagram of a Solar Air Heating and Domestic Hot Water

System [26]

B-2 9
Figure B-3, Schematic Diagram of a Solar Domestic Hot

Water System [13]

B-30
0.0254

tr

UJCDa

o

(/) CD o

I-<

z

o

CO 0- z <

B-31

Figure

B-4-

Schematic

Diagram

of

Flat-Plate

Liquid-Heating

Solar

Collector

[15]
Figure B-5. Air-cooled Solar Collectors, (a) Double-glazed, finned

absorber plate; (b) Single-glazed, overlapping glass

plate; (c) Single-glazed, porous absorber [6]

B-32
100 h

Double-Glazed

Water-Heating

Collector

[17]

in'

GO O

u=j a

o*

O

CD

c

CD

O

CO

O o

csi

T3C

•HU

G

QJ

O

U

as

a)>

a)w

4-1o

c

o

cn

>4

a)G.Eo

a

a)u

c

a)E

G

o

4-1G

0) Gi

<D

I PQ

QJ

i-i 3

M)

•H

Ph

% ‘X0U8I0I^3

B-33

experimental

solar

collectors

of

practical

design

[6].
1

S (Di) ,ad °V

B-34
(ra)s

A

C

F

R

U

L

(tref-V^

L

Figure B-8. f- Chart for Solar Air Heating Systems [26]

B-35
Collector

Efficiency,

0/©

1

* Btu

Figure B-9. Efficiency Curve for a Double-Clazed Flat-Plate

Liquid-Heating Solar Collector with a Selective

Coating on the Absorber [27]

B-36
(do 2u)/nia si di aanddns Nouovdd

uvios as aanddns Nonovdd avon

B-37

Figure

B-10.

Correction

Factor

for

Storage

Capacities

Other

than

15

BTU/
LOAD

FRACTION

SUPPLIED

BY

SOLAR

€|fm G)mj 0

UA

Figure B-ll Correction Factor for Various Values of

e (mC ) . / (UA) (Liciuid Solar Heating

L p mm

systems [25]

B-38
Figure B-12a 20° North Latitude; 5° Collector Tilt

B-39
1.5

V1

,,

Figure B-12d 20° North Latitude; 90° Collector Tilt

B-40
125 .

Figure B-13b 25° North Latitude; 25° Collector Tilt

B-41
Figure B-13d 25° North Latitude; 90° Collector Tilt

B-42
B-43
Ih/I0

Figure B-14d 30° North Latitude; 90° Collector Tilt

B-44
B-45
2.0

Ih/Io

° o Figure B-15c 35 North Latitude; 50 Collector Tilt

Ih/Io

Figure B-15d 35° North Latitude; 90 Collector Tilt

B-46
IhAo

Figure B-16b 40° North Latitude; 40° Collector Tilt

B-47
Ih/Io

Figure B-16c 40° North Latitude; 55° Collector Tilt

Ih/Io

Figure B-16d 40° North Latitude; 90° Collector Tilt

B-48
Ih/I0

Figure B-i7b 45 North Latitude; 45 Collector Tilt

B-49
3.0

Dec

2.6

2.2

1.8

1.4

1.0

0.6

.1 .4 .5 i|A.

.6

Figure B-17c 45 North Latitude; 60° Collector Tilt

B-50
2.8

Figure B-18b 50° North Latitude; 50° Collector Tilt

B-51
^•h^o

Figure B-18c 50° North Latitude; 65° Collector Tilt

B-52
1000

800

600

400

200

0

-200

-400

-600

-800

1000

2000 4000 6000 8000 10,000 12,000 14,000 16,000

INITIAL INVESTMENT, $

Figure B-19 Results of Cost Analysis for Example Problem,

Solar Heating and Hot Water

B-53
1000

800

600

400

200

0

-200

-400

-600

-800

-1000

1200 ft2 TOWNHOUSE, WASHINGTON, D.C. SOLAR HOT WATER

DISCOUNT RATE = 10%; 15 YEARS

AUXILIARY ENERGY -ELECTRIC

TOTAL YEARLY LOAD =20 x l0

6

Btu

75% SOLAR CONTRIBUTION

1

12,000 14,000 16,000

INITIAL INVESTMENT, $

Figure B-20 Results of Cost Analysis for Example Problem,

Solar Hot Water

B-54
Figure B-21 Map of Net Annual Dollar Savings for Space and

Domestic Water Heating with Solar Energy in a Residential Building. Small to Large Dots

Represent Net Annual Savings of 0-100, 100-200,

200-300, and over 300 $/year [31]

B-55
North

Latitude,

degrees

Table B-l AVERAGE DAILY EXTRATERRESTRIAL SOLAR ENERGY

RECEIVED ON A HORIZONTAL SURFACE (ly/day)

Months of Year

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

20 636 725 819 896 929 935 929 904 843 750 657 609

25 571 671 785 806 940 956 946 904 818 702 585 541

30 502 613 744 870 945 972 957 896 786 650 529 471

35 432 551 697 848 944 982 962 883 749 593 461 399

40 359 485 646 819 937 987 962 864 706 532 390 325

45 287 417 589 785 925 987 957 839 657 467 319 253

50 215 346 529 745 908 983 947 808 604 399 247 182

55 145 274 464 701 887 976 934 774 546 329 177 114

60 81 203 396 652 864 969 920 735 484 258 110 54

B-56
Table

B-2

AVERAGE

DAILY

TERRESTRIAL

SOLAR

ENERGY

RECEIVED

ONA

HORIZONTAL

SURFACE

(lv/dav)

I ZD ,

to co *a- *3- lo LO O CO to CO CO to cr» O ^ to 03 o to i— 03 to co <3- ,

^3" CM co to to co *3* LO to co LO 00

in o CO CNJ CNJ CO cr* cm i— o CO 1— co •=f CO CO 03 00 LO LO LO i— co •=3" 03 co O LO LO i— i— LO 03 r—

<

CO 03 rs. c

C\J C\J CM CM CNJ CO <3- LO LO LO CO LO ro *a- co co «3* CO CO •=3- *3- <3* <3- <3- CO «3* LO *3" co co

0 O O CM LO LD N CO ,

LO ,CO ,

0 LO , ,

*3" to O to CM CM CM CM *3- ,

CM ,

<3- O CM 03 <3

- O O ,

O t— 03 «3- ,

LQ *3" CM r— 00 *3" CO O *3“ co LO 03 CM *d- CO CO to LO CO CO

00 *3" to 03 LO CO 03 1— CM LO O O r\ *3* CM CO Q 1— CM CM CO CM •

•»

CM CM CM CM CM CM •

CM 1— •

CM »

<

CM CM CM CM CM co CM CM CO CM CM co co •

•

> 03 O *3- LO CO *3" O *3" to 0 to 03 ,

LO r\ 03 ,

,

03 03 CO 00 CM O *3- CM CM CO CO *3

- CM ^3 00 *3- to LO 00 to CO CM to 0 LO ^3" CM CO 3 1— *3" LO co 1r— LO <3" LO r-v co 00 0 CM 1

*3

- CM LO CO 03 CO 1

1

co LO to LO LO CO CM 03 CO 2: CM co CO co co CM »— CM CO CM cm CM CM co CM co CM CM CM CM •— CO co co CM co CO CM co CO CM 00 «3- co 1

1

CM *— LO CM O CO CM 03 CM CM CO 03 LO *3* O co CM to 0 CM 03 O co ,

CO co to CO ,

*3" 03 ^3 CO 0 0 CM LO ,

to 0 CM ^3 1— CO O 3 O *3" *3- *3* *3* 00 cm f-' LO to 0 co r— LO 1— LO r— to to <Q 03 CO 03 LO 0 LD 0 LO O CO O 1— '— r- CO *3* *3* *3- *3* CO CM co *3" co co CO co *3" CO *3* co co co co CM *3- co CO CO CO co co CO *3- CO co LO *3" CO CM

Q_ to LO CM O CO 03 to to 0 0 00 CM CO CO 03 CO 0 CM 1— LO *3" O CM *3* LO *3* to 0 *3" co LO O *3- <3" CM r^. CO to O CM LQ LO 1— O 00 03 CO 1— to r^ co 03 *3" O "3~ CO 0 0 CO CM CM CM 1— r— r— r\ to LO 0 *3* CO *3* •3" CO CM LO r— co CO LO co 00 CM 1— CM •— 1— *3* LO LO LO LO *3" CO LO to CO LO LO •3" LO ^3 LO LO *3* LO *3

- CO •3" *3

- *3" CO <3* *3" ^3 *3* •3 3* 3“ LO LO •3" *3*

CD CM LO CM -3- co LO co 00 ,

LO to 00 3- •

,

03 CO r^ CO ,

03 LO LO O ,— ,

co to ,00 03 3- CM CO CM LO to 0 LO LO LO 1 1 1— 03 1— 00 co 1

0 0 co tO CO OO 03 O 1

CO co 03 0 *3 r— to 0 O 0 O co 03 O CM 1— r^ 3- CO CM CM CO CO LO LO to in LO to •3- to <3- LO LO LO to *3- to to *3“ LO LO 3“ LO *3

- LO *3- LO LO LO LO 3- LO LO to LO LO LO

—I ,

03 tO 3- 03 LO 0 00 to CM O CM CO 3-

«

1— 3- CvJ 0 0 0 0 to 0 to 03 CO 0 CM 3- 3* 3" co 03 LO O O CM

CO CMNCOOLO 00 LO CM LO 03 LO LO co 03 3" LO co LO 3- 00 to CM 0 03 CM CO CM CM co co co 3- co co LO 1— r— 0

•~D 3“ 3* CO 3* 3" LO to LO to LO to 3" to 3- to to to LO LO LO LO to to 3* LO LO LO LO LO LO LO LO LO LO LO LO to LO

2: LO 00 =* c\j cr> 03 03 LO CM 3 r- to 1"-. to 3 O LO 00 3 ,

LO 00 CM 0 co 3 3 LO CO ,

00 to 3 3 O LO CM LO CM

ZD to c\j lo 0 co lo 0 co 03 0 0 03 03 co CO 03 00 00 LO 03 03 03 CM 0 co 1— LO 3 CM 3 co to 1^ LO 00 1— LO co 03

*"Q 3" LD '3- lo *a- LD to 3 to 00 ^1- LO LO LO to LO to LO LO to LO LO 3 LO LO LO LO LO 3 LO LO LO to LO to LO

>- co •— LO CO LO 3 03 co LO ,03 to CM LO 03 CO LO LO O LO CM co CO to to 03 CM :m CO to LO r\ LO CM

LO 1— LO tO CO CM 03 CM CM 0 co co 00 0 ^ LO to 0 co r— to 1— LO to 0 CO CO LO LO LO 3 03 CO r— 00 LO 3 lo

d- ^a- ld to LO 3 to r>v LO LO LO LO to LO to LO 3 to LO 3 to 3 LO LO LO LO LO LO LO LO LO to LO LO LO

ai O 0 3 to to to co co LO CO 00 03 LO ,

f\ LO CO 03 to CM CM ,— O LO CM CO LO CO 03 3 CM 3 03 CO 03 3 03 03 to LO CM

Cl. to co *a- LO 3 r- CO LO co CM 03 3 O LO '

CO O CM 1— LO LO to 3 r— 03 CO to CO 1— 3 O 00 CO CO 1— LO 00 CO to <C CO CO 3 co co 3 LO LO to to LO CO LO 3 LO 3 LO LO LO LO LO 3 LO LO CO LO 3 LO LO LO LO LO 3 LO 3 LO LO LO 3 3

CC , O CM CO CM CO to to O CM to 00 00 r- O to 03 CO 03 CM 3 ,

3 co CM 1

CM LO CO O ,LO CO 3 CO to CO CM LO

CO 00 00 !— 3 LO r— CM 3 r— O O CO r^ cn l'' co co to O CO O CO CM CM 3 r— 3 CM 03 03 O CM CO 1— co 3 LO CM r— CM CM CM CO LO LO LO LO 3 CO 3 LO co ^a- 3 3 3 3 3 co 3 3 3 CO 3 3 3 3 3 3 3 3 3 co CO LO 3 co co

CQ CO CO CO r— CM 0 03 ,

,— to 3 to 03 CM r— co CM CM to to co 3 co ,

r\ 0 to 0 to ,

,

,

3 CM CM 3 to O LQ CO O N 03 tO to 0 03 0 LO 03 03 1— O CO CM co to 00 3 r— to CM 1— co to co to 3 1

1

CM 103 CO O CM O CO 3 Ll. 1— r— CM CO 3 co 3 CM «

CM 3 CO co CO co CO CM CO CO CM co CO CM co CO CO co 3 3 co CO co CM co 3 3 CM CM

CO 0 00 *X) c\j co 3 1— LO LO CO to to CM 3 CO CO «

1— LO CO CO ,

CM CO CO 00 co 0 3 00 CO CO LO 00 co

<a; to co r— <T> OO 03 O 1— O LO 3 00 1— 3 3 LO 03 to CM O CM 1— LO 03 03 to CM 3 LO r\ CM CM CO to LO co to

•"D 1— CM CO co co «

1— Ico CM CM CM CM CM «

CM CM CM CM CM •

CM CM CM CM co CO CM CM CO CM CM co co 1— 1—

<x. ^ ^

<D * +> 3 •—

4-> O <D

<D S- _C C S- 4-> c 03 cd < CQ DQ

<c c c ~

* « o

to 03 o

cc c to

03 3 CD JD C r03 -M

•p- +-> 4-> fO fD-r-

(J 03 o

oo * O fDU

CQ CQ O S3 03 03 03 03 I I 03 O O •'tO O O tO WU 03 03 O

OO

cz o

o o

CJ Ll. I Q

-f-3 « * 03 - <DCD • co: Nl 03 03 CD CD •r- C O O CD C <— CD 1— r— CD CD CD JD co

(O O r— r— ^ (D O s- •r— C O O • r—- *r— • 1— 03 CO 1— S- TD

|SJ #> M O C 03 CD CD 03 TD CD 03 * 3 03 -M O (/) *r— > +-> u_ 1— CO Ll_ r, « 3 03 y—t ,

C X #« c »> L 1— 03 03 C r- -*-> Q. S- •3 —1 03 -r- h-h > C CO O 03 03 C f— in 03 c 03 O CD r— C C CD 00 03 OO CD C jz in 0 CD * U -C r. 4-> •r- 3 n Ll. * c= 0 ^ (/> C 0 < <C •0 s- s: 03 O “O TD -r- O CD CD CO 2 r- 03 03 03 C r— r— CD <D <D (/> fO *r- CD LO O *3 03 CD -M 03 1— C C 03 •— C ^ E CO 1— CL 03 *4— O S- CO c

cn 0 u E > i- CD >> </) (/) to > C C TD 3 03 03 CO «— <— *r- O >, <D sz 1— E r — •r- C 03

(O -SZ 3 3 fO 3 L C fD O O 03 -p- fO 03 O O S- L 03 a (1) 05 03 CU -i- CD 03 03 4-> S- 0 CD O

Q- O- h- >- Q LQ U_ « _J _J _1 Q_ Cd 00 t/3 OO CQ CD O 2 < CQ O O CL t— 1— <C cd zn CL CQ 1—

B-57

/"
Table

B-2

(cont)

AVERAGE

DAILY

TERRESTRIAL

SOLAR

ENERGY

RECEIVED

ONA

HORIZONTAL

SURFACE

(ly/day)

LOCATION

JAN

FEB

MAR

APR

MAY

JUN

JUL

AUG

SEP

OCT

NOV

DEC

ANNUAL CO CO C\J LO LO o- o ,

,

,

O d cr> o 00 ,

CM C\J LO cr> LO 1

I— CO 00 o co LO CM PO O'! CO Ob CO o LO CM Ob Ob CM d lo d d d 00 i— LO 1— CTb o CM 1— CM CM f— LO LO i— LO 1— co d co co LO 1— LO Ob LO =3- 00 d LD i— LO O o CM CO CO CO CO d CO CO co d CO d co d co CO CO co CO CO CO CO CO CO co co CO CO co CO co co CO co *3" co co co LO d LO d co

LO ,

d o CO d d LO LO LO o CM O LO LO Ob d O lo CO CO 00 LO co CO LO CM LO Ob o 00 d LO Ob LO LO O 00 Ob LO co co CO d co LO LD LO LO CO CM O CO 1

CM d o LO LO O CO o Ob CM LO i

i— LO r^ CM Ob co LO CM LO O Ob

•

'•

•

CM •

1— •

•»

CM CM CM 1— 1— •

•

— •

••

1— •1— 1— 1— •

•'

•

•— CM i

1

i

CM CM CM CM O r-- LO LO LO LO r^ d LO O LO Ob d CM LO d co LO Ob CM •— LO LO LO LO d d CM Ob d O ,

d co CM LO d CO O CM LO 00 00 i

CM 1— d Ob Ob LO LO LO d LO LO co 00 O r— LO CO o d CM LO LO O Ob o CM LO CO d Ob Ob co co CM

••

•

<•

CM CM CM CM CM •— CM CM CM i— •— '— '

'

'— CM r— •

'«•

CM '— '*— i— CM CM i— CM CM i

co CM CO CM i

LO O CO d o r^ CM O r\ CO CM Ob d LO 00 CO 00 «

d LO CM CO LO LO .

CM r\ d LO LO 00 CM CM ,

CM LO d 00 co Ob LO ,

O LO Ob Ob CO CM Ob CM LO o o 00 LO LO CO LO LO d Ob Ob i— r- LO i— d CM LO LO i— Ob Ob CM r\ LO CM CO Ob co Ob CM Ob CO

CM CM CM CM CM co co CM CO CO CO d- co CO CM CM CM CM CM CM CM CM CM CM CM CM co CM CM CM CM CM CO CM co CO CM CM d- oo d- CO CM

CO d r^ LO co LO o d d 00 00 00 d d iLD «— CO LO CO co CM o CO o d LO o CM o CM LO LO Ob d Ob , CM LO I— 00 O O LO Ob CM 1

CM Ob o d •

i

LO d LO LO 3- oo CO 00 CM LO LO r— o LO Ob 1CO Ob o 00 CO LO i— LO co d CO co d d co d- d- d d- d d d d d CO co co CO CO CO CO CO co co co CO d d d CO co d d CO d d CO CO LO LO LO LO co

co LO CO LO o CM LO LO CM CO CO LO ,

00 Ob LO d LO CM Ob Ob 00 CM LO CM 1— CM .

CM o d Ob o LO r^. LO Ob LO co r^ LO CO o CO Ob 00 LO Ob CM CM 1

LO Ob o Ob CM d CM LO CO co LO LO d CO LO Ob CM co co 1— co 1— d 1— LO CO LO LO CM o CM d LO d d d d d LO LO LO LO LO d LO d LO d d d d d d d d d d d d LO LO LO LO d LO LO LO LO d d d LO LO LO LO d

CO LO CM LO CM Ob ,CM o ,CM 00 CM LO CM LO 00 CM LO oo (

O CO LO d LO Ob o CO CO 00 r-v Ob d CO o co oo LO r*^ LO

CM LO d CO d CO LO 1

LO CM o o Ob 00 Ob CM d 1— o LO d LO d co LO LO LO Ob 1

CM d t

d CO -=3- o t— d LO LO LO d LO LO LO LO LO LO LO LO LO LO d d d LO LO LO LD LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO UD LO LO

CO co CO ,o Ob ,

d CO o CM Ob o Ob LO CO Ob LO o ,

,

d LO CO co d LO O' o LO d CM LO VD CO CO d ,

LO LO LO d d LO CO LO LO CM LO CO d LO 1— Ob o d LO LO d d LO d r\ o oo Ob d d Ob Ob d LO CM d CM o d o d LO LO LO LO LO LO LO LO LO LO LO LO LO LO d d LO LO LO LO d LO LO LO LO LO LO LO d LO LO LO LO LO LO LO LO LO d co ,— o CO CM LO ,

LO d Ob 00 Ob CM o CM d 00 co LO co co co Ob O CO CO CM d LO CO O LO ,— 00 LO d CM d o CM Ob Ob Ob oo LO CM CM o 00 1

LO co LO LO CM LO LO CO i

i

CO CM Ob co LD CM LD Ob i— CM LO d co ^ CO CM O LO d d d d d d LO LO LO LO LO LO LO LO LO d d d d d d LO d LO d LO d LO LO LO d d LO LO LO LC LO d LD LD r*^ o d

,

o CM co co CO ,

CO o o o co Ob LD Ob d o LO d CTl CO O LO Ob LO CO d LO d d LO co LD ,

Ob ro d cc d CM d co Ob o Ob o CM d CO CO CO CM 00 d 00 LO o 00 Ob 1— co o o LO I

CM co LO co i

i— LO d LC O CM ,

LO CM cr. PO co co d co d LD d d d d d d d d co CO d CO CO d d d d CO d d d d d d d d d d LO d d d •D D LC ID CO

LO CM LO 00 CM LO r^ LD LO CO d Ob co CO LO o o o d Ob Ob LO LO o LO LO co o LO 00 LO CM d 00 CO — d Ob O CM CM CM r— i

CM (

d d co LD CM Ob Ob 00 i— Ob CM o Odd LO LO o LO LO d 00 LO LO LO LO LO LO CO LO 1d <sO i

d

CM CO CO co CO d co CO co CO CO CO CO CO co CM co CO co co co CO CO co CO co co co oo CM co co co CO d ^o CO PO D d LO d CM

r\ CM O d co LO ,

d Ob co ,d LO CM 00 00 LO 00 Ob CO d ,O LO

,

CO CM CM Ob Ob LD O LD d LO PO d d d

d oo CM (

LO ,

LO LO d LO co o Ob Ob CM Ob CO i

O d CO co 1— CM LO LO LD PO LO LO CM LO LO i

CM — M. d cc CM Ob

CM CM CM CM CO CM CM CM CM CM co CM CM CM

CM CM CM CM CM CM CM CM CM CM CM CM CM iCM CM (Ml CM CP CM (-• ) d CO CO <—

LO , Ob d LD CM CM CM CM d Ob CM CO Ob CO o 00 LO CM CO ,O o CO d O CM cc co o d O p^ d 00 d LO

Ob r— LO d LO 00 Ob Ob r^ LO CO co CO LO CO LO d oo CO LO CM CO LD d CM cc cr o LD d O D ^ D co r-v. d r—

i

1

i

i— CM •i

•

r— i— CM CM CM i

1

1— i

•— i— i

1— i

•1

1— 1

••

i

.•

CM •CM CM — — co -~vj CM CM' —

LD c fO ro • r- CD

1—

cn _(O ^

TD z: CD CD

oo ^ —

ro •t— • * LD

r. LO _J ro ID TD r* S- e Q LO zz d) >

L0 r\ LO r» E CD Ob rO z: o CD ro z r— • r— * >) CD CO ro i

CD z: c: z: 4-> L0 CD ro +J S- ^ d CD t—i r— r— i

to ^ <L) c -4—

ro -C 1

•i— z: i

4-> 21 -O 4-> CD O 2 13 >-

*—* —

o +-> -r- c: ^ C r- S- ro i

QJ CD LO •i

* U1 CD TD i

<0 ro 4-b L- c

LO

0» CL (O •r- O <D O 1— ro a) o r Ob S- «0 -r- ID * TD c -M O rO * ro E 1— +-> 0 O ^ L- ro > o * * ID i O -5—1 ^ -1- JZ r— Q. •r— * TD ro Z r- o C rO CO o •i

2 U_ ^ c O Q_ O ro -O O C CD > Ob #> CD 4-J CD c LO 4-> rO Ob > o s- CD =c C •r— 12 o S*. o fO _J r— JD O +-) «

£- ZI LO S- O 3 CD ro ns e C ID 0) 03 ID ^ C (A o > o S- ^ Q_ a> jD r— 4-> LD E Ob +-> •r- O jZ (O sz CQ 4-> cr > •N L> u o •i

-r- co Ob LO _£Z a) *r~ -r- O) CD CD JO -M C «0 > •p- +-> 4-> i

Z3 LO ro E CD 4-> 4-> E CD CD C 3 O rO

•r- E r— -o O) TD C e Q. X Z3 <: 3 L0 E LO C C i

s- S- LO =3 i

ro CD E. c L. LO Q_ CD 03 CD -O >*> LO c jZ -D O) o c E O ID <D O CD o rO CD JZ i

o ro ro >b c •i

ro o ro ro 4-> O i— O -r- O O •

1— ro S- CD s_ ro <D 4-b O —I 2: »—

C Q ^ 1— —1 —

1 C/b CQ CO O LU —J <c oo c_> o_ LU co cn o LD LD U1 _1 CQ LD LD LO f— <C L.J —

CtL '—

B-58
Table

B-2

(cont)

AVERAGE

DAILY

TERRESTRIAL

SOLAR

ENERGY

RECEIVED

ONA

HORIZONTAL

SURFACE

(ly/day)

cZD d" CM CM LO o o OsJ LO LO ( OsJ LO LO Ob LO OsJ d- o LO LO , LO LO OsJ LO d* C\J O OsJ cr> co ( o r^ d- LO ro 00 2 CM LO 00 LO OsJ d- CO CO o o CO LO CO CO o oy LO OY 00 CO 1

CO r- LO d" OsJ oy 00 i

OsJ cn LO o C\J OsJ d- *5j" o 2

c

co CO OsJ CO CO oo CO d" d- CO OsJ CO CO CO d- CO CO CO CO d" d

- d- LO d" d- d- d- CO CO CO CO CO CO OsJ CO CO CO CO co d- d*

o 00 OsJ <3- LO LO oy O'* OY OY OsJ o ,— 00 CO co d* ,— co o — CO LO LO LO LO LO d- CO LO LO o OY LO d- o LO o LO LO

LU OsJ d- o <3- I— OsJ o co o LO OsJ d- OsJ LO LO CO LO LO d- OsJ 1

d" LO i

d" 00 O O- OY o LO LO r— OsJ OY CO Q i— '

1'

OsJ OsJ

1— *— OsJ •

«

••

OsJ OsJ OsJ CO OsJ Osl OsJ OsJ •

1—••••

•

> o LO CO OsJ ,

LO d- d* OY r— CO ,— LO LO ,d" co CO d- LO ,— r^. LO LO LO OsJ d- co OsJ LO LO o ,— d" OY LO ,— OY OY o LO CO OsJ CO d- d" CO LO i— 1— OY LO r\ CO o 1— CO i— CO 00 LO LO o OsJ OY LO o OsJ OsJ CO d" co OY co o CO d“ LO CO OsJ 2 i— 1— 1

1

i

OsJ OsJ i— »

r— «

•

OsJ OsJ OsJ OsJ OsJ OsJ OsJ OsJ co co CO OsJ OsJ OsJ OsJ <— .— i

•

•

<— >

•

1

OsJ OsJ

OsJ OY 00 CO OY LO LO OY d* OY r^. co LO co OY LO CO d- LD co CO OsJ CO LO CO OsJ LO o

d- LO d* d- LO CO o ,

d- d" o LO CO 1

OY CO CO LO O o OY d- I

1

LO OsJ o o LO LO o OY OY LO r— 1

co OY d" r\ OsJ CO d- d- LO LO OsJ o OsJ OsJ OsJ OsJ OsJ OsJ OsJ co co OsJ OsJ OsJ OsJ OsJ co CO CO CO CO *3- *3- CO d“ d" CO CO co CO co OsJ •

OsJ OsJ •— OsJ 1— OsJ OsJ OsJ co CO

Q- r LO OY ,

CO OsJ OsJ d* LO d" OY co , o LO LO OsJ 00 LO O CO LO CO OsJ CO LO LO CO CO r— o 00 o d- d- co C0 OsJ OsJ C0 LU LO co cr> cr> OsJ CO CO LO LO CO CO LO 00 t

co i

d" OsJ LO f^ LO IS* o LO OY OsJ d- OY d- LO r— LO r— O OsJ LO d- O' co CO CO co OsJ CO OsJ d* CO •vj- d- CO CO <n co CO d- d* d- d- d* d- d- d- LO LO LO d- d- d- co CO CO d- d" co d- co co O)

e> CVI OsJ UD 00 LO ,

OY LO *d" OY LO ,CO LO d~ LO co co OY CO d- LO 00 ,

,

LO OsJ d- ,

LO OsJ OsJ CsJ LO LO LO ZD OY LO OY N OY CO 00 •d- LO o LO LO d- OY d* CO OY LO LO CO CO OY CO CO LO CO LO O LO o co LO LO LO LO oo CO co C •d* •d- co •d- •d- •d- *d- LO LO •d- •d- d- d- d- d- LO d- LO d* LO LO LO LO LO LO LO LO LO d- d- LO LO LO d" LO d* d d* d- LO LO

—1 CO 00 ,— co CsJ C\J ,O LO OY CO CO co o LO CO CO OY OY 00 o CO 00 OY OY o O OsJ LO OY ,

LO LO OY , OsJ , LO ZD d- d- d- lo d- lo i

OY CO OY CO OsJ 1OsJ OY OsJ CO LO iOsJ 00 i

o CO OY OsJ LO CO CO O^ o SO LO co CO LO LO O •"D LO LO d* LO LO LO LO LO LO LO d- LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO

2: LO LO oo ro Csj Csj d- CO O OY ,

d* d- 00 LO LO ,

OY O'* d- d- LO O ,OJ o i

OJ o co co O ,

LO ,OJ d- LO 00 co ZD OJ so ^ LO LO d- OJ O LO OY LO d" CO LO CO LO 00 LO O O OY co LO i

r— LO OsJ co LO co r^ OY i

d- i— LO dr“D LO LO d- lo LO LO LO LO LO d" d- LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO d- LO LO LO LO LO LO LO

>- LO d- co OJ OJ ,

CO o d- OJ OY co OY co OJ CO d" r^ LO ,

,

LO OJ ,

,— LO o o lo d- co LO LO co co o LO OY ^ d" i

LO OY f— o o LO d* o OY CSJ OY LO CO LO co 1

LO i— LO LO CSJ r— LO i— d- LO d- OY r— LO i— d- LO o OY LO o cc LO

d- LD LO d- d* LO LO d- d* d- d* d* LO LO LO LO LO LO LO LO LO LO LO LO LO LO d- LO LO LO d" LO LO d- d- LO LO uO

cn 00 LO CO 00 LO ,

LO co d- LO r\ LO CO LO r^. CSJ o o o co d- d- LO oo o LO OJ OY r^. co oj ,

O d“ co LO d" CO co co Q_ 1— CO OJ co OY co OY LO i

CSJ OY i

00 LO r\ LO LO LO LO co LO LO OJ LO •— LO CSJ LO O 00 OY o ^ o

<c co d- co d- oj co co d" d- oo co d* co co LO d” d- d- d* d- d- d- LO LO d* UY d- d* co d- d- LO CO d- d- co CO d- LD LO

cn OJ LO CO OY CO OJ o o LO r\ o co o 1

OY OY OJ CO d- OY LO co d- OJ o d" ,

d- ,

LO OJ CO OJ OJ d- t— CO N CO O OY o o OY 1— d- OY co OY o CO LO OJ o 1— OY d" OJ p— d- LO !\ O O LO d- OJ LO 1

1— (

LO OJ

co CO OJ co co OJ co d- co OJ OJ co OJ co CO d- CO CO CO d- d- co LO d" d- d- d~ CO co CO OJ co co OJ co C\J CO co CO d- d”

CD O OY o OJ CO o d- OY OJ OY OJ OJ i

CO OY o- o LO o r^. OJ O CO 00 LO o CO LO OJ d- d" OY o O O d* LO

LU r— d- o CO CO o o i00 LO LO d- o co o co LO d- co CO o CO OJ LO d- OY LO OY LO o CM CM O CO 1OJ CJ OY

Ll» OJ OJ OJ OJ 1

OJ OJ co OJ t— i

OJ OJ OJ CO OJ OJ OJ OJ co CO co d* CO OJ co OJ C\J OJ i

«

Csj CM iCM iCM CM OJ CO CM

2: LO O O LO LO 00 LO LO LO O LO LO OY LO o co 1

CM co CM 1

i

o co OY 00 co CO OY i

o OY lo r\ CO OY LO LO c d- LO co LO OJ OJ OJ LO o OY i

CO 1LO 00 LO OY LO 00 LO co co LO 00 co LO O CM CO r- i

(

r\ co d- d- CM i

•

1— 1— 1— 1— *— 1— CM CM «

*«

«

OJ ‘

•••

CM OJ CM CO CM CM CM CM •— OJ •

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CM OJ

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2: -C •S »» CD O h- X 1— ** ^Y 4-5 *

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h- CD 4-> > s- >- >- * 0 JZ +-> 03 CD h- h- p 4-5 •S CH-r- O — 3 z >> O •r— * S- s- • r— (D 1—

»* c CD CO X r. X 0 s- 0 ro « JD ro ro ro 03 3 -r- TD >^o %- O 0 -0: r— cn C - h— * i

•1— X h— -C 1— • p— O > C S- 3: 3 ro 3 #\

p> * 03 >- “O CO CD CL r— O 4-> O) CD 1— s- h- 4-5 C O CD O ro 3 CD 2: Q) 4-> ^ c CO CO <T3 +-> •s 1— O « 4-5 • 1— OY ^ 1— •

1— 0 •S s.. O p 4-5 in •S *S *S n •* CD 0 r— O 03 Z3 E 03 (O -0 CD O 4-5 CO CD TD if) 1— > PS 0 0 TD 4-5 cn ro cn C S- CD CD «s ro C LL

t—t 0 i— CL) * t— JD c O •r— S- TD S- CD •T— -1— •1— (/) CO CO to 3 a C C _J 1— c X fO CD p— C ro _Q O 3

h- >- •r- C £Z CD E •r- 1

S- 0 03 CD 0 p— TD cn _c > C 3 (O co 03 C •r— O •r- 03 E co 4-> 03 E C C/Y 03 <c >0)0 > Z3 <0 1

0 *4- f— CL S- •1

cl m CL r— Q- 4-5 1

E 4-5 <4- r- TD 1 CO 4-> O CD *p- 0 >>_c: 4-> CD r— 1— •1— 4—> “O •r— 03 03 CLDaC E CO O 1 i- “O c 03 <

S- -r- 1 O 03 O CD CD TD 0 cu ro O CL 1

O 3 4—

CO CD -C 4-5 <D -C 03 03 CD 03 S- O 03 1O *r— ro >— 03 O 3 S- 3 S- CD Q_ 03 S- ro

1 00 00 ZD O O Q_ O OO <C 21 D- 00 O cn 0 s: 2: CO O Q LU U_ 21 OO Ll. iS) 2 CQ Ll_ CL CL O0 00 1— O

* QJ

S- -i- <D E

TD 03 C S03 fU B-59

mum
Table B-3 CAPITAL RECOVERY FACTORS FOR INTEREST RATES FROM 0% to 25%

0% 2% 4% 6% 8% 10% 12% 15% 20% 25%

i 1.00000 1.02000 1.04000 1.06000 1.08000 1.10000 1.12000 1.15000 1.20000 1.25000

2 0.50000 0.51505 0.53020 0.54544 0.56077 0.57619 0.59170 0.61512 0.65455 0.69444

3 0.33333 0.34675 0.36035 0.37411 0.38803 0.40211 0.41635 0.43798 0.47473 0.51230

4 0.25000 0.26262 0.27549 0.28859 0.30192 0.31547 0.32923 0.35027 0.38629 0.42344

6 0.20000 0.21216 0.22463 0.23740 0.25046 0.26380 0.27741 0.29832 0.33438 0.37184

6 0.16667 0.17853 0.19076 0.20336 0.21632 0.22961 0.24323 0.26424 0.30071 0.33882

7 0.14286 0.15451 0.16661 0.17914 0.19207 0.20541 0.21912 0.24036 0.27742 0.31634

8 0.12500 0.13651 0.14853 0.16104 0.17401 0.18744 0.20130 0.22285 0.26061 0.30040

9 0.11111 0.12252 0.13449 0.14702 0.16008 0.17364 0.18768 0.20957 0.24808 0.28876

10 0.10000 0.11133 0.12329 0.13587 0.14903 0.16275 0.17698 0.19925 0.23852 0.28007

11 0.09091 0.10218 0.11415 0.12679 0.14008 0.15396 0.16842 0.19107 0.23110 0.27349

12 0.08333 0.09456 0.10655 0.11928 0.13270 0.14676 0.16144 0.18448 0.22526 0.26845

13 0.07692 0.08812 0.10014 0.11296 0.12652 0.14078 0.15568 0.17911 0.22062 0.26454

14 0.07143 0.08260 0.09467 0.10758 0.12130 0.13575 0.15087 0.17469 0.21689 0.26150

15 0.06667 0.07783 0.08994 0.10296 0.11683 0.13147 0.14682 0.17102 0.21388 0.25912

16 0.06250 0.07365 0.08582 0.09895 0.11298 0.12782 0.14339 0.16795 0.21144 0.25724

17 C . 05882 0.06997 0.08220 0.09544 0.10963 0.12466 0.14046 0.16537 0.20944 0.25576

18 0.05556 0.06670 0.07899 0.09236 0.10670 0.12193 0.13794 0.16319 0.20781 0.25459

19 0.05263 0.06378 0.07614 0.08962 0.10413 0.11955 0.13576 0.16134 0.20646 0.25366

20 0.05000 0.06116 0.07358 0.08718 0.10185 0.11746 0.13388 0.15976 0.20536 0.25292

25 0.04000 0.05122 0.06401 0.07823 0.09368 0.11017 0.12750 0.15470 0.20212 0.25095

30 0.03333 0.04465 0.05783 0.07265 0.08883 0.10608 0.12414 0.15230 0.20085 0.25031 40 0.02500 0.03656 0.05052 0.06646 0.08386 0.10226 0.12130 0.15056 0.20014 0.25003

50 0.02000 0.03182 0.04655 0.06344 0.08174 0.10086 0.12042 0.15014 0.20002 0.25000

100 0.01000 0.02320 0.04081 0.06018 0.08004 0.10001 0.12000 0.15000 0.20000 0.25000 00 0.02000 0.04000 CO o o 0.08000 0.10000 0.12000 0.15000 0.20000 0.25000

B-60
APPENDIX C. HEAT AND CHILLED WATER DISTRIBUTION SYSTEMS

CONTENTS

PAGE

1. Introduction C-2

2. Typical Heat Distribution Systems C-4

2.1 Concrete Tunnel/Trench System C-4

2.2 Air Space Conduit System. C-4

2.3 Sealed Non-Air Space Conduit System C-7

2.4 Sealed-Conduit System with Non-Welded Joint C-8

2.5 Insulating Concrete Envelope System C-8

2.6 Poured-In-Place Insulation Envelope System C-10

2.7 Glass-Fiber-Reinforced Plastic Pipe System C-10

3. Operation and Maintenance of Existing Systems C-ll

4. Finding Leaks in Distribution Systems C-20

5. Assessing the Thermal Performance of Existing Systems C-22

6. Economic Considerations for Estimating Optimum Thermal

Insulation of Underground Distribution Systems C-31

7. Summary C-35

REFERENCES C-36

APPENDIX C—1 Calculation of Underground Pipe Heat-Transfer

Factors C-37

APPENDIX C-2 Earth Temperature Tables for Underground HeatDistribution-System Design C-42
APPENDIX C. HEAT AND CHILLED WATER DISTRIBUTION SYSTEMS

1. Introduction

Many Air Force Bases utilize heat distribution systems (both underground and aboveground) to carry heat and/or chilled water to outlying

buildings from a central power plant. Most of these systems were, however, constructed immediately following World War II. The underground

systems were usually selected on the following basis:

(1) It had been established by careful economic analysis that the

central heating and cooling plant with underground heat and

chilled water distribution network is most cost effective

for heating and cooling of sprawling industrial complexes,

campus-type housing projects, shopping centers, university

campuses and Air Force Bases.

(2) Better utilization of expensive ground-surface area was possible as compared to the aboveground piping network, which

tends to crowd, clutter and obstruct the valuable surface

area.

(3) The heat loss is less, due to milder ground-temperature con- ditions around the pipe than for aboveground pipes which are exposed to severe ambient temperature fluctuations. This is

especially true for the chilled-water distribution systems.

(4) If properly installed, piping systems can be protected to

minimize the exposure to severe weather as well as to traffic

abuse. (Some of the underground systems have been in operation

for more than 20 years with no appreciable reduction in their

thermal performance.)

Many systems were, however, installed hastily without thorough

engineering analysis, field experience, and technical data, which has

resulted in numerous failures manifested in the leakage of steam and

heat. In some installations, pipe heat loss amounts to as much as 10

percent of the total steam heat generated at the plant.

C-2
Most common cause of underground system failure is the seepage of

ground water into the thermal insulation through poorly constructed and/

or installed insulation envelopes. Examples:

Thin black-iron casings, sometimes painted with a light

bituminous material, were used as a conduit. Low-melt asphalt

materials were poured around the insulated pipe.

Insulating concretes containing large amounts of construction

water were utilized.

0 Prefabricated metal conduits with little, if any, space for

drainage and drying, utilized a loose-fill insulation material.

° Pipe supports which consisted only of the stub end of a bolt were being used to carry piping weight.

0 Shredded rubber made from used tires mixed with a cement binder

was installed, and with little supervision.

0 Some of the insulating materials used were hygroscopic (absorbing

moisture instead of hydrophobic (repelling ground water)

Careful evaluation of the thermal performance of existing underground

systems, therefore, should be conducted to determine the thermal distribution efficiency of the plant before deciding whether to replace or to

repair either all or part of an underground distribution system.

Aboveground systems are also very common in many Air Force Bases,

especially in localities where the ground water table is high and where

the ground surface is not congested. The aboveground heat-distribution

systems have several advantages over underground systems in that they

are easy to install, inspect, maintain, repair and replace. However,

certain shortcomings inherent in the aboveground systems must be recognized.

1. They are unsightly and occupy precious and expensive surface

areas, often causing inconvenience and unwanted obstruction to

surface traffic.

2. They are easily damaged by external mechanical shocks, vandalism

and accidental damage from passing vehicles.

3. In some localities, they are subject to much more severe weathering cycles than underground systems, such as excessively

C-3
large temperature changes. They are also exposed to vibrations,

corrosive salt air, rain and snow loading.

4. The freeze-up of the system due to the failure of heat supply

is also of serious consequence.

In order to assist the Air Force Base engineers in evaluating their

underground systems, this section is prepared to briefly describe the

various types of systems used, methods of determining the heat loss

characteristics of existing systems, and methods of arriving at economic

optimal pipe insulation thicknesses for the retrofit design. A comprehensive bibliography is provided at the end of this chapter for those

who are interested in further information regarding underground heat

distribution technology.

2. TYPICAL HEAT DISTRIBUTION SYSTEMS

2 . 1 Concrete Tunnel/Trench System

Concrete trench/tunnel system is a utility tunnel or a poured-inplace reinforced concrete box with immovable concrete slab. Pipes are insulated with preformed insulation and are supported on steel rollers

of some type which are embedded in the sides of the concrete walls. The

concrete trench tunnel is extremely durable, almost indestructible, but

it is quite expensive to construct compared to other types of systems.

The tunnel system is extremely well constructed and provides for operation,

maintenance and checking. It should be well ventilated to keep its temperature below 100° F for personnel entry. The trench cover is, however,

very difficult to make watertight. In fact, when the ground water

level is high, concrete trenches frequently leak profusely. In order to

ensure satisfactory operation, means must be provided to remove the water

which drains into the trench. A modified version of the basic design is

the half-round clay tile system (fig. C-l) and concrete conduit system

(fig. C-2) . These systems are no longer popular in this country.

2 . 2 Air-Space Conduit System

One of the most widely used underground systems is the prefabricated

pressure-testable, drainable, driable system (fig. C-3) . This type of

C-4
INSULATION TOP TILE

Figure C-l

Figure CROLLER PIPE SUPPORT ROLLER ROD BASE TILE

DRAIN

iNCRETE

Half-round clay tile trench system.

TAR PAPER, COVERED WITH

2. Concrete conduit system.

C-5
AIR SPACE

INSULATION

Figure C-3. Air-space conduit system (drainable, driable

and testable) .

Figure C-4. Sealed non-air space conduit system.

C-6
system is sold by several manufacturers, each of whom has incorporated

certain proprietary features in their product. The system consists of

a steel outer casing which may be either smooth or corrugated, either

galvanized or ungalvanized. One or more interior pipes are insulated

with a preformed pipe insulation such as calcium silicate. Pipe support

is usually achieved with a thermal insulating material. Various materials used to protect the outside casing from corrosion include cold tar

enamel, glass-fiber reinforced epoxies, and glass-fiber reinforced

asphalt compounds with a felt wrap. The system is prefabricated in the

factory in 20- or 40-foot lengths which are welded together in the

field. The completed system is intended to be pressure tight and hence

water tight. Ordinarily, water tightness is verified by applying air

pressure to the interior of the casing after welding and before back

filling. Unless properly protected, however, its metallic outer casing

is subject to corrosion. Even if water does seep into the casing during

or after a rain storm it can be drained and the casing dried by removing

drain and vent plugs at the end of the conduit.

2 . 3 Sealed Non-Air Space Conduit System

Figure C-4 shows a sealed non-air space conduit system, which is

commonly used for chilled water or low temperature hot-water distribution

systems. The system is available in a variety of configurations, but

basically all systems of this type consist of a single carrier pipe en- closed with pipe insulation having a tight outer casing around the

insulation. The most commonly used insulation for such systems is

urethane foam, provided that the foam is not exposed to temperatures

higher than 200° F. Calcium silicate and cellular glass insulation are used for high-temperature systems. The most popular outer jacket is

glass-fiber reinforced epoxy or polyester. However, plastic materials

such as PVC and asphalt-coated felt wraps are also used. Generally,

such systems are prefabricated. In one version of this system, the

jacket around the insulation is bonded to the carrier pipe at both ends

of the carrier pipe so that each segment of the system is in effect a sealed unit. In most systems, however, insulation and jacket are

C-7
continuous for the whole run of the system. Since many of these systems

are not air pressure testable, neither drainable nor driable, it is

absolutely essential that the insulation be kept dry under all conditions.

This is rather difficult to achieve in practice.

2. 4 Sealed-Conduit System with Non-Welded Joint

Figure C-5 shows a sealed-conduit system comprised of a single

carrier pipe surrounded by annular regions of calcium-silicate and

urethane-foam insulation. This system is presently not used by the Air

Force. Cellular glass insulation could be used instead of calcium

silicate. The outer casing consists of an asbestos cement or plastic

sheet. The system is prefabricated in 30-foot sections. Each section

is sealed at both ends so that infiltrating water cannot migrate into

other sections. In the field, sections are connected with holding seals

and specially designed gaskets. This system is highly resistant to

water infiltration, but the leakage of the carrier pipe fluid into the

insulation is possible when the sealing rings fail. Its outer casing,

being asbestos cement, is not subject to corrosion. The system usually

is easier to install than the previously mentioned systems.

2 . 5 Insulating Concrete Envelope System

This system consists of a concrete-slab base which supports carrier

piping surrounded by an envelope of insulating concrete. The envelope

is wrapped in a water-resistant sheet material such as polyvinyl chloride.

Drain holes are placed in the concrete envelope to permit the water

originally present in insulating concrete during its construction to be

drained off and discharged into a manhole. Various types of insulating

concretes are used, but the most prevalent is Portland cement/ vermiculite

aggregate.

During the past few years, a new type of insulating concrete

employing a polystyrene bead aggregate has been developed. The polystyrene bead is highly water resistant, but the vermiculite aggregate

concrete is not. Therefore, a good water-resistant coating is essential

for the satisfactory performance of the system using vermiculite concrete.

C-8
A. CARRIER PIPE B METALIC COUPLING

C SEAL GASKET

D SECONDARY SEAL - 0 - RING

E COUPLING SEALING RING

F PIPF END SEALING RING

G. INSULATION- THERMO BESTOS

H LOCK BLOCK

| CEMENT ASBESTOS CASING

J THRUST SAFETY SHOULDER

K INSULATION- POLYURETHANE

Figure C-5. Sealed conduit system with non-welded joint.

Figure C-6 . Poured-in-place insulation envelope system.

C-9
2. 6 Poured-In-Place Insulation Envelope System

Figure C-6 shows the poured- in-place insulation envelope system,

which is found at several Air Force Bases. This system consists of

nothing more than an envelope of loose-fill insulation material poured

around the carrier pipe in the trench. Several loose-fill materials

have been used with this system over the years. Currently two materials

are in widespread use: powdered hydrocarbon material and a chemically

treated (oleic acid) powdered chalk material. Both are said to be

resistant to water infiltration. Systems are constructed by suspending

carrier pipe in a trench, building a form around the pipe to establish

a surrounding envelope, and then pouring insulation uniformly around the

pipe. In some cases a plastic film is laid over the complete envelope.

The water tightness of the system depends on the water resistance of

the insulation material. If water should get into the material, it is

assumed that the heat of the pipe will drive it out and/or the water

penetration resistance of the material will confine damage to a relatively

small section of the system. Such systems are probably significantly

less expensive than other systems. This system is also relatively easy

to install and repair. Since the resistance of the insulation material

to water penetration diminishes as the water pressure increases, such

systems have to be evaluated carefully when the ground-water level is of

such height that it imposes an excessive head on the system. Ingress of

roots, insects, moles and earthworms should be prevented from these

systems. This type of system, however, should not be used for chilledwater distribution systems because the water vapor permeance of the

insulation is very high. Water vapor that passes through the insulation

in such instances will condense on the interior chilled water pipe.

2. 7 Glass-Fiber-Reinforced Plastic Pipe System

Glass-fiber-reinforced plastic pipe is sometimes found in the steam

condensate return lines because of their extremely high resistance to

corrosion. Being used as return lines, these pipes are not usually

insulated. There appear to be no major problems connected with these

plastic pipes, except when the field joints have been made without

appropriate supervision of preparing the epoxy resin.
3. OPERATION AND MAINTENANCE OF EXISTING SYSTEMS

Any underground system performs satisfactorily as long as the pipe

insulation is kept dry. The pipe insulation becomes wet when ground

water seeps into the insulation or when water or steam in the carrier

pipe breaks through the seal. The drainable, driable and air-testable

system (commonly referred to as DDT System) permits the Base Civil

Engineer to inspect the system, perform preventative maintenance, and

locate areas where corrective repairs are necessary, even though the

system is buried and out of sight. The Base Civil Engineer should

utilize these features for establishing a sensible inspection program

which includes regular examination of the conduit pipe openings for

signs of water. Drain caps located at the bottom of the conduit or end

plate should be removed to ascertain if water is present in the conduit

system. Manholes should be kept dry or ventilated, and all pipes and

fittings should be insulated. Many conduit systems have been saturated

by a combination of flooded manholes and missing drain and/or vent

plugs.

A provision for avoiding the problem of missing drain and/or vent

plugs is to extend the conduit vent piping to a point above the manhole

top, ending with a 180° gooseneck. Also, drain valves could be installed

on the drain-pipe nipples. Surface water may be prevented from entering

the system through manholes by raising the level of manholes at least 6

inches above ground level. If this is not feasible, the manhole cover should be sealed tight to prevent entrance of surface water, but still

permitting access for maintenance. Adequate ventilation of manholes

should be provided in accordance with Air Force specifications, since it

is dangerous for workmen to enter manholes that are too hot. Unventilated

manholes may be hotter than manholes equipped with two vent pipes by as much as 50 ° F. In the event that water or moisture is detected in the conduit

system, the water should be drained and the conduit system completely

dried by blowing air through the conduit.

Other non-conduit systems which have been developed in recent years

also have this driable and air-testable feature although they may not be

C-ll
drainable. The dryness of a system may be determined by holding a cool

mirror near the vent pipe opening, allowing forced air to strike the

mirror. When the mirror no longer fogs, the system is dry. After all

precautions have been taken and the conduit system has been completely

dried out as described above and a subsequent inspection indicates the

presence of water or moisture, a more serious problem exists.

In general, the successful operation of a heat-distribution system

hinges upon a good preventive maintenance program as prescribed by the

manufacturer of the specific system and periodic monitoring of its

operational performance. Suggested procedures are the following:

(1) The heat-distribution system may be isolated from the site

load during weekends or holidays by shutting off the supply

valves to each of the load-using facilities. In this manner

heat loss/gain characteristics of the distribution system

may be ascertained provided the load for the plant itself is

known or separately measured. By keeping this type of record,

it is possible to detect significant changes in pipe performance

due to pipe failures.

(2) Manholes and the building terminals should be checked weekly

for water leakage, wisps of steam, corrosion or any other

signs of developing troubles. The system should be "walked"

occasionally to look for evidence of potential trouble, particularly noise, water puddling, shallow cave-ins, melted snow

cover, or wisps of steam from drains and vents. Auxiliary

external drainage facilities should be checked at least monthly

to ascertain that the proper operating conditions exist.

(3) The failure of insulation in underground heat-distribution

systems creates elevated ground-surface temperatures above

the pipe which are accompanied by dead brown grass or melted snow. Recent NBS studies show that the ground-surface

temperature over a failed pipe system could be as much as 16° F

higher than the undisturbed surrounding ground. A temperature

rise of 4-6° F may be considered normal for a system with a 6-

to 8-foot ground cover.

C-12
Since surface temperatures are very difficult to measure and

fluctuate rapidly due to wind and sun conditions, it is recommended

that a 6 -inch ground temperature probe be used. Figure C-7 illustrates 6 -inch depth ground temperature profiles measured over pipe

systems with good and failing insulation. An inexpensive

ground temperature probe consisting of a mercury thermometer within

a protective glass sheath (figure C- 8 ) could be used to measure the

ground-temperature profile. The procedure for obtaining these

profiles is to measure the earth temperature with the ground temperature probe over a distance of approximately 15 feet from the

pipe in both directions normal to the pipe. This method assumes

that the ground temperature at 15 ft away from the pipe represents

the undisturbed earth temperature. If the thermal conductivity (k

g

) of the ground, depth of the pipe ( 6 ), and the pipe heat loss (Q) are known, the ground temperature excess ( 0 ) over the undisturbed

earth temperture due to the presence of the pipe can be calculated

by the relation:

i o Q

= 2TT*k *0/£n 7 (1)

s y

- o

Here y is the distance from the ground level to the center of the

pipe. The quantity 0 in the foregoing equation is the difference

between the soil temperature measured at the depth ( 6 ) directly

above the pipes and the undisturbed earth temperature of the ground.

Equation (1) was used to calculate the 6-inch-depth groundtemperature excess as a function of pipe heat-transfer factor (kp)

for various pipe depths (y). Here the pipe heat-transf er factor

is the pipe heat loss/gain per foot of pipe per hour per temperature

difference between the pipe and the undisturbed earth. The results

of these calculation are given in figure C-9. When the measured

C-13
•o+

EH

PmH

Pmm

PM

Pi

PmPJU

%H

COM

Q

o o

(&) SS3DX3 3'aniVH33W3X aNT1033 HX33Q H0NI~9

C-X4

Figure

C-7.

Measured

6-inch

depth

temperatures

above

underground

heat

distribution

systems

with

good

and

faiiing

pipe

insuiation.
Figure C-8. Ground- temperature probe.

C-15
6-INCH

DEPTH

GROUND

TEMPERATURE

EXCESS’

(

0

”)

PIPE HEAT-TRANSFER FACTOR (K ) P Figure C-9. Calculated values of the 6-inch depth

ground- temperature excess. C-16
ground-temperature excess is significantly greater than the

predicted values given in figure C-9, the pipe insulation has

probably failed.

(4) The thermal conductivities for most pipe insulations range

2 between 0.3 and 0.4 Btu*in/h*ft • °F. According to the Building

Research Advisory Board (BRAB), optimum insulation thicknesses

for typical pipe sizes range between 1 and 3 inches even including

pipe sizes as large as 14 inches in diameter [11] . Based on these

results, figure C-10 was constructed to determine a recommended "pipe

insulation factor" which is defined on the figure. The concept of

pipe insulation factor is illustrated in the example below:

Example - A 4-inch pipe is insulated with 2-inch-thick insulation,

yet its conduit surface temperature was measured and found to be

110° F. when the ambient temperature was 70° F. The question is,

"Is the insulation failing?" From table C-l the pipe temperature,

which is usually assumed to be the same as the steam temperature,

at 150 psig is 366° F. The pipe insulation factor under these

conditions is

Pipe ins. factor = ^ x 100 = 13.5%

On the other hand, from figure C-10, the predicted insulation

factor for a 4-inch pipe with 2-inch insulation is 6.25. The fact

that the measured pipe insulation factor is significantly greater

than the predicted value of figure C-10 indicates that the insulation

of the subject pipe is not functioning as it should be.

Had the insulation been adequate, the conduit surface temperature should not have exceeded

„ , . r -7 ^ , 6.25 x (366 - 70) on .-o-^ Conduxt surface temp. = 70 3 = 88.5 F

For large installations, the performance of aboveground pipe

insulation may be evaluated by scanning the conduit surface temperature using an infrared television system.

C-17
1

^"INSULATION

00

o

TD

CN

00

tc

•H

u.

«o

CO

CN

yOOVJ NOIlVinSNI

C-18

NOMINAL

PIPE

SIZE,

inches
psi;

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

TABLE C-l. PROPERTIES OF SATURATED STEAM

Absolute

Pressure

psia

Temp

°F

Gage

Pressure

Psig

Absolute

Pressure

psia

Temp

°F

14.696 212.00

24.696 239.39 260 274.696 409.35

34.696 258.77 270 284.696 412.57

44.696 274.02 280 294.696 415.72

54.696 286.72 290 304.696 418.78

64.696 297.67 300 314.696 421.75

74.696 307.33 310 324.696 424.66

84.696 316.01 320 334.696 427.50

94.696 323.90 330 344.696 430.28

104.696 331.16 340 354.696 432.99

114.696 337.88 350 364.696 435.65

124.696 344.16 360 374.696 438.25

134.696 350.05 370 384.696 440.79

144.696 355.61 380 394.696 443.29

154.696 360.86 390 404.696 445.74

164.696 365.87 400 414.696 448.14

174.696 370.63 410 424.696 450.50

184.696 375.19 420 434.696 452.82

194.696 379.56 430 444.696 455.09

204.696 383.75 440 454.696 457.32

214.696 387.77 450 464.696 459.52

224.696 391.68 460 474.696 461.68

234.696 395.45 470 484.696 463.81

244.696 399.08 480 494.696 465.91

254.696 402.61 490 504.696 467.97

264.696 406.03 500 514.696 470.00

C-19
(5) Simple repair techniques, short of complete system rehabiliitation, are often available from the manufacturer of the heatdistribution system. Excavation for repair, however, should be

done with great care to avoid further damage to pipe sections.

Usually, it is recommended that the last 6 inches of earth be re- moved by hand. Protective measures should be applied immediately

to preserve the integrity of the undamaged portion of the system

in the vicinity of the excavation.

(6) For aboveground systems, frequent system inspection to

detect conduit surface failure or wet insulation should be conducted.

Particular attention must be given to moisture seepage into the

joints and fittings, where pipe insulation usually is broken. Although rain water which seeps into the insulation can be dried ouf for hot-pipe systems, conduit failure is much more critical for

chilled-water systems. Many chilled-water pipe insulations,

including the moisture-impervious polyurethane systems, may be

found waterlogged due to localized failures permitting the ingress

of water vapor. Condensed moisture can literally seep along the

pipe through the narrow space between the pipe and its insulation.

4. FINDING LEAKS IN DISTRIBUTION SYSTEMS

There is no easy way to locate leaks in underground distribution

systems

The "hit-or-miss" method consists of observing melted snow above

the system, or of burned grass, or maybe just the feel of the ground

that is dug up where it is suspected the leak is located. This is a tedious and often a frustrating method.

In a pressure-testable system, leaks in the casing may be found

by applying 15 pounds of air pressure. In some of the modern systems,

an automatic monitoring device consisting of an elaborate indicator

console, nitrogen pressurization mechanism and alarm mechanism is available.

If the pressure drops, leaks are indicated. The task then is to locate

the leaks in the casing. This could be done by pressure testing each

section between manholes. If the problem can be narrowed to a specific

C-20
section, the exact location of the leak can be ascertained by one of

several methods.

A soap bubble leak detector may be employed to detect pressurized

air leaks from the conduit or steam leaks from steam or condensate

lines.

Another method of locating leaks in conduit casing is the use of a halogenated-hydrocarbon refrigerant gas as a tracer. The conduit

system is plugged at the terminal ends, a pressure of 5 pounds is

applied, and a small amount of refrigerant gas is introduced. Special

probes are positioned along the conduit at about 10-foot intervals. A

leak detector will show the presence of refrigerant gas in the vicinity

of leaks. Instead of refrigerant, helium or sulfur hexafluoride (SF^)

have been used in conjunction with their special purpose detectors. The

SF, leak detection is especially attractive for a large system because

b

of its extremely sensitive chromatographic detection by the use of the

ion-capture principle. This means that a very small amount of tracer

gas is needed for a large-scale leak detection operation.

Leaks also can be located by use of an odorant called mercaptan,

introduced into the conduit through an open vent with 15 psig air applied.

All drains and vents, of course, must be closed except ones at the end

seals in manholes. After the odorant is introduced, the line should be

walked until the leak is located. The length of time required and success of the detection depend on the depth of the conduit, porosity of

the soil, potency of the odorant, and length of the conduit.

If tests indicate a tight conduit system, there must be leaks in

the steam or condensate lines. These leaks may be isolated by excavating

midway between manholes. An opening cut through the conduit at this

location will reveal the direction and nature of flow. Keeping in mind

that pipe sections are often 21 feet long, additional excavations and

openings may be made until the leak(s) are located. Intermittent flow

indicates a leak in a condensate line, whereas continuous vapor flow

usually indicates a leak in a steam line.

C-21
Another method of locating a conduit leak is to pressurize the

conduit to approximately 15 psig and lay down a 2- to 4-inch thick layer

of fire-extinguishing foam on the ground above the path of the distribution

system. Air bubbles will appear in the foam above the point where the

leak is located.

A radioactive isotope also may be used for the purpose of leak

detection, but its use requires a license from the Nuclear Regulatory

Commission.

5. ASSESSING THE THERMAL PERFORMANCE OF EXISTING SYSTEMS

It is recognized that there is no simple method to measure heat

loss from underground steam lines. At installation, where there is

excess boiler capacity at the steam generating plant, distributionsystem losses are often ignored unless the users complain of insufficient

steam or hot water. Although not always easily measured, heat loss from

the underground mains can be estimated using several procedures:

(1) Calorimetric method . Fluid-flow meters and temperature

measurements across a given segment of a steam line may be used

to determine the change in fluid enthalpy which in turn equals

the pipe heat loss. If the pipe fluid is saturated steam, the

measurement of condensate accumulation along the test section

by means of condensate collectors and traps is also necessary.

This method, however, may entail the installation of new transducers,

which requires temporary shutdown of the system.

(2) Heat-Flux Meter Method . In the case of tunnel systems', it is

possible to wrap several heat-flux meters (figure C-ll) around the

pipe insulation surface at selected spots. The heat-flux-meter

output signal should be integrated over a period of at least one

hour. For the non-tunnel system, use of the heat-flux readings of

the back-filled system should be monitored for at least two weeks

to permit a stablized heat loss/gain value to be reached.

In many cases, especially in the air conduit system, the

measured heat loss by the heat-flux meter strapped around the

C-22
Figure C-ll. Heat-flux meter for heat-loss measurement.

023
exterior surface of the piping system can be much different from

the total heat loss from the carrier pipe. This situation occurs when water is boiling in the air space and the generated steam

* is exhausted to the manhole.

Measurement of heat loss/gain of aboveground heat-distribution

systems can be more readily performed than for underground systems

because the surface heat-flux transducers can be readily installed

without excavation. The heat-flux meter method has been used

successfully in the past to monitor the heat-flow rate at the

exterior surface of pipes. For the aboveground system, however, it

is recommended that these transducers be installed at not less than

three circumferential places (i.e., the top, bottom, and side of

the conduit). This is because the heat-flux value tends to vary

considerably from the top to the bottom. It is also recommended

that the transducer output be integrated for approximately one hour to reduce uncertainty due to fluctuations in conduit surface

temperature and pipe temperature.

(3) Pipe Heat-Loss Gain /Calculation Methods . Although the measurement of existing underground pipe heat loss/gain is rather difficult,

it can be estimated by the pipe heat-transfer factor (K^). Typical

values of K are given in figure C-12 for various sizes of pipes

buried at a depth of 6 ft in relatively moist soil. The lineal

heat loss in Btu/h per foot of pipe is determined by multiplying

this heat-transfer factor (K^) by the temperature difference between the pipe and the undisturbed ground temperature. For this

calculation, the pipe temperature is usually assumed to be equivalent to the fluid temperature within the pipe. Precise ground

temperatures are usually not available. Approximate values for

selected cities in the United States are given in Appendix C-2.

*According to a recent test conducted at NBS, the heat loss from

water boiling in the conduit could be as much as 30,000 Btu/h, an equivalent of 30 lb of steam per hour per foot of pipe, which is almost

300 times larger than the heat-loss rate for a well insulated system.

C-24
Figure C-12. Heat-transfer factors ^ or insul ated

underground pipes.

C-25
As an example, the heat-loss rate from a 14-inch pipe in a sealed

insulation conduit with a 6-foot earth cover in Washington, D.C. is

calculated below. Assumptions for the calculation are given in

the following:

pipe temperature: 350° F

ground temperature: 47° F (winter ground temperature given in

appendix C-2)

pipe insulation thickness: 1.5 inch

2 thermal conductivity of pipe insulation: k^. = 0.35 Btu-in/h.ft • °F

pipe heat-transfer factor: = 0.78 Btu/h»ft*°F (from fig. C-12)

the pipe heat loss is found to be: Q

= 0. 78- (350-47)

= 236 Btu/h*ft

For underground distribution systems having air spaces in the

conduit, calculation procedures given in appendix C-l should be

used.

The pipe heat-transfer factor is very strongly dependent on

the thermal resistance of the pipe insulation. It is a weak function

of the depth and the soil thermal conductivity, provided the pipe is well

insulated. One inch of calcium silicate installed around a 6-inch

pipe can reduce its heat loss by a factor of 3 as compared to the

pipe with no thermal insulation. (Figure C-13 depicts the heattransfer factors for pipes with no thermal insulation. ) When the

measured or estimated heat loss by the method described in previous

sections substantially exceeds the calculated heat-loss value (based

upon the design data) , it is very likely that the pipe system has

dramatic failures.

(4) Pipe Heat-Loss Calculations for Aboveground Systems . Heatloss calculation for aboveground pipes can be obtained by using

table C-2 and figure C-14 in conjunction with the following equation:

Q = (T - T )/R (2)

p at

where R = R + R + RT t a c I

Q = pipe heat loss, Btu/h*ft

C-26
OUTSIDE PIPE DIAMETER, INCHES

Figure C-13. Heat- transfer factors for uninsulated underground pipes.

C-27
d 0

- 4J • H/m !N3IDIdd30D d3dSNViU 1V3H =

d

h n cn o

CN CN CN

-o n cn o

o

n00

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00

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C-28

to

LLI X

u

Z

Q

o

IDQ

Z

o

u

l’ij;ure

C-I4

.

Surface*

llicrmal

resistance

of

aboveground

boa

t-d i

s

tr

ibu t

Ion

conduits.
TABLE

C-2.

THERMAL

RESISTANCES

FOR

VARIOUS

THICKNESSES

OF

PIPE

INSULATION

fj-i G

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4-)

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1

CD

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m o o o o o G m i—1 sO o o o o 40 CN CN m m o o o

-Guc

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m i3 sO o o o

rH 1—1 i—1 i—1 CN CN CO

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C-2 9

Typical

values

of1

Glass

fiber

Asbestos
Tp = pipe temperature which is usually approximated by the

pipe fluid temperature, °F

= ambient temperature, °F

R = total thermal resistance, h-ft*°F/Btu

R = pipe surface thermal resistance as found in figure C-14

cl R^ = conduit air space (if any) thermal resistance as found in table C-2 h-ft-°F/Btu

R^ = thermal resistance of pipe insulation as found in

table C-2 ,h- f t • °F/Btu

As an example, the heat loss from a nominal 4-inch pipe with

2-inch-thick fibrous glass insulation (thermal conductivity

2 0.3 Btu-in/h-ft • °F in an 8-inch-diameter steel conduit is calculated

The pipe is exposed to still-air conditions. The detail of the

calculation are given in the following:

R for the 8-inch diameter conduit from fig. C-14 0.24

aR conduit air-space thermal resistance from table C-2 0.28

c R thermal insulation resistance from table C-2 4.05

R total thermal resistance 4.57

t

Thus, the heat loss for the system carrying 150 psig saturated

steam to the ambient of 50° F, is

Q = (366 - 50) / 4 . 5 7 = 69.1 Btu/h-ft

For the foregoing calculation, the pipe temperature (T^) was obtained

from table C-l.

If the same system were exposed to a 15-mph wind condition,

the surface resistance would be determined by the equation given in

figure C-14 as follows:

R

a

12

TT X 8x9

0.053

In this case R becomes 4.38, resulting in a pipe heat-loss

rate of 72.1 Btu/h*ft.

C-30
This indicates the significance of the wind for pipe heat loss.

Moreover, the increase of the heat loss due to wind is more pronounced

for poorly insulated pipes than for well insulated pipes.

(5) Heat Loss from Pipe Fittings . Very often, even when the pipe

is well insulated, fittings such as flanges, elbows, and tees are

left bare because it is difficult to insulate them, and because of

the belief that losses from these parts are not large. However,

the fact that a pair of 10-inch standard flanges having an area of

5.20 sq ft of surface could lose a heat equivalent of as much as 40,000 cu ft of natural gas per year for a 250-psig steam system

shows the necessity for insulating such surfaces. Table C-3 gives

approximate surface areas of 250-psig fittings, together with the

bare surface per linear foot for various pipe sizes. Unfortunately,

simixar data for the valves are not available. It is suggested

that the surface area equivalent of linear foot of pipe be used for

estimating the heat-transfer surface area for valves, unless better

data are available.

6. ECONOMIC CONSIDERATIONS FOR ESTIMATING OPTIMUM THERMAL

INSULATION OF UNDERGROUND DISTRIBUTION SYSTEMS

When a portion of an underground system is to be replaced by a new

system, the cost of pipe materials, the installation costs, and the cost

of energy expenditures must be considered in order to estimate the

economically optimum amount of thermal insulation.

A suggested procedure to determine the optimum insulation thickness

is described below:

Step #1 — Determine pipe size by taking into account the heatcarrying capacity and pressure-drop requirement of the

heat distribution system.

Step #2 — Determine

a) total pipe length

b) number of expansion loops needed

c) number of anchors to be used

d) number of couplings, fittings and other accessories

to be used in the system.

C-31
TABLE

C-3.

SURFACE

AREA

OF

PIPE

FITTINGS o

-d

cn

Cfi cnouu

ominOrio\(NmNa'tNHHn

cNtNrivrmvoaiOoioovDsfntN i—I r—I i—l CN CO Nf 40

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-d

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<d

CD H

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ri'j mCT'\^oooroOLnvor'''cr-^o^oc^

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d

ct3 rdu

cn

cn

0)

cn3H

T3

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&0Co

-J HHHCJNCOsfcONHLnOOinH i—I i—I i—I CNI CO

toO •H

cn o CL O

<T\

O

UO

CN

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rH i—I CNi CNI

S'?

r-^ CN

rO rH

a)

4-1 coe

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CLd

CDHd

cnd

CDUd

T)

CD

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4-4 -I—

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n <t <r COHNNfOOOrHWtoClNOHOin 'JinNCOiH<fO\HNNtolNCOO

OOOOiHiHiHr^CNCOinNOOOO

a)od

4-1u3

cn

CD X4-1

CD

CJd

44 4-1 H 4-1 3

cn

Hd

CD CD CL d H •H

CL rH

'fcncocNicoNoo\DooiNiNOOcnco sfcoaicNOHoinoinHcoooo co<r<rvOrNa'H<rNcNoocovOH

OOOOOOrHi

—I H CN (N CO CO <t

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ad i—I *H dd

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4-1

4-1 •H

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C-22

This

table

excerpted

from

Piping

Handbook,

Sabin

Crocker,

pg.

698,

McGraw

Hill,

1945.
Step #3 — Obtain from manufacturers the cost of piping system

including freight, supervision, and installation labor

for the five insulation thicknesses given in the table

below.

2 Insulation Thermal Conductivity (k^.) , Btu’in/h*ft • °F

These five insulation thicknesses should be analyzed to determine

which one is most economical.

Step #4 — Determine amortization period for the distribution

system and discount rate for the capital investment.

Step #5 — Determine from these economic factors the annual

owning cost ($ ) of the system for a unit pipe length

from the following equation:

. _ Total pipe cost as installed

o present worth factor x pipe length

C-33
Present worth factors are given in the following table:

Amortization period Discount rate 7 , /o Years 6 7 8 10

10 7.36 7.02 6.71 6.14

15 9.71 9.11 8.56 7.60

20 11.47 10.59 9.82 8.51

Step #6 — a) Obtain from manufacturer or calculate using formulas

given in reference [8] the pipe heat-transfer factors

(lO and pipe heat loss per unit length (Q).

b) Repeat (a) for the five insulation thicknesses under

consideration.

c) Obtain five sets of cost figures for the five

insulation thicknesses from the following formula:

Q* HR* C

$

H

H

10

Where $ TT = cost of heat loss per year per ft of pipe

pipe heat loss per foot of pipe per hour

H

Q

HR = total hours of operation per year

C = cost of heat/10 Btu

H

Step #7 — Summarize the foregoing calculation in a table as shown

below. The numbers in parenthesis denote the five

insulation thicknesses.

Insulation type Heat-trans- Heat

Annual pipe

cost as inAnnual

heat

Here = total cost = $ + $

Total

cost

or tnicKx

t I

less

(1)

L IdL LUJ.O K (1)

P

Q (1) (1) /-—s tH a

</> $ T

(1)

4

(2) K (2)

P Q (2) »0 (2) $H

(2) $ T

(2)

4

(3) K (3) P Q (3) $ o

(3) $H O) $ T

(3)

t ! (4) K (4)

P Q (4) »0 (4) $H

(4) $ T

(4)

(5) K (5)

P

Q (5) (5) $H

(5) $ T

(5)

H

C-34
Step #8 — Choose the insulation thickness or the type of insulation

which yields the smallest total costs (

$

(j, ) .

7. SUMMARY

In summary, the following measures are suggested for the improvement

of thermal performance of existing heat-distribution systems.

1. Conduct frequent inspections along the system to determine

possible insulation failures by observing telltale signs of steam or pipe-fluid leakage. Measurements of the ground surface or the conduit

surface (in case of the aboveground system) could indicate excessive

pipe heat loss or failure of the insulation.

2. Pipe heat loss can be minimized by shielding the pipe surface

from high wind and water.

3. Advanced techniques such as the use of nitrogen pressurization

for the air-testable system, the SF tracer-gas method, and use of

D thermographies may be applicable to expedite failure detection for large

installations

4. Insulate pipe fittings, since heat loss from them can be significant. Data are provided to estimate the heat loss from uninsulated

fittings.

5. Construct fences or other barriers to protect aboveground pipes

from vandalism or surface traffic.

C-35
REFERENCES

1. Hasler, E. A. , District Heating and Telethermics , Building

Services Engineer, Feb., 1976.

2. Proceedings for 1966 Symposium on Underground Heat Distribution

Systems, Federal Construction Council Publication 1412, National

Academy of Sciences, Washington, D.C., 1966.

3. Proceedings of 1973 Symposium on Underground Heat and Chilled Water

Distribution Systems, National Bureau of Standards, Building Science

Series 66, May, 1975.

4. BRAB Report, Underground Thermal Distribution Systems, Publication

of Building Research Advisory Board, Washington, D.C., 1970.

5. BRAB Report, Underground Corrosion and Cathode Protection, Publication 1097 of Federal Construction Council, National Academy of

Sciences, Washington, D.C., 1963.

6. BRAB Report, Supplementary Field Investigation of Underground Heat

Distribution Systems, FCC Technical Report No. 475, National

Academy of Sciences, Publication 1481, Washington, D.C., 1966.

7. BRAB Report, Underground Heat Distribution Systems, FCC Technical

Report 30R-64, National Academy of Sciences, Publication 1186,

Washington, D.C., 1964.

8. BRAB Report, Criteria for Underground Heat Distribution Systems,

FCC Technical Report No. 66, National Academy of Sciences,

Washington, D.C., 1975.

9. Mesko, J. , Economic Advantages of Central Heating and Cooling

Systems, Proceedings of 1973 Symposium on Underground Heat and

Chilled Water Distribution Systems, National Bureau of Standards,

Building Science Series 66, May, 1975 of #3.

10. BRAB Report, Evaluation of Components for Underground Heat Distribution Systems, FCC Technical Report 39-64, National Academy of

Sciences, Publication 1196, Washington, D.C., 1964.

11. BRAB Report, Thermal Insulation Thickness Charts and Material

Characterization for Piping, FCC Technical Report No. 45 NAS/NRC

publication 1084, 1963.

12. BRAB Report, Field Investigation of Underground Heat Distribution

Systems, FCC Technical Report No. 47 NAS/NRC Publication 114,

Washington, D.C., 1963.

13. BRAB Report, Piping Handbook, Table II, page 698, McGraw Hill Book

Company Inc.

1945.

C-36
APPENDIX C-l. CALCULATION OF UNDERGROUND PIPE HEAT-TRANSFER FACTORS

1. Definitions

2. Circular Systems

d = distance from ground surface to

center of pipe, inches

r = radius of conduit, inches

C = thermal conductance of pipe and

conduit, Btu/h*ft^*°F

1^

= undisturbed earth temperature

1^

= temperature of fluid in pipe, °F

k = thermal conductivity of undisturbed

earth, Btu* in/h* f t^* °F (table C-l.l)

2.1 Heat-Transfer Factors

when

1 =1

K C

P

Pipe heat-loss rate:

Q

= K • (T - T ) Btu/h* ft

P P g

Note: Heat- transfer-factor calculation procedures for more complex

piping systems are found in the references cited in the

list of references for the main text.

C-37
TABLE C-l.l THERMAL CONDUCTIVITY OF SOIL (k )-, Btu* in/h* f

2

- a F

s

Moisture

Content

Type Soil

Sandy Silty Clay

Dry 2 1 1

Med ium 13 9 7

Wet 15 15 15

*_/ These data are approximate values and should be used only when

precise data are unavailable from the site or from the manufacturer.

TABLE C-1.2 THERMAL CONDUCTIVITY OF PIPE INSULATION (k )-^

Insulation Type Btu* in/h* ft

2

* °F

Asbestos 1.3

Calcareous loose fill 0.8

Calcium silicate 0.3

Cellular glass 0.4

Cork 0.3

Hydrocarbon loose fill 0.7

Polyurethane 0.2

These data are to be used only when no precise data are available

from the site or from the manufacturer.

C-38
2. 2 Pipe Conductances

Define the following parameters for all the pipes involved in the

system. If the pipe is in a conduit, exclude the conduit.

CONDUCT

AIR SPACE

Insulation

Thickness, in.

Thermal conductivity,

Btu’in/h-ft * e F (table C-1.2)

INSULATION

Pipe

Thickness, in.

Pipe thermal conductivity*,

2 Btu*in/h*ft •

PIPE Outside diameter, in.

(^A)I

t„ =

k_ =

t = w

k = w

D =

For steel kw = 360 Btu*in/h*ft • °F

plastic ky = 2-3 Btu* in/h* f t2* °F

concrete = 12 Btu ' in/h’ f t^ * °F

^ cement asbestos = 16 Btu*in/h‘ft • °F.

C-39
If the single pipe is in a conduit with air space, adjust the C value

of the pipe as follows:

1

C

of pipe

+ In /—

Id -2t

\ C c

where D

P

k

c

t c D

c

= outside diameter of the insulation, in

2 = thermal conductivity of conduit, Btu*in/h*ft ’°F

= thickness of conduit, in

= outside diameter of the conduit, in

t

C-40
3. Non-circular systems

For non-circular underground distribution systems, such as shown

below, the manufacturer should provide one of the following heat-transfer

factors for specified soil conductivity, temperature, and depth.

Case 1 Case 2

Case 1 _ Heat loss per foot of pipe

p pipe temperature - soil temperature

Case 2 K

P

heat loss per foot of pipe

Average temperature of pipe - soil temperature

When the manufacturer provides calculated values for

required to submit the calculation procedure used to

K , he

P derive

should be

the values.

C-41
APPENDIX C-2. EARTH TEMPERATURE TABLES FOR UNDERGROUND

HEAT-DISTRIBUTION-SYSTEM DESIGN

Tables TG-1 through TG-11 were developed by using monthly average

temperatures prepared by the U.S. Weather Bureau for many localities

in the United States which include cities next to U.S. Air Force Bases.

These tables were generated by using the procedure outlined in a 1965

ASHRAE technical paper entitled "Earth Temperature and Thermal

Diffusivity at Selected Stations in the United States" by T. Kusuda

and P. R. Achenbach.

C-A2
10-FT AVERAGE EARTH TEMPERATURE FOR UNDERGROUND PIPE HEAT TRANSFER

STATE CITY WINTER

Alabama Anniston AP*/ 55.

Birmingham AP 54.

Mobile AP 61.

Mobile CO 61.

Montgomery AP 58.

Montgomery CO 59.

Arizona Bisbee COOP-^ 55.

Flagstaff AP 35.

Ft Huachuca

Prvg. Grn. 55.

Phoenix AP 60.

Phoenix CO 61.

Prescott AP 46.

Tucson AP 59.

Winslow AP 45.

Yuma AP 65.

Arkansas Fort Smith AP 52.

Little Rock AP 53.

Texarkana AP 56.

California Bakersfield AP 56.

Beaumont CO 53.

Bishop 47.

Blue Canyon AP 43.

Burbank AP 58.

Eureka CO 50.

Fresno AP 54.

Los Angeles AP 58.

Los Angeles CO 60.

Mount Shasta CO 41.

Oakland AP 53.

Red Bluff AP 54.

Sacramento AP 53.

Sacramento CO 54.

Sandberg CO 47.

San Diego AP 59.

San Francisco AP 53.

San Francisco CO 55.

San Jose COOP 55.

Santa Catalina AP 57.

Santa Maria AP 54.

SPRING SUMMER AUTUMN

TGANNUAL

58. 70. 67. 63.

58. 71. 68. 63.

63. 74. 71. 67.

64. 75. 72. 68.

61. 73. 70. 65.

62. 74. 71. 66.

58. 70. 67. 62.

39. 54. 50. 45.

58. 71. 68. 63.

64. 79. 75. 69.

65. 80. 76. 70.

49. 65. 61

55.

62. 76. 73. 68.

49. 65. 61

55.

69. 84. 80. 75.

56. 72. 68. 62.

57. 72. 68. 62.

60. 74. 71. 65.

60. 74. 70. 65.

56. 67. 64. 60.

51. 65. 61. 56.

46. 58. 55. 50.

60. 68. 66. 63.

51. 54. 54. 52.

58. 72. 68. 63.

59. 64. 63. 61.

61. 68. 66. 64.

44. 57. 54. 49.

54. 60. 59. 56.

58. 72. 69. 63.

56. 67. 64. 60.

57. 68. 65. 61.

50. 63. 60. 55.

60. 66. 65. 62.

54. 59. 57. 56.

55. 59. 58. 57.

57. 64. 62. 59.

58. 64. 62. 60.

55. 60. 59. 57.

*/

AP = Airport Data

~Ti

j

CO = City Office Data — COOP = Cooperative Weather Station

C-43
10-FT AVERAGE EARTH TEMPERATURE FOR UNDERGROUND PIPE HEAT TRANSFER

TG-2

STATE CITY WINTER SPRING SUMMER AUTUMN ANNUAL

Colorado Alamosa AP 30. 35. 52. 48. 41.

Colorado Sprgs. AP 39. 43. 59. 55. 49.

Denver AP 39. 43. 60. 56. 50.

Denver CO 41. 45. 61. 58. 51.

Grand Junction AP 39. 44. 65. 60. 52.

Pueblo AP 41. 45. 62. 58. 51.

Connecticut Bridgeport AP 40. 44. 61. 57. 50.

Hartford AP 39. 43. 61. 57. 50.

Hartford AP Brainer 39. 43. 60. 56. 50.

New Haven AP 40. 44. 60. 56. 50.

Delaware Wilmington AP 44. 48. 64. 60. 54.

D.C. Washington AP 47. 51. 66. 63. 56.

Washington CO 47. 51. 66. 63. 57.

Silver Hill OBS 46. 50. 65. 61. 55.

Florida Apalachicola CO 63. 65. 75. 73. 69.

Daytona Beach AP 65. 67. 75. 74. 70.

Fort Myers AP 70. 71. 78. 76. 74.

Jacksonville AP 63. 66. 75. 73. 69.

Jacksonville CO 64. 66

76. 73. 70.

Key West AP 74. 75. 80. 79. 77.

Key West CO 75. 76. 81. 79. 78.

Lakeland CO 68. 69. 77. 75. 72.

Melbourne AP 68. 70. 77. 75. 72.

Miami AP 72. 74. 79. OO 76.

Miami CO 72. 73. 78. 77. 75.

Miami Beach COOP 74. 75. 80. 78. 77.

Orlando AP 68. 70. 77. 75. 72.

Pensacola CO 62. 64. 74. 72. 68.

Tallahassee AP 61. 64. 74. 72. 68.

Tampa AP 68. 69. 77. 75. 72.

West Palm Beach 71. 73. 79. 77. 75.

Georgia Albany AP 60. 63. 75. 72. 67.

Athens AP 54. 58. 71. 68. 63.

Atlanta AP 54. 57. 70. 67. 62.

Atlanta CO 54. 57. 70. 67. 62.

Augusta AP 56. 59. 72. 69. 64.

Columbus AP 56. 59. 72. 69. 64.

Macon AP 58. 61. 74. 71. 66

Rome AP 53. 56. 70. 67. 61.

Savannah AP 60. 63. 74. 71. 67.

Thomasville CO 62. 64. 74. 72. 68.

Valdosta AP 61. 64. 74. 72. 68.

C-44
10-FT AVERAGE EARTH TEMPERATURE FOR UNDERGROUND PIPE HEAT TRANSFER

TG-3

STATE CITY WINTER SPRING SUMMER AUTUMN ANNUAL

Idaho Boise AP 40. 44. 62. 58. 51.

Idaho Falls 46 W 30. 35. 55. 50. 42.

Idaho Falls 42 NW 28. 33. 54. 49. 41.

Lewiston AP 42. 46. 63. 59. 52.

Pocatello AP 35. 40. 59. 55. 47.

Salmon CO 32. 37. 56. 52. 44.

Illinois Cario CO 49. 53. 70. 66. 60.

Chicato AP 38. 43. 62. 57. 50.

Joilet AP 37. 42. 61. 56. 49.

Moline AP 38. 43. 62. 58. 50.

Peoria AP 39. 44. 63. 58. 51.

Springfield AP 41. 45. 64. 60. 52.

Springfield CO 43. 47. 66. 62. 54.

Indiana Evansville AP 47. 51. 67. 63. 57.

Fort Wayne AP 39. 43. 61. 57. 50.

Indianapolis AP 41. 46. 64. 59. 52.

Indianapolis CO 43. 48. 65. 61. 54.

South Bend AP 38. 42. 61. 56. 49.

Terre Haute AP 42. 47. 65. 60. 53.

Iowa Burlington AP 39. 44. 64. 59. 51.

Charles City CO 33. 38. 60. 55. 46.

Davenport CO 39. 44. 64. 59. 51.

Des Moines AP 37. 42. 63. 58. 50.

Des Moines CO 38. 43. 64. 59. 51.

Dubuque AP 34. 39. 60. 55. 47.

Sioux City AP 35. 40. 62. 57. 49.

Waterloo AP 35. 40. 61. 56. 48.

Kansas Concordia CO 42. 47. 67. 62. 54.

Dodge City AP 43. 48. 67. 62. 55.

Goodland AP 38. 43. 62. 57. 50.

Topeka AP 43. 47. 66. 62. 55.

Topeka CO 44. 49. 68. 63. 56.

Wichita AP 45. 50. 68. 64. 57.

Kentucky Bowling Green AP 47. 51. 67. 63. 57.

Lexington AP 44. 48. 65. 61. 54.

Louisville AP 46. 50. 67. 63. 56.

Louisville CO 47. 51. 67. 64. 57.

C-45
10-FT AVERAGE EARTH TEMPERATURE FOR UNDERGROUND PIPE HEAT TRANSFER

TG-4

STATE CITY WINTER SPRING SUMMER AUTUMN ANNUAL

Louisianna Baton Rouge AP 61. 63. 74. 72. 67.

Burrwood CO 65. 67. 77. 74. 71.

Lake Charles AP 61. 64. 75. 73. 68.

New Orleans AP 63. 65. 75. 73. 69.

New Orleans CO 64. 66. 77. 74. 70.

Shreveport AP 58. 61. 75. 72. 66.

Ma ine Caribou AP 24. 29. 50. 45. 37.

Eastport CO 33. 37. 51. 48. 42.

Portland AP 33. 38. 56. 51. 44.

Maryland Baltimore AP 45. 49. 65. 61. 55.

Baltimore CO 47. 51. 67. 63. 57.

Frederick AP 44. 48. 65. 61. 55.

Massachusetts Boston AP 41. 44. 61. 57. 51.

Nantucket AP 41. 44. 57. 54. 49.

Pittsfield AP 34. 38. 55. 51. 44.

Worchester AP 36. 40. 58. 54. 47.

Michigan Alpena CO

Detroit - 33. 37. 54. 50. 43.

Willow Run A 38. 42. 60. 56. 49.

Detroit City AP 38. 43. 60. 56. 49.

Escanaba CO 30. 35. 53. 49. 42.

Flint AP 36. 40. 58. 54. 47.

Grand Rapids AP 36. 40. 58. 54. 47.

Grand Rapids CO 38. 42. 60. 56. 49.

East Lansing CO 36. 40. 58. 54. 47.

Marquette CO 31. 35. 53. 49. 42.

Muskegon AP 36. 40. 57. 53. 47.

Sault Ste Marie AP 28. 32. 51. 47. 39.

Minnesota Crookston COOP 25. 31. 55. 49. 40.

Duluth AP 25. 30. 52. 47. 38.

Duluth CO 26. 31. 52. 47. 39.

International Falls22. 27. 51. 45. 36.

Minneapolis AP 32. 37. 60. 54. 46.

Rochester AP 31. 36. 58. 53. 44.

Saint Cloud AP 28. 33. 56. 51. 42.

Saint Paul AP 32. 37. 60. 54. 46.

C-46
10-FT AVERAGE EARTH TEMPERATURE FOR UNDERGROUND PIPE HEAT TRANSFER

TG-:

STATE CITY WINTER SPRING SUMMER AUTUMN ANNUAL

Mississippi Jackson AP 57. 61. 73. 70. 65.

Meridian AP 57. 60. 72. 69. 64.

Vicksburg CO 58. 61. 74. 71. 66

Missouri Columbia AP 43. 48. 66. 62. 55.

Kansas City AP 44. 49. 68. 64. 56.

Saint Joseph AP 42. 47. 67. 62. 54

Saint Louis AP 45. 49. 67. 63. 56.

Saint Louis CO 46. 50. 68. 64. 57.

Springfield AP 45. 49. 66

62. 56.

Montana Billings AP 35. 40. 59. 55. 47.

Butte AP 27. 31. 50. 45. 38.

Glasgow AP 27. 33. 56. 51. 42.

Glascow CO 28. 34. 57. 52. 43.

Great Falls AP 34. 38. 56. 52. 45.

Harve CP 31. 36. 57. 52. 44.

Helena AP 31. 36. 55. 50. 43.

Helena CO 32. 36. 55. 50. 43.

Kalispell AP 32. 37. 54. 50. 43.

Miles City AP 32. 37. 59. 54. 45.

Missoula AP 33. 37. 56. 51. 44.

Nebraska Grand Island AP 38. 43. 64. 59. 51.

Lincoln AP 39. 44. 64

60. 52.

Lincoln CO UNI 40. 45. 65. 61. 53.

Norfolk AP 35. 40. 62. 57. 48.

North Platte AP 37. 42. 62. 57. 49.

Omaha AP 39. 44. 65. 60. 52.

Scottbluff AP 36. 41. 60. 56. 48.

Valentine CO 35. 40. 61. 56. 48.

Nevada Elko AP 34. 39. 57. 53. 46.

Ely AP 35. 39. 56. 52. 45.

Las Vegas AP 56. 60. 78. 74. 67.

Reno AP 40. 44. 58. 55. 49.

Tonopah 41. 45. 61. 57. 51.

Winnemucca AP 38. 42. 60. 56. 49.

New Hamp- Concord AP 33. 38. 56. 52. 45.

shire Mt Washington COOP 17. 21. 37. 33. 27.

New Jersey Atlantic City CO 45. 49. 63. 60. 54.

Newark AP 43. 47. 63. 59. 53.

Trenton CO 43. 47. 64. 60. 53.

C-47
10- FT AVERAGE EARTH TEMPERATURE FOR UNDERGROUND PIPE HEAT TRANSFER

TGSTATE CITY WINTER SPRING SUMMER AUTUMN ANNUAL

New Mexico Albuquerque AP 46. 50. 67. 63. 57.

Clayton AP 43. 47. 63. 59. 53.

Raton AP 38. 42. 58. 54. 00 Roswell AP 51. 54. 69. 66. 60.

New York Albany AP 36. 40. 59. 54. 47.

Albany CO 38. 43. 61. 56. 49.

Bear Mountain CO 38. 42. 59. 55. 48.

Binghampton AP 34. 38. 56. 52. 45.

Binghampton CO 38. 42. 59. 55. 48.

Buffalo AP

New York La

37. 41. 58. 54. 47.

Guard ia 44. 48. 64. 60. 54.

New York CO

New York Central

44. 47. 63

59. 53.

Par 44. 48. 64. 60. 54.

Oswego CO 36. 40. 58. 54. 47.

Rochester AP 37. 41. 58. 54. 47.

Schenectady COOP 35. 40. 59. 55. 47.

Syracuse AP 38. 42. 60. 56. 49.

North Asheville CO 48. 51. 64. 61. 56.

Carolina Charlotte AP 52. 55. 69. 66. 60.

Greensboro AP 49. 53. 67. 64. 58.

Hatteras CO 56. 59. 70. 68. 63.

Raleigh AP 51. 55. 69. 65. 60.

Raleigh CO 52. 56. 70. 66. 61.

Wilmington AP 56. 59. 71. 69. 64.

Winston Salem AP 50. 53. 67. 64. 58.

North Bismarck AP 27. 33. 56. 51. 42.

Dakota Devils Lake CO 24. 29. 54. 48. 39.

Fargo AP 26. 32. 56. 50. 41.

Minot AP 25. 31. 54. 49. 39.

Williston CO 27. 33. 56. 50. 41.

Ohio Akron-Canton 39. 43. 60. 56. 50.

Cincinnati AP 43. 47. 64. 60. 54.

Cincinnati CO

Cincinnati ABBE

46. 50. 66. 63. 56.

OBS 45. 49. 65. 61. 55.

Cleveland AP 40. 44. 61. 57. 51.

Cleveland CO 41. 45. 62. 58. 51.

Columbus AP 41. 46. 62. 59. 52.

Columbus CO 43. 47. 64. 60. 53.

Davton AP 42. 46. 63. 59. 52.

C-48
10- FT AVERAGE EARTH TEMPERATURE FOR UNDERGROUND PIPE HEAT TRANSFER

TG-7

STATE CITY WINTER SPRING SUMMER AUTUMN ANNUAL

Ohio Sandusky CO 41. 45. 62. 58. 51.

(Continu ed) Toledo AP 38. 43. 60. 56. 49.

Youngstown AP 39. 43. 60. 56. 50.

Oklahoma Oklahoma City AP 50. 54. 71. 67. 60.

Oklahoma City CO 50. 55. 71. 68. 61.

Tulsa AP 50. 54. 71. 67. 61.

Oregon Astoria AP 47. 48. 56. 54. 51.

Baker co 36. 40. 56. 52. 46.

Burns CO 36. 40. 58. 54. 47.

Eugene AP 46. 48. 59. 57. 52.

Meacham AP 34. 38. 52. 49. 43.

Medford AP 46. 49. 62. 59. 54.

Pendelton AP 42. 46. 63. 59. 53.

Portland AP 46. 49. 60. 57. 53.

Portland CO 48. 50. 61. 59. 55.

Roseburg AP 47. 49. 60. 57. 53.

Roseburg CO 48. 51. 61. 59. 55.

Salem AP 46. 49. 60. 57. 53.

Sexton Summit 42. 44. 55. 52. 48.

Troutdale AP 45. 48. 59. 57. 52.

Pennsylvania Allentown AP 40. 44. 62. 58. 51.

Erie AP 38. 42. 58. 55. 48.

Erie CO 40. 44. 60. 56. 50.

Harrisburg AP 43. 47. 63. 59. 53.

Park Place CO 36. 40. 57. 53. 46.

Philadelphia AP 44. 48. 64. 61. 54.

Philadelphia CO

Pittsburgh

46. 50. 66. 62. 56.

) Allegheny

Pittsburgh Grtr

42. 46. 62. 58. 52.

Pitt 40. 44. 61. 57. 51.

Pittsburgh CO 44. 48. 64. 60. 54.

Reading CO 43. 47. 64. 60. 54.

Scranton CO

Wilkes Barre40. 44. 61. 57. 50.

Scranton 39. 43. 60. 56. 49.

Williamsport AP 40. 44. 61. 57. 51.

Rhode Island Block Island AP 41. 45. 59. 55. 50.

Providence AP 39. 43. 59. 56. 49.

Providence CO 41. 45. 62. 58. 51.

C-49
10-FT AVERAGE EARTH TEMPERATURE FOR UNDERGROUND PIPE HEAT TRANSFER

TG-8

STATE CITY WINTER SPRING SUMMER AUTUMN ANNUAL

South Charleston AP 58. 61. 72. 70. 65.

Carolina Charleston CO 60. 62. 74. 71. 67.

Columbia AP 56. 59. 72. 69. 64.

Columbia CO 57. 60. 72. 69. 64.

Florence AP 55. 59. 72. 69. 64.

Greenville AP 53. 56. 69. 66

61.

Spartanburg AP 53. 56. 70. 66. 61.

South Dakota Huron AP 31. 37. 60. 55. 46.

Rapid City AP 34. 39. 58. 54. 46.

Sioux Falls AP 32. 37. 60. 55. 46.

Tennessee Bristol AP 4

> 00 51. 65. 62. 56.

Chattanooga AP 51. 55. 69. 65. 60.

Knoxville AP 50. 54. 68. 65. 59.

Memphis AP 52. 56. 71. 68. 62.

Memphis CO 53. 57. 72. 68. 62.

Nashville AP 51. 54. 69. 66. 60.

Oak Ridge CO 49. 52. 67. 64. 58.

Oak Ridge 8 S 49. 52. 67. 64. 58.

Texas Abilene AP 55. 58. 73. 70. 64.

Amarillo AP 47. 50. 67. 63. 57.

Austin AP 60. 63. 76. 73. 68.

Big Springs AP 56. 59. 74. 70. 65.

Brownsville AP 68. 70. 79. 77. 74.

Corpus Christi AP 65. 68. 78. 76. 72.

Dallas AP 57. 61. 76. 72. 66.

Del Rio AP 62. 65. 77. 75. 70.

El Paso AP 54. 58. 72. 69. 63.

Fort Worth AP

Forth Worth Amon

57. 60. 75. 72. 66.

Cart 57. 60. 75. 72. 66.

Galveston AP 63. 66. 77. 74. 70.

Galveston CO 63. 66

77. 74. 70.

Houston AP 62. 65. 76. 73. 69.

Houston CO 63. 66. 77. 74. 70.

Laredo AP 67. 70. 81. 79. 74.

Lubbock AP 50. 54. 69. 65. 59.

Midland AP 55. 59. 73. 70. 64.

Palestine CO 58. 62. 74. 71. 65.

Port Arthur AP 61. 64. 75. 72. 68.

Port Arthur CO 63. 65. 76. 74. 69.

San Angelo AP 58. 61. 74. 71. 66.

San Antonio AP 61. 64. 77. 74. 69.

Victoria AP 64. 67. 78. 76. 71.

C-50
10- FT AVERAGE EARTH TEMPERATURE FOR UNDERGROUND PIPE HEAT TRANSFER

TG-9

STATE CITY WINTER SPRING SUMMER AUTUMN ANNUAL

Texas Waco AP 58. 62. 76. 73. 67.

(Continued) Wichita Falls AP 53. 57. 73. 69. 63.

Utah B landing CO 39. 43. 60. 56. 50.

Milford AP 37. 42. 61. 56. 49.

Salt Lake City AP 40. 44. 63. 59. 51.

Salt Lake City CO 41. 46. 65. 60. 53.

Vermont Burlington AP 32. 37. 57. 52. 44.

Virginia Cape Henry CO 51. 55. 68. 65. 60.

Lynchburg AP 48. 51. 66. 62. 57.

Norfolk AP 51. 54. 68. 64. 59.

Norfolk CO 52. 56. 69. 66. 61.

Richmond AP 48. 52. 67. 63. 58.

Richmond CO 50. 53. 68. 64. 59.

Roanoke AP 48. 51. 66. 62. 57.

Washington Ellensburg AP 37. 41. 59. 55. 48.

Kelso AP

North Head L H

45. 47. 57. 54. 51.

Resvn 47. 49. 54. 53. 51.

Olympia AP 44. 46. 56. 54. 50.

Omak 2NW 36. 40. 59. 55. 47.

Port Angeles AP

Seattle AP Boeing

45. 46. 53. 52. 49.

FI 46. 48. 58. 56. 52.

Seattle CO 47. 50. 59. 57. 53.

Seattle-Tacoma AP 44. 47. 57. 55. 51.

Spokane AP 37. 41. 58. 54. 47.

Stampede Pass 32. 35. 48. 45. 40.

Tacoma CO 46. 48. 58. 55. 52.

Tattosh Island CO 46. 47. 52. 51. 49.

Walla Walla CO 44. 48. 65. 61. 54.

Yakima AP 40. 44. 61. 57. 50.

West Charleston AP 47. 50. 65. 61. 56.

Virginia Elkins AP 41. 45. 59. 56. 50.

Huntington CO. 48. 52. 67. 63. 57.

Parkersburg CO 45. 49. 65. 61. 55.

Petersburg CO 44. 48. 63. 60. 54.

C-51
10- FT AVERAGE EARTH TEMPERATURE FOR UNDERGROUND PIPE HEAT TRANSFER

TG-10

STATE CITY WINTER SPRING SUMMER AUTUMN ANNUAL

Wisconsin Green Bay AP 31. 36. 56. 51. 44.

La Crosse AP 32. 38. 60. 55. 46.

Madison AP 34. 39. 59. 54. 47.

Madison CO 34. 39. 60. 55. 47.

Milwaukee AP 35. 40. 58. 54. 47.

Milwaukee CO 36. 41. 59. 55. 48.

Wyoming Casper AP 34. 38. 57. 52. 45.

Cheyenne AP 35. 39. 55. 51. 45.

Lander AP 31. 35. 56. 51. 43.

Rock Springs AP 31. 35. 54. 50. 42.

Sheridan AP 33. 37. 56. 52. 44.

Hawaii Hilo AP 72. 72. 74. 74. 73.

Honolulu AP 74. 75. 77. 77. 76.

Honolulu CO 74. 74. 77. 76. 75.

Lihue AP 72. 73. 76. 75. 74.

Alaska Anchorage AP 25. 29. 46. 42. 35.

Annette AP 40. 42. 51. 49. 46.

Barrow AP 4. 7. 16. 14. 10.

Bethel AP 18. 23. 41. 37. 30.

Cold Bay AP 33. 35. 43. 41. 38.

Cordova AP 32. 35. 45. 43. 39.

Fairbanks AP 14. 19. 38. 34. 26.

Galena AP 13. 18. 37. 33. 25.

Gambell AP 15. 19. 34. 30. 24.

Juneau AP 34. 36. 47. 45. 41.

Juneau CO 36. 39. 49. 46. 42.

King Salmon AP 25. 28. 44. 40. 34.

Kotzebue AP 10. 14. 31. 27. 21.

McGrath AP 14. 18. 37. 33. 25.

Nome AP 16. 20. 37. 33. 26.

Northway AP

Saint Paul Island

12. 16. 32. 29. 22.

AP 31. 32. 40. 38. 35.

West Indies

Yakutat AP

Ponce Santa Isa33. 36. 45. 43. 39.

bel AP 75. 76. 78. 78. 77.

San Juan AP 77. 77. 79. 79. 78.

San Juan CO 77. 77. 79. 79. 78.

Swan Island 80. 80. 82. 81. 81.

St. Croix V I AP 78. 78. 81. 80. 79.

C-52
10— FT AVERAGE EARTH TEMPERATURE FOR UNDERGROUND PIPE HEAT TRANSFER

TG-11

STATE CITY WINTER SPRING SUMMER AUTUMN ANNUAL

Pacif ic Canton Island AP 00 84. 00 -O* 84. 00 Islands Koror 81. oo i

1 81. 81. 81.

Ponape Island AP 81. 81. 81. 81. 81.

Truk Moen Island 00 f—

1 81. 81.

i

00 { 81.

Wake Island AP 79. 79. |

—

00 81. 80.

Yap 81. 00 rH 82. 82. 00 CM

C-53

APPENDIX D. A SURVEY OF COMPUTER PROGRAMS FOR EVALUATING

BUILDING AND SYSTEM PERFORMANCE

CONTENTS

PAGE

1. Introduction and Background D-2

2. Program Survey D_6

Alternate Choice Comparison for Energy Systems

Selection (AXCESS) D_7

Building Load Analysis and Systems Thermodynamics

Program (BLAST) D_ 9

Energy Conservation Utilizing Better Engineering (ECUBE) D-ll

Meriwether Energy Systems Analysis Series (ESAS) D-13

APEC Heating-Cooling Calculation Program--

Version III (HCC-III) D-15

McDonnel Douglas Automation Company's Annual Consumption

of Energy Program (MACE) D-17

MEDSI Annual Energy Consumption D-18

National Bureau of Standards Load Determination

Program (NBSLD) D-19

NASA's Energy Cost Analysis Program (NECAP) D-20

Gard Program for Facility/HVAC Design and Energy Analysis

(SCOUT) d-22

Trane Air Conditioning Economics (TRACE) D-23

D-l
APPENDIX D. SURVEY OF COMPUTER PROGRAMS FOR EVALUATING

BUILDING AND SYSTEM PERFORMANCE

1. INTRODUCTION AND BACKGROUND

The use of computers for building thermal loads and energy consumption analysis has seen a rapid increase, from almost no activity, in the

last ten years. Appendix A of this report identified those factors which

contribute to the. heating and cooling loads of buildings, and described

in detail the mechanisms by which they do so. Methods for calculating

the amount of energy required by building HVAC systems and equipment to

satisfy those loads were also described. The complexity of the load and

system energy consumption rate calculations at any given time, and the

repetitive nature of these calculations when determining cumulative

energy consumption over some extended period of time, (particularly

annual consumptions) make it difficult, if not impossible, to accomplish

detailed energy consumption analyses unless the calculation procedures

are computerized. Recent (and still developing) calculation procedures

recommended by ASHRAE have been allowed to become as complex in the pursuit of accuracy as they have only because of the explicit recognition

that they would be computerized. In other than the simplest buildings

with the simplest HVAC systems, it is not feasible to employ such procedures manually. The speed of the computer allows greater accuracy

because all processes that contribute to energy consumption in a building

can be modeled in great detail, using as few simplifying assumptions as possible. In addition, repetitive calculations can be made at specific

intervals (usually on an hourly basis) to allow for the real-time variation of parameters such as weather, sun location and occupant activity,

and related equipment-use rates which affect energy consumption requirements. The feasibility of performing hourly calculations eliminates the

need for simplifying shortcuts, such as degree-day, or temperature bin

methods, which decrease the accuracy of energy analysis calculations.

Computerization also lends itself to the capability to store many different

simulation algorithms (particular calculation sequences) representing

D-2
models of the different construction designs and systems that can occur

in buildings, and to link alternative components in system models in

many ways. This allows the program to be very comprehensive, and flexible enough to simulate closely the actual energy performance of a diverse

range of building designs.

Programs developed for energy analyses tend to be structured alike,

and are usually divided into four main segments. The first part calculates, for each thermal zone in a building, the space loads (heating

and/or cooling) necessary to maintain specified interior conditions.

Input data required include details of the building design, weather conditions, and interior occupancy and equipment use schedules. The second

segment simulates the HVAC air-side system (or systems) which are con- trolled to satisfy the previously calculated space loads. Input to this

section of the program includes type of system, performance characteristics, and operation and control procedures. Many of the existing programs

contain generic simulations of all or most of the HVAC systems usually

encountered, so that the program user has only to specify which ones are

to be used in any particular analysis. Some programs are able to simulate

more than one HVAC system simultaneously, with different systems satisfying

the loads of different thermal zones in the building. The third program

segment simulates primary equipment such as chillers, boilers and on-site

power generation, and computes the purchased energy requirements necessary

for the primary equipment to satisfy the system energy requirements of the

HVAC zones in the building. Input requirements include specification of

performance characteristics and actual thermal configuration of the equipment. Like the HVAC systems segment, the equipment segment of some programs contains generic simulations of many types of equipment that are usually encountered, and the program user merely specifies the ones which

are to be used in any particular analysis. The minimum outputs from this

section are usually compilations of monthly and annual energy consumptions

for each type of energy to be purchased. In addition, energy consumption/

conversion by particular pieces of equipment, monthly and annual operating

hours and peak consumption rates can often be output at the discretion of

the user. The fourth general program segment consists of an economic

D-3
analysis of some appropriate type. Such analyses account for the owning

and operating cost of the building energy-related systems, and require

as input data the cost of the building equipment and purchased energy

and/or fuel.

The structure described above is not followed exactly by all programs

to be mentioned later, some of which do only part of the analysis sequence

To be considered comprehensive, however, the programs considered should

accomplish the majority of the analysis segments described above. For

the most part, the proprietary programs to be described are the most com- prehensive in aspects of the analysis sequence. They have been set up

that way in order to offer a complete analysis sequence in a convenient

manner to the potential user. The flexibility of the proprietary programs

is also in part due to the engineering services that are provided in

conjunction with the use of the program itself.

Both the public domain programs and the proprietary programs to

be described have the capability of being applied to either new designs

or to effects of retrofit actions for existing buildings. Some of the

programs are set up in such a manner that they can analyze several similar

alternative building/system configurations automatically during the course

of one analysis sequence. This allows direct comparison of energy consump

tion and/or economic consequences of the alternatives.

The computer programs in this survey have been selected on the basis

of their overall comprehensiveness and flexibility, as well as being

representative of the accepted state of the art for such analyses. They

are generally available in one of three ways.

(1) The program is not considered proprietary and the source code

may be purchased (in some cases for a nominal fee) for implementation on the purchaser's computer facilities.

(2) The program is proprietary in nature but can be utilized by

means of time-sharing facilities or by leased object language

codes

(3) The program is proprietary and can be utilized only by

submitting input data to the program developer who checks the

input data and actually makes the program runs.

D-4
Outright purchase of a source code is generally most desirable only

when significant in-house computer facilities exist. The purchase price

of the source code will generally be only a small fraction of the total

cost of implementing a program. In addition, the purchaser normally must

expend considerable effort in order to assure compatibility with his

computer system, to perform debugging and program checkout, and to

maintain the program. The problem is compounded by the lack of adequate

documentation for a number of the programs being offered. For all of

these reasons, acquisition and maintenance of a complex energy analysis

program are probably not feasible below the command level. Such a program (to be described subsequently) has been developed by the U.S.

Army Construction Engineering Research Laboratory (CERL) for the Air

Force.

The problem of initial implementation and day-to-day maintenance of

a program can be overcome by utilizing programs that are available on nationwide computer time-sharing networks and service bureaus. The disadvantage of utilizing these programs is that, since the program listings

are generally proprietary, the user is frequently unaware of the assumptions and limitations of the program. In addition, the user gives up

the flexibility to modify or improve the program which would be possible

if he owned the program. These considerations are probably less important

at the Base level than they are to the researcher or to active building

designers. Most important of all, effective use of a complex program in

a time-sharing mode requires that the user be thoroughly trained in both

HVAC design and engineering and ip correct use of the program itself.

This expertise takes some time to be acquired and may not be readily available at the base level.

The third category of program availability, that of submitting input

data to a developer for execution, is normally offered by engineering

firms, by manufacturers of equipment or architectural materials, and by

utilities. The manufacturers and utilities generally offer the service

to customers or potential customers at no (or nominal) charge, while the

engineering firms' charges vary and are in many instances given as "negotiable". In these cases, the distinction between available computer

D-5
programs and consulting services which include computer capabilities

becomes somewhat unclear. Generally, the user pays more for such a service than if an in-house staff were maintained for such services.

This situation can be advantageous, however, if the user requirements

for energy analysis are infrequent enough to justify the support of

such a staff.

Many of the programs that are subsequently described were at one

time available only for batch runs. In the case of proprietary programs,

the input data had to be submitted through the program owner who also

served as a technical consultant on the proper input of data to the

program. The cost of this service is reflected in the rates charged for

the use of the programs in this mode. More recently, there has been a gradual and increasing implementation of these programs on time-sharing

systems so they are directly available to the user. The benefits of this

development mean wider availability of the programs, faster turnaround

times, and generally lower costs, since the user requires no technical

consulting expertise of the program owner. Royalties for program use are included in the time-sharing fee structure. The primary disadvantage

of direct use of the program is the necessity for the user to become

familiar with all aspects of the use of the programs through training,

which is sometimes extensive.

2. PROGRAM SURVEY

Pursuant to the above discussion, a representative survey of existing

programs is presented. The programs are listed in alphabetical order,

and their inclusion or discussion does not imply any program endorsement

or lack thereof.

The format is consistent for each program and consists of a short

description, input requirements, outputs, source code language, systems

on which the software is implemented, maintenance of software, its

availability, and any additional comments which might be relevant.

D-6
ALTERNATE CHOICE COMPARISON FOR ENERGY

SYSTEMS SELECTION

(Code Name: AXCESS)

DESCRIPTION: AXCESS permits the simultaneous comparison of up to

six alternate methods for meeting the energy requirements of

a building. The program may be used at various points in the

design process. If the structure is still in the conceptual

state, the program utilizes routines which approximate the full

input information which would normally be available during the

later stages of design. The program calculates hourly zone solar and transmission loads for the year (if not input from

another program) . These loads are utilized along with base

energy loads to calculate net zone space conditioning requirements. Terminal system operation is the simulated and equipment

energy consumption calculated in one of three general subroutines.

INPUT REQUIREMENTS: Input requirements include weather data and control

information along with user- supplied information such as project

description, base load profiles, design heating and cooling load,

space type data, zone data, HVAC system description, and output

desired

PROGRAM OUTPUTS: Energy consumption and demand for each of up to 36

"meters" for each of the alternative systems. Numerous optional

outputs

PROGRAM LIMITATIONS: Up to 180 energy zones may be calculated per run. A maximum of six schemes or combinations of primary and secondary

systems are possible. Each scheme may have up to 12 different

types of fan systems and six primary systems.

MAINTAINED BY: S&H Information Systems, Inc., New York, New York,

a subsidiary of Syska & Hennessy and the Edison Electric Institute.

AVAILABILITY: AXCESS is available through five different means

(1) Through participating utilities

(2) Time sharing systems (National C.S.S., Inc.)

(3) Source deck may be purchased

(4) Object deck may be purchased

(5) As a service from a participating consulting firm.

For more information contact:

E.S. Douglass

Edison Electric Institute

90 Park Avenue

New York, New York 10017

D-7
ADDITIONAL COMMENTS: This program series offers a complete energy

analysis of a single or multi-building project, including load

determinations, air-side system simulations, plant equipment

simulations, and annualized owning and operating costs. The

series consists of a complex energy analysis program and an independent short financial analysis program. The period of

analysis is usually one year.

The thermal load calculations and complete energy analysis are accomplished each hour before proceeding to the next hour.

Therefore the program will not size the plant equipment and base

part-load efficiencies on that size. All calculations assume steady-state or equilibrium conditions. Thermal loads are scaled based on design loads and design weather conditions.

Building loads based on these calculations are suitable for

comparison of alternatives. Response factors may be input

(from another program) or default values for light, medium and

heavy construction may be utilized.

The air-side and plant systems simulation package is one of the

more complete of the program series surveyed. Addition or adaptation of equipment simulations is facilitated by the modular package

structure. Estimated equipment size is a required input for partload performance curves. If the demand exceeds capacity, the

design efficiency will be used. The air-handling and plant system

simulations available are:

a. Dual Duct

b. Multi-Zone

c. Single Zone Reheat

d. 100% Variable Volume

e. Variable Volume with Reheat

f. Ceiling Induction

g. Heating and Ventilating

h. 2-Pipe Induction

i. 4-Pipe Induction

j . 2-Pipe Fan Coil

k. 2-Pipe Unit Ventilator

l. 4-Pipe Fan Coil

m. 4-Pipe Unit Ventilator

n. Unitary Cooling Units with Separate Heating

o. Unitary Heat Pumps

p. Boilers

q. Furnace

r. Refrigeration

s. Simultaneous Heat Pumps

t . Changeover Heat Pumps

u. On-Site Generation-KW Balance

v. On-Site Generation-Thermal Balance

D-8
BUILDING LOAD ANALYSIS AND SYSTEMS

THERMODYNAMICS PROGRAM

(Code Name: BLAST)

DESCRIPTION: The Building Load Analysis and Systems Thermodynamics

Program was developed by the U.S. Army Construction Engineering

Research Laboratory for the Air Force (see Additional Comments).

The program contains three simulation segments (loads, air-side

systems, and building equipment), a well developed, almost con- versational, user-oriented input language and preprocessor for

inputting and checking data and setting default values, an output

report writer, and provisions for a library of data of building

materials and component properties, equipment characteristics,

various use schedules and system control procedures. The unique

program structure together with sophisticated programming techniques has resulted in a more efficient and faster running

program than others using comparable analysis methodology. The

library is easily expandable to include a vast amount of data,

thereby shortening considerably the amount of data required for

input by the user in most cases, while still allowing the user

input control if it is desired.

The loads portion is based on algorithms developed from NBSLD,

the NBS Loads Determination Program. The systems simulation is

in part based on algorithms derived from the NASA Energy and Cost

Analysis Program (NECAP) . The building equipment simulation segment is a newly developed software package which provides great

flexibility in simulating energy configurations of components.

INPUT REQUIREMENTS: Is highly user-oriented and variable in the

amount of detail that has to be provided. The user can input a minimum of information and use many built-in default values from

the program library, or alternatively provide complete information

as input.

PROGRAM OUTPUTS: Input data echo, diagnostic messages plus assigned

default values to override erroneous input data, system configurations description, equipment energy consumption analysis (monthly

and annual)

PROGRAMMING LANGUAGE: The program is written in CDC FORTRAN Extended,

Version 4.

SYSTEM IMPLEMENTATION: Can be used on CDC 6000/7000 series computers

without modification.

DOCUMENTATION: The documentation is expected to be very clear and

comprehensive. Volume I will provide detailed user instructions

and Volume II will contain detailed flowcharts and algorithmic

descriptions of the program. •

D-9
MAINTAINED BY: Dept, of the ArmyConstruction Engineering Research Laboratory (CERL)

AVAILABILITY: For more information contact:

F. Beason

Air Force Civil Engineering Center (AFCEC)

Tyndall Air Force Base, Florida 32403

ADDITIONAL COMMENTS: This development was conducted at the U.S. Army

Construction Engineering Research Laboratory (CERL) for the Air

Force Civil Engineering Center, Tyndall AFB , under Work Unit

201021003, Optimization of Energy Usage in Military Facilities.

D. Hittle is the principal investigator at CERL.

D-10
ENERGY CONSERVATION UTILIZING BETTER ENGINEERING

(Code Name: ECUBE)

DESCRIPTION: The ECUBE series of programs (except for ECUBE III)

utilizes design point calculations of peak thermal and electrical

loads to make hourly, monthly, and annual estimates of the energy

requirements of a building. The energy consumption of various

types of systems which may be used to meet these requirements

is then calculated and the program compares the total owning

and operating costs of the various systems being considered. The

program series consists of three basic computer programs:

(1) Energy Requirements Program, (2) Equipment Selection and

Energy Consumption Program, and (3) Economic Comparison Program.

INPUT REQUIREMENTS: Maximum value and hourly percentage profiles for

internal heat gain, electrical load and process load. Transmission

and outside air loads as a function of ambient temperature. Maximum

solar load on the building. Hourly weather data (available in

ready-to-use form for many cities). Heating value of fuel. Partload equipment performance characteristics. Capital cost differential for alternative systems, salvage values, maintenance costs.

PROGRAM OUTPUTS: Monthly, annual, and peak energy requirements.

Annual fuel requirements for alternative systems. Cash flow and

discounted rate of return on alternative investments.

COST: Charges based on number and size of runs made.

RATE AND STATUS: The present form of the program which became available

in 1975 is technically labeled as Version 2.3 and is marketed under

the name ECUBE 75.

MAINTAINED BY: The American Gas Association and Control Data Corporation.

AVAILABILITY: Program can be utilized via Control Data Corporation's

Cybernet time sharing network or via leasing agreement. For more

information contact:

Mr. K. T. Cuccinelli

Manager—Energy Systems

American Gas Associations

1515 Wilson Boulevard

Arlington, Virginia 22209

Ph. (703) 524-2000

D-ll
ADDITIONAL COMMENTS: This proprietary program is another which falls

in the category of offering a complete energy analysis of a single or multi-building project, from building loads to mechanical

systems energy requirement simulation, to utility costs based on those requirements, to economic comparisons between alternate

configurations. The period of performance analysis is usually

taken to be one year. Thermal load calculations are done on an hourly basis for this entire period. Transmission loads are obtained by scaling, according to weather conditions, from peakload values and their associated weather conditions, which must

be supplied to the program. Loads based on this type of calculation are suitable for determining comparative energy performance

of alternate systems. Since the program is available in the time

sharing or remote batch mode, user familiarily is necessary for

proper utilization. The American Gas Association sponsors

regularly scheduled workshops in training for new program users,

and publishes a newsletter for all program users. A new and

greatly revised version of the program, E-CUBE III is presently

under development and should be available shortly. It is expected

to have a more sophisticated and complete load calculation sequence,

extensive weather data files, and more comprehensive system and

equipment simulation.

D-12
MERIWETHER ENERGY SYSTEMS ANALYSIS SERIES

(Code Name: ESAS)

DESCRIPTION: The Energy Systems Analysis Series is a library of

Computer programs which determine the annual energy consumption

of various types of systems and equipment for a typical year of

operation, and determine the relationship between these energy

costs and other owning and operating costs. The programs nor- mally used in conducting an energy analysis consist of the Energy

Requirements Estimate (ERE) which calculates the hour-by-hour

thermal and electrical loads for a building, the Equipment Energy

Consumption (EEC) which simulates the operation of the various

pieces of equipment, and the Economic Comparison of Systems (ECS)

which calculates the total owning and operating costs of each

system. A variety of auxiliary programs are available to

complement the basic analysis series.

INPUT REQUIREMENTS: Engineering design data; description of system

design and operation, weather data, utility rate structure, owning

and operating cost and financial data.

PROGRAM OUTPUTS: Monthly and annual demand and consumption of energy

for systems and equipment; monthly and annual utility costs; life

cycle and cash flow analysis.

DOCUMENTATION: No algorithm ever published, since software is proprietary.

A user's manual, available only from the program owner, has instructions which are complete, however.

DEVELOPER: Ross F. Meriwether and Associates, Inc., San Antonio, Texas.

AVAILABILITY: The Energy Systems Analysis Series is available via

consulting agreements with R. F. Meriwether and Associates,

various time sharing systems, or through a special lease agreement.

For more information contact:

Ross F. Meriwether and Associates, Inc.

1600 N.E. Loop 410

San Antonio, Texas 78209

Ph. (512) 824-5302

D-13
ADDITIONAL COMMENTS: The program series is another of those proprietary

systems which offers a complete energy analysis of a single or multi-building project, from load determination to energy requirements simulations of building air-side systems and plant equipments,

to economic comparisons between alternative candidate configurations.

In this series mid-stream evaluation of results is possible. The

period of performance analysis is usually taken to be one year.

Thermal load calculations are done on a hourly basis for this period.

Transmission loads are linearly scaled from design values, at design

point weather conditions. Both loads and design values are supplied

to the program. Building loads based on this type of calculation are suitable for determining comparative energy performance of different

mechanical systems, (or the same system controlled in different ways),

for the same building.

All simulations of air-side systems and mechancial equipment

energy performance are of a steady-state, energy-balance nature.

The user needs a comprehensive knowledge of air-side systems, not

too easy to use otherwise. It is important that the user understand

the computer system simulation.

Equipment and air-handling systems configurations are available

because separate types of equipment have separate simulations,

which can be limited in many possible ways. The air-handling

system simulations available are:

a. No excess cooling or reheating, demand coil leaving temperatures.

b. Terminal reheat with scheduled (or fixed) cold coil discharge

temperature during cooling.

c. Terminal reheat with scheduled (or fixed) cold coil discharge

temperature during cooling or heating.

d. Introduction or fan-coil type system with scheduled primary air

temperature.

e. Terminal reheat with cold coil discharge temperature set by

maximum demand of any section.

f. Dual-duct or multi-zone with scheduled (or fixed) hot and cold

deck temperatures.

g. Dual-duct or multi-zone with deck temperatures set by greatest

demand

h. Variable volume system for solar and internal loads, with

separate single-duct system to offset transmission.

i. Standard variable volume system.

A wide range of mechnical and plant configurations can be simulated

by construction from the individual simulations. Although total

energy systems are not simulated as a single configuration, some types are constructable from the individual equipment simulations.

A simulation of a bulk hot water thermal storage system is available.

D-14
APEC HEATING-COOLING CALCULATION PROGRAM

VERSION III

(Code Name: HCC-III)

DESCRIPTION: The program calculates design heating and cooling load

utilizing ASHRAE methodology. The room is the basic level of

calculation for which the requisite design data is specified.

Heating load calculations consist of conventional transmission

loss analyses involving areas, U factors, and temperature differences. Infiltration is calculated on an input or master

factor basis. The maximum glass solar heat gain for the specified

winter month is calculated and its effect on the heat loss for

the room is determined along with lighting and occupant heat

gain. Cooling load calculations are made on an hourly basis over

a 24-hour period for the selected design day, and radiant load

components are time-averaged in accordance with the building mass. Glass loads are separated into transmission and solar components,

taking into account the glazing material and shading devices.

Hourly room loads and cfm values are accumulated and analyzed

psychometrically , and peak loads on equipment are determined.

INPUT REQUIREMENTS: Building description, weather data, solar radiation

data, zone/room designations, room description, and system

description.

PROGRAM OUTPUTS: Room loads and cfm values, zone loads and cfm values,

system analysis results, building peak refrigeration and heating

load. Optional output available for cooling load analysis for

12 hours of a design day.

PROGRAMMING LANGUAGE: FORTRAN IV

SYSTEM IMPLEMENTATION: IBM 1130 or 360, CED Cybernet System,

GE MARK III

MAINTAINED BY: Automated Procedures for Engineering Consultants (APEC),

Dayton, Ohio

AVAILABILITY: Program available under a fee for license arrangement.

For more information, contact:

APEC Executive Office

Grant-Deneau Tower, Suite M-15

Dayton, Ohio 45402

Ph. (513) 228-2602

D-15
ADDITIONAL COMMENTS: HCC-III calculates only peak heating and cooling

loads for a building for each thermal zone; it does not have a subsequent systems analysis capability. APEC is presently in the

process of developing a more comprehensive energy analysis program

based on the NECAP program (see subsequent entry in this survey)

APEC membership consists primarily of engineering firms who use

the APEC programs as design tools in building design projects.

The APEC programs are available, then, along with the services of

such firms who as APEC members are knowledgeable in their use.

D-16
McDonnell douglas automation company's annual

CONSUMPTION OF ENERGY PROGRAM

(Code Name: MACE)

DESCRIPTION: MACE uses methods recommended by ASHRAE wherever possible.

The load calculation section utilizes methods outlined in

Proposed Procedures for Determining Heating and Cooling Loads for

Energy Calculations , ASHRAE 1969. These methods include the use

of thermal response factors for calculation of the transient heat

transfer through roofs and walls. The component and system

simulation section uses procedures outlined in Proposed Procedures

for Simulating the Performance of Components and Systems for

Energy Calculations , ASHRAE, 1969. The economic section uses

the local prevailing utility rates, which are input into the

program by the user. The U.S. Weather Bureau is the source of the

following hourly weather variables: dry and wet-bulb temperature,

wind velocity and direction, cloud cover, cloud type, and barometric

pressure. MACE will accept other sources of weather data, once they have been prepared in the proper format.

INPUT REQUIREMENTS: Weather specification, building and system descriptions, months for which calculations are to be made, energy

rate structures, master time schedules and appropriate loads

(such as occupants, lights, appliances, etc.).

PROGRAM OUTPUT: Hourly space and building loads, electrical usage,

fuel consumption, and cost of each on hourly basis and monthly

and yearly totals of each.

PROGRAMMING LANGUAGE: FORTRAN IV for IBM system/360 Computer

MAINTAINED BY: McDonnell Douglas Automation Company

AVAILABILITY : Program is available on McDonnell Douglas Time Sharing

System. For more information contact.

Mr. Charles E. Whitman

Engineering Services

McDonnell Douglas Automation Company

Box 516

St. Louis, Missouri 63166

D-17
MEDSI ANNUAL ENERGY CONSUMPTION

DESCRIPTION: Four programs, model reheat, heat-cool-off, multizone,

or double duct, and variable volume systems. Weather files are derived from Air Force Manual 88-8 and U.S. Weather Bureau Climates

of States. Calculations are performed for each weather occurrence

listed in AFM 88-8 with probabilities of occupancy and solar gain

superimposed. Unique features of each system are modeled, and

system behavior is a fundamental part of each program. A program

checks input data and prints it for documentation. An auxiliary

program gives input energy requirements in KWH and 10^ Btu fuel

input, considering equipment efficiencies and part-load profiles

for- inputs of fuel and electricity to heating and cooling equipment

and auxiliaries. Additional programs sum up to four system program

runs, model internal source heat pumps, total energy plants,

and heat recovery devices.

INPUT REQUIREMENTS: Building design loads, occupancy schedule,

temperatures, humidities, enthalpies, air quantities, building

gains and losses, internal gains, fan heat.

PROGRAM OUTPUT: Cooling requirements in ton-hours and heating requirements in 10-* Btu for night, day, and evening periods of each

month, plus subtotals and totals. Separate tabulations of monthly

use of energy for illumination, fans, and pumps, heating/refrigeration system auxiliaries, domestic hot water system can be output.

MAINTAINED BY: Mechanical Engineering Data Services, Inc. (MEDSI)

AVAILABILITY: Program written in FORTRAN and currently available

for time-sharing and batch customers of United Computing Systems.

For more information contact:

Mechanical Engineering Data Services, Inc.

30 Kimler Drive

Maryland Heights, Missouri 63043

Ph. (314) 434-2340

or

United Computing Systems, Inc.

2525 Washington Street

Kansas City, Missouri 64108

Ph. (816) 221-9700

ADDITIONAL COMMENTS: This is a series of programs that can find use

in certain comparative design and retrofit applications. Training

in its proper use by the program owner is required. It is somewhat

less expensive to use than the more comprehensive programs.

D-18
NATIONAL BUREAU OF STANDARDS LOAD

DETERMINATION PROGRAM

(Code Name: NBSLD)

DESCRIPTION: NBSLD calculates the hour-by-hour heating and/or cooling

load in buildings. The program utilizes the thermal response

factor technique for calculating transient heat conduction through

walls and roofs. The program also includes a routine which can calculate the "floating" temperature of those rooms with limited

heating or air-conditioning and natural ventilation, based on the

actual net heat loss or gain to the room.

INPUT REQUIREMENTS: Building parameters such as wall properties,

ceiling and floor properties, window area and location, operating

schedules. Weather data from U.S. Weather Bureau tapes.

PROGRAM OUTPUTS: Hour-by-hour heating or cooling loads and temperatures

for each zone for the entire year. Design-day data may be examined

as an option.

PROGRAMMING LANGUAGE: FORTRAN V

DEVELOPER: T. Kusuda - National Bureau of Standards

DOCUMENTATION: NBSLD, the Computer Program for Heating and Cooling Loads

in Buildings, NBS Building Science Series 69, (1976), and ASHRAE

bulletin entitled. Algorithms for Building Heat Transfer Subroutines,

1975.

AVAILABILITY: Source code and documentation may be obtained for a very nominal fee. For more information contact:

James P. Barnett

Thermal Engineering Section

Center for Building Technology, IAT

National Bureau of Standards

Washington, D.C. 20234

ADDITIONAL COMMENTS: NBSLD, while only a loads program, is generally

recognized as the most comprehensive and accurate program for

that purpose that exists today. It has been linked with the

Meriwether ESAS programs, and with NECAP to produce two hybrids

with complete analysis capability.

D-19
NASA’s ENERGY COST ANALYSIS PROGRAM

(Code Name: NECAP)

DESCRIPTION: The NECAP program follows the procedures outlined in the

ASHRAE booklet "Procedures for Determining Heating and Cooling

Loads for Energy Calculation" to estimate the energy requirements

for buildings. The program is actually a set of six individual

computer programs including (1) a Response Factor program, (2) a Data Verification program, (3) a Thermal Loads Analysis Program,

(4) a Variable Temperature program (5) a System and Equipment

Simulation program, and (6) an Owning and Operating Cost program.

Standard wall construction and schedules can be used to simplify

program input. The program is an extension of the Energy Utilization

Program developed for the U.S. Postal Service, but incorporates

extensive modification to improve its usability including com- pletely revised documentation.

INPUT REQUIREMENTS: Building parameters, building coordinate system,

azimuth angle, surface description and tilt angle, floor, ceiling,

furnishing data, space description, thermostat schedules, type

of energy distribution system and pertinent parameters, cost

information.

PROGRAM OUTPUTS: Response factors if requested, summary of design day

weather, space and building loads, surface shadow pictures and

shadow calculations, recommended space heat extraction and addition

rates, variable temperature loads if requested, zone air flows,

summary of loads not met, equipment capacity summary, monthly

and annual energy summary.

PROGRAMMING LANGUAGE: FORTRAN IV

SYSTEM IMPLEMENTATION: CDC 6400, 6600

AVAILABILITY : Program is available through

COSMIC

Suite 112

Barrow Hall

University of Georgia

Athens, Georgia 30602

Ph. (404) 542-3265

Attn. Ron English

D-20
For more information contact:

R. N. Jensen

Technical Assistant

Construction Engineering Branch

Mail Stop 227

Langley Research Center

Hampton, Virginia 23665

ADDITIONAL COMMENTS: NECAP, an extension of the early-developed Postal

Service energy analysis program, is in turn the basis for a number

of subsequent developments, because it is the most comprehensive

program in the public domain. One of the subsequent developments

is the CEKL program, which is presently being developed for the

U.S. Air Force and is described in a subsequent entry in this

Survey. Another is the proposed development of an extremely com- prehensive and accurate public domain program for use by the

States and by ERDA for use in creating and implementing energy

conservation standards for buildings.

D-21
GARD PROGRAM FOR FACILITY/HVAC

DESIGN AND ENERGY ANALYSIS

(Code Name: SCOUT)

DESCRIPTION: The SCOUT program follows procedures outlined in the

ASHRAE booklets "Procedures for Determining Heating and Cooling

Loads for Energy Calculations" and "Procedures for Simulating the

Performance of Components and Systems for Energy Calculations"

to estimate the energy requirements for buildings. SCOUT is an extension of NASA's Energy/Cost Analysis Program (NECAP)

but incorporates complete data verification, a full set of selfinstructional input forms, 13 distribution system simulations,

plus packaged systems and heat recovery devices, and complete

internal restructuring resulting in reduced core requirements

and reduced running times.

INPUT REQUREMENTS : Building construction and orientation parameters,

exterior surface description and orientation data, interior floor,

ceiling, wall and furnishing data, optional shadow data (requiring

building coordinate system), space description data, thermostat

schedules, space heat addition and extraction rates, optional user- specified air flows, type of energy distribution and conversion

systems, and pertinent cost information.

PROGRAM OUTPUTS: Space and building peak loads broken out into com- ponents, optional surface and space response factors, optional

design-day weather summary, optional shadow pictures and calculations, recommended space air flows and heat extraction and

addition rates, equipment capacity summary, summary of space and

system loads not met, monthly and annual energy summary by system

and building, minimum and maximum space temperatures, and payback

period comparison of alternatives.

PROGRAMMING LANGUAGE: FORTRAN IV

SYSTEM IMPLEMENTATION: CDC 6400 and 6600, IBM 360 and 370, Univac 1108

and Univac Spectra 70/46

AVAILABILITY: Services involving the use of SCOUT are available from

GARD , Inc

GARD, Inc.

7449 N. Natchez Avenue

Niles, Illinois 60648

Ph. (312) 647-9000

Attn. SCOUT Support Team

SCOUT will be available on nationwide computer networks in 1976.

D-22
TRANE AIR CONDITIONING ECONOMICS

(Code Name: TRACE)

DESCRIPTION: The program calculates peak and hourly zone loads based

on coincident hourly climatic data for temperature, solar radiation,

wind and humidity of typical days in the year representing seasonal

variations. The average days are compiled based on the most recent

ten years of U.S. Weather Bureau data. The design phase then

receives input from the load phase as well as system type information

and zone design information, and calculates supply air quantities

and temperatures. The system simulation phase utilizes hourly

zone loads and calculates return air quantities and temperatures

and accounts for system loads (such as reheat loads) . The

equipment simulation phase takes the hourly output from the

system simulation phase and calculates the annual energy con- sumption based on part-load performance data which is available

on tape. The economic phase then does an economic comparison of

the various design alternatives based on input consisting of

energy consumption data, utility rate structures, and expected

installation and maintenance costs.

INPUT REQUIREMENTS: Building, system, and equipment descriptions.

Economic factors.

PROGRAM OUTPUTS: Peak building loads, building and equipment yearly

and monthly energy consumption, economic comparison of lifecycle cost for up to four alternatives in one computer run.

MAINTAINED BY: Applications Engineering, The Trane Company, LaCrosse,

Wisconsin.

AVAILABILITY: Program source code is proprietary but the program may

be utilized through local Trane representatives or through timesharing

systems. For more information, contact the local Trane representative

or

Applications Engineering

The Trane Company

3600 Pammel Creek Road

LaCrosse, Wisconsin 45601

D-23
ADDITIONAL COMMENTS: Load calculation procedures follow ASHRAE

recommended procedures (1967) . Although weather data is input

for the whole year (8760 hours) , the program calculates from

this data twelve "typical weather days" (each with values for

24 hours) , one for each calendar month. All subsequent monthly

energy requirements are based on use of the same "typical weather

day" profile for a whole month.

All simulations of air-side systems and mechanical equipment

performance are of an equilibrium nature. Part load performance

curves for equipment (mostly TRANE equipment) can be either input

by the user, or by user option, some are available on computer

files. A wide range of total system configurations can be simulated

by utilizing appropriate individual simulations. Separate scheduling of different types of base and auxiliary loads allows for

close reproduction of actual situations. Total energy plant

configurations and thermal storage devices are not simulated,

but are presently being developed.

D-24
APPENDIX E. BIBLIOGRAPHY OF ENERGY CONSERVATION DOCUMENTS

1. Acoustical and Thermal Performance of Exterior Residential Walls,

Doors and Windows, Flynn, D.R. , Quindry, T.L., Savine, H.J. and

Lacher , M.B., NBS Building Science Series 77, 11-75, Superintendent

of Documents, SD Catalog No. C13. 29/2:77 pages 170, $2.35, 1975.

2. Action Plan for Energy Conservation and Efficiency in Large Buildings,

Appliances and Transportation, Interdepartmental Fuel and Energy

Committee of the State of New York, August 9, 1972. (See #5.)

3. Action Plan for Power Conservation in Federal Facilities, General

Services Administration Pamphlet, Summer 1971, Attachment to letter

Action Plan for Power Conservation in Federal Facilities, Associate

Director, Directorate of Civil Engineering, HQ USAF, Department of

the Air Force, August 6, 1971.

4. Actions to Decrease Energy Consumption, Attachment to letter,

Energy Conservation, of Director of Civil Engineering, HQ USAF,

Department of the Air Force, August 17, 1973.

5. Ad Hoc Committee on Energy Efficiency in Large Buildings, New York

State Office of General Services, Interdepartmental Fuel and

Energy Committee of the State of New York, March 7, 1973.

6. Air Conditioning and Refrigeration Log Program, The Hartford Steam

Boiler Inspection and Insurance Co., Hartford, Connecticut.

7. Air Conditioning Manual, The Trane Company, 1968.

*8. Air Force Design Manual , Criteria and Standards for Air Force

Construction, AFM 88-15, Department of the Air Force, January, 1975.

9.

Air Force/Energy Problem, Supplement to the Air Force Policy

Letter for Commanders, Yarymovych, Michael I., June 1974, pp. 2-16.

10. Air Force Energy/Engineering Programs, Supplement to the Air Force

Policy Letter for Commanders, Crockett, Rufus L. , AFRP 190-2,

No. 8-1974, August 1974, pp. 5-14.

11. Alternate Choice Comparisons for Energy System Selection (AXCESS)

Edison Electric Institute, 90 Park Ave., New York, N.Y. 10016.

NOTE: The symbol denotes publications that are recommended as supplemental on-the-shelf references at the Base level.

E-l
12. America's Energy Crisis, Newsweek, January 22, 1973.

13. APEC Reports Progress on Duct Design Program, Heating, Piping, Air

Conditioning magazine, November 1968.

14. Application of Climatic Data to House Design, U.S. Housing and Home

Finance Agency, Washington, D.C. 195^, Housing Research paper 225.

15. Application of Computers to Air Conditioning Ducts Systems, Heating,

Piping, Air Conditioning magazine, February 1969.

16. Applying Static Pressure Control in Building Areas and Duct Systems,

Busch, C.J., Air Conditioning, Heating, and Ventilating magazine,

April 1964.

17. Architecture and Energy, Stein, Richard G. , FAIA, New York Chapter,

American Institute of Architects, Committee on the Natural Environment.

18. ASHRAE Enters Energy Conservation Crisis —with Proposed Standard 90P

Design and Evaluation Criteria for Energy Conservation in New Buildings,

Tumilty, Jack E. , ASHRAE Journal, July 1974, I-XII.

*19. ASHRAE Guide and Data Books:

Applications

1974

Equipment , 1972

Fundamentals , 1972 , Systems , 1973

20. An Assessment of Energy and Materials Utilization in the U.S. A.,

Makhijani, Lichtenberg. Paper presented at the Department of

EECS, University of California/Berkeley, seminar on the ecology of

power production.

21. An Assessment of Solar Energy as a National Energy Resource,

NSF/NASA Energy Panel, December 1972.

22. Audubon Society Studying Energy Needs, Thomas J. Scott, Boston

Globe, July 19, 1973.

23. Bicycle vs. Energy Crisis, U.S. Environmental Protection Agency,

Washington, GPO, 1974.

24. Boiler Care Handbook, Cleaver-Brooks Company, P.0. Box 421,

Milwaukee, Wisconsin 53201, 1964.

25. Boiler Log Program, The Hartford Steam Boiler Inspection and

Insurance Co., Hartford, Connecticut.

26. Brownouts and Building Operation, Syska & Hennessey, Inc.

Technical Letter, Vol. 21, No. 1, May 1971.

E-2
27. Building Energy Authority and Regulations Survey, Eisenhard, R.M.

State Activity, NBSIR 75-747, 6-75, National Technical Information

Service, COM 75-11131, pages 25, $3.25.

28. Buildings that Conserve Energy—I, Grumman, David L. , Building

Systems Design, February/March 1974.

29. The Case for Solar Energy, Glazer, Peter E. , Ph.D. , Arthur D. Little,

Inc., Cambridge, Mass. 02140. Presented at Conference on Energy

and Humanity, Queen Mary College, London, September 3, 1972.

30. Changing Electrical Energy Priorities, National Electrical

Contractors Association, Washington, D.C. 20014, December 1973.

31. A Check-Off List on Energy Conservation with Regard to Power

and Illumination, Dubin, Fred. S. , P.E., Electrical Consultant

magazine, Vol. 89, No. 4, p. 20, May 1973.

32. Citizen Action Guide to Energy Conservation, Citizen's Advisory

Committee on Environmental Quality, Washington, D.C., September

1973.

33. Clean Power from Dirty Fuels, Squires, Arthur M. , Scientific American,

Vol. 227, No. 4, October 1972.

34. Coal Gasification: State of the Art, Huebler , Jack; Heating, Piping,

Air Conditioning, January 1973.

35. Coal is Cheap, Stein, Jane, Smithsonian, Vol. 3, No. 11, February 1973.

36. Coal Making Comeback in Response to Fuel Shortage, Hornig, Roberta

(Washington Star News), Boston Globe, August 25, 1973.

37. Code for Steam Metering, International District Heating Association,

Pittsburgh, Pa. 15206. (in draft 1976 - $10 to members)

38. Comparative Ultimate Cost of Building Walls, Brick Institute of

America, 1750 Old Meadow Road, McLean, Virginia 22101, 1972.

39. Comparison Between Measured and Computer-Predicted Hourly Heating

and Cooling Energy Requirements for an Instrumented Wood-Framed

Townhouse, Burch, D.M. , Peavy, B.A. , and F. J. , Powell, ASHRAE

Transactions, Volume 81, Part 2, 1975.

40. Comparison of Measured and Computer-Predicted Thermal Performance

of a Four-Bedroom Wood-Frame Townhouse, Peavy, B.A. , Burch, D.M.

Hunt, C.M. , and F. J. Powell, Building Science Series 57, 4-75,

Superintendent of Documents, SD Catalog No. C13. 29/2:57, pages 62,

$ 1 . 20 .

41. A Comprehensive Summary, Gas Supply and the National Energy

Situation, American Gas Association, Arlington, Va. 22209, 1972.

E-3
42 . Conservation and Better Utilization of Electric Power by Means of

Thermal Energy Storage and Solar Heating; Phase III Progress Report,

NSF/Rann/SE/G127976/Pr73/1, March 1973.

43. Conservation and Efficient Use of Energy, Parts 1, 2, 3, and 4,

Hearings before the Committees on Government Operations and Science

and Astronautics, House of Representatives, 93d Congress, 1st Session

Washington, GPO, 1974.

44. Conservation of Utilities, General Services Administration/Public

Building Service, Washington, D.C. 20405.

45. Conservation Via Effective Use of Energy at the Point of Consumption,

Berg, Dr. Charles A., IAT/NBS , NBSIR 73-202, April 1973.

46. Conserve Energy and Save Money, Changing Times, Vol. 27, August 1973,

pp. 45-46.

47. Conserve Energy by Design, The Trane Company, 1974.

48. Conserving Energy in Existing Buildings, Wetherington, T.I., Jr.,

Building Systems Design, June/July 1974.

49. A Consultant Looks at Heat Recovery Systems, Olivieri, Joe B.

Air Conditioning, Heating & Refrigeration News, P.0. Box 6000,

Birmingham, Michigan 48012.

50. Coping with the Energy Shortage, The Research Institute of America,

New York, New York, August 1973.

51. Crisis Helps Oil Companies, Sloan, Allan, Boston Globe, July 16, 1973

52. The Crunch—An Energy Management Idea Kit for Building Owners,

Managers and Engineers, Honeywell Inc., Minneapolis, Minnesota.

53. Definition and Goals, Federal Power Commission, The National Power

Survey.

54. Demand Controllers Disconnect Some Loads During Peak Periods,

Murphy, E.E. and Dorsett, J.G., Transmission and Distribution,

July 1971.

55. A Description of the Energy Conversion System, Dr. Boer, K.W.

University of Delaware Solar House, July 20, 1973.

56. Design Concepts for Optimum Energy Use in HVAC Systems, Electric

Energy Association, 90 Park Avenue, New York, New York, 10016.

57. Determination of the Comfort Zone, Houghten, F.C. and Yaglou, C.P.,

ASHRAE Transactions, Vol. 29, p. 361, 1973

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58. A Diet for Energy-Fat Buildings, Casberg, T.R. , Defense Management

Journal, Vol. 10, pp. 33-38, July 1974.

59. Don't be Fuelish, Federal Energy Administration, Office of Energy

Conservation and Environment, Washington, D.C.

60. Durability of Insulating Glass, H.E. Robinson, Building Science

Series 20, Superintendent of Documents, SD Catalog, No. C13. 29/2:20,

cost is $ .75.

61. Dynamic Thermal Performance of an Experimental Masonry Building, Peavy,

B.A., Powell, F. J., and Burch, D.M., Building Science Series 45, 7-73,

Superintendent of Documents, SD Catalog No. C13. 29/2:45, pages 103,

cost is $1.25.

62. ECUBE Program Series, Control Data Cybernet Centers, (Contact:

James Ousley, ECUBE National Marketing Manager, Omaha, Nebraska.

Available to architects and engineers.)

2 63. e=mc , General Services Administration/Public Buildings Service.

Round Table on Energy Conservation (May 1972). Report issued

July 1972; PBS/GSA, Washington, D.C. 20405.

64. Economic Evaluation of Large-Scale Residential Energy Systems,

Decision Sciences Corporation, Summary of Current Activities.

Report done in conjunction with Meridian Engineering Inc. for

the Office of Research and Technology, DHUD.

65. Economic Objectives of Utility Companies and Developers, Bartter, B.J.,

Evaluating a MIUS, NBSIR 75-721, 11-75, National Technical Information

Service, PB 246864, pages 40, $4.00.

66. The Economy of Energy Conservation in Educational Facilities,

Educational Facilities Laboratories (EFL) Report, July 1973.

67. Effect of Energy Conservation on Architecture, Codella, Frank L.

Paper presented at the Workshop on Total Energy Conservation in

Public Buildings, Albany, New York, January 12, 1972.

68. Effects of Energy Problem on DOD, Sonenhein, N. , Commanders

Digest, November 22, 1973, pp . 2-12.

69. Effect of Envelope Design on Cost Performance of Office Buildings,

Anson, Kennedy, Spencer, CSIRO, Melbourne, Australia, NBS Special

Publication No. 361, Vol. 1, pp. 395-406, Superintendent of

Documents, SD C13. 10:361, Vol. 1, price $6.50, February 1972.

70. Effect of Geographic Location, Residential Energy Consumption,

Report No. HUD-HAI-6, August 1973

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71 . The Effect of Moisture on the Heat Transfer Performance of

Insulated Flat-Roof Constructions, NBS Building Science Series 37,

October 1971.

72. Effective Energy Utilization in Buildings, Achenbach, P.R.

Third Urban Technology Conference, Boston, Mass., 9-73, U.S.

Department of Commerce (85.1), pages 20.

73. Efficiency: Lightings Response to Energy Demands, Electrical

Contractor, May 1974.

74. Efficiency of Energy Use in the United States, Hirst, Eric, Moyers,

John D. , Science , Volume 179, pp. 1299-1304, March 30, 1973.

75. Efficient Management and Conservation of Defense Energy, Commanders

Digest, pp. 2-5, 8-11, October 24, 1974.

76. Electrical Energy and Its Environmental Impact—Progress Report of

December 31, 1972, Oak Ridge National Laboratory Energy Team.

ORNL-NSF Environmental Program.

77. Electricity: A Year of Change and Crisis, Factory , May 1974.

78. 11 Ways to Reduce Energy Consumption and Increase Comfort in

Household Cooling, Knauer, V. and Branscomb, L.M. , Consumer

Bulletin, 7-71, Superintendent of Documents, SD Catalog No.

C13.2:EN2, pages 20, cost is $.40.

79. Energy, Science , April 19, 1974.

80. Energy and Architecture, Stein, Richard G. , FAIA, The Architectural

Forum, Vol. 139, No. 1, July/August 1973, pp. 38-58.

81. Energy and Environment, Schenectady Gazette, June 1-6, 1972.

82. Energy--and How to Boost Efficiency in Electrical Systems and

Loads, Electrical Construction and Maintenance, June 1974.

83. Energy and Power Issue, many contributors. Scientific American , September 1971, Vol. 224, No. 3.

84. Energy and The Built Environment, The American Institute of

Architects, Washington, D.C.

85. Energy Conservation Activities of G.S.A. , PCDR/Office of Construction

Management, GSA.

86. Energy Conservation at the NBS Laboratories, Hoffman, J.D., NBSIR

74-539, 7-74, National Technical Information Service, COM 74-11574,

pages 81, $5.00.

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87. Energy Conservation Checklist, The Hartford Steam Boiler Inspection

and Insurance Co., Hartford, Connecticut.

88. Energy Conservation Design Guidelines for New Office Buildings,

AIA Research Corporation, General Services Administration/Public

Buildings Service, Washington, D.C. 20405. July 1975.

89. Energy Conservation Guidelines for Existing Office Buildings,

AIA Research Corporation, General Services Administration/Public

Buildings Service, February 1975.

90. Energy Conservation in Buildings: Its Foundation, Cost, and

Acceptance, Achenbach, P.R. , Minneapolis, Minn., May 1973,

Proceedings of Conference on Energy Conservation Implications

for Building Design & Operation, 5-73, U.S. Department of Commerce

(88. 1) , pages 40.

91. Energy Conservation in Commercial Buildings, Stubblefield, Richard R.

Heating, Piping. Air Conditioning, June 1974.

92. Energy Conservation in Housing, Tremble, Martin, Publisher, Cahners

Publishing Company, INBEX Exhibit, November 1973.

*93. Energy Conservation in New Building Design, ASHRAE Standard 90-75,

The American Society of Heating, Refrigerating, and Air Conditioning

Engineers, Inc., 1975.

94. Energy Conservation in USAF Medical Facilities, Letter of Director

of Professional Services, Office of the Surgeon General, Department

of the Air Force, November 27, 1973.

95. Energy Conservation Manual, Part I: Residential Buildings; Part 2:

Apartments and Non-residential Buildings, State Building Commission,

Austin, Texas, 1976.

96. Energy Conservation Measures in the National Bureau of Standards

Laboratory Complex, Achenbach, P.R. , Didion, D.A. , NBS Proceedings

of the Joint Conference of the Institution of Heating and Ventilating

Engineers, Illuminating Engineering Society, and Institute of Fuel

(Dept, of Energy), November 13-14, 1975, London, pages 51-68.

97. Energy Conservation Needs New Architecture and Engineering, Dub in,

Fred S. , Public Power, March-April 1972.

98. Energy Conservation Opportunities in Building Design, Villecco,

Marguerite, Editor. A Report to the Ford Foundation Energy Policy

Project, (Washington, D.C., AIA Research Corporation, October 1973).

E-7
99.

Energy Conservation, Parts I and II, Hearing before the Committee

on Interior and Insular Affairs, U.S. Senate, 93d Congress, 1st

Session, Washington, GPO, 1973.

100. Energy Conservation Performance Vector Report, Fourth Quarter

FY 1974, Letter of Deputy Director of Maintenance, Engineering

and Supply, HQ USAF, Department of the Air Force, August 21, 1974.

101. Energy Conservation Potential of Modular Gas-Fired Boiler Systems,

Kelly, G.E. and Didion, D.A. , NBS Building Science Series 79, 12-75,

Superintendent of Documents, SD Catalog No. C13. 29:2/79, pages 54,

$1.15.

*102. Energy Conservation Program Guide for Industry and Commerce, EPIC

Handbook 115, Gatts, Robert R. , Massey, Robert G. , and Robertson,

John C. , U.S. Department of Commerce/National Bureau of Standards

in Cooperation with Federal Energy Administration, 1974, Superintendent of Documents, GPO, Washington, D.C. 20402.

103. Energy Conservation-Program Guide for Industry and Commerce, Massey,

R. G. , EPIC Handbook 115-Supplement 1.

104. Energy Conservation Research Needs, Darmstadter, Joel and Hirst,

Eric. Combined paper by Resources for the Future, Inc. , Washington,

D.C. 20036, and Oak Ridge National Laboratory.

105. Energy Conservation Skills, Rocks, Lawrence, and Runyon, Richard,

Hicksville, New York, Research Media, Inc., 1974.

106. Energy Conservation Strategies, May 1973 , Seidel, Marquis R.

Platkin, Steven M. and Beck, Robert 0. Implementation Research

Division, Office of Research and Monitoring, U.S. Environmental

Protection Agency (EPA-R5-73-021)

107. Energy Conservation Techniques, Attachment to letter. Reduction

of Energy Consumption in Military Facilities, of Deputy Director

of Civil Engineering, HQ USAF, Department of the Air Force,

January 18, 1974.

108. Energy Conservation through Building Design and a Wiser Use of

Electricity, Dub in, Fred S. , Paper presented at the Annual

Conference of the American Public Power Association, San Francisco,

California, June 26, 1972.

109. Energy Conservation through Building Design in Perspective, Dubin,

Fred S., (Dubin, Mindell & Bloom, New York, N„Y. 10018, presented

at the Energy Conservation Conference, University of Minnesota,

May 23, 1973.

E-8
110 . Energy Conservation through Design, Professional Engineer , pp. 21-24,

October 1973.

111. Energy Conservation through Effective Energy Utilization,

Proceeding of Conference, Henniker , N.H. 1973., NBS Special

publication 403, SD #C13. 10:403 - GPO, Washington, D.C. 20402,

$3.30 (1976).

112. Energy Conservation through Effective Utilization, Berg, C.A.,

Science , Vol. 181, 7-73.

113. Energy Conservation with Solar Climate Control, Arthur D. Little,

Inc., March 1, 1973; a technical memorandum.

114. Energy Consumption Analysis of Buildings in the New York Area,

Flack, Peter and Kurtz, N.D. , Consulting Engineers, 29 W 38 St.,

New York, N.Y. 10018. Prepared for Con Edison, April 1973.

115. Energy Consumption in Commercial Buildings in Philadelphia,

Enviro-Management & Research, Inc. of Washington, D.C.

116. The Energy Crisis, Rocks, Lawrence, and Runyon, Richard, Crown

Publishers, New York, N.Y. 1972.

117. Energy Crisis, Are We Running Out? Time, June 12, 1972.

118. Energy Efficiency in Room Air Conditioners, NBS Publication

LC 1053, Department of Commerce, National Bureau of Standards,

Washington, D.C. 20234. 1974.

119. Energy Facts, Hearings before the Committee on Science and

Astronautics, House of Representatives, 93d Congress, 1st

Session, November 1973, Committee Print, Washington, D.C. GPO. 1974.

120. Energy for Architects, Architecture Plus , Vol. 1, No. 6 pp . 38-49,

July 1973.

121. Energy: How Critical is the Crisis, Consulting Engineer , March,

1973.

122. Energy Impact Index, Kurtz, N.D. and Flack, Peter. Consulting

Engineers, 29 W 38 St., New York, N.Y. 10018.

123. Energy Labeling of Household Appliances, NBS LC 1054, U.S. Department of Commerce, National Bureau of Standards, Washington, D.C.

20234. 1975.

124. Energy Options for the Future, Gould, William R. , quoted in Vital

Speeches of the Day, Vol. 39, pp. 605-607, July 15, 1973.

E-9
125. Energy Policy, Nixon, Richard M. , President, President's Message

to the Congress, April 18, 1973.

126. The Energy Policy Report, The Energy Policy Project, The Ford Foundation, New York, N.Y. 10017 or Ballinger Publications, Cambridge,

Mass. 02138, November 1972.

127. The Energy Question, Erickson, Edward W. and Waverman, Leonard, Editors,

Vol. 2, Toronto, University of Toronto Press, 1974.

128. Energy-Related R&D in the Air Force, Supplement to Air Force Policy

Letter for Commanders, pp. 22-25, October 1974.

129. Energy Research and Development—Problems and Prospects. Hearings

before Committee on Interior and Insular Affairs, U.S. Senate,

93d Congress, 1st Session 5. Res. 45, Washington, D.C. GPO 1973.

130. Energy Savers—Proven Ways to Save Fuel in Your Heating System

without Sacrificing Comfort, Hydronics Division of Burnham Corporation, Lancaster, Pennsylvania.

131. Energy Saving Ideas for Existing Buildings, Tsung, Clarence P.

Electrical Construction and Maintenance, pp. 75-77, June 1974.

132. Energy-Saving Lighting, Modern Plant Operation and Maintenance , Spring 1974.

133. Energy Savings in Residential Buildings, Nelson and Tobias, ASHRAE

Journal, February 1974.

134. Environmental Demonstration Project, FOB Saginaw, PCDR/Office of

Construction Management, GSA. Washington, D.C. 20405

135. Evaluation of Building Characteristics Relative to Energy Consumption

in Office Buildings, Federal Energy Administration, Washington, D.C.

20461.

136. Experimental Energy Office Building at Manchester, N.H. , Powell, F.J.,

Proceedings of Energy Conservation Seminar, Orlando, Florida,

March 1974, U.S. Department of Commerce (94.1).

*137. Family Housing Energy Conservation Handbook, U.S. Department of the

Navy, Naval Facilities Engineering Command, March 1974.

138. Subpanel Report on Total Energy Systems, Urban Systems, and

Residential Consumption, Federal Council on Science and Technology,

(FCST) Committee on R&D Goals in Energy Conservation, Department of

HUD, pp. 352, NTIS #PB 221-374, October 1972, cost $10.50.

E-10
139. Finding a New Approach to Energetics—Fast, Seaborg, Glenn, SR/World,

December 14, 1974.

140. Findings and Recommendations of the Task Force on Combustion Controls

and Instrumentation, New York Office of General Services, Design and

Construction Group. Division of Rehabilitation Planning.

141. The First Symposium on the Use of Computers for Environmental

Engineering Related to Buildings, NBS Building Science Series 39,

October 1971, pp. 826, SD Catalog // C13. 29/2:39, cost $7.75.

142. Future Air Force Energy Needs—Fuels and Systems, Report of the

USAF Scientific Advisory Board Ad Hoc Committee, Department of the

Air Force, November 1974.

143. FY 74 Energy Conservation in Building and Facility Operations,

letter of Deputy Director of Civil Engineering, HQ USAF, Department

of the Air Force, August 29, 1974.

144. FY 76 MPH Improvements Program Guidance Letter 75-1, letter of

Chief, Family Housing Division, Directorate of Civil Engineering,

HQ USAF, Department of the Air Force, October 31, 1974.

145. GSA' s Energy Conservation Test Building - a Report, Actual

Specifying Engineer, Vol. 30, No. 2, pp. 84-92, August 1973.

146. Gasification - New Fuels Source? Government Executive, November

1972.

147. A Generalized Computer Program for Modeling the Performance of

Solar Energy Systems, Yu, H.C. , and Hankins, Richard P. , Jr.,

presented to a meeting of the International Solar Energy Society,

August 1974. (Hankins Assoc., Richmond, Va. 23200)

148. Government Activities and Regulations for Buildings on Energy

Saving Standards, Achenbach, P.R. , Heating, Piping and Air

Conditioning, pp. -41-46, December 1976.

149. Group Relamping of Fluorescent Lighting for Greater Efficiency and

Economy, Bradley, Joseph A., paper presented at the 25th National

Plant Engineering and Maintenance Conference, Cleveland, Ohio,

March 19-21, 1974.

150. Guide for the Development and Use of Utility Targets, U.S. Department of the Navy, NAVDOCKS MO-303, January 1966.

151. Guidelines for Energy Conservation for Immediate Implementation:

Small Business and Light Industries, Federal Power Commission,

Washington, D.C. 20426, February 1974.

E-ll
*152. Guidelines for Saving Energy in Existing Buildings, Building Owners

and Operators Manual ECM 1, 1975. Federal Energy Administration,

Washington, D.C. 20461.

*153. Guidelines for Saving Energy in Existing Buildings, Engineers,

Architects, and Operators Manual ECM 2, 1975. Federal Energy

Administration, Washington, D.C. 20461.

154. Handbook of Air Conditioning. Heating and Ventilating, Strock,

Clifford, and Koral, Richard L. , Industrial Press, Inc., New York,

New York, 1965.

155. Handbook of Air Conditioning System Design, Carrier Air Conditioning

Company, Syracuse, N. Y. 13201. 1965.

156. Hidden Waste, Large, David B. , Ed., The Conservation Foundation,

1717 Massachusetts Ave. , N.W. , Washington, D.C. 20036, August 1973.

157. Hidden Waste Potentials for Energy Conservation, Large, David B.

The Conservation Foundation, 1717 Massachusetts Ave. , N.W.

Washington, D. C. 20036. May 1973.

158. Home Energy Saving Tips, U.S. Department of Commerce, National

Bureau of Standards, Washington, D.C.

159. How Employees and Employers Can Conserve Energy, Air Conditioning

and Refrigeration Business Magazine, March 1972.

160. How M/E Engineers Design Energy Conserving Systems, Actual

Specifying Engineer, August 1974.

161. How to Save Fuel at Home, U.S. News and World Report, Vol. 75,

pp. 19-21, December 17, 1973.

162. How to Start an Energy Management Program, U.S. Department of

Commerce, National Bureau of Standards, Washington, D.C.

163. How to Work with a Consultant in Setting Up an Industrial Plant

Energy-Conservation Program, Power , September 1972.

164. HVAC System Design Criteria for Energy Conservation, Schoenberger

Paul K. , ASHRAE Journal, August 1974.

165. The Hydrogen Economy, Gregory, Derek P., Scientific American,

Vol. 228, No. 1, January 1973.'

166. IES Recommendations for the Better Utilization of Energy Expended

for Lighting, Illuminating Engineering Society, 345 East 47th

Street, New York, New York 10017.

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167. If You Want to Save Energy, Dubin, Fred S. , AIA Journal,

December 1972.

168. Impact of Improved Thermal Performance in Conserving Energy,

National Mineral Wool Insulation Association, Inc. , New York,

April 1972.

169. Impact of Improved Thermal Performance in Conserving Energy,

Technical Committee of the -National Mineral Wool Insulation

Associates, Inc., Supporting Statement to Proposed Revision

to the Southern Building Code, March 1973.

170. The Industrial Energy Conservation Program, U.S. Bureau of

Domestic Commerce, DIBA, Department of Commerce, Washington, D.C.

20230, June 30, 1971.

171. An Input-Output Matrix for the United States, 1963: User's Guide,

Herendeen, Robert A., University of Illinois, CAC Document #69

March 4, 1973.

172. Insulation Manual; Homes, Apartments, National Association of

Home Builders, Rockville, Md. 20850, NAHB Research Foundation,

1971. (For sale to members) 44 p. 360 71-30.

*173. Interim Design Criteria, Technical Guidelines for Energy

Conservation in Existing Buildings, Department of the Navy,

January 1975.

*174. Interim Design Criteria, Technical Guidelines for Energy

Conservation in New Buildings, Department of the Navy, January 1975.

175. A Joint Energy Policy Statement Toward Responsible Energy Policies,

American Gas Association, American Petroleum Institute, Atomic

Industrial Forum, Inc. , Edison Electric Institute, National Gas

Association, March 12, 1973.

176. A Laboratory Test of the Modular Concept as Applied to Gas-Fired

Boilers, Kelly, G.E. and Didion, D.A. , Proceedings of the Purdue

Conference on Improving Efficiency of HVAC Equipment and Components,

pp. 18-30, October 1974.

177. Let's Meet the Energy Crunch—Now, Laird, Melvin R. , Readers Digest,

pp. 49-52, January 1974.

178. Life-Cycle Budgeting and Costing as an Aide in Decision Making,

Department of Health, Education and Welfare, Office of the

Secretary, Office of Facilities Engineering and Property Management,

November 16, 1973.

179. Life Support Systems for a Dying Planet, Dubin, Fred S., Progressive

Architecture, October 1971.

E-13
180. Light, Heat, Ventilating and Noise Control, New York, New York,

Building Code of the City of New York, 1970.

181. Lighting and Air Conditioning, Illuminating Engineer , March 1966.

182. Lighting and Energy Conservation, Environmental Design, Spring 1974.

183. Lighting Handbook, Illuminating Engineering Society, 345 E 47th St.

New York, N.Y. 10017, 5th Edition, 1972

*184. Lighting Systems Study, Ross & Baruzzini, Inc., General Services

Administration/Public Building Service, Washington, D.C. 20405,

March 1974.

185. Lighting and Thermal Operations, Energy Management Action Program

for Commercial, Public, Industrial Buildings, Federal Energy

Administration, Office of Energy Conservation and Environment,

Washington, D.C. 20461. GPO, 1974.

186. List of Conservation Ideas, Attachment to letter, "Reduction of

Energy Demands in Family Housing," of Director of Civil Engineering,

HQ USAF, Department of the Air Force, September 18, 1973.

*187. Making the Most of Your Energy Dollars in Home Heating and Cooling,

Jacobs, M. and Petersen, S.R. , NBS Consumer Information Series 8,

June 1975, Superintendent of Documents, GPO, SD Catalog No. C13.53:8,

pages 17, $ .70.

188. Managing DOD Energy Resources: A Real Ball of Wax.’, Defense

Management Journal, July 1974.

189. Manchester's New Federal Building: An Energy Conservation Project,

Hill, J.E. and Kusuda, T. , ASHRAE Journal, 8-75, pages 47-54.

190. Master Specifications for Temporary Heat, New York Office of General

Services, Design and Construction Group, March 28, 1972.

191. Mechanical and Electrical Equipment for Buildings, McGuinness, W.J.

and Stein, B. , 5th Edition. (John Wiley & Sons, 1971).

192. Meeting National Energy Needs, Prepared by the Community and

Regional Development Group of the National Chamber of Commerce of

the United States (November 1972).

193. A Method of Evaluating the Visual Effectiveness of Lighting Systems,

PQQ Report No. 4, Illuminating Engineering , Vol. 65, August 1970.

194. Method of Testing for Rating Solar Collectors Based on Thermal

Performance, Hill, J.E. , Kusuda, T. , NBSIR 74-635, National

Technical Information Service, COM 75-10276, pages 59, $4.50.

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195. Method of Testing for Rating Thermal Storage Devices Based on Thermal Performance, Kelly, G.E. and Hill, J.E. , NBSIR 74-634,

5-75. National Technical Information Service, COM 75-10685,

pages 45, $4.00.

196. Minimization of Residential Energy Consumption, Harvey, D.G.

Kudrick, J.A. , and Leighton, G. , Proceedings of the 7th Intersociety Energy Conversion Engineering Conference, San Diego,

California, 1972.

197. Modification of Existing System to Conserve Energy, Gupton, Guy W.

Building Systems Design, June/July 1974.

198. Modification of Fluorescent Luminaires for Energy Conservation,

Beausoliel, R.W. , Meese, W.J., and Yonemura, G. , NBS Technical

Note 886, October 1975, Superintendent of Documents, GPO , Catalog

No. C13. 46:886, pages 15, $ .65.

199. Nashville Central Heating and Cooling Plant to be Powered by City's

Solid Wastes, Air Conditioning and Refrigeration Business, August

1972.

200. NBS/GSA, Action Plan for Power Conservation in State and Local

Facilities, Government Printing Office, Washington, D.C. 20402,

Summer 1972.

201. National Bureau of Standards Heating and Cooling Load Calculation

Program, (NBSLD) , Kusuda, T. , APEC Journal, October 1973, pages 3-11.

202. NBSLD, The Computer Program for Heating and Cooling Loads in

Buildings, Kusuda, T. , NBS Building Science Series 69, Superintendent of Documents, GPO, Washington, D.C. 20402, SD No. C13. 29/2:69

$4.60.

203. NBS Research in Support of Energy Conservation Standards for Buildings,

Achenbach, P.R. , (Proceedings 10th International Energy Conservation

Engineering Conference, Newark, Delaware, August 17, 1975), National

Bureau of Standards, Washington, D.C. 20234.

204. The National Energy Problem, Connery, Robert H. and Robert S. Gilmour,

Eds, D.C. Heath Co. Inc., Lexington, Mass., 1974.

205. The Nature of Thermal Comfort for Sedentary Man, Newlin , R.G. and

Rohles, F.H. , ASHRAE transactions, Vol. 77, Part 1, 1971.

206. Procedures Employed by the ASHRAE Task Group for the Determination

of Heating and Cooling Loads for Building Energy Analysis, Kusuda, T.

ASHRAE Transactions, Vol. 82, Part I, 1976, p.305-322.

E-15
207. Now, A Change in Wasteful Habits, Time, Vol. 102, p. 51, October 29,

1973.

208. Nuclear Energy and the Future, Simpson, John W. , January 1975,

Position Paper of Atomic Industries Forum Inc., pp. 27-31.

209. Operating the HVAC System as a Function of Available Power,

Tweed, Francis E., Paper presented at the 25th National Plant

Engineering and Maintenance Conference, Cleveland, Ohio, March 18-21,

1974.

210. Operational Readiness and Conservation, McCall, Craig C. , Supplement

to the Air Force Policy Letter for Commanders, AFRP 190-2, No. 2-1975,

February 1975, pp. 8-16.

211. Opportunities for Improving Energy Utilization in Residences,

Harvey, C.G. and Achenbach, P.R. , Proceedings of Symposium on Effective Energy Utilization, Drexel University of Philadelphia,

Pennsylvania, June 1972, 11-72, U.S. Department of Commerce (68.1),

pages 13.

212. Optimizing the Use of Energy for Lighting, Daufman, John E.

Report to the Ad Hoc Subcommittee on Design, November 1972.

213. Optimizing the Use of Energy for Lighting, Illuminating Engineering

Society, Draft January 24, 1973.

214. Optimum Use of Energy, An Electric Industry Report, ASHRAE Journal,

February 1973.

215. Options for Energy Conservation, Hammon, Bruce, Energy Research

Group at the Center for Advanced Computation of the University

of Illinois.

216. Outlook for Energy in the U.S. to 1985, Winger J.G. , Emerson, J.D.,

Gunning, G.D. , Sparling, R.C., Zrely, A. J. , Energy Economics

Division, Chase Manhattan Bank, New York, N.Y. , June 1972.

217. Patterns of Energy Consumption in the United States, prepared by

Stanford Research Institute for the President's Office of

Science and Technology, Washington, D.C., January 1972, U.S.

Government Interagency Staff Report, GPO Stock No. 4106-0034.

218. Petroleum Today, 1972, Vol. 13, No. 2, published by the Committee

on Public Affairs, American Petroleum Institute.

219. Plan for Review of the Operating Efficiencies of Heating Plants

and Heating Systems, Attachment to letter. Review of the Operation

Efficiencies of Heating Plants and Heating Systems, of Deputy

Director of Civil Engineering, HQ USAF, Department of the Air Force,

April 18, 1973.

E-16
220. Plentiful Energy from the Sun, Gilmore, C.P. , Popular Science , December 1972.

221. The Potential for Energy Conservation, Stanford Research Institute

for the Executive Office of the President, Office of Emergency

Preparedness, (U.S. Government Printing Office No. 013.46:789,

July 1973). Also available: NTIS PB213-722, pp.247, $8.00.

222. Pre-Design Analysis of Energy Conservation Options for a MultiStory Demonstration Office Building, Kusuda, T. , Hill, J.E.,

Liu, S.T., Barnett, J.P., and Bean, J.W., NBS Building Science

Series 78, 11-75, Superintendent of Documents, SD Catalog No.

C13. 29/2:78, pages 64, $1.25.

223. Pressure Differences Across Windows in Relation to Wind Velocity,

Emswiler, J.E. and Randall, W.C., ASHRAE Transactions, Vol. 36,

1930.

224. Principles of Economical Heating, International District Heating

Association, Pittsburgh, Pa. 15206, Seventh Edition, 1973.

225. Procedure for Determining Heating and Cooling Loads for Computerized

Energy Calculations. Algorithms for Building Heat Transfer Subroutines, ed., Metin Lokmanhekim, 1971, American Society of Heating,

Refrigerating and Air Conditioning Engineers, Inc. (345 East 47th St.,

New York, N.Y. 10017. $8.00)

226. A Program for Energy Management, Plant Engineering, May 16, 1974.

227. A Proposed Concept for Determining the Need for Air Conditioning

for Buildings Based on Building Thermal Response and Human Comfort,

NBS Building Science Series 71, 8-75, Superintendent of Documents,

GPO, SD Catalog No. C13. 29/2:71, pages 155, $2.25.

228. Proposed Procedures for Simulating the Performance of Components

and Systems for Energy Calculations, Second Edition, 1971. Stoecker,

W.F. , Ed., American Society of Heating, Refrigerating and Air

Conditioning Engineers, Inc. (345 East 47th St., New York, N.Y.

10017) $4.00.

229. Proposed Revision to Southern Building Code, Natural Mineral Wool

Insulation Association, Inc. , May 1973. (New Chapter XXIXThermal Performance.)

230. Radical Techniques of Energy Conservation, Munk, Michael E.

ASHRAE lecture series, March 14, 1974.

231. Recommendations for Greater Energy Efficiency in Large Buildings,

Pennsylvania Department of Commerce, Harrisburg, Pennsylvania.

E-17
*232. Recommended Criteria for Retrofit Materials and Products Eligible

for Tax Credit, Rossiter, W.J. and Mathey, R.G., National Bureau

of Standards Internal Report (NBSIR) 75-795, 11-75, National

Technical Information Service, PB-246866, pages 44, $4.00.

233. Recommended Guidelines for Supermarket Energy Conservation,

Commercial Refrigerator Manufacturers Association, Washington, D.C.

234. Recommended Practice of Daylighting, Illuminating Engineering , August 1962.

235. Reduction of Energy Consumption in Military Facility Construction

Projects, Letter of Directorate of Civil Engineering, HQ USAF,

Department of the Air Force, January 21, 1974.

236. Reduction of Shower Head Flowrate, Letter of Director of Civil

Engineering, HQ USAF, Department of the Air Force, November 19,

1973.

237. Report of Ad Hoc Committee on Energy Efficiency in Large Buildings,

Interdepartmental Fuel and Energy Committee of the State of New

York, March 7, 1973.

238. Report to Congress on Resource Recovery, U.S. Environmental

Protection Agency, February 22, 1973.

239. Report on Temporary Heat, New York Office of General Services,

Design and Construction Group, Division of Design.

240. Residential Energy Conservation, U.S. Department of Housing and

Urban Development, Office of Policy Development and Research,

Washington, D.C., GPO, 1974.

241. Residential Energy Consumption, Single-Family Housing—Data

Acquisition, U.S. Department of Housing and Urban Development

Office of Policy Development and Research, Washington, D.C. GPO,

Report No. HUD-HAI-1, March 1972.

242. Residential Energy Consumption, Single-Family Housing—Data

Acquisition, Report No. HUD-HAI-2, March 1973, U.S. Department of

Housing and Urban Development, Office of Policy Development and

Research, Washington, D.C. , GPO.

243. Residential Energy Consumption, Multi-Family Housing—Data

Acquisition, Report No. HUD-HAI-3, October 1972, U.S. Department

of Housing and Urban Development, Office of Policy Development and

Research, Washington, D.C. GPO.

E-18
*244. Retrofitting Existing Housing for Energy Conservation: An

Economic Analysis, Petersen, S.R., National Bureau of Standards

Building Science Series 64, 12-74, Superintendent of Documents,

GPO, SD Catalog No. C13. 29:2/64, page 76, $1.35.

245. Retrofitting a Residence for Solar Heating and Cooling: The

Design and Construction of the System, National Bureau of Standards

Technical Note 892, 11-75, Superintendent of Documents, SD Catalog No.

C13. 46:892, pages 99, $1.70.

246. A Round Table On Energy Conservation through Higher Quality Building,

Architectural Record, Vol. 151, No. 1, pp. 97-104, January 1972.

247. Rickover Sees U.S. Energy Sources Key to Future, Schenectady

Gazette, October 25, 1972.

248. S.2176 Energy Bill, Senator Jackson, Congressional Record,

Vol. 119, No. 109, July 13, 1973.

249. Save a Watt, Newsweek , Vol. 81, pp. 91-92, May 28, 1973.

250. Save Energy—Save Money: Simple Do-It-Yourself Projects to

Insulate Your Home. Report 590E, 1975, Free from Consumer

Information, Public Document, District Center, Pueblo, Calf. 81009.

251. Scientists Move to Produce Solar Energy Commercially, Michael

Oliver, Boston Globe, July 5, 1973.

252. Scrap House Priced at $60,750, Associated Press, Boston Globe,

August 24, 1973.

253. 7 Ways to Reduce Fuel Consumption in Household Heating—Through

Energy Conservation, Knauer , V. and Branscomb, L.M. , Consumer

Bulletin 1-71, Superintendent of Documents, SD Catalog No.

C13.2:F95, pages 10, $ .35.

254. Site Analysis and Field Instrumentation for an Apartment

Application of a Total Energy Plant, Coble, J.B. and Achenbach, P.R.

National Bureau of Standars Internal Report NBSIR 75-711, 5-75,

National Technical Information Service, COM 75-10689, pages 63, $4.50.

255. Site Analysis for the Application of Total Energy Systems to

Housing Developments, Achenbach, P.R. and Coble, J.B. , National

Bureau of Standards. Presented at the 7th Intersociety Energy

Conservation Engineering Conference San Diego, California, 1972.

256. Solar Heating and Cooling in Buildings: Methods of Economic

Evaluation, Ruegg, R.T., National Bureau of Standards NBSIR 75-712,

7-75, National Technical Information Service, COM 75-11070, pages 47,

$4.00.

E-19
257. Spotlight on the Energy Crisis: How Architects Can Help, AID

Journal, June 1972.

258. State Building Design Guidelines for the Conservation of Energy,

Department of Administration, State Bureau of Facilities Management,

(Madison, Wisconsin, September 1973).

259. State Energy Organizations, Federal Energy Administration,

Washington, D.C., GPO, 1974.

260. A Study of Air Conditioning, Heating and Ventilating Design for

Veterans Administration Hospital Kitchens and Laundries, DubinMindell-Bloome Associates, 42 W. 39th St., New York, N.Y. 10018.

261. A Study of Room Air Conditioners, New York Department of Public

Service, September 21, 1972.

262. Suggested Energy Conservation Methods, Attachment to letter,

"Energy Conservation," of Director of Civil Engineering, HQ USAF,

Department of the Air Force, October 4, 1973.

263. Suggested Measures for Conserving Electrical Energy in Industry,

U.S. Bureau of Domestic Commerce, Washington, D.C. 20230, June 30,

1971.

264. Survival and Sun "Light", Logan, H.L. , Paper presented at I.E.E.E.

1972 Intercom, United Engineering Center, New York, N.Y., March 20-23,

1972.

265. A Technical Basis for Energy Conservation, A Staff Report

FPC/OCE/2, Federal Power Commission, Washington, D.C., April 1974.

*266. Technical Options for Energy Conservation in Buildings, NBS

Technical Note 789, 7-73, U.S. Government Printing Office,

SD Catalog No. C13.46;789, $2.35.

267. Thermal Design of Buildings, Rogers, Tyler Stewart, (New York:

Wiley and Sons, Inc., 1964).

268. Thermal Performance of Materials, Cady, S.H., National Mineral

Wool Association, Sumit, New Jersey 07901, Gordon Research

Conference: Research on Materials for Buildings, July 11, 1973,

Tilton, N.H.

269. Thermal Resistance of Airspaces and Fibrous Insulations Bounded by

Reflective Surfaces, Robinson, H.E., Cosgrove, L. and Powell, F.

National Bureau of Standards Report BMS 151, 1957.

E-20
270. Thirty-Five Ways to Save Energy Right Now, American Air Filter,

Louisville, Kentucky.

271. Thirty-Five Money Saving Ways to Conserve Energy in Your Business,

U.S. Department of Commerce, Office of Energy Programs, Washington,

GPO , 1973.

272. The Time Has Come for Electrical Energy Management, National

Electrical Contractors Association, Washington, D.C., 1973.

273. Tips for Energy Savers, Federal Energy Administration, Office of

Energy Conservation and Environment, Washington, GPO, 1974.

274. Total Energy Conservation In Public Buildings, sponsored by New

York State Public Commission and Office of General Services,

January 12, 1972, Albany, New York.

*275. Total Energy Management, National Electrical Manufacturing

Association, National Electrical Contractors Association.

276. Total Energy Systems: A Review of Recent NBS Activities, Snell,

J.E. , and Achenbach, P.R. , Paper presented at Symposium of

Effective Energy Utilization, Drexel University, 6-72, U.S. Department of Commerce (79.1), pages 32.

277. Total Energy Systems and the Environment, Actual Specifying

Engineering, October 1972.

278. Total Energy Systems for Mass Housing—Why It Makes Sense, Actual

Specifying Engineer, February 1973.

279. Total Energy Systems for Mass Housing, Prepared for presentation at

Urban Technology Conference 2, San Francisco, California, July 1972.

280. Total Energy TR2, A Technical Report, Educational Facilities

Laboratories, Inc., May 1970.

*281. Underground Heat and Chilled Water Distribution Systems, Kusuda, T.

National Bureau of Standards Building Science Series 66, 4-75,

Superintendent of Documents, SD Catalog No. C13. 29:2/66, pages 146,

$ 2 . 10 .

282. Use of Coal in Heating and Industrial Boiler Plants, Letter of

Chief, Engineering Division, Directorate of Civil Engineering,

HQ USAF, Department of the Air Force, June 14, 1974.

283. The Use of Solar Energy for Residential Space Heating, Lorsch, H.G.

Energy Conversion, Vol. 13, 1973.

284. Using the Computer for Lighting Computations, Hankins, Richard P.J.,

Heating Piping Air Conditioning, October 1968.

E-21
285. Using Technical Guidelines to Evaluate Conservation Decisions,

Jones, Robert S. , Paper presented at the 25th Meeting of the National

Plant Engineering and Maintenance Conference, Cleveland, Ohio.

March 18-21, 1974.

286. Utilities Conservation Program Survey Manual, U.S. Department of

the Navy, NAVDOCKS P-75, Vol. 1, October 1963.

287. Utilization and Conservation of Utilities, U.S., Stock No. PBS P

5800. 18A CHGE5, Government Printing Office, August 6, 1965.

288. The Values of Thermal Insulation in Residential Construction:

Economics and the Conservation of Energy, Moyers, John C. , Oak

Ridge National Laboratory, ORNL-NSF-EP-9 , December 1971.

289. Verification of the Time-Response Method for Heating Load

Calculations, Residential Energy Consumption, Report No. HUD-HAI-5

Department of Housing and Urban Development, Washington, D.C. 20410,

June 1973.

290. Ways to Relieve Energy Crisis, Anglin, Robert J. , Consumer Corner,

Boston Globe, July 5, 1973.

291. We Will Air Condition and Heat with Garbage, Briley, Beverly, The

American City Magazine, November 1972.

292. When Computers Assume Building Operations, Kmetzo, John L. , AIA

Journal, December 1972, (American Institute of Architects, 1785

Massachusetts Ave. , N.W. , Washington, D.C. 20036.

293. Will Industry Flicker as Energy Fades? Lawrence, Floyd G. , Miller,

William H. , and Larsen, David H. , Management Review, November 1972.

294. Windows and People: A Literature Survey, Collins, B.L. , National

Bureau of Standards Building Science Series 70, 6-75, Superintendent

of Documents, SD Catalog No. C13. 29/2:70, pp . 93, $1.55.

295. Winter Infiltration Through Swinging-Door Entrances in Multi-Story

Buildings, Min, T.C., ASHRAE Transactions, Vol. 64, 1958.

296. A Wiser Use of Electricity and Energy Conservation Through Building

Design, Dubin, Fred S. , Building Systems Design, June 1972.

E-22
CONVERSION FACTOR TO METRIC (S.I.) UNITS

Physical To Convert Multiply

Quantity from To by

Energy Btu J 1* 056xl03

kWh J 3* 60x10°

Wh J 3* 60xl03

Heat flux rate Btu/ f

2

*

W/m2 3*15

Thermal conductivity Btu* in/h* ft 2 * °F W/m* K 1* 442xl0

-1

Energy flux Btu/ft 2 J/m2 l*136xl04

Thermal conductance Btu/h*ft 2 . °F W/m2

•

5*68

Heat capacity Btu/lbm* °F j/kg* K 4*19

Power Btu/h W 2 • 93xl0

-1

horsepower W 7 • 46xl02

Temperature Fahrenheit Celsius t c=(t f-32)/l*8

Absolute temperature Rankine Kelvin 0-556

Temperature Difference Fahrenheit AK 0*556

Thermal Resistance °F*h*ft

2 /Btu K*m2 /W 1* 761xlO_1

Distance ft m 3* 05xl0

-1

in m 2 • 54xl0-2

Volumetric flow rate ft 3

/ min m3 /

4 * 72xl0-4

gal/min m3 /s 6-31xl0“5

Area ft 2 m2 9 * 29xl0-2

in 2 m2 6* 45xl0-4

Velocity ft/ sec m/

3* 05x10-!

mi/h m/ s 4 * 47x10”!

Illumination level footcandle lm/m2 1-076X101

Volume gal m3 3 * 79xl0-3

ft 3 m3 2*83xl0-2

Pressure in Hg Pa 3* 39xl0 3

in H2 O Pa 2 • 49xl02 psi Pa 6* 89xl03

Permeance Perm kg/Pa* s*m2 5* 75xl0

-11

Force lbf N 4*45

Mass lbm kg 4 • 54xl0

-1

Density lbm/ft 3 kg/m3 1-602X101
NBS-1 14A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 77-12382. Gov’t Accession

No.

3. Recipient’s Accession No.

4. TITLE AND SUBTITLE

TECHNICAL GUIDELINES FOR ENERGY CONSERVATION

5. Publication Date JUNE 1977

6. Performing Organization Code

7. AUTHOR(S)

Building Environment Division of National Bureau of Sta

8. Performing Organ. Report No. ndards

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 1+62 6il+l

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

USAF Civil Engineering Command

AFCEC/DE/21—Tyndall Air Force Base

Panama City, Fla. 32^+01

13. Type of Report & Period Covered Final Report

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) This report provides detailed technical material on various energy conservation actions for existing Air Force facilities and utility systems. It is specifically tailored

to serve as a working document for Base engineers and technical personnel. The report

covers energy conservation for Air Force facilities, including the equipment for pro- viding hot water, space heating and cooling, lighting, and humidification. It also covers centrai plant systems and underground distribution systems (hot water, steam, and chilled water). It does not cover energy conservation measured for tactical or mission-related equipment such as ground vehicles or fighter aircraft.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Air Force facilities; building energy conservation; energy management; evaluation and monitoring; survey of buildings.

18. AVAILABILITY ft

-1 Unlimited C For Official Distribution. Do Not Release to NTIS

|

I Order From Sup. of Doc., U.S. Government Printing Office Washington, D.C. 20402, SD Cat. No. Cl

7] Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

21. NO. OF PAGES

UNCL ASSIFIED

20. SECURITY CLASS

(THIS PAGE)

22. Price

UNCLASSIFIED

USCOMM-DC 29042-P74

* U. S. GOVERNMENT PRINTING OFFICE : 1977--240-848/193