A111D2 ISETME

NATL INST OF STANDARDS & TECH R.I.C.

A1 11 02 152942

NBS building science series •A435 .U58 V161;1984 C.2 NBS-PUB-C 1974 n

NBS BUILDING SCIENCE SERIES 161

Effectiveness of Solar Shading

for an Office Building

.U58

No. 151 PARTMENT OF COMMERCE • NATIONAL BUREAU OF STANDARDS

198^

C. A

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'
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards' was established by an act ot Congress on March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology

and facilitate their effective application for public benefit. To this end, the Bureau conducts

research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau's technical work is per- formed by the National Measurement Laboratory, the National Engineering Laboratory, and

the Institute for Computer Sciences and Technology.

THE NATIONAL MEASUREMENT LABORATORY provides the national system of

physical and chemical and materials measurement; coordinates the system with measurement

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Absolute Physical Quantities^ — Radiation Research — Chemical Physics —

Analytical Chemistry — Materials Science

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provides engineering measurement traceability services; develops test methods and proposes

engineering standards and code changes; develops and proposes new engineering practices;

and develops and improves mechanisms to transfer results of its research to the ultimate user. The Laboratory consists of the following centers:

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Engineering — Building Technology — Fire Research — Chemical Engineering^

THE INSTITUTE FOR COMPUTER SCIENCES AND TECHNOLOGY conducts

research and provides scientific and technical services to aid Federal agencies in the selection,

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'Headquarters and Laboratories at Gaithersburg, MD, unless otherwise noted; mailing address Washington, DC 20234. 'Some divisions within the center are located at Boulder, CO 80303.
NBS BUILDING SCIENCE SERIES 161

Effectiveness of Solar Shading

for an Office Building

S. Treado

J. Barnett

W. Remmert

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

Washington, DC 20234

'JIATIOHAL BUREAU OF r:TA:,DArii>s

6F

r 9-

Sponsored by:

Design and Construction Division

General Services Administration

Washington, DC 20407

Naval Facilities Engineering Command

U.S. Navy

Washington, DC 20350

Directorate of Civil Engineering

U.S. Air Force

Washington, DC 20330

Office of Chief of Engineers

U.S. Army

Washington, DC 20310

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Issued May 1984
Library of Congress Catalog Card Number: 84-601038

National Bureau of Standards Building Science Series 161

Natl. Bur. Stand. (U.S.), BIdg. Sci. Ser. 161, 111 pages (May 1984)

CODEN: BSSNBV

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1984

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402
ABSTEIACT

The impact of solar shading of windows on building energy consumption, energy

costs and occupant comfort is examined for a typical office building. Measurements of the solar and thermal performance characteristics of three solar screens are reported. Using the DOE-2 computer program, annual building energy

simulations were performed for seven climatic locations in the United States.

Thirteen combinations of window thermal transraittance and shading coefficient

are examined for each location. The analysis includes separate evaluations for

buildings with all-year cooling and summer-only cooling. The percentage of

occupied hours when overheating occurs in perimeter office areas is presented.

A life-cycle cost analysis is used to determine payback periods and savings-toinvestment ratios for three combinations of shading device first cost and

expected life. The evaluation assumes that any shading devices are fixed, and

that daylighting is not used to offset interior lighting requirements.

The results indicate that solar shading can reduce building energy consumption

and improve comfort conditions in buildings with significant cooling loads. The

optimum shading device characteristics vary with climatic location. Solar

shading is more beneficial to buildings which are cooled all year, than

buildings with summer-only cooling.

Keywords: Building energy analysis; cooling loads; heating loads; solar

screens; solar shading; window management; windows.

iii
PREFACE

A. AUTHORITY

This study has been executed pursuant to a GSA/NBS agreement, through the

National Capital Region Design and Construction Division of the General

Services Administration,

B. PURPOSE

The objective of this study is to evaluate the effects of solar shading on heating and cooling loads and energy requirements of building HVAC system, and

to determine the cost-effectiveness of solar shading for an office building

for seven climatic regions of the United States. Guidelines are developed and

presented to enable effective utilization of solar shading for office building

applications

C. DISCLAIMER OF APPLICATION

The results and analysis are intended to be used only for the purpose described

herein, and may not be applicable to other cases. Neither GSA nor NBS are responsible for any other use or application of the data, results or conclusions

contained in this report.

The user is cautioned to evaluate the local weather conditions, building design

and type of construction, location, height usage, and other relevant factors

prior to any application of the data, results or conclusions contained in this

report. Each building must be considered on an individual basis.

iv
TABLE OF CONTENTS

Page

ABSTRACT iii

PREFACE Iv

LIST OF TABLES vl

LIST OF FIGURES vil

ACKNOWLEDGMENTS ix

1 . INTRODUCTION 1

2. BACKGROUND 3

2.1 Purpose of Solar Control Devices 3 2.2 Solar and Thermal Performance 4

3. MEASUREMENTS OF SOLAR AND THERMAL PERFORMANCE OF SOLAR SCREENS 7

3.1 Description of Screens 7 3.2 iVfeasurement Procedure 8

3.3 rfeasurement Results 9

4. BUILDING SIMULATION 11

4.1 The DoE 2 Computer Program 11

4.2 The Building Model 12

4.3 Climatic Zones 12

4.4 Simulation Verification 13

4.5 Computer Simulation Results for Seven Climatic Zones 14

4.6 Economics of Solar Shading 15

5. RESULTS 17

5.1 Phoenix 19

5.2 Atlanta 19

5.3 Houston 20

5.4 Washington, D.C 20

5.5 Chicago 20

5.6 Boston 20

5 .7 San Jose 21

6. CONCLUSIONS 23

7. REFERENCES 25

APPENDIX A ~ DESCRIPTION OF BUILDING MDDEL 27

V
LIST OF TABLES

Page

Table 1 . Description of Screens 8

Table 2. Average Screen Properties 10

Table 3. TRY Heating and Cooling Degree Days (Base 18.3 C) for Study

Cities 13

Table 4. Values of Shading Coefficients and U-f actors Used for the

Simulation for Each City 14

Table 5. Annual Energy Consumptions (MBTU) for the Subsystems of the

Simulated Building (Washington, D.C. with Clear Glass) SummerOnly Cooling 15

Table 6a. Cost-effectiveness for Phoenix U = 0.50, Summer-only Cooling . 46

Table 6b. Cost-effectiveness for Phoenix U = 0.84, Summer-only Cooling , 47

Table 6c. Cost-effectiveness for Phoenix U = 0.50, All-year Cooling .... 48

Table 6d . Cost-effectiveness for Phoenix U = 0.84, All-year Cooling .... 49

Table 7a. Cost-effectiveness for Atlanta U = 0.50, Summer-only Cooling . 55

Table 7b. Cost-effectiveness for Atlanta U = 0.84, Summer-only Cooling . 56

Table 7c. Cost-effectiveness for Atlanta U = 0.50, All-year Cooling .... 57

Table 7d. Cost-effectiveness for Atlanta U = 0.84, All-year Cooling .... 58

Table 8a. Cost-effectiveness for Houston U = 0.50, Summer-only Cooling . 64

Table 8b. Cost-effectiveness for Houston U = 0.84, Summer-only Cooling . 65

Table 8c. Cost-effectiveness for Houston U = 0.50, All-year Cooling .... 66

Table 8d. Cost-effectiveness for Houston U = 0.84, All-year Cooling .... 67

Table 9a. Cost-effectiveness for Washington, D.C. U = 0.50, Summer-only

Cooling 73

Table 9b. Cost-effectiveness for Washington, D.C. U = 0.84, Summer-only

Cooling 74

Table 9c. Cost-effectiveness for Washington, D.C. U = 0.50, All-year

Cooling 7 5 Table 9d . Cost-effectiveness for Washington, D.C. U = 0.84, All-year

Cooling 76

Table 10a. Cost-effectiveness for Chicago U = 0.50, Summer-only Cooling . 82

Table 10b. Cost-effectiveness for Chicago U = 0.84, Summer-only Cooling . 83

Table 10c. Cost-effectiveness for Chicago U = 0.50, All-year Cooling .... 84

Table lOd. Cost-effectiveness for Chicago U = 0.84, All-year Cooling .... 85

Table 11a. Cost-effectiveness for Boston U = 0.50, Summer-only Cooling .. 91

Table lib. Cost-effectiveness for Boston U = 0.84, Summer-only Cooling .. 92

Table 11c. Cost-effectiveness for Boston U = 0.50, All-year Cooling 93

Table lid. Cost-effectiveness for Boston U = 0.84, All-year Cooling 94

Table 12a. Cost-effectiveness for San Jose U = 0.50, Summer-only

Cooling 100

Table 12b. Cost-effectiveness for San Jose U = 0.84, Summer-only

Cooling 101

Table 12c. Cost-effectiveness for San Jose U = 0.50, All-year Cooling ... 102

Table 12d. Cost-effectiveness for San Jose U = 0.84, All-year Cooling ... 103

VI
LIST OF FIGURES

Page

Figure 1. Schematic diagram of window calorimeter 30

Figure 2. Photograph of window calorimeter apparatus 31

Figure 3a. Maasured shading factor for screen A 32

Figure 3b. Measured shading factor for screen B 33

Figure 3c. Maasured shading factor for screen C 34

Figure 4a. Measured thermal transmittance for screen A 35

Figure 4b. >feasured thermal transmittance for screen B 36

Figure 4c. Nfeasured thermal transmittance for screen C 37

Figure 5. Photograph of study building 38

Figure 6. Map showing locations of climatic regions 39

Figure 7. Monthly energy consumptions for actual and simulated

building 40

Figure 8a. Phoenix electric consumption 41

Figure 8b. Phoenix steam consumption 42

Figure 8c. Phoenix total building energy 43

Figure 8d . Phoenix percent hours overheating, U = 0.50 44

Figure 8e. Phoenix percent hours overheating, U = 0.84 45

Figure 9a. Atlanta electric consumption 50

Figure 9b. Atlanta steam consumption 51

Figure 9c. Atlanta total building energy 52

Figure 9d. Atlanta percent hours overheating, U=0.50 53

Figure 9e . Atlanta percent hours overheating, U = 0.84 54

Figure 10a. Houston electric consumption 59

Figure 10b. Houston steam consumption 60

vii
LIST OF FIGURES (Continued)

Page

Figure 10c. Houston total building energy 61

Figure lOd. Houston percent hours overheating, U = 0.50 62

Figure lOe. Houston percent hours overheating, U = 0.8A 63

Figure 11a. Washington, D.C. electric consumption 68

Figure lib. Washington, D.C. steam consumption 69

Figure 11c. Washington, D.C. total building energy 70

Figure lid. Washington, D.C. percent hours overheating, U = 0.50 71

Figure He. Washington, D.C. percent hours overheating, U = 0.84 72

Figure 12a. Chicago electric consumption 77

Figure 12b. Chicago steam consumption 78

Figure 12c. Chicago total building energy 79

Figure 12d. Chicago percent hours overheating, U = 0.50 80

Figure 12e. Chicago percent hours overheating, U = 0.84 81

Figure 13a. Boston electric consumption 86

Figure 13b. Boston steam consumption 87

Figure 13c. Boston total building energy 88

Figure 13d. Boston percent hours overheating, U = 0.50 89

Figure 13e. Boston percent hours overheating, U = 0,84 90

Figure 14a. San Jose electric consumption 95

Figure 14b. San Jose steam consumption 96

Figure 14c. San Jose total building energy 97

Figure I4d. San Jose percent hours overheating, U = 0.50 98

Figure 14e. San Jose percent hours overheating, U = 0.84 99

viii
ACKNOWLEDGMENTS

W. S. Fleming and Associates were consulted to develop the initial building

simulation file for the DOE-2 computer procedure.

This work was supported by the National Capital Region of the General Services

Administration, Additional support was provided by the Naval Facilities

Engineering Command, the Directorate of Civil Engineering (Air Force) and the

Office of Chief of Engineers (U.S. Array),

ix
\

I

i
1 . INTRODUCTION

Fenestration systems are integral and Important components of building

envelopes. Typical windows admit large fractions of Incident solar radiation,

and allow relatively high rates of heat exchange with the surroundings, com- pared to other portions of the building envelope. Window system properties,

characteristics and designs have a significant impact on building energy

requirements, building thermal performance, occupant comfort, and HVAC system

sizing [ 1, 2 , 3]

.

For a new building design, proper selection and sizing of window systems can minimize building energy requirements while maintaining the benefits traditionally associated with windows. These benefits Include daylight, view and

occupant related psychological factors [4]. In existing buildings, window

system retrofit procedures are sometimes needed to compensate for changes in

1
HVAC equipment or operating schedules, or to Improve building thermal

performance and occupant comfort.

The use of daylight to reduce lighting energy needs (and cooling loads) can be particularly effective in minimizing annual total building energy

requirements [5, 6, 7], However, daylighting strategies usually require

automatic lighting controls designed to maintain constant levels of interior

illumination. In this evaluation, the daylighting effects of windows are not

considered, since the incorporation of daylighting effects would greatly

increase the complexity of the analysis, and since the report is concerned

mainly with window system retrofit procedures for existing buildings which do

not have automatic lighting control systems.

This report examines the impact of solar control strategies on annual building

energy requirements, energy costs, and occupant comfort conditions for a typical office building with single glazing amounting to 54 percent of the total

area of exterior building envelope. A wide range of window system options are examined on a parametric basis using thermal transmittance (U-factor) and

shading coefficient (SC) to characterize each window system option. Comparisons

are made between a base building with single-pane clear glass windows and the same building retrofitted with fixed solar shading systems, such as screens,

films or shades. The analysis includes buildings with all-year cooling and

summer-only cooling. In this manner, various solar shading options can be

compared on the basis of their solar performance (SC) and thermal performance

(U-factor) characteristics.

Results are presented for seven climatic regions of the United States. The

evaluation includes measurements of the solar-thermal properties of three

solar screens, and simulations of building thermal performance using the

DOE-2.1 computer program. The results of an economic analysis are presented

in the form of payback period and savings-to-investment ratio, for three

combinations of first cost and life.

2
2 . BACKGROUND

2.1 PURPOSE OF SOLAR CONTROL DEVICES

Solar shading devices and other window management systems are used to

selectively alter the thermal and solar properties of building fenestration

systems in order to reduce building energy requirements and to improve comfort

conditions. The selection of window management strategies is strongly dependent

upon building parameters, building location, and occupant requirements. When

designing new buildings, fenestration systems can be specified by choosing from a wide range of alternatives, with the ultimate goal of minimizing energy

requirements associated with the fenestration [8]. In existing buildings,

fenestration retrofit alternatives are much more limited since the size and

location of the fenstration are fixed. Thus, effective use of solar shading

or other window management strategies requires different considerations for

retrofit procedures than for new design applications.

3
Windows can have a significant impact on building energy requirements for

several reasons. First, conductive heat transfer (due to an inside-to-outside

air temperature difference) is generally much greater through a window than

through an equal area of wall [9]. The vast majority of the time, this conductive heat transfer results in increased heating and/or cooling loads, since the

inside-to-outside air temperature difference causes a heat loss in winter and a heat gain in summer. Occasionally, conductive heat loss is a benefit, as on cool summer nights when the interior air temperature is warmer than the ambient

air or cool days when internal heat sources can cause overheating.

The second major energy impact of windows is their transmission of solar

energy. At first glance, it could be assumed that solar heat gain is a benefit

in winter and a detriment in summer. While this assumption is basically correct, particularly for summer, excessive winter solar heat gain can cause overheating in areas near the windows, resulting in unacceptable comfort conditions,

especially in buildings which are air-conditioned only in summer. The precise

level of solar heat gain which would be considered excessive is a function of

building and HVAC system design and operation and building internal heat gain,

which varies from building to building.

The third major energy related impact of windows is the natural daylight

admitted to interior spaces. Since lighting frequently accounts for 50 percent

of the building's electrical energy requirements, the use of daylight to offset

electric lighting can be very beneficial. However, since visible light is only

a portion of the total solar spectrum, the admission of daylight also results

in the admission of solar heat. Evaluation of the net effect of using solar

radiation as a lighting source requires consideration of the trade-offs between

solar heat gain, daylight levels, lighting requirements, and window thermal heat

transfer. In addition, daylighting is used most effectively if the electric

lighting is controlled in response to the available daylight.

Other window-associated considerations include glare and comfort conditions

in perimeter building areas. Glare problems can occur near windows if the

window appears very bright compared to the interior surfaces (walls, ceilings,

partitions, etc.) [10]. This physiological effect is due to the response of

the eye to the bright source (pupil contraction) causing other objects within

the field of view to appear dim. Reflection of direct beam solar radiation

from interior surfaces can also lead to glare problems. Building occupants

are rarely comfortable if direct beam solar radiation impinges directly upon

their bodies or work stations. In these cases, partial or total shading of

the window is usually desired or implemented by the building occupants.

2.2 SOLAR AND THERMAL PERFORMANCE

Many different classes and types of solar shading devices are available. Some

of the more common devices are:

drapes, curtains

shades

• blinds

• reflective films

4
• screens (louvered or nonlouvered)

• shutters

• overhangs

These devices can be manually or automatically controlled, although most screens

and films are fixed. Adjustable devices allow the benefit of tailoring the

thermal and solar characteristics of the window to match the current weather

conditions and building HVAC load conditions. That is, solar radiation can be

admitted when beneficial (winter) and rejected in summer. In contrast, when

fixed shading devices are used, their characteristics must be selected to

provide the best annual performance, striking a balance between beneficial

solar gains in winter and undesirable solar gains in summer. While adjustable

solar shading devices have the potential for greater energy savings than fixed

devices, studies have shown that in many cases manually adjustable devices are

in fact left in fixed positions by the occupants for long periods of time [11].

Automatically adjusting devices can overcome this limitation, however they tend

to be more complex and expensive, and long-term durability may be a significant

consideration.

Solar shading devices reject incident solar radiation by reflection and

absorption [12]. Reflected solar energy is instantly rejected while absorbed

energy is partially convected and radiated to the exterior with the balance

eventually transferred to the building interior. Louvered sun screens are configured to block incident radiation from high solar and sky elevations

while allowing relatively unobstructed view of the ground. The transmittance

of nonlouvered screens is greatest at normal incidence, where the transmittance is essentially controlled by the percentage of open mesh area. Transmittance decreases as incident angle deviates from normal in any direction. Thus, louvered screens can be more effective in rejecting direct beam

solar radiation, particularly at high sun angles.

The solar control properties of solar shading devices can be characterized by

two related parameters. The shading factor (F) is defined as the ratio of solar

heat gain into the building to the solar energy incident upon the window. The

shading coefficient (SC) is defined as the ratio of the shading factor of the

solar shading device to the shading factor of a reference single-pane clear

glass [ 13]

.

Utilization of solar shading devices also influences the thermal performance

of a window, that is the heat transfer due to an inside-to-outside air temperature difference. For a single-pane window, most of the resistance to thermal

heat transfer is provided by the air film on both window surfaces. The glass

itself has a very low thermal resistance due to its small thickness [14].

Installation of a solar screen will increase the thermal resistance of the

window system for two main reasons. First, a still-air space will be created

between the outer window glass and the screen, in the manner of a double-pane

window. The screen must fit tightly against the window frame on all sides for

this effect to be significant. Second, the screen acts as a radiation shield,

reducing infrared heat exchange between the window glass and the cold night

sky or hot exterior surfaces [15]. Thus, the use of a solar screen should

reduce the thermal transmittance (U-factor) of the window system.

5
Exterior screens should be more effective in controlling solar heat gain than

interior screens or shades, since a higher percentage of absorbed solar energy

will be transferred to the outdoors. Interior shading devices tend to create

a hot layer near the inside window surface and this heat can easily be

transferred into the building space [16].

6
3. MEASUREMENTS OF SOLAR AND THERMAL PERFORMANCE OF SOLAR SCREENS

3.1 DESCRIPTION OF SCREENS

Three typical screens were examined, two louvered screens and one flat mesh

screen. A description of the screens is given in table 1.
Table 1 . Description of Screens

Screen A - Louvered, 23 louvers/in., width over spacing ratio 1.51/1, black

colored, woven from bronze.

Screen B - Louvered, 17 louvers/in., width over spacing ratio 0.85/1,

unpainted aluminum.

Screen C- Nonlouvered, flat mesh, woven brown glass fiber, 22 percent open.

3.2 MEASUREMENT PROCEDURE

Measurements were made of the solar and thermal properties of the three solar screens. The thermal transraittance (U-factor) and shading factor (F) were determined from in situ measurements for a south-facing window, using a window

calorimeter. A detailed description of the calorimeter has been previously

published [17], but a brief description follows.

Apparatus

The window calorimeter was constructed of polystyrene with 12.7 cm (5 in.)

thick walls. The overall dimensions of the box are 144.8 cm (57 in.) wide x 132.1 cm (52 in.) deep x 198.1 cm (78 in.) high, with a window opening of

153.5 X 96.4 cm (25 x 38 in.) (see figure 1). The box is mounted flush with a south facing exterior wall (R40) with a cutout for the window so 1.5 m^ (16 ft^)

of box wall and 0.6 m^ (6.6 ft^) of window area are exposed to exterior conditions. The box was mounted in the room so that none of the remaining five surfaces (floor, wall, ceiling, etc.) touched the walls, floor or ceiling of the

room, thus maintaining an air space all around the box. The room air temperature was controlled to match the box air, so no significant heat transfer would

occur through any portions of the box envelope except for the exterior wall.

The window frame was constructed of polystyrene and was 20.3 cm (8 in.) deep

total, with the glass inset 2.5 cm (1 in.) from the exterior. A photograph of

the window calorimeter is shown in figure 2.

The air temperature in the box was controlled using a water-to-air heat

exchanger mounted inside the box, with a constantly operating circulation fan.

The heat exchanger fan was a constant heat source in the box, releasing 94.1 w

(321 Btu/hr). The supply air was directed downward 0.5 m (1.5 ft) above the

floor, with the return located near the box ceiling facing the window opening.

Thus, supply air tended to sweep the walls of the box and good mixing was achieved. An individual HVAC system, consisting of a water chiller, in-line

electric heater, pump, and storage tank in series with the box heat exchanger,

enabled precise control of box air temperature. A temperature sensor in the

heat exchanger return air stream was used to automatically control the operation of the chiller and heater to maintain box air temperature within a small

band

The amount of heat added to or extracted from the box (Q) was determined from

the following equation:

8
Q = VdCpAT (1)

where

V

d

volumetric flow rate of water,

density of water,

specific heat of water, and

temperature change of water flowing through box heat-exchanger.

The water flow rate was held constant, the specific heat of water was assumed

to be a constant 4.2 (10^) J/Kg»K (1 Btu/lb'°F) and the density of water was assumed to be a constant 1000 Kg/m3 (62.4 Ih/fO).

The temperature rise of the circulating water was measured using a copperconstantan thermopile with 21 pairs of junctions which produced a millivolt

signal proportional to the difference between the inlet and outlet water

temperatures of the box heat-exchanger. The millivolt signal was read by an analog integrator which printed hourly integrated average values of the temperature difference for each hour. A rise in water temperature indicates heat

extracted from the box (cooling), while a negative temperature difference

indicates heating has occurred.

The window calorimeter test setup was instrumented with Type T thermocouples

to measure various surface and air temperatures, solar pyranometers to measure

incident and transmitted radiation, and an infrared prygeometer to measure

incident long wave (4-50 ym) (4000-50,000 Nm) radiation.

All of the sensors, except the box flowmeter and thermopile, were monitored

using a microcomputer controlled data acquisition system. The sensor outputs were connected to a data logger which provided thermocouple temperature compensation and analog-to-digital conversion. The microcomputer continuously

scanned all sensors, computing and printing average and instantaneous values

every hour

.

Subsequent processing provided separate files of reduced data, including

temperature differences, derived quantities, and calculated components, and

allowed inclusion of the box flowmeter and thermopile readings.

Thus, the hourly measurements of box heat loss/gain, temperature, and

environmental conditions enabled determination of U-values , shading factors,

shading coefficients, and window energy performance.

3.3 MEASUREMENT RESULTS

The measured shading factors for screens A, B, and C are presented in

figures 3a, 3b, and 3c, respectively. These figures include measurements made

over a 1 year period under a variety of seasonal and climatic conditions.

Each screen was installed on the calorimeter, on a rotating basis and

representative data is presented.

9
The measured shading factors for screen A ranged primarily between 0.18 to

0.22, screen B 0,18 to 0.32, and screen C 0.16 to 0.32. The variability in

shading factor is due to the dynamic, nonuniform angular distribution of the

incident solar radiation, which includes direct beam, diffuse sky, ground

reflected and externally reflected energy.

The measured thermal transmittances of screens A, B, and C are shown in

figures 4a, 4b, and 4c, respectively. The U-f actors for all three screens were

in the range between 2.3 to 5.4 w/m^K (.40 to .95 Btu/h»f t^ • °F) . The variation

in U-factor is due to its dependence on the magnitude of the air temperature

difference across the window, air flow conditions at the window surfaces, and

incoming infrared radiation from the surroundings [18].

Table 2 lists the average U-f actors, shading coefficients for each of the

three screens. These are the best values to use to obtain energy and costeffectiveness data from the computer simulation results.

Table 2. Average Screen Properties

U-Factor

(Btu/h»f t2.F) (w/m^K) Shading Factor Shading Coefficient

Screen A .62 3.52 .19 .22

Screen B .65 3.64 .24 .28

Screen C .59 3.35 .24 .28

* Assumes shading factor of 0.87 for clear glass as per ASHRAE

Handbook of Fundamentals.

10
4. BUILDING SIMULATION

4.1 THE DOE 2 COMPUTER PROGRAM

The DOE computer program (version 2.1) was used in this study to predict

the annual building energy requirements. The DOE program is a building energy

analysis tool developed by the Department of Energy for improving the energy

performance of buildings [19]. The program uses dynamic rather than steadystate calculation procedures and thus accounts for the thermal lag due to the

building envelope construction. The algorithms used by the program are based

on procedures developed by the American Society of Heating, Refrigerating, and

Air-Conditioning Engineers. The program performs hour-by-hour simulations of

the plant (e.g. boilers, chillers, cooling towers, etc.) and HVAC system (e.g.,

fans, coils, pumps, etc.) as they respond to variations in the weather induced

envelope load and internal heat gains.

11
4.2 THE BUILDING MODEL

The building considered in this study is a six-story federal office building

located in Washington, D.C. The building is approximately 132 m (434 ft)

long, 29 m (96 ft) wide, and 22 m (71 ft) high, having a gross above grade

floor area of approximately 2322 (249,984 ft^). The north and south

facades of the building each have approximately 1608 (17313 ft^) of glass area and the east and west facades each have approximately 342 m^ (3686 ft^)

of glass area. The windows are single-pane, clear glass with no operable sash,

overhangs, or fins, and are mounted flush with exterior wall surface. Overall,

approximately 54 percent of the gross exterior wall area consists of glass (see

figure 5 for photograph). The long axis of the building runs in an east-west

direction, with greatest exposures to the north and south. The ratio of glass

area to wall area is the same on each facade.

After obtaining blueprints of the building, a walkthrough was conducted in

order to gather additional information on space temperatures, occupancy, lighting, and equipment use. Interviews were also conducted with the personnel

operating the building central equipment and daily operating records were reviewed. On the basis of this information the building model was developed, a description of which can be found in appendix A.

4.3 CLIMATIC ZONES

The "Test Reference Year" (TRY) hourly climate data tapes, prepared by the

National Oceanic and Atmospheric Administration (NOAA), were used in this study

[20]. Each TRY data tape consists of one year's climate records chosen from a population of 27 years of records of the U.S. National Weather Service. The

year chosen as the TRY year varies with location. The weather data are generally recorded at nearby airport weather stations. The weather variables

used by the DOE program are:

Dry-bulb temperature

Wet-bulb temperature

Atmospheric pressure

Wind speed

Wind direction

Cloud amount

Cloud type

The GSA selected the following seven locations, giving a broad climatic

variation, for this study:

Phoenix, Arizona

Houston, Texas

Atlanta, Georgia

Washington, D.C.

Chicago, Illinois

Boston, Massachusetts

San Jose, California

12
Table 3 lists the cities and their TRY annual heating and cooling degree-days.

Figure 6 shows a map of the United States with each of the seven locations

used in the study.

Table 3. TRY Heating and Cooling Degree-Days (Base 18.3°C)* for

Study Cities

CITY HDD CDD

Phoenix 842 1852

Houston 888 1525

Atlanta 1627 816

Washington, D.C. 2312 828

Chicago 3439 396

Boston 3238 374

San Jose 465 223

* Miltiplication of the above HDD's and CDD's by 1 .8 will give values in

degree-days base 65°F.

4.4 SIMULATION VERIFICATION

A computer run was made using the Washington, D.C. TRY weather tape. The

results of this run were then compared with the most recent annual energy con- sumption records (1980) for the building, to assure that the building model,

together with the DOE computer program, adequately simulated the actual building. Figure 7 shows the monthly energy consumptions for both the simulated and

actual building.

The predicted values for steam consumption track the metered values well (with

the exception of the very high February metered value). It should be noted

that the TRY weather tape was from a different year than the measured data.

The predicted results for the prime heating months were expected to be somewhat

greater than the metered values since the TRY weather tape heating degree-days

(base 18.2°C) are 7 percent greater than for the year 1980 (2312 vs. 2162).

The predicted values for electric consumption also track the metered values

well except for the extremely low metered values for the months of tferch,

April, and June. The previous years metered values show an average increase

of slightly less than 10 percent each month in electric energy consumption

from February through July. This correlates very well with the predicted

results. It is unclear why the metered results are so low for March, April,

and June in 1980. The metered results for the prime cooling months were expected to be higher than the predicted values since the cooling degree-days

for 1980 are much higher than for the Washington, D.C. TRY weather tape (1115

vs. 828).

13
4.5 COMPUTER SIMULATION RESULTS FOR SEVEN CLIMATIC ZONES

Nineteen computer simulations were run for each city. Baseline runs were made

to establish the energy performance of the building with clear window glass

for both the all-year cooling and summer-only cooling cases. In these runs it was assumed that clear glass covered the window areas on all four building

facades. Additional runs were made, one for each different combination of

shading coefficient and U-f actor. In these runs it was assumed that the

shading device had been placed on all glazing surfaces of the building. The

U-values and shading coefficients used in this study are listed in table 4. A

total of 139 computer simulations were run.

Table 4. Values of Shading Coefficients and U-Factors Used for the

Simulation for Each City

Run SC U

(Btu/h»ft^ ) (w/m^K)

1 1 .0 1.17 6.64

2 1.0 0.84 4.77

3 0.8 0.84 4.77

4 0.6 0.84 4.77

5 0.4 0.84 4.77

6 0.2 0.84 4.77

7 0.1 0.84 4.77

8 1.0 0.50 2.84

9 0.8 0.50 2.84

10 0.6 0.50 2.84

11 0.4 0.50 2.84

12 0.2 0.50 2.84

13 0.1 0.50 2.84

The computer simulation results were analyzed to determine electrical energy

consumption, steam consumption, total building energy requirements and the

percentage of occupied hours when overheating occurs in perimeter office areas. Overheating did not occur in the all-year cooled building. The first-year

energy savings in dollars was calculated and used to determine payback periods

and savings-to-investment ratios for each of three combinations of first cost

and expected life for a shading device. The results are presented as functions

of shading coefficient and U-f actor, for each city. Thus, the user of this

report can evaluate the energy, comfort and economic performance of generic

solar shading devices, and determine the characteristics of the most appropriate

device for a particular climatic region.

The building heating energy consumption is highly climate dependent, since

it is primarily driven by ambient temperature and wind conditions. The building

electric energy consumption, on the other hand, does not exhibit much climatic

variation. This is because this building (like most office buildings) consumes

14
a large quantity of electric energy for lighting and office equipment (see

table 5) and the majority of the electric cooling energy is used to eliminate

these internal heat gains. Thus there is little climate dependence in the

electric cooling energy consumption and even less in the total electric energy

consumption. The cooling energy consumption is about 5 percent of the total

electric energy consumption for this building as simulated.

Table 5. Annual Energy Consumptions (MBTU) for the Subsystems of the

Simulated Building (Washington, D.C. with Clear Glass),

Summer-Only Cooling

Energy Type

Steam Electricity

In Situ MBtu (GJ) MBtu (GJ)

Category of Use

Space Heat 10383 (10954) 0

Space Cool 0 1250 (1319)

HVAC Auxiliary 0 3637 (3837)

Domestic Hot Water 1067 (1125) 0

Auxiliary Solar 0 0

Lights 0 11073 (11682)

Vertical Trans. 0 1491 (1573)

Miscellaneous Equipment 0 2350 (2479)

TOTAL 11450 (12080) 19803 (20893)

4.6 ECONOMICS OF SOLAR SHADING

In order to determine if a particular solar shading device is cost-effective

consideration must be given to energy costs, purchase and installation costs,

and maintenance costs. In this report the first year dollar savings, the

discounted payback period, and the savings-to-investment ratio are used to

determined if a solar shading device is cost-effective. Installed costs of

one, three, and six dollars per square foot are used, with expected life of 10,

20, and 30 years, respectively. A salvage value of zero was assumed, meaning

any costs associated with removing worn shading devices was not considered.

The solar shading device was assumed to require no extra maintenance cost.

The first year dollar savings were calculated from the following equation:

First year dollar savings = (EC * ECD) - (HEC * HCI) (2)
where

EC = electricity cost per kWh,

ECD = electrical consumption decrease,

HEC = heating energy cost per kWh, and

HCI = heating consumption increase.

In the above calculation, electrical demand rates were not considered and for

gas and oil savings an annual system efficiency of 70 percent was assumed. The

first year energy costs were typical costs for each region.

The discounted payback period was determined by calculating the cumulative

savings in energy costs at yearly intervals until the savings met or exceeded

the investment cost. That is, MPWFg and MPWFj^ were found for a year (Y) such

that the following equation was satisfied:

E$ * MPWFe(Y) - H$ * MPWFh(Y) > COST (3)

where

COST = material, installation, and maintenance costs for useful life

of solar shading device,

ULIFE = useful life of solar shading device,

E$ = EC * ECD = base year electricity dollar savings,

MPWFe(Y) = modified uniform present worth discount factor for electricity for

given year (Y) (the values for MPWFg are taken from the tables in

reference 21 and are based on a 7 percent real discount rate and

include projected real escalation rates in energy cost) [21],

H$ = HEC * HCI = base year increase in cost for heating, and

MPWFh(Y) = modified uniform present worth discount factor for heating energy

for a given year(Y) (from tables in reference 21).

The savings-to-investment ratios were calculated from the following

equation:

E$*MPWF (ULIFE) - H$*MPWF (ULIFE)

Savings-to-investment ratio = 1 £1 . (4)

COST

16
5 . RESULTS

The results are presented separately for each city in a series of figures and

tables. Data presented includes:

For summer-only cooling

1. Annual building electrical consumption as a function of shading coefficient,

for U-f actors of 0.50 and 0.84 Btu/h'ft^.p, and the base case SC = 1.0,

U-factor = 1.17 Btu/h'ft2.F.

2. Annual building steam consumption as a function of shading coefficient for

U-factors of 0.50 and 0.84 Btu/h'ft^'F, and the base case.

3. Annual total building energy as a function of shading coefficient and

U-factor

.

17
4. Annual percentage of occupied hours when overheating occurs in perimeter

office areas, for north, south, east, and west facing offices, as a function

of shading coefficient. Separate plots are presented for U = 0.50 and

U = 0.84 Btu/h'ft^'F (overheating is defined as space air temperature

greater than 79°F).

5. First year energy savings (dollars)

6. Payback periods (years) and savings-to-investment ratios for the three

combinations of first cost and expected life. The combinations are $1 per

square foot-10 year life, $3 per square foot-20 year life, and $6 per square

foot-30 year life.

Items 5 and 6 are presented as separate sets of tables for each U-f actor, as functions of shading coefficient.

For all-year cooling

Items 5 and 6 from above are repeated for all-year cooling.

The tables and figures are designed to present the energy, comfort, and economic

impacts of solar shading. While these results can only strictly be applied to

buildings which are very similar to the study building, careful analysis of

the results can prove useful in determining appropriate shading strategies and

general design guidelines.

Several trends are apparent throughout all of the results.

• Electric energy consumption decreases with decreasing SC, with the

lower U-f actor usually causing a slight reduction or no net change,

• Steam consumption increases with decreasing SC, the lower U-factor

decreases steam use significantly,

• The shape of the total energy curve as a function of shading

coefficient exhibits the most variability among cities. For the warmweather cities, total energy use tends to decrease with decreasing SC,

with the opposite true for cold-weather cities. Sometimes a minimum

or relatively flat section is seen in the total energy curve.

• In buildings which are cooled only during summer, significant

overheating can occur in perimeter office areas with unshaded windows.

This is not only true for locations with hot climates, but also even

in colder locations.

• South-facing offices exhibit the most overheating, with east and west

about equal.

Shading saves more energy in all-year cooled buildings than in summercooled buildings , but shading of summer-cooled buildings reduces

overheating due to solar gains in perimeter office areas.

18
The savings-to-investment ratios of $6/ft2 shading systems are only

cost-effective for the lower U-factor and only in areas with

significant heating loads.

It should be noted that the overheating described above occurs on sunny days

when the cooling system is not used, primarily spring and fall (for the summeronly cooling case, the cooling system in the study building was only operated

between May 15th and October 15th, typical of federal buildings). In buildings

which have year-round cooling system operation, this type of overheating would

rarely occur, however electric consumption for cooling and heating energy

consumption would be much greater.

5.1 PHOENIX

Electric consumption is minimum for SC of 0.1 (figure 8a), and steam consumption

minimum at SC of 1.0 (figure 8b). Minimum total energy consumption occurs at

a SC of 0.2, for the lower U-factor (figure 8c). Figures 8d and 8e show con- siderable overheating, even for the lowest shading coefficient. Since both

total energy and overheating are minimum for the lower shading coefficients,

a SC of 0.1 to 0.2 would be most effective. The higher U-factor causes a slightly lower percentage of overheating, and slightly higher total energy

requirements

.

Tables 6a through 6d show the cost-effectiveness results for Phoenix, for

U = 0.50 and U = 0.84, summer-only cooling and all-year cooling. Maximum

dollar savings and savings-to-investment ratios, and minimum payback periods

are seen to occur for the lower SC values. The low cost shading device

($l/ft2, 10 year life) is the most favorable, while the high cost ($6/ft^,

30 year life) is not. Savings are much greater for the all-year cooled

buildings than the summer-only cooled building, because the former has a larger base case cooling load when shading is not used.

5.2 ATLANTA

Electric and steam consumption as functions of shading coefficient follow the

usual pattern (figures 9a and 9b). Total building energy is minimum and fairly

constant for SC between 0.4 and 1.0. From an energy standpoint, a SC of 0.4

to 0.6 with the lower U-factor gives the best performance. However, the slightly

higher total energy requirements for the lowest SC may be offset by the improved

comfort conditions as evidenced by the plots of overheating hours, figures 9d

and 9e

.

The cost-effectiveness results are given in tables 7a through 7d . Within each

group, a SC of 0.1 to 0.2 has the shortest payback period, and highest savings

to investment ratio. The $3/ft2-20 year life summer-only cooling case would

not quite pay for itself during its expected lifetime, however, considering

the uncertainty of predicting future energy prices and expected life for a shading device, may be cost-effective in an actual installation. The results

are not favorable for the $6/ft-30 year life cases.

19
5.3 HOUSTON

Electric and steam consumption follow the usual pattern (figures 10a and 10b).

From figure 10c, total building energy is minimum for SC = 0.1, U = 0.50. Ten

to 15 percent hours of overheating may occur even at SC = 0.1, unless auxiliary

shading (drapes, etc.) is used.

Tables 8a through 8d show the cost-effectiveness results. The shading

coefficient of 0.1 is most effective and the $3/ft2-20 year life cases are favorable, but the $l/ft2-10 year life rates the best.

5.4 WASHINGTON, D.C.

Electric and steam consumption follow the usual pattern (figures 11a and lib).

Total building energy shows a broad minimum for SC from 0.6 to 1.0

(figure 11c). However, the percentage of overheated hours is cut in half

going from SC = 0.6 to SC = 0.4 (figures Ud and lie).

Examination of the economic results, tables 9a through 9d , shows the SC of

0.2 to be most favorable for summer-only cooling, and SC of 0.1 most favorable

for all-year cooled buildings. The low U-f actor, $6/ft2-30 year life, all-year

cooling case is cost-effective at the lower shading coefficients,

5.5 CHICAGO

Electric and steam consumption follow the usual pattern (figures 12a and 12b).

Total building energy is minimum at SC = 1.0, but does not change much between

SC = 0.6 to 1.0 (figure 12c). The percent hours of overheating drops off

sharply for SC below 0.6 (figures 12d and 12e).

Tables lOa through lod indicate a SC of about 0.4 to be most cost-effective for

summer-only cooling. A SC of 0.1 is best for all-year cooling. The $l/ft2-10

year life case has the best savings-to-investment ratio; the $3/ft2-20 year

life cases and a few of the $6/ft2-30 year life cases also have positive

paybacks, for the lower U-f actor, particularly for the all-year cooling case.

It is interesting to note that for summer-only cooling the $6/ft2 case pays

off only for higher SC indicating that the heating impacts of the low U-factor

are responsible for the savings.

5.6 BOSTON

Electric and steam consumption follow the usual pattern (figures 13a and 13b).

Total building energy is minimum for SC of 1.0, but changes little between SC

0.6 to 1.0 (figure 13c). Overheating falls off sharply below SC of 0.6 (fig- ures 13d and 13e). Tables 11a through lid indicate a SC of 0.4 to 0.6 to be

most cost-effective for summer-only cooling, with greater savings for the

lower U-factor. A SC of 0.1 is best for all-year cooled buildings. A few of

the $6/ft2-30 year life, low U-factor cases shows a savings-to-investment

ratio of 1.0 or greater, the minimum required for cost-effectiveness.

20
5.7 SAN JOSE

Electric and steam consumptions follow the usual pattern (figures 14a and

14b). Figure 14c shows that total building energy is minimum for SC = 0.6,

but fairly level between SC of 0.4 to 0.8. However, figures 14d and I4e show

that significant overheating would be expected for SC greater than 0.2

Tables 12a through 12d show that the $l/ft2-10 year life case with SC = 0.2,

U = 0.50 is the only cost-effective alternative for summer-only cooling.

Other cases are not cost-effective because the mild climate of San Jose does

not produce large, expensive heating and cooling loads. Comfort may be the

major selection criteria for a location such as this.

21

6 . CONCLUSIONS

The results of this investigation indicate that solar shading can be effective

in reducing heat transfer and solar heat gain into buildings. Solar shading

strategies, such as solar screens, can also reduce building annual energy

consumption and improve comfort conditions. The economic analysis indicates

that solar shading can be cost-effective, dependent upon the energy performance,

first cost and expected life of the shading system. Detailed information on

the most effective shading strategy varies for different climatic locations.

In all cases, solar shading increased heating energy consumption and decreased

cooling energy consumption. A net energy savings occurred if the cooling

energy decrease exceeded the heating energy Increase. A net dollar savings

can occur if the cost of cooling decreased more than the Increase in cost of

heating.

For a building which uses cooling all year, the most cost-effective shading

coefficient was 0.1, and savings were much greater than for an equivalent

building using summer-only cooling.

For a building which is cooled only in summer, in most cases the minimum energy

usage and the miniraura energy cost would not be obtained at the same combination

of shading device characteristics. In a majority of cases, the most costeffective shading device had a lower shading coefficient than the most energy

efficient shading device due to the relative costs of heating and cooling

energy

.

For summer-cooled buildings, the lower U-f actor was best on an energy and

economic basis, but caused a slight Increase in overheating in perimeter areas.

The control of overheating usually required a shading coefficient of less than

0.5. In cooling-dominated climates, energy, economic, and comfort considerations all favored low shading coefficients. In climates with significant heating loads, improved comfort conditions required shading coefficients slightly

lower than the most cost-effective, which in turn were lower than the most

energy effective.

The economic results were more favorable for the lower cost-short life option

($l/ft2-10 year life) than for the $3/ft2-20 year life option, although both

were usually cost-effective, at least for the low U-factor (U = 0.50) cases.

The $6/ft2-30 year life case was rarely favorable, except for the colder

climates .

23

7. REFERENCES

1. Kusuda, T. and Collins, B. L., "Siraplified Analysis of Thermal and Lighting

Characteristics of Windows: Two Case Studies," National Bureau of

Standards, BSS 109; 1978.

2. Owens, P. G. T., "Analysis of the Energy Requirement of Buildings with

Particular Reference to the Window," Glass in Buildings Conference,

International Council for Building Research, Studies and Documentation

(CIB); 1977.

3. King, W. J., "High Performance Solar Control Office Windows," Lawrence

Berkeley Laboratory Report 7825, 1977.

4. Collins, B. L., "Windows and People: A Literature Survey," National

Bureau of Standards, BSS 70, 1975.

5. Bitterice, M. G. and McKinley, R. W., "Use Solar Daylight and Heat from

Windows to Save Fossil Fuel," PPG Industries, Inc., 1978.

6. Treado, S. and Kusuda, T., "Daylighting, Window Management Systems and

Lighting Controls," NBSIR Sept. 80-2147, December 1980.

7. Treado, T., Gillette, G., Kusuda, T., "Evaluation of the Daylighting

and Energy Performance of Windows, Skylights and Clerestories," National

Bureau of Standards, NBSIR 83-2726, June 1983.

8. Ruegg, R. T. and Chapman, R. E., "Economic Evaluation of Windows in

Buildings: Methodology," National Bureau of Standards, BSS 119, 1979.

9. Barakat, S. A,, "Solar Heat Gain through Windows in Canada," National

Research Council of Canada, Division of Building Research, Paper No. 944,

October 1980.

10. Hopkinson, R., "A Note on the Use of Indices of Glare Discomfort for a Code of Lighting," Transactions of the Illuminating Engineering Society,

Vol. 25, No. 3, 1960.

11. Rubin, A., Collins, B., Tibbot, R., "Window Blinds as a Potential Energy

Saver - A Case Study," National Bureau of Standards, BSS 112, May 1978.

12. Ozisik, N., Schutrura, L., "Heat Flow Through Glass with Roller Shades,"

ASHRAE Transactions , Vol. 65, p. 697, 1959.

13. ASHRAE Handbook of Fundamentals, published by ASHRAE, New York, 1981.

14. Yellott, J. I., "Shading Coefficients and the Sun-Control Capability of

Single-Glazing," ASHRAE Transactions , Vol. 72, Part 1, 1966.

15. Yellott, J., "Effect of Louvered Sun Screens Upon Fenestration Heat Loss,"

ASHRAE Transactions , No. 2227, 1972.

25

J
16. Parmelee, G., Anbele, W., Vild, D., "The Shading of Sunlit Glass," ASHRAE

Transactions, Vol. 59, p. 221, 1953.

17. Treado, S., Barnett, J., Kusuda, T., "Energy and Cost Evaluation of Solar

Window Film Use in an Office Building," National Bureau of Standards

Technical Note 1174, March 1983.

18. Ito, N., Kimura, K., and Oka, J., "A Field Experiment Study on the

Convective Heat Transfer Coefficient on the Exterior Surface of a Building," Transactions of the Architectural Institute of Japan, 1968.

19. DOE-2 Users Guide , prepared by the Lawrence Berkeley Laboratory and

Los Alamos Scientific Laboratory for the U.S. Department of Energy under

Contracts W-745-ENG-48 , 1979.

20. National Climatic Center, 1976, Tape Reference Manual "Test Reference

Year," National Climatic Center, Asheville, N.C., Also published in the

ASHRAE Journal, February 1977, p. 47.

21. Ruegg, R. T., "Life-Cycle Costing Manual for the Federal Energy Management

Programs," National Bureau of Standards Handbook 135, December 1980.

26
APPENDIX A

A.l DESCRIPTION OF BUILDING MODEL

° Infiltration was simulated using air change (AC) method - the rates and

profile were as follows:

1 . Basement - none

2. Garage .8AC - all hours

3. All Floors - .6AC when main fans are off for perimeter zones -

none for interior zone

4. Lobby - 2, GAG peak during entry and exit of occupants

° Partitions between zones were treated as having a U factor of

5.68 W/(m2°K) ( 1 ,0/ (f t2hr°F) representing a fairly free convective flow

with doors open.

° Lighting levels were simulated at 21.5 W/m^ (2 W/ft^) in office areas

and 10.8 W/m^ (1 W/ft^) in Basement and Garage.

° Equipment levels (typewriters, copy machines, CRTs, etc.) were simulated

at 16.1 W/m2 (1.5 W/ft2) in office areas.

° Computers and associated air-conditioning systems were simulated as a single energy user at 150 kW for all hours.

° Custom weighting factor method was used to generate weighting factors

for the simulation.

° Average domestic hot water load was estimated at 0.88 kW (3000 Btu/hr)

.

° Thermostat setpoints simulated were as follows:

1. Basement - 18.3°C (65°F)

2. Garage - 12.8°C (55°F)

3. Offices - 18.3°C (65°F) for heating

25.6°C (78°F) for cooling

° Elevator loads were included in the simulation.

° Occupant loads were simulated using standard operating schedules.

27
Air handling system type and fan operating hours Input were as follows

1 . Basement - Single Zone Heat and Vent - 100 percent

outside air - fans on all hours

2 . Garage - Same as basement

3. Perimeter Offices - Two pipe fan coil heating only October 15

through May 15 - cooling only May 16 to

October 14 (summer-only cooling) or year

round (all-year cooling)

Fan hours on at 0600 - off at 1700 weekdays

only off weekends and holidays

4. Interior Offices - Interior Offices - Reheat fan system heating

only October 15 through May 15 - cooling only

May 16 through October 14 (summer-only cooling)

or year round (all-year cooling)

Fan hours on at 0600 - off at 1700 weekdays

off weekends and holidays

Assumptions or Simplifications Used for Preparing Input

The DOE-2 program can only accept three (3) separate plenum inputs.

The ground floor, first floor and lobby were all simulated as being

served by a single interior air system with a common return air plenum.

This left a plenum for the typical floors (2 through 5), and another

for the top floor (6).

Since the second floor was treated as a typical floor with a typical

plenum, the conference rooms over the lobby areas were treated as office space.

The penthouse equipment room was not input as an unconditioned space.

The roof areas of the sixth floor plenum excluded the surface area in

contact with the penthouse.

A standard outdoor reset of supply air temperatures on the reheat fan

systems was input to simulate the combined effect of manual daily

settings of preheat, outside air, and chilled water reset.

A minimum percent outside air for the reheat fan systems was input as

5 percent even though the operator maintains dampers "closed" in very

cold weather. The 5 percent was used to reflect leakage of dampers in

the closed position.

The chilled water plant in the study building (B) also serves an adjacent building (A). To simulate building B two chillers were input

28
of a size to accoramodate building B's load, with no attempt to evaluate

the loading of building A.

The exhaust fans in the building were assumed to have the same operating schedules as supply units. The fan static air pressure and

fan efficiencies were combined into a single input.

29
O Thermocouple ^ Solar pyranometer Plan View

Figure 1. Schematic diagram of window calorimeter

30
Figure 2. Photograph of window calorimeter apparatus

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38
39
BUILDING nONTHLY ENERGY CONSUMPTION

e 2 4 6 8 le le

nONTH

MEASURED • SOLID LINE« PREDICTED - DOTTED LINE

Figure 7. Monthly energy consumptions for actual and simulated buildi

for Washington, D.C., clear glass, summer-only cooling

40
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Table 6a. Cost-effectiveness for Phoenix U = 0.50, Suiraner-onlv Cooling;

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4

•**«*» «***»« GAS 12274. 11598. 9652.

OIL 11249. 10885. 9494.

STEAM 10822. 10589. 9429.

SC = 0.6 SC = 0.8 SC»:1.0 «*«*»« ****** ******

7502. 5142. 2659.

7635. 5840. 3829.

7973. 6130. 4033.

ASSUMPTIONS: ELECTRICITY COST = $.062/KWH

HEATING FUEL COST = $.023(GAS) .038(0IL), .045( STEAM)/KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (C0ST» $1.0/S0. FT.. U=0.50)

HEATING ENERGY SC=G. 1 SC=0.2 SC=0.4 SC«0.6 SC=0.8 SC=1.0

»*•*•*

GAS 4.0 4.0 5.0 7,0 10.0 29.0

OIL 4.0 4.0 5.0 6.0 9.0 16.0

STEAM 5.0 5.0 5.0 6.0 8.0 14.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (C0ST» $1.0/50. FT.. U=0.50)

HEATING ENERGY SC'0.1 SC=0.2 SC=0.4 SC-0.6 SC=0.8 SC-1.0

*•••**«»•*•• *•**• ««•«*«

GAS 2.4 2.3 1.9 1.5 1.0 .6 OIL 2.2 2.1 1.9 1.5 1.1 .7 STEAM 2.1 2.1 1.8 1.6 1.2 .8

10 YEAR PRESENT WORTH FACTOR = 9.2(GAS) MATERIAL & INSTALLATION COST = $ 42000.8.0(0IL), 8.7(STEAM). 8.3(ELEC)

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $3.0/S0. FT., U=0.50)

HEATING ENERGY SC»0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

**•«•»»*»««»** «««*** **•*»• ****** ****** «***»« ****** GAS 15.0 16.0 24.0 >30.0 >30.0 >30.0

OIL 18.0 19.0 25.0 >30.0 >30.0 >30.0

STEAM 19.0 20.0 25.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST. $3.0/50. FT.. U=0.50)

HEATING ENERGY SC-0.1 SC=0.2 SC«0.4 SC=0.6 SC=0.8 SC=1.0

GAS 1.2 1.1 .9 .7 .5 .3 OIL 1.1 1.0 .9 .8 .6 .4 STEAM 1.0 1.0 .9 .8 .6 .4

20 YEAR PRESENT WORTH FACTOR « 14.3(GAS), 14.8(0IL). 13.6(STEAM) MATERIAL & INSTALLATION COST » $126000.12.4( ELEC)

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $6.0/S0. FT. HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8

****** *««*»* ****** ****** *•*«** GAS >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0

U=0. 50)

SC=1 .0 ****** >30.0

>30.0

>30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $6.0/S0. FT., U=0.50)

HEATING ENERGY SC»0. 1 SC=0.2 SCxO.4 SC«0.6 SC=0.8 SC=1.0

« •** «•«*** ****** ****** ****** ****** ****** ****** GAS .7 .7 ,6 .4 .3 .2 OIL .6 .6 .5 .5 .4 .3 STEAM .6 .6 .5 .5 .4 .3 30 YEAR PRESENT WORTH FACTOR = 17.3(GAS), 21.3(0IL). 16.2(STEAM) MATERIAL & INSTALLATION COST = $252000.

14. 5( ELEC)

46
Table 6b. Cost-effectiveness for Phoenix U = 0.84, Sumraer-only Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U»0.84)

HEATING ENERGY SC'0.1 SC=0.2 SC-0.4 SC»0.6 SC=0.8 SC>1,0

*«**t<«*«<*«*« ••**•* •««••• GAS 9347. 9202. 7482. 5524. 3499. 1406. OIL 8144. 7813. 6662. 5204. 3610. 1900. STEAM 7435. 7235. 6321. 5070. 3656. 2106.

ASSUMPTIONS: ELECTRICITY COST = $.062/KWH

HEATING FUEL COST = $.023(GAS). .038(0IL). . 045 ( STEAM ) /KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST- $1.0/SQ. FT.. U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

GAS 5.0 5.0 7.0 10.0 19.0 >30.0

OIL 6.0 6.0 7.0 10.0 18.0 >30.0

STEAM 7.0 7.0 8.0 11.0 17.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (C0ST« $1.0/S0. FT.. U=0.84)

HEATING ENERGY SC=0. 1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC»1.0 ••••**•*••*«• *««««• GAS 1.9 1.8 1.4 1.1 .7 .3 OIL 1.6 1.6 1.3 1.0 .7 .4 STEAM 1.4 1.4 1.2 1.0 .7 .4

10 YEAR PRESENT WORTH FACTOR = 9.2{GAS). 8.0(0IL), 8.7(STEAM). 8.3(ELEC) MATERIAL & INSTALLATION COST = $ 42000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $3.0/S0. FT., U=0.84)

HEATING ENERGY SC=0.1 50=0.2 SC=0.4 SC=0.6 SC=0.a SC=1.0

GAS 25.0 30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (C0ST= $3.0/S0. FT., U»0.e4)

HEATING ENERGY SC'0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

«*«4<*v m w m m m * GAS .9 .9 .7 .5 .3 .1 OIL .7 .7 .6 .5 .4 .2 STEAM .7 .7 .6 .5 .4 .2

20 YEAR PRESENT WORTH FACTOR = 14.3(GAS). 14.8(0IL). 13.6(STEAM). 12.4(ELEC) MATERIAL & INSTALLATION COST $126000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST* $6.0/S0. FT.. U=0.a4)

HEATING ENERGY SC:'0.1 SC = 0.2 SC = 0.4 SC = 0.6 SC = 0.8 SC:«1.0 ««*••«•.>••••« «»»«•» ,..*.. »«»»,» »»..*• »»,,,. •.«..«

GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST- $6.0/S0. FT.. U=0.84)

HEATING energy'" SC«0.1 SC=0.2 SC-0.4 SC=0.6 SC=0.8 SC-1.0

•••.«».«...<«* •*•«»« «..». ««». «....• *•••»* GAS .5 .5 .4 .3 -2 .1 OIL .4 .4 .3 .3 .2 .1 STEAM .4 .4 .3 .3 .2 .1

30 YEAR PRESENT WORTH FACTOR - 17.3(GAS). 21.3(0IL). 16.2(STEaM). 14.5(ELEC) MATERIAL & INSTALLATION COST $252000.

47
Table 6c. Cost-effectiveness for Phoenix U = 0.50, All-year Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS <U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

************** ****** ****** ****** ****** ****** ******

GAS 19063. 17819. 15095. \02BS . 5727. -36.

OIL 17356. 16592. 14794. 10556. 6377. 1086.

STEAM 16645. 16081. 14668. 10627. 6648. 1554.

ASSUMPTIONS ELECTRICITY COST = $.062/KWH

HEATING FUEL COST = $.023(GAS), ,038(OIL), .045(STEAM)/KWH

PAY-BACK PERIODS (YEARS) FOR SOLAP SCREENS (COST= $1.0/SQ. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 3.0 3.0 3.0 5.0 9.0 >30.0

OIL 3.0 3.0 3.0 5.0 8.0 >30.0

STEAM 3.0 3.0 3.0 5.0 7.0 >30.0

SAVINGS-TO-INVESTMENT RATIOS FOP SOLAR SCREENS (COST= Sl.er/SQ. FT, U=0. 50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.5 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 3.7 3.5 3.0 2.0 1.1 .0 OIL 3.4 3.3 2.9 2.1 1.2 .2 STEAM 3.2 3.1 2.9 2.1 1.3 .3

10 YEAR PRESENT WORTH FACTOR

MATERIAL & INSTALLATION COST

9 . 2< GAS ) 4 2000.

8.0{OIL), 8.7(STEAM> 8.3<ELEC)

PAY-BACK PERIODS (YEARS) FOP SOLAP SCREENS (COST= $3.0/SQ. FT. U=0.50)

HEATING ENERGY **************

GAS

OIL STEAM

SC=0.

******

3.0

9 .0 10. d

SC=0.

******

9.0

9.0

10.0

SC=0.

******

11.0

11.0

11.0

SC=0.

******

20 .0 19.0

19.0

SC=0.

******

>30.0

>30.0

>30.0

SC = * * ) ,0 >30.0

>30.0

>30.0

SAVINGS-TO-INVESTMENT PATIOS FOR SOLAR SCREENS {COST= %3.0/SO. FT. U=0. 50)

HEATING ENERGY

****  :t** ***

GAS

OIL

S TEAM

SC=0.

******

1 . 8

1 . 6

1 . 6

SC=0 .

******

1 . 7

1 . 6

1 . 5

SC=0.

******

1 . 5

1 . 4

1 . 4

SC=0.

******

1 .0

1 .0

1 .0

SC=0.

******

. 6

. 7

. 7

SC=1 .0 ******

.0

.2

.2 20 YEAR PRESENT WORTH FACTOR = 1 4 . 3 t GAS ) MATERIAL & INSTALLATION COST = $126000.

14.8{OIL), 13.6(STEAM), 12.4(ELEC)

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $6.0/SQ. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.5 SC=0.8 ************** ****** ****** ****** ****** ******

GAS 25.0 30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0

SC-I .0

**.*** * >30.0

>30.0

>30.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $6.0/SQ. FT, HEATING ENERGY SC=0.4 SC=0.6 SC=0.8 **************

GAS

OIL

STEAM

SC=0.

******

1 . 1

. 9

. 9

SC=0.

******

1 .0

. 9

. 9

. 9

SC=0.6

******

. 6

. 6

. 6

. 3

. 4

. 4

J=0. 50)

SC= 1 . 0^ ******

.0

. 1

. 1 30 YEAR PRESENT WORTH FACTOR

MATERIAL & INSTALLATION COST

17. 3 (GAS)

$252000.

21.3(0IL). 16.2(STEAM), 14.5(ELEC)

48
Table 6d. Cost-effectiveness for Phoenix U = 0.84, All-year Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.3 SC=1.0 *«««**«****««* ****** ****** ****** ****** *••«•*

GAS 17128. 15949. 13391. 9289. 5423. -455.

OIL 14940. 14132. 12316. 8760. 5440. 99. STEAM 14029. 13376. 11869. 8540. 5447. 330.

ASSUMPTIONS: ELECTRICITY COST = $.062/KWH

HEATING FUEL COST = S.023(GAS), .038(OIL), . 04 5 ( STEAM ) / KWH

PAY-BACK PERIODS (YEARS) FOR SOLAP SCREENS (COST= $1.0/SQ. FT.. U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** **:k*** ****** ****** ****** ****** ******

GAS 3.0 3.0 4.0 5.0 ier.0 >30.0

OIL 3.0 4.0 4.0 6.0 10.0 >30.0

STEAM - 4.0 4.0 4.0 6.0 10.0 >30.0

SAVINGS-TO-INVESTMENT PATIOS FOR SOLAR SCREENS <COST= S1.0/SQ. FT., U=0.84)

HEATING ENERGY SC=e.l SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 3.3 3.1 2.6 1.8 1.1 OIL 3.0 2.8 2.4 1.7 1.1 .0 STEAM 2.7 2.S 2.3 1.7 1.1 .1

10 VEAR PRESENT WORTH FACTOR = 9 . 2 ( GAS ) , 8.0(OIL). 8.7(STEAM), 3.3(ELEC) MATERIAL & INSTALLATION COST = $ 42000.

PAY-SACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= S3.0/SQ. FT., U=0.84>

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 9.0 10.0 13.0 27.0 >30.0 >30.0

OIL 11.0 12.0 15.0 >30.0 >30.0 >30.0

STEAM 12.0 13.0 16.0 >30.0 ^30.0 >30.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAP SCREENS (COST= $3.0/SQ. FT.. U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC = 0.4 SC = 0.6 SC = Cr.3 SC = 1.0 ************** ****** ****** ****** ****** ****** ******

GAS 1.6 1.5 1.3 .9 .5 OIL 1.4 1.3 1.2 .8 .5 .0 STEAM 1.3 1.3 1.1 .8 .5 .0 20 YEAR PRESENT WORTH FACTOR = 1 4 . 3 ( GAS > , 14.g(0IL), 13.6<STEAM), 12.4(ELEC) MATERIAL i, INSTALLATION COST = $125000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= S6.0/SQ. FT., U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= S6.0/SQ. FT.. U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 ^0=1.0 ************** ****** ****** ****** ****** ****** ***««•

GAS .9 .9 .8 .5 .3 ----

OIL .7 .7 .5 .5 .3 .0 , STEAM .8 .7 .7 .5 .3 .»

30 YEAR PRESENT WORTH FACTOR = 1 7 . 3 ( GAS ) , 21.3(OIL>. 16.2(STEAM), 14.5(ELEC) MATERIAL 3, INSTALLATION COST = $252000.

49
50
51
52
Q_ uj a: oLd z: i53
54
Table 7a. Cost-effectiveness for Atlanta U = 0.50, Summer-only Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U»0.50)

HEATING ENERGY SC«0. 1 SC = 0.2 SC»0.4 SC»0.6 SCxO.8 SC»1,0 ••*••••*•*•**« ««•*•« *«•*«« •«•••« >••••• GAS 8961. 8691. 7620. 6221. 4740. 3253.

OIL 8425. 8622. 8359. 7724. 6900. 5991.

STEAM 8221. 8596. 8640. 8294. 7720. 7030.

ASSUMPTIONS: ELECTRICITY COST = $ . 053/KWH

HEATING FUEL COST = $.022(GAS). .038(0IL). . 045 ( STEAM ) /KWH

PAY-QACK PERIODS (YEARS) FOR SOLAR SCREENS (COST. $1.0/SQ. FT.. U»0.50)

HEATING ENERGY SC^^O.I SC = 0.2 SC = 0.4 SC = 0.6 SC = 0.8 SC=1.0

«*•*«« •«*««« GAS 5.0 6.0 6.0 8.0 10.0 14.0

OIL 6.0 6.0 6.0 7.0 8.0 9.0

STEAM 6.0 6.0 6.0 6.0 6.0 7.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST. $1.0/S0. FT., U»0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC«0.6 SC=0.8 SC=1.0 *«««**•*««**«* «*•••« GAS 1.8 1.8 1.6 1.3 1.1 .8 OIL 1.7 1.8 1.7 1.5 1.3 1.1 STEAM 1.7 1.7 1.8 1.7 1.6 1.5

10 YEAR PRESENT WORTH FACTOR " lO.O(GAS). 8.0(0IL). 9.0(STEAM). 8.5(ELEC) MATERIAL & INSTALLATION COST « $ 42000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST. $3.0/50. FT.. U=0.50)

HEATING ENERGY $C=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.a SC^I.O

««««•* «*••• «••««« GAS 24.0 24.0 28.0 >30.0 >30.0 >30.0

OIL 28.0 25.0 24.0 26.0 28.0 30.0

STEAM 28.0 25.0 24.0 25.0 23.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (C0ST= $3.0/S0. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

m * w* * ¥ «*•«««

GAS .9 .9 .8 .7 .6 .5 OIL .9 .9 .9 .9 .8 .7 STEAM .9 .9 .9 .9 .9 .8

20 YEAR PRESENT WORTH FACTOR . 17.5(GAS). 14.6(0IL). 14.2(STEAM). 13.4(ELEC) MATERIAL & INSTALLATION COST $126000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST. $6.0/S0. FT.. U=0.50)

HEATING ENERGY SC. 0.1 SC = 0.2 SC = 0.4 SC.0.6 SC = 0.8 SCl.O

«««*t««*s«tai«* *••*•« •«•*•• «••••« **••*• >••••• GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST. $6.0/S0. FT., U.0.50)

HEATING ENERGY SC«0.1 SC = 0.2 SC. 0.4 SC = 0.6 SC = 0.8 SCl.O

•«*«••••«•«>•* »»«••* »»«« «,»•»« •••••« GAS .6 .6 .5 .5 .4 .3 OIL .5 .6 .6 .6 .5 .5 STEAM .5 .6 .6 .5 .5 .5

30 YEAR PRESENT WORTH FACTOR « 23.3(GAS). 20.8(0IL). 17.1(STEAM). 16.3{ELEC) MATERIAL S INSTALLATION COST « $252000.

55
Table 7b. Cost-effectiveness for Atlanta U = 0.84, Summer-only Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.84)

HEATING ENERGY SC»0.1 SC=0.2 SC-0.4 SC'0.6 SC=0.8 SC«1.0

•«*«•« *•*••« «•«**« GAS 6573. 6380. 5640. 4301. 2914. 1621.

OIL 4451. 4728. 4870. 4265. 3570. 2924.

STEAM 3646. 4102. 4578. 4251. 3819. 3417.

ASSUMPTIONS: ELECTRICITY COST = $.053/KWH

HEATING FUEL COST . $.022(GAS). .03a(0IL). .045( STEAM)/KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST. $1.0/S0. FT.. U=0.84)

HEATING ENERGY SC = 0.1 SC = 0.2 SC:"0.4 SC. 0.6 SC = 0.8 SC^I.O

««•*«•«*««««•« **««•« «»*»««

GAS 8.0 8.0 9.0 13.0 20.0 >30.0

OIL 11.0 10.0 10.0 13.0 16.0 20.0

STEAM 19.0 15.0 12.0 13.0 14.0 16.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (C0ST= $1.0/50. FT.. U=0.84)

HEATING ENERGY SC«0.1 SC=0.2 SC-0.4 SC=0.6 SC=0.8 SC 1 .

*««««**«*««•*«

GAS 1.2 1.2 1.1 .9 .6 .4 OIL 1.0 1.0 1.0 .9 .7 .6 STEAM .7 .8 .9 .9 .8 .7

10 YEAR PRESENT WORTH FACTOR = 10.0(GAS). 8.0(0IL). 9.0(STEAM), 8.5(ELEC) MATERIAL & INSTALLATION COST - $ 42000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST. $3.0/S0. FT.. U=0.84)

HEATING ENERGY SCO.I SC = 0.2 SC = 0.4 SC. 0.6 50 = 0.8 SC=1.0

*»«»*«»«•»••»» ••«***

GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST- $3.0/S0. FT.. U=0.84)

HEATING ENERGY SC-O.I SC = 0.2 SC = 0.4 SC='0.6 SC = 0.8 SC=1.0

• •• *••«•«•••'* * **•**« »«««*• ««*«••

GAS .6 .6 .6 .5 .3 .2 OIL .4 .5 .5 .5 .4 .3 STEAM .3 .4 .5 .5 .4 .4

20 YEAR PRESENT WORTH FACTOR . 17.5(GAS), 14.6(0IL), 14.2(STEAM). 13.4(ELEC) MATERIAL & INSTALLATION COST » S126C00.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST" $6.0/S0. FT., U=0.84)

HEATING ENERGY SC'O.I SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

«••»*»•••••»»• »«»•»» tttrtt «•*«*• GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST. $6.0/S0. FT., U=0.84)

HEATING ENERGY SC.Q. 1 SC=0.2 SC=0.4 SC=0.6 50=0.8 SC=1.0

*««v*4r •^^v**

CAS .3 .4 .3 .3 .2 .2 OIL .2 .2 .3 .3 .3 .2 STEAM .2 .2 .3 .3 .3 .2

30 YEAR PRESENT WORTH FACTOR = 23.3(GAS), 20.8(0IL), 17.1(STEAM), 16.3(ELEC) MATERIAL & INSTALLATION COST = $252000.

56
Table 7c. Cost-effectiveness for Atlanta U = 0.50, All-year Cooling

FIRST YEAR ENERGY SAVINGS {DOLLARS) FOR SOLAR SCREENS (U=0.50)

HEATING ENERGY SC=jer.l SC=0.2 SC=0.4 SC=0.6 SC=0.3 SC=1.0 «***«**« «« ** **** ****** ****** **•«*« ****** ******

GAS 15289. 13S88. 10345. 7252. 3986. 306. OIL 15203. 13913. 11170. 8701. 6010. 2943.

STEAM 15170. 13999. 11483. 9250. 6778. 3944.

ASSUMPTIONS: ELECTRICITY COST = $.053/KWH

HEATING FUEL COST = $.022(GAS). .038(OIL). . 04 5 ( STEAM ) / KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= SI. 0/50. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.3 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 3.0 4.0 5.0 7.0 12.0 >30.0

OIL 3.0 4.0 4.0 6.0 9.0 19.0

STEAM 3.0 4.0 4.0 5.0 7.0 12.0

SAVING3-T0-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $1.0/Sa. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 3.1 2.8 2.1 1.5 .9 .2 OIL 3.1 2.8 2.2 1.7 1.2 .5 STEAM 3.1 2.8 2.4 1.9 1.4 .9 10 YEAR PRESENT WORTH FACTOR = 10.0(GAS), 8.0<OIL), 9.0(STEAMi, 8.5(ELEC)

MATERIAL & INSTALLATION COST = $ 42000r.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS {COST= $3.0/SQ. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 10.0 12.0 17.0 28.0 >30.0 /30.0

OIL 10.0 11.0 15.0 22.0 >30.0 >30'.0 STEAM 10.0 11.0 15.0 20.0 ^30.0 ^^30.0

SAVING3-T0-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $3.0/SQ. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC-0.6 SC=0.8 SC=1.0 ************** ***A** ****** ****** ***\** ****** ******

GAS 1.6 1.5 1.1 .8 .5 .1 OIL l.G 1.5 1.2 1.0 .7 .4 STEAM 1.6 1.5 1.2 1.0 .3 .5 20 YEAR PRESENT WORTH FACTOR = 1 7 . 5 ( GAS ) . 14.5(OIL>, 14.2<STEAM), 13.4(ELEC)

MATERIAL & INSTALLATION COST = $126000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $6.0/SO. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-T0-1nVESTMENT RATIOS FOR SOLAR SCREENS (COST= $6.0/SQ. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC = er.G SC = 0.8 SC=1.0 ************** ****** ****** ****** ****** V***** ******

GAS 1.0 .9 .7 .5 .3 .1 OIL 1.0 .9 -8 .6 .5 .3 STEAM 1.0 .9 .7 .6 .5 .3

30 YEAR PRESENT WORTH FACTOR = 23.3(GAS), 20.8(OIL), 17.1{STEAMi. l6.3iELEC)

MATERIAL & INSTALLATION COST = $252000.

57
Table 7d. Cost-effectiveness for Atlanta U = 0.8A, All-year Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.S SC=0.8 SC=1.0

****** ****** ****** ****** ****** ******

GAS 12793. 11534. 8846. 6159. 3487. 675. OIL 11076. 10153. 8112. 6097. 4095. 1931.

STEAM 10424. 9629. 7834. 6073. 4327. 2408.

ASSUMPTIONS: ELECTRICITY COST = $.053/KWH

HEATING FUEL COST = $.022(GAS>. .038(OIL), . 04 5 ( STEAM ) / KWH

PAY-BACK PERIODS < YEARS > FOR SOLAR SCREENS (COST= $1.0/SQ. FT.. U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ******  f**  ******

GAS 4.0 4.0 6.0 3.0 16.0 >30.0

OIL 4.0 5.0 6.0 8.0 14.0 29.0

STEAM 5.0 5.0 6.0 8.0 12.0 30.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $1.0/SQ. FT., U=gr.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 2.5 2.3 1.8 1.2 .7 .2 OIL 2.3 2.1 1.7 1.2 .8 .4 STEAM 2.1 1.9 1.6 1.2 .9 .5 10 /EAR PRESENT WORTH FACTOR = 10.0(GAS), 8.0<OIL), 9.0<STEAM), 8.5(ELEC>

MATERIAL & INSTALLATION COST = $ 42000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= S3.0/SQ. FT., U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.a SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 13.0 16.0 25.0 >30.0 >30.0 >30.0

OIL 16.0 18.0 >30.0 >30.0 >30.0 >30.0

STEAM 13.0 21.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS <COST= $3.0/SQ. FT., U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.5 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 1.3 1.2 .9 .7 .4 .1 OIL 1.1 1.0 .8 .6 .4 .2 STEAM 1.1 1.0 .8 .6 .5 .3 20 YEAR PRESENT WORTH FACTOR = 17.5(GAS), 14.6(0IL;, 14.2(STEAM), 13.4(ELEC)

MATERIAL & INSTALLATION COST = $126000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS ( COST= S6.0/SQ. FT.. U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

«-««««*«**«** ****** «**««* ****** ****** ****** ******

GAS >30.0 >30.0 >30.0 >30.0 ^30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >3er.0 >30.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS {COST= $6.0/SQ. FT., U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

************** ****** ****** ****** ****** *««**« ******

GAS .8 .7 .5 .4 .2 .1 OIL .6 .6 .5 .4 .3 .2 STEAM .7 .6 .5 .4 .3 .2

30 YEAR PRESENT WORTH FACTOR = 23.3(GAS), 20 . 8 ( 0 1 L ) . 17.1(STEAM), 16.3(ELEC>

MATERIAL & INSTALLATION COST = S252000.

53
uj -J uj o I- Qt: •-• o t- > £:aj(-3

59
—I

— 1 T 1 1 r O <S> O O (S o o ® o o 
 <s m ^ n fu '-t

"<r "V

T

60
61
Q- UJ :: O UJ z t62
Q-LiJQ:0|jLJZf63
Table 8a. Cost-effectiveness for Houston U = 0.50, Summer-only Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.50)

HEATING ENERGY SC-0.1 SC=0.2 SC=0.4 SC=0.6

«*«*«*

GAS 10187. 9234. 7246. 5116.

OIL 9227. 8700. 7519. 6076.

STEiM 8970. 8557. 7593. 6333.

SC=0.8 SC»1.0

••*•«* «««*••

3102.

4641 . 5053.

990.

2986.

3520.

ASSUMPTIONS: ELECTRICITY COST » $.050/KWH

HEATING FUEL COST a $.015(GAS) ,038(0IL), .045(STEAM)/KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST« $1.0/S0. FT., U=0.50)

HEATING ENERGY SC^O.I SC=0.2 SC=0.4 SC=0.6 SC=0.8 SCxI.O

*«•««**•«•«•*«

GAS 5.0 5.0 7.0 10.0 20.0 >30.0

OIL 5.0 6.0 7.0 8.0 12.0 19.0

STEAM 5.0 6.0 6.0 8.0 10.0 16.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST* $1.0/S0. FT., U=0.50)

HEATING ENERGY SC^O.I SC=0.2 SC»0.4 SC^O.e SC=0.8 SC»1.0

«««*«**•••.•** *•*«««

GAS 2.0 1.8 1.4 1.0 .6 .2 OIL 1.8 1.7 1.5 1.2 .9 .6 STEAM 1.8 1.7 1.5 1.3 1.0 .7

10 YEAR PRESENT WORTH FACTOR » 9.3(GAS). MATERIAL & INSTALLATION COST » $ 42000.8.0(0IL). 8.8(STEAM). 8.3(ELEC)

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST» $3.0/50. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC«0.4 •••*•*•••***•

GAS OIL

STEAM

19.0

25.0

25.0

23 .0 28 .0 28 .0

>30. 0 >30.0

>30.0

SC=0.6

>30 .0 >30.0

>30.0

SC=0.8

>30.0

>30.0

>30.0

SC=1 .0 >30.0

>30.0

>30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST* $3.0/50. FT HEATING ENERGY SC=0.2 »»•••«•«»•»•

GAS

OIL STEAM

SC=0.

«*••»«

1 .0.9.9

SC=0.

•* **»»

.9 .7

.9 .8

.9 .8

SC=0.6 ••»•»

.5.6

.7

SC=0.8

•*•»*•

.3

.5

.5

20 YEAR PRESENT WORTH FACTOR « 15.2(GAS). 14.6(0IL), 14.1(STEAM) MATERIAL & INSTALLATION COST = $126000.

U=0.50)

SC=1 .0 *«•**«

. 1 .4

.4

12. 9( ELEC)

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST- $6.0/S0. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 ^SO.O >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $6.0/50. FT.. U=0.50)

HEATING ENERGY SC«0.1 SC=0.2 SC«0.4 SCxO.6 SC»0.8 SC»1.0

«•<•••••.•«<«• •**••« •*•««« «•*««« *»>««* GAS .6 .6 .5 .3 .2 .1 OIL .5 .5 .5 .4 .3 .3 STEAM .5 .5 .5 .4 .3 .2 30 YEAR PRESENT WORTH FACTOR = 19.3(GAS). MATERIAL 5 INSTALLATION COST = $252000.

21.0(0IL). 17.4(STEAV), 15.6(ELEC)

64
Table 8b. Cost-effectiveness for Houston U = 0.84, Summer-only Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.84)

HEATING ENERGY SC«0.1 SC=0.2 SC-0.4 SC»0.6 SC=0.8 SC»1.0 ««•«««•«*>•»*• •*«••* ••**** ««>«• •••••« GAS 8980. 8111. 6227. 4367. 2532. 608.

OIL 6857. 6397. 5294. 4162. 2954. 1577.

STEAM 6289. 5938. 5044. 4107. 3067. 1836.

ASSUMPTIONS: ELECTRICITY COST :i $ . 050/KWH

HEATING FUEL COST = $.015(GAS). .03a(01L), . 045( STEAM)/KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST. $1.0/SQ. FT.. U^-O.BA)

HEATING ENERGY 30*0.1 SC=0.2 SC=0.4 SC.0.6 SC=0,8 SC=1.0

«•«**« ««««^« GAS 6.0 5.0 8.0 13.0 >30.0 >30.0

OIL 7.0 8.0 10.0 14.0 23.0 >30.0

STEAM 8.0 9.0 11.0 14.0 22.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (C0ST« $1.0/S0. FT., U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC^I.O

««*««« *««*•« «•*«•« GAS 1.8 1.6 1.2 .9 .5 .1 OIL 1.4 1.3 1.1 .8 .6 .3 STEAM 1.2 1.1 1.0 .8 .6 .4

10 YEAR PRESENT WORTH FACTOR = 9.3(GAS). 8.0(0IL), 8.8(STEAM). 8.3(ELEC)

MATERIAL & INSTALLATION COST » $ 42000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST» $3.0/S0. FT.. U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.a SC=1.0

t m * m * t GAS 26.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (C0ST= $3.0/S0. FT., U=0.84)

HEATING ENERGY SC^O.I SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

*«*«««

GAS .9 .8 .6 .4 .3 .1 OIL .7 .6 .5 .4 .3 .2 STEAM .6 .6 .5 .4 .3 .2

20 YEAR PRESENT WORTH FACTOR = 15.2{GAS). 14.6(0IL). 14.1(STEAM). 12.9(ELEC)

MATERIAL & INSTALLATION COST « $126000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST- $6.0/S0. FT., U=0.84)

HEATING ENERGY SC^O.1 SC=0.2 SC=0.4 SC=0.6 SC=0.a SC=1.0

GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $6.0/SQ. FT., U=0.84)

HEATING ENERGY 50*0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

*»«*««•« •««** *«««*( ««».»• «»*«*• ««*•»* ».».»• •«•••• GAS .5 .5 .4 .3 .2 .0 OIL .3 .3 .3 .3 .2 .1 STEAM .4 .3 .3 .3 .2 .1

30 YEAR PRESENT WORTH FACTOR = 19.3(GAS). 21.0(0IL). 17.4(STEAM). 15.6(ELEC) MATERIAL & INSTALLATION COST = $252000.

65
Table 8c. Cost-effectiveness for Houston U = 0.50, All-year Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.5 SC=0,8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 14375. 13093. 10650. 5905. 3224. -423.

OIL 12649. 11985. 10806. 7701. 4665. 1670.

STEAM 12187. 11689. 10848. 7913. 5051. 2230.

ASSUMPTIONS: ELECTRICITY COST = $.050/KWH

HEATING FUEL COST = $.015{GAS). .038(OIL), . 04 5 ( STEAM > / KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $1.0/SQ. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 4.0 4.0 5.0 7.0 19.0 >30.0

OIL 4.0 4.0 5.0 6.0 12.0 29.0

STEAM 4.0 4.0 5.0 6.0 10.0 >30.0

SAVINGS-TO-INVESTMENT PATIOS FOR SOLAR SCREENS (COST= $1.0/SQ. FT., U=0.50>

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 2.8 2.5 2.1 1.4 .7 OIL 2.5 2.4 2.1 1.5 .9 .3 STEAM 2.4 2.3 2.2 1.5 1.0 .5

10 YEAR PRESENT WORTH FACTOR = 9 . 3 ( GAS ) . 8.0(OIL), 8.8(STEAM), 8.3(ELEC)

MATERIAL i INSTALLATION COST = $ 42000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= S3.0/SQ. FT., U-0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 11.0 13.0 17.0 >30.0 >30.0 >30.0

OIL 13.0 15.0 17.0 30.0 >30.0 >30.0

STEAM 15.0 15.0 17.0 30.0 >30.0 >30.0

SAVINGS-TO-INVESTMENT PATIOS FOR SOLAR SCREENS (COST= $3.0/SQ. FT., i.'=0.30)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.S SC=0.8 SC=I.0 ************** ****** ****** ****** ****** ****** ******

GAS 1.5 1.3 1.1 .7 .3 OIL 1.3 1.2 1.1 .8 .5 .2 STEAM 1.2 1.2 1.1 .8 .5 .3 ?0 YEAR PRESENT WORTH FACTOR = 1 5 . 2 ( GAS ) , 14.6{0IL), U.KSTEAM). 12.9(£LEC>

MATERIAL i, INSTALLATION COST = $126000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (CDST= S6.0/SQ. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVING3-?0-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $6.0/SQ. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.5 SC=0.8 SC=1.0

************** ****** ****** ****** ****** ****** ******

GAS .9 .8 .7 .4 .2 OIL .7 .7 .7 .5 .3 .2 STEAM .7 .7 .7 .5 .3 .2 30 YEAR PRESENT WORTH FACTOR = 1 9 . 3 ( GAS ) , 21.0(OIL>. 17.4{STEAM), 15.G(ELEC)

MATERIAL & INSTALLATION COST = $252000.

66
Table 8d. Cost-effectiveness for Houston U = 0.84, All-year Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=£r.4 SC=0.6 SC=0.8 SC=1.0 **««***«**•«»* *««*«« * * * * X • ****** ****** ****** ******

GAS 13108. 11963. 9754. G475. 3198. -42. OIL 10091. 9571. 8626. 6046. 3497. 950.

STEAM 9283. 8931. 8324. 5932. 3577. 1216.

ASSUMPTIONS: ELECTRICITY COST = $.050/KWH

HEATING FUEL COST = $.015(GAS), .038(OIL). . 04 5 ( S TEAM ) / KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= 'E1.0/SQ. FT., U=0.34)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 4.0 4.0 5.0 8.0 21.0 >30.0

OIL 5.0 5.0 6.0 8.0 18.0 >30.0

STEAM 5.0 5.0 6.0 9.0 17.0 >30.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= S1.0/SQ. FT., U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

*************** ****** ****** ****** ****** ****** ******

GAS 2.6 2.3 1.9 1.3 .6 .0 OIL 2.0 1.9 1.7 1.2 .7 .2 STEAM 1.8 1.7 1.6 1.2 .7 .3

10 YEAR PRESENT WORTH FACTOR = 9.3(GAS), 8.0(OIL>, 3.8(STEAM), 8.3'ELEC)

MATERIAL & INSTALLATION COST = $ 42000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $3.0/SQ. FT., U=0.S4)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

**:tik:k-^it-k*1icit*ifti ii * 1r k ic It It it it -k it -k * k it k it * ir k It * it k it k k k k k k k k k k k GAS 13.0 15.0 21.0 >30.0 >30.0 >30.0

OIL 24.0 29.0 >30.0 >30.0 >30.0 >30.0

STEAM 26.0 28.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO-INVESTMENT PATIOS FOR SOLAR SCREENS (COST= $3.0/SQ. FT., U=0.84)

HEATING ENERGY SC=0.l SC=0.2 SC=0.4 SC=0.5 SC=0.3 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 1.3 1.2 1.3 .7 .3 .0 OIL 1.0 .9 .9 .6 .4 .1 STEAM .9 .9 .8 .6 .4 .1 20 YEAR PRESENT WORTH FACTOR = 1 5 . 2 ( GAS ) . 14.G{0IL). 14.1(STEAM). 12.9(ELEC)

MATERIAL & INSTALLATION COST = $126003.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= S6.0/Sa. FT.. U=a.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1 0 *****»«*«***** ««**«« ****** ****** **«««* «««*«* ******

GAS )30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO-INVESTMENT PATIOS FOR SOLAR SCREENS (COST= $6.0/SO. FT., U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 ^0=1 0 ************** ****** ****** ****** ****** ****** ***,«.

GAS .8 .7 .6 .4 .2 .0 OIL .5 .5 .5 .4 .2 STEAM .5 .5 .5 .4 .2 .1

30 YFAR PRESENT WORTH FACTOR = 1 9 . 3 ( GAS ) , 21.0(OIL). 17.4(STEAM>, 15.6(ELEC)

MATERIAL & INSTALLATION COST = S252000.

67
LlU LU O I- Q: »-* O H-i I- > EOQI-ZD

68
V)I-lj<ie:

69

QL Lj o ui z: I71
CLIxIQ^OUJZh72
Table 9a. Cost-effectiveness tor Washington, D.C. U = 0.50, Summer-o

Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.50)

HEATING ENERGY SC»0.1 SC=0.2 SC»0.4 SC'0.6 SC=0.8 SC-1.0 «««««***«*««*« «*»*•« *««••• GAS 11782. 11722. 10663. 9193. 7387. 5370.

OIL 11605. 11867. 11364. 10404. 9050. 7427.

STEAM 11473. 11974. 11882. 11300. 10280. 8949.

ASSUMPTIONS: ELECTRICITY COST = $.073/KWH

HEATING FUEL COST = $.028(GAS). .038(0IL). . 045 ( STEAM ) /KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST* $1.0/S0. FT.. U»0.50)

HEATING ENERGY SC«0.1 SC=0 2 SC»0.4 SC-0.6 SC=0.8 SC=1.0 ••*•««•*«•«•«' ****«« «••»•«

GAS 4.0 4,0 5.0 5.0 6.0 8.0

OIL 4.0 4.0 4.0 5.0 6.0 7.0

STEAM 4.0 4.0 4.0 4.0 5.0 5.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST- $1.0/SQ. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

••««•• GAS 2.3 2.4 2.2 2.0 1.6 1.3 OIL 2.3 2.4 2.2 2.0 1.7 1.4

STEAM 2.3 2.4 2.4 2.3 2.1 1.9

10 YEAH PRESENT WORTH FACTOR = 9.8(GAS). 8.0(0IL), 8.9(STEAM). 8.4(ELEC) MATERIAL & INSTALLATION COST a $ 42000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $3.0/SQ. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ««•*•«««*«•«« «««««* tf m t * w * «*••«« «***•• •«««•« GAS 15.0 15.0 16.0 19.0 24.0 >30.0

OIL 15.0 15.0 15.0 17.0 20.0 24.0

STEAM 15.0 14.0 14.0 15.0 17.0 20.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $3.0/SQ. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ««•>•«•««•«•«• ••**•* *••«•« *•*•** ••«»«• GAS 1.2 1.2 1.2 1.1 .9 .7 OIL 1.2 1.2 1.2 1.1 1.0 .9 STEAM 1.2 1.2 1.3 1.2 1.1 1.0

20 YEAR PRESENT WORTH FACTOR = 16,6(GAS). 14.6(0IL). 14.2(STEAM). 13.0(ELEC) MATERIAL & INSTALLATION COST « $126000.

PAY-3ACK PERIODS (YEARS) FOR SOLAR SCREENS (COST. $6.0/S0. FT., U=0.50)

HEATING ENERGY SC-0. 1 SC=0.2 SC=0.4 SC=0.6 SC=0.a SC=1.0

•«*«•«.,..<'•* »••»« ,,,».. «.«.»« ***>.* »,...» ».•.«» GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST- $6.0/50. FT.. U=0.50)

HEATING ENERGY^ SC-0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC-1.0

*•*«>••••••••* «•»»•» »»•••» «»•••« •»»••• •».»•» »••»»• GAS .7 .7 .7 .7 .6 .5 OIL .7 .7 .8 .7 .7 .6 STEAM .7 .7 .8 .7 .7 .6

30 YEAR PRESENT WORTH FACTOR = 21.4(GAS). 20.8(0IL). 17.5(STEAM). 15.6(ELEC) MATERIAL & INSTALLATION COST « $252000.

73
Table 9b. Cost-effectiveness for Washington, D.C. U = 0.84, Summer-only

Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.84)

HEATING ENERGY $C«0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC»1.0

•«•••*•«••*•*« •*•*•« ••««*• *«*•«• ••*>*• *««•** «>**«*

GAS 7242. 7331. 6937. 5786. 4361. 2616.

OIL 5806. 6238. 6468. 5841. 4909. 3589.

STEAM 4744. 5430. 6120. 5883. 5316. 4309.

ASSUMPTIONS: ELECTRICITY COST = $,073/KWH

HEATING FUEL COST = $.028(GAS) .038(0IL), .045(STEAM)/KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (C0ST= $1.0/S0. FT.. U=0.84)

HEATING ENERGY SC'0.1 SC=0.2 SC«0.4 SC=0.6 SC=0.8 SC=1.0

**«««*••««««*«

GAS 7.0 7.0 7.0 9.0 12.0 19.0

OIL 8.0 8.0 8,0 9.0 1 1 .0 16.0

STEAM 13.0 10.0 8.0 9.0 9.0 12.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (C0ST= $1.0/S0. FT. HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 *••«••••••«»«« «»*»«• *•«••* GAS 1.3 1.4 1.3 1.2

OIL 1.2 1.3 1.3 1.2 STEAM .9 1.0 1.2 1.2

.9

1 .0

1 .

10 YEAR PRESENT WORTH FACTOR = 9.8(GAS) MATERIAL & INSTALLATION COST » $ 42000.

U=0. 84)

SC=1 .0 *«««*«

.6

. 7

.9 8.0(0IL). 8.9(STEAM). 8.4(ELEC)

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $3.0/S0. FT.. U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC«0.4 SC=0.6 SC=0.8 SC=1.0

•*«*** •«•*«« GAS >30.0 >30 0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COSTx $3.0/S0. FT., U=0.84)

HEATING ENERGY SC^O.I SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

GAS .6 .7 .7 .6 .5 .4 OIL .5 .6 .6 .6 .5 .4 STEAM .4 .5 .6 .6 .6 .5 20 YEAR PRESENT WORTH FACTOR = 16.6(GAS). 14.6(0IL), MATERIAL & INSTALLATION COST = $126000.

14.2(STEAM). 13.0(ELEC)

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST« $6.0/SQ. FT., U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC»1.0

«««**«•«««*.«* *««^*« **««*<i GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $6.0/50. FT HEATING ENERGY

GAS

OIL STEAM

SC=0.

•»*••»

.3

.2

.2

SC=0 .

«****«

.4

.3.3

SCxO.4

*•«*••

.4

.4

.4

SC=0.5

.4

.4.4

SC=0.8

*••»••

.3

.3

.3 30 YEAR PRESENT WORTH FACTOR « 21.4(GAS), 20.8(0IL), 17.5(STEAM) MATERIAL & INSTALLATION COST = $252000.

U«0. 84)

SC=1 .0

.2

.3.3

15. 6( ELEC)

74
Table 9c. Cost-effectiveness for Washington, D.C. U = 0.50, All-year

Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=gr.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

iiltliiiii*li**-k*-k-*iii ****** ****** ****** ****** ****** ******

GAS 21790. 19251. 14526. 10331. 6334. 2437.

OIL 22063. 19675. 15275. 11411. 7824. 4423.

STEAM 22265. 19988. 15830. 12210. 8327. 5855.

ASSUMPTIONS: ELECTRICITY COST = $.073/KWH

HEATING FUEL COST = $.028(GAS). .038(OIL), . 04 5 ( STEAM ) / KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= S1.0/SQ. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 2.0 3.0 3.0 5.0 7.0 16.0

OIL 2.0 3.0 3.0 4.0 7.0 13.0

STEAM 2.0 3.0 3.0 4.0 5.0 8.0

SAVINGS-TO-INVESTMENT PATIOS FOR SOLAR SCREENS (COST= $1.0/SQ. FT., U=0.50>

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.3 SC=1.0

*******-******* ****** ****** ****** ****** ****** ******

GAS 4.4 3.9 3.0 2.2 1.4 .7 OIL 4.4 3.9 3.0 2.2 1.5 .3 STEAM 4.5 4.0 3.2 2.5 1.9 1.3

10 YEAR PRESENT WORTH FACTOR = 9.8(GAS>, 8.0(OIL). 8.9(STEAM), 8.4<ELEC) MATERIAL & INSTALLATION COST = $ 42000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS {COST= S3.0/SQ. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.5 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 7.0 8.0 11.0 16.0 /30.0 ^30.0

OIL 7.0 3.0 ier.0 15.0 24.0 >30.0

STEAM 7.0 7.0 10.0 13.0 21.0 >30.0

SAVINGS-TO-INVESTMENT PATIOS FOP SOLAR SCREENS (COST= $3.0/SQ. FT., U=0.50)

HEATIMG ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=,7.3 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 2.3 2.0 1.5 1.2 .8 .4 OIL 2.3 2.0 1.6 1.2 .9 .6 STEAM 2.3 2.1 1.7 1.3 1.0 .7 20 YEAR PRESENT WORTH FACTOR = 16.6{GAS), 14.6(0IL). 14.2(STEAM). 13.0(ELEC> MATERIAL & INSTALLATION COST = S126000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $6.0/SQ. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 16.0 20.0 >30.0 >30.0 >30.0 >30.0

OIL 16.0 20.0 30.0 >30.0 >30.0 >30.0

STEAM 16.0 19.0 30.0 >30.0 >30.0 >30.0

SAVINGS-TO-INVESTMENT PATIOS FOR SOLAR SCREENS (COST= $6.0/SQ. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.5 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 1.4 1.2 .9 .7 .5 .3 OIL 1.4 1.2 1.0 .8 .5 .4 STEAM 1.4 1.2 1.0 .8 .6 .4 30 YEAR PRESENT WORTH FACTOR = 2 1 . 4 ( GAS ) , 20.8(OIL). 17.5(STEAM^, 15.6(ELEC) MATERIAL & INSTALLATION COST = $252000.

75
Table 9d . Cost-effectiveness for Washington, D.C. U = 0.84, All-year

Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 17426. 15439. 11243. 7979. 4748. 1692. OIL 16401. 14605. 10802. 7966. 5185. 2624.

STEAM 15642. 13988. 10477. 7956. 5509. 3314.

ASSUMPTIONS: ELECTRICITY COST = $.073/KWH

HEATING FUEL COST = $.028(GAS). .038(OIL), . 04 5 ( STEAM ) / KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $1.0/SQ. FT.. U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 3.0 3.0 4.0 6.0 11.0 30.0

OIL 3.0 3.0 5.0 5.0 10.0 21.0

STEAM 3.0 4.0 5.0 6.0 9.0 16.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS <COST= S1.0/SO. FT., U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 3.4 3.0 2.2 1.5 1.0 .4 OIL 3.3 3.0 2.2 1.5 1.0 .5 STEAM 3.1 2.8 2.1 1.6 1.1 .7 10 /EAR PRESENT WORTH FACTOR = 9.8(GAS), 8.0<OIL). 8.9{STEAM). 8.4(ELEC)

MATERIAL & INSTALLATION COST = $ 42000.

PAY-BACK PERIODS 'YEARS) FOR SOLAR SCREENS (COST= S3.0/Sa. FT., U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC-0.8 SC=1.0

**r************ ****** ****** ****** ****** ****** ******

GAS 9.0 10.0 17.0 >30.0 >30.0 y30.l3 OIL 9.0 11.0 17.0 >30.0 >30.0 >30.0

STEAM 10.0 12.0 18.0 >30.0 >30.0 >30.0

SAV I NGG-TO- I NVESTMENT RATIOS FOR SOLAR SCREENS (COST= S3.0/SQ. FT., U=0.34)

HEATING ENERGY SC = 0f.l SC=0.2 SC = 0.4 SC=0.6 SC=0.8 SC=1.0

  ** ******* ****** ****** ****** ****** ****** ******

GAS 1.7 1.5 1.1 .3 .5 .3 OIL 1.6 1.5 1.1 .8 .6 .3 STEAM 1.6 1.4 1.1 .8 .6 .4 20 YEAR PRESENT WORTH FACTOR = 1G.6(GAS), 14.5(OIL), 1 4 . 2 ( S T ^AM ) , 13.0'ELEC)

MATERIAL i INSTALLATION COST = $126000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $6.0/Sa. FT., U=0.34)

HEATING ENERGY SC = 0.1 SC=0.2 SC=0.4 SC=0.6 SC = Cr.8 SC=1.0

********* ^  ** **** ****** ****** ****** ****** ******

GAS 30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.er STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= S5.0/SQ. FT., U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

************** ****** ****** ****** ****** ****** ******

GAS 1.0 .9 .7 .5 .3 .2 OIL .9 .8 .6 .5 .4 .2 STEAM .9 .8 .6 .5 .4 .2 30 YEAR PRESENT WORTH FACTOR = 2 1 . 4 ( GAS ) , 20.8(OIL), 17.5<STEAM), 15.6(ELEC)

MATERIAL & INSTALLATION COST = $252000.

76
77
78
l-OI-« J

79
a. q: uj o Lj z {-

80
Q_ LU O LjJ Z: E81
Table 10a. Cost-effectiveness for Chicago U = 0.50, Summer-only Cooli

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.50)

HEATING ENERGY SC-0 . 1 SC«0.2 SC»0.4 SC-0.6 SC=0.8 SCal.O

*««*«« •«*«»• ««*««• ««•«*• GAS 12002. 12152. 11787. 10592. 9158. 7425.

OIL 12843. 13683. 14583. 14462. 14032. 13149.

STEAM 13162. 14264. 15643. 15930. 15830. 15320.

ASSUMPTIONS: ELECTRICITY COST x $.068/KWH

HEATING FUEL COST . $.022(GAS). .038(011). .045( STEAM)/KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST. $1.0/S0. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC»0.6 SC=0.8 SC=1.0

•««««« «*•««« «*•«*« GAS 4.0 4.0 4.0 4.0 5.0 6.0

OIL 4.0 4.0 4.0 4.0 4.0 4.0

STEAM 4.0 4.0 3.0 3.0 3.0 3.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (C0ST= $1.0/SQ. FT.. U=0.50)

HEATING ENERGY SC^O.1 SC = 0.2 SC = 0.4 SC = 0.6 SC = 0.8 SC= 1 .

GAS 2.4 2.5 2.5 2.3 2.0 1.7

OIL 2.6 2.7 2.9 2.8 2.7 2.5

STEAM 2.7 2.9 3.2 3.3 3.3 3.2

10 YEAR PRESENT WORTH FACTOR = 9.6(GAS). 8.0(0IL). 8.a(STEAM). 8.4(ELEC) MATERIAL & INSTALLATION COST = $ 42000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (C0ST= $3.0/SQ. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

GAS 14.0 13.0 14.0 15.0 18.0 22.0

GIL 13.0 12,0 11.0 11.0 12.0 13.0

STEAM 12.0 11.0 10.0 9.0 9.0 10.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST. $3.0/S0. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC= 1 .

«««««« GAS 1.3 1.3 1.3 1.2 1.1 1.0

OIL 1.3 1.5 1.6 1.6 1.6 1.5

STEAM 1.4 1.5 1.7 1.7 1.7 1.7

20 YEAR PRESENT WORTH FACTOR . 16.2{GAS). 14.7(0IL). 13.9(STEAM). 12.9(EL£C) MATERIAL & INSTALLATION COST = $126000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST. $6.0/S0. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0 2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

«***^«

GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 29.0 27.0 27.0 27.0

STEAM >30.0 >30.0 >30.0 29.0 28.0 29.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST. $6.0/S0. FT.. U.0.50)

HEATING ENERGY SC-Cl SC = 0.2 SC. 0.4 SC = 0.6 SC = 0.8 SC=1.0

•••*•••*•*•*•• »••• ««««•

GAS .8 .8 .8 .8 .7 .6 OIL .8 .9 1.0 1.1 1.1 1.1 STEAM .8 .9 1.0 1.0 1.0 1.0

30 YEAR PRESENT WORTH FACTOR = 21.0(GAS). 21.1(0IL). 16.7(STEAM). 15.4(ELEC) MATERIAL & INSTALLATION COST = $252000.

82
Table 10b. Cost-effectiveness for Chicago U = 0.84, Summer-only Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.84)

HEATING ENERGY SC=G. 1 SC = 0.2 SC3O.4 SC:»0.6 SC = 0.a SC=1,0 «*«*****«****^ «««««« GAS 6137. 6675. 6747. 6184. 4959. 3627.

OIL 3386. 4730. 6176. 6856. 6706. 6374.

STEAM 2342. 3992. 5960. 7111. 7369. 7416.

ASSUMPTIONS: ELECTRICITY COST « $.068/KWH

HEATING FUEL COST « $.022(GAS), .038(0IL). . 045 ( STEAM )/ KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST. $1.0/S0. FT., U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC»0.6 SC=0.8 SC=1.0 *•*•**••*««»** ••*•** ««•..*

GAS 9.0 8.0 7.0 8.0 10.0 13.0

OIL >30.0 11.0 8.0 7.0 8.0 8.0

STEAM >30.0 15.0 9.0 7.0 7.0 6.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST. Sl.O/SO. FT.. U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC. 0.4 SC=0.6 SC=0.3 SC=1.0

• •*•** ««*«*• GAS 1.1 1.3 1.3 1.3 1.1 .8 OIL .7 1.0 1.3 1.4 1.3 1.2 STEAM .4 .8 1.2 1.4 1.5 1.6

10 YEAR PRESENT WORTH FACTOR = 9.6{GAS). 8.0(0IL). 8.8(STEAM), 8.4(ELEC) MATERIAL & INSTALLATION COST = $ 42000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST. $3.0/S0. FT.. U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC. 0.4 SC=0,6 SC=0.8 SC=1.0

«•««••

GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 30.0 28.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS- TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COSTx $3.0/S0. FT.. U.0.84)

HEATING ENERGY SC. 0.1 SC = 0.2 SCO. 4 SCO. 6 SC = 0.8 SC 1 .

0

««•««« GAS .5 .6 .7 .7 .6 .5 OIL .3 .4 .6 .7 .7 .7 STEAM .2 .4 .6 .7 .8 .8

20 YEAR PRESENT WORTH FACTOR = 16.2(GAS). 14.7(0IL). 13.9(STEAM). 12.9(ELEC) MATERIAL & INSTALLATION COST » $126000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST. $6.0/S0. FT.. U=0.84)

HEATING ENERGY SC.Q.I SCO. 2 SC = 0.4 SC = 0.6 SC = 0.8 SC=1.0

*v*-«v *••••• GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST. SS.O/SQ. FT.. U=0.84)

HEATING ENERGY SC = 0.1 SCO. 2 SC=0.4 SC = 0.6 SC = 0.8 SC 1 .

0

*•«•<•««,>«•** *•«*»• •.»».« GAS .3 .3 .4 .4 .4 .3 OIL .1 .2 .3 .5 .5 .5 STEAM .1 .2 .4 .4 .5 .5

30 YEAR PRESENT WORTH FACTOR « 21.0(GAS), 21.1(0IL). 16.7(STEAM). 15.4(ELEC) MATERIAL & INSTALLATION COST « $252000.

83
Table 10c. Cost-effectiveness for Chicago U = 0.50, All-year Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.50)

HEATING ENERGY SC=0.1 SC=j0f.2 SC=0.4 SC=0.6 SC=0.8 SC = 1.0

GAS

OIL

STEAM

******

19215 . 20799

21399.

******

17404

19418.

20182

******

13311.

16713

17813 .

10585

1 4350.

15778 .

7391 ,

1 2043

1 3803

******

3947 . 9434 . 11515.

ASSUMPTIONSELECTRICITY COST = $.068/KWH

HEATING FUEL COST = $.022(GAS) .038(OIL), .045(STEAM)/KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS {COST= $1.0/SQ. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 3.0 3.0 4.0 4.0 5.0 11.0

OIL 3.0 3.0 3.0 4.0 4.0 5.0

STEAM 3.0 3.0 3.0 3.0 4.0 4.0

SAVINGS-TO-INVESTMENT PATIOS FOR SOLAR SCREENS {COS"r= $1.0/SQ. FT. U=0. 50)

HEATING ENERGY **************

GAS

OIL STEAM

SC=0.

******

3 . 9

4 . 1 4 . 3

SC=0.

******

3 . 5

3 . 9

4 . 1

SC=0.

******

2 . 9

3 . 3 3 . 7

" PRESENT WORTH FACTOR = 9 . 5 ( GAS )

& INSTALLATION COST = $ 42000.

SC=0.

******

2 . 3

2 . 8

8 .0(OIL ) .

SC=0.

******

1 . 7

2 . 9 8.8(STEAM)

SC= 1 .0 ******

1 .0

1 . 8

2 . 5

8 . 4( ELEC )

-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $3.0/SQ. FT., U=0.50)

G ENERGY

********

GAS

0 I L STEAM

SC=0 .

******

8.0

7.0

7.0

SC=0.

******

9 .0 8.0

7.0

SC=0.

******

11.0

9 .0 8.0

SC=0.G SC=0.3 SC=1.0

****** ****** ******

15.0

11.0

3 .0

23.0

14.0

1 1 . Gf

>30.0

18.0

14.0

/INGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $3.0/SQ. FT. U=0. 50)

BATING ENERGY *************

GAS

OIL STEAM

SC=0.

******

2 .0

2 . 2 2 . 2

SC=0.

******

1 . 9 2 . 1 2 . 1

SC=0.4

******

1 . 5

1 . 8

1 . 9

SC=0.

******

1 . 2

1 . 6

1 . 7

SC=0 .

******

. 9

1 . 4

1 . 5

SC = 1 .0 ******

. 6

1 . 1

1 . 3 20 YEAR PRESENT WORTH FACTOR = 1 6 . 2 ( GAS ) MATERIAL & INSTALLATION COST = S125000.

14.7(OIL), 13.9<STPAM), 12.9(ELEC>

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS {COST= $6.0/SQ. FT. U=0. 50)

HEATING EN^

************Tr.

SC=0.

******

20.0

13.0

17.0

SC=0.

******

24 .0 20.0

13.0

SC=0.

******

>30.0

24.0

23.0

SC=0.5

******

>30.0

28.0

29.0

SC=0.

****** >30.0

>30.0

>30.0

SC= 1 .0 ******

> 30 .

>30.0

>30.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= SG.0/SQ. FT.. U=0.50)

HEATING ENERGY SC=0.

************** ******

GAS 1.2 OIL 1.4

STEAM 1.3

30 YEAR PRESENT WORTH FACTOR

MATERIAL & INSTALLATION COST

SC=0.

******

1 . 1

1 . 3

1 . 3

SC=0 .

******

. 9

1 . 2

I . 1

SC=0.

******

. 8

1 . I

1 .0

SC=0.

* * X * * *

. 5

1 .0

. 9

SC=1 .0 ******

. 4

. 9

2 1 .0( GAS ) , $252000.

84

21.1{0IL), i5.7(STEAM), 15.4fELEC)
Table lOd. Cost-effectiveness for Chicago U = 0.8A, All-year Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 30=0.4 SC=0.6 SC=0.8 SC=1.0 **««»«**«*»**« ****** ****** ****** ****** ****** ******

GAS 13398. 12647. 9478. 7139. 4300. 3523.

OIL 11384. 11112. 8999. 7739. 6479. 6 190. STEAM 10620. 10530. 8817. 7966. 7115. 7199.

ASSUMPTIONSELECTRICITY COST = $.068/KWH

HEATING FUEL COST = $.022(GAS). .038(OIL). . 045 ( STEAM i /KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= S1.0/SQ. FT., U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 4.0 4.0 5.0 7.0 10.0 14.0

OIL 4.0 4.0 5.0 6.0 3.0 9.0

STEAM 5.0 5.0 6.0 6.0 7.0 7.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= S1.0/SQ. FT. U=0. 84

)

HEATING ENERGY SC=0.1 SC=0.2 ************** ****** ******

GAS

OIL STEAM

2 . 6

2 . 3

2 . 1

2 . 5

2 . 3

2 . 1

SC=0.

******

1 . 9

1 . 8

1 . 8

SC=0.6

******

1 . 5

1 . 5

1 . 6

SC=0.

8

******

1 .0

1 . 3

1 . 5

SC=1 .0 ******

I . 2

1 . 5

10 YEAR PRESENT WORTH FACTOR = 9.6(GAS)

MATERIAL i INSTALLATION COST = S 42000.

8 .0(OIL

)

8. 8 (STEAM) 8 . 4 ' ELEC)

PAY-BACK PERIODS (YEARS) FOP SOLAR SCREENS (COST= B3.0/SQ. FT.. U=0.34)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 13.0 14.0 23.0 >30.0 >30.0 >30.0

OIL 16.0 1 7.0 27.0 30.0 :^30.0 29.0

STEAM 13.0 19.0 27.0 >30.O >30.0 >30.0

SAVIHGS-TO-INVESTMENT PATIOS FOR SOLAR SCREENS (COST=

HEATING ENEPGV

* *************

GAS

OIL STEAM

SC=0.

******

1 . 3

1 . 1

1 .0

SC=0.

******

1 . 2

1 . 1

1 .0

SC=0.

******

1 .0

. 9

. 9

SC=0.

6

******

. 8

. S

. 8

I3.0/SQ. FT. SC=0.

8

. 6

. 7

. 3

U=0. 34

)

SC=1 .0 ******

. 5

. 7 .8 20 YcAR PFESENT WORTH FACTOR

MA'EPIAL & INSTALLATION COST

1 6 . 2 ( GAS ) , 14

II 26000.

7(0IL), 13.3(STIAM!, 12. 9 (EL EC)

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS ( COST= 56.0/30. FT.

HEATING ENERGY SC=0.

************** ******

GAS >30.0

OIL >30.0

STEAM >30.0

SC=0.

******

>30 .0 >30 . 0 >30.0

SC-0.

******

>30.0

>30.0

>30.0

SC=0.

6

******

>30.0

>30.0

>30 .0

SC=0.

8

******

> 30 .

0

>30 .0 >30.0

U=0.34)

SC= I .0

* **•** *

> 30 . 0 >30. 0 >30.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $6.0/SQ. FT

HEATING ENERGY SC=0.

*************** ******

GAS -B OIL -6 STEAM -6

SC=0.2

******

. 7.6

.6

SC=0.

******

. 6 .5

. 5

SC=0.

6

******

. 5

. 5

. 5

SC=0.8

******

U=0. 84

)

SC= 1 . 0 ******

. 3

. 5

. 5

30 YEAR PRESENT WORTH FACTOR = 21.0(GAS).

MATERIAL & INSTALLATION COST = $252000.

85

21.1{0IL). 16.7(STEAM). IS.'KELEC)
86
87
88
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Table 11a. Cost-effectiveness for Boston U = 0.50, Suramer-only Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.50)

HEATING ENERGY SC=0.1 SC»0.2 SC-0.4 SC-0.6 SC=0.8 SC»1.0

*•****•*•••**• *«*••* *«••«* ••*>«* •••,«• GAS 13943. 14497. 14255. 13170. 11180. 8888. OIL 14191. 15028. 15253. 14591. 12953. 10976.

STEAM 14711. 16138. 17337. 17558. 16657. 15338.

ASSUMPTIONS: ELECTRICITY COST - $ . 087/KWH

HEATING FUEL COST . $.029(GAS). .035(0IL). . 047 ( STEAM ) /KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST. SI.O/SQ. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

w***********^* «««*** GAS 4.0 3.0 3.0 4.0 4.0 5.0

OIL 4.0 3.0 3.0 4.0 4.0 5.0

STEAM 3.0 3.0 3.0 3.0 3.0 3.0

SAVINGS- TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST. $1.0/S0. FT.. U=0.50)

HEATING ENERGY SC^O.I SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

«««««« «••«*«

GAS 2.7 2.9 2.9 2.8 2.4 2.0

OIL 2.7 2.9 2.9 2.3 2.5 2.1 STEAM 2.8 3.1 3.3 3.4 3.2 3.0

10 YEAR PRESENT WORTH FACTOR « 9.5(GAS). 8.0(011.). S.KSTEAM). S.KELEC)

MATERIAL & INSTALLATION COST « $ 42000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST. $3.0/S0. FT.. U=0.50)

HEATING ENERGY SC = 0.1 SCO. 2 SCO. 4 SC.0.6 SC = 0.a SC=1.0

GAS 12.0 11.0 11.0 12.0 14.0 17.0 OIL 12.0 11.0 11.0 12.0 13.0 16.0

STEAM 11.0 10.0 9.0 9.0 9.0 11.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST. $3.0/S0. FT., U=0.50)

HEATING ENERGY SC=0.1 SCO. 2 SC=0.4 SC = 0.6 SC = 0.8 SC 1 .

0

»»•*»••••••»» «•*•*• ««»»»» «*•«** «•••«• «**••> GAS 1.3 1.4 1.4 1.4 1.3 1.1 OIL 1.3 1.4 1.5 1.5 1.4 1.3 STEAM 1.3 1.5 1.6 1.7 1.6 1.5

20 YEAR PRESENT WORTH FACTOR = 15.6(GAS). 14.5(0IL). 12.2(STEAM), 11.4(ELEC) MATERIAL & INSTALLATION COST = $126000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $6.0/S0. FT.. U=0.50)

HEATING ENERGY SC. 0.1 SC = 0.2 SC = 0.4 SCO. 6 SC = 0.8 SC 1 .

0

«,,*........** ••.*•« ...... ...... ...... ...... ...... GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST. $6.0/S0. FT.. U=0.50)

HEATING ENERGY SC-0.1 SC = 0.2 SC.0.4 SCO. 6 SC^O.S SC 1 .

0

.............. »»•». ...... ...... ...... ...... ...... GAS .7 .a .9 .9 .8 .7 OIL .8 .9 1.0 1.0 1.0 .9 STEAM .8 .8 .9 1.0 .9 -9

30 YEAR PRESENT WORTH FACTOR = 19.8(GAS). 20.9(0IL). 14.7(ST£AM). 12.7(ELEC) MATERIAL 4 INSTALLATION COST " $252000.

91
Table lib. Cost-effectiveness for Boston U = O.SA, Summer-onlv Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.84)

HEATING ENERGY SC«0.1 SC=0.2 SC»0.4 SC=0.6 SC=0.8 SC«1.0 ••«**>**•«*>*• •**«•* «••••« «*«*** »•••«• GAS 6622. 7487. 7971. 7411. 6369. 4600.

OIL 5560. 6742. 7758. 7659. 7037. 5629.

STEAM 3341. 5186. 7315. 8178. 8432. 7778.

ASSUMPTIONS: ELECTRICITY COST = $.087/KWH

HEATING FUEL COST - $.029(GAS), .035(0IL), . 047 ( STEAM ) /KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST» $1.0/S0. FT.. U=0.84)

HEATING ENERGY SC»0.1 SC=0.2 SC-0.4 SC«0.6 SC=0.8 SC»1.0

«*«^«* GAS 9.0 7.0 6.0 7.0 7.0 10.0

OIL 9.0 7.0 6.0 7.0 7.0 10.0

STEAM >30.0 11.0 7.0 6.0 6.0 6.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST^ $1.0/S0. FT., U=0.84)

HEATING ENERGY SC=0 . 1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ••»••••«*•* «««««« GAS 1.1 1.3 1.5 1.5 1.3 1.1 OIL 1.1 1.3 1.5 1.5 1.3 1.1 STEAM .6 1.0 1.4 1.6 1.6 1.5

10 YEAR PRESENT WORTH FACTOR = 9.5(GAS). 8.0(0IL), 8.1(STEAM). 8.1(ELEC) MATERIAL & INSTALLATION COST = $ 42000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $3.0/SQ. FT.. U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 50=0.8 SC=1.0

•••••«*•*»«*

GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30,0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST" $3.0/S0. FT., U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC»0.4 SC=0.6 SC=0.8 SC=1.0

t ^ * * * * **«•*« GAS .4 .6 .7 .7 .7 .6 OIL ,3 .5 .7 .7 .7 .7 STEAM .2 .4 .7 .e .8 .8 20 YEAR PRESENT WORTH FACTOR = 15.6(GAS), 14.6(0IL). 12.2(STEAM). 11.4(ELEC) MATERIAL & INSTALLATION COST = $125000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST- $6.0/S0. FT., U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 «•»«<•••••»• ***««« mm  ** **** ****** GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $5.0/S0. FT., U=0.84)

HEATING ENERGY^ SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC= 1 .

«««**•**«**«*« ****** ****** ****** m m m m * # GAS .2 .3 .4 .4 .4 .4 OIL .1 .2 .4 .4 .5 .5 STEAM .1 .2 .4 .4 .5 .5

30 YEAR PRESENT WORTH FACTOR »= 19.8(GAS), 20.9(0IL). 14.7(STEAM), 12.7(ELEC) MATERIAL & INSTALLATION COST = $252000.

92
Table 11c. Cost-effectiveness for Boston U = 0.50, All-year Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.5jer)

HEATING ENERGY **************

GAS

OIL STEAM

SC=0.

******

22271

.

22699

.

23593

SC=0 .

******

20478

.

2 1119.

22458 .

SC=0.

******

1 7251 .

1 8297 . 20481

.

SC=0.

6

******

9560.

10209

.

1 1567 .

SC=0.

8

******

3756 . 104 18. 13889.

SC = 1 .0 ******

4750.

6723 . 10844

.

ASSUMPTIONS : ELECTRICITY COST

HEATING FUEL COST

$ .08 7/KWH

$.029(GAS) .035(OIL), .04 7 ( STEAM ) /KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= S1.0/SQ. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 2.0 3.0 3.0 5.0 5.0 8.0

OIL 2.0 3.0 3.0 5.0 5.0 8.0

STEAM 2.0 2.0 3.0 4.0 4.0 4.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= S1.0/SQ. FT, HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 ************** ****** ****** ******

GAS 4.3 4.0 3.5

OIL 4.4 4.0 3.5

STEAM 4.5 4.3 3.9

SC = 0 . 6

t * * *

1 . 9 2.0

2 . 2

SC=0.

8

******

2.0

2.0

2 . 7

U=0. 50)

SC=1 .0

* * X * * *

1 . 2

1 . 3

2 . 1 10 VEAP PRESENT WORTH FACTOR = 9 . 5 ( GAS )

,

MATERIAL & INSTALLATION COST = $ 4200^.

3.0(OIL). S.KSTEAM) 8 . 1 ( ELEC)

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST

SC=0.

$3.0/SQ. FT. HEATING ENERGY **************

GAS

OIL STEAM

SC=0.

******

7 . 0 7.0

6 .0

SC=0.

******

7.0

7.0

7.0

9 .0

9 . 3 7.0

SC=0.

6

******

22 .0 20.0

17.0

SC=0.

8

******

19.0

17.0

12.0

U=0. 50

)

SC=I .0 ****** 30.0

23.0

18 . ar

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $:

HEATING ENERGY . 5 **************

GAS

OIL STEAM

SC=0.

******

2 . 1 2 . 1 2 . 2

SC=0.

****** 2.0

2.0

2 . 1

SC=0.

******

1 . 7

1 . 3

1 . 9

SC=i£

* * * a

.0/SQ

.

SC =

1 .0

1 .0

1 .

FT.

1 . 1 1 . 2

1 . 3

U=0. 50)

SC= 1 .0 ******

. 7

. 9

1 . 1 20 YEAR PRESENT WORTH FACTOR = 1 5 . 6 ( GAS ) MATERIAL & INSTALLATION COST = $126000.

14.6(OIL). 12.2(STEAM), 11.4(ELEC)

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $6. 0/SQ. FT.

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 ************** ****** ****** ******

GAS 19.0 22.0 30.0

OIL 18.0 20.0 25.0

STEAM 17.0 19.0 23.0

SC=0.

6

******

>30.0

>30.0

>30.0

SC=0.

3

******

>30.0

>30.0

>30.0

U=0 . 50

)

SC = 1 .0 ******

>30. 0 >30. 0 >30.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $6. 0/SQ. FT

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 ************** ****** ****** ******

GAS 1.2 1.1 1-0 OIL 1.2 1.2 1.1 STEAM 1.2 1.2 1.1

SC=0.

6

******

. 6

. 6

. G

SC=0.8

******

. 7

U=0. 50)

SC= 1 . 0  )

30 YEAR PRESENT WORTH FACTOR = 19.8(GAS). 20.9(GIL

MATERIAL i INSTALLATION COST = $252000.

93

14.7(STEAM). 12.7(ELEC>
Table lid. Cost-effectiveness for Boston U = 0.84, All-year Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS {U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.S SC=0.8 SC=1.0 ** ************ ****** ****** ****** ****** ****** ******

GAS 15351. 14069. 11885. 8769. 5738. 4644.

OIL 14535. 13467. 11720. 8984. 6335. 5622.

STEAM 12834. 12209. 11375. 9433. 7581. 7666.

ASSUMPTIONS

ELECTRICITY COST = $.087/KWH

HEATING FUEL COST = $.029(GAS> .035(OIL), .047(STEAM)/KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $1.0/50. FT, HEATING ENERGY

***** V ********

GAS

OIL STEAM

SC=0.

******

3.0

3.0

4 .0

SC=0.

******

4.0

4 .0

4 .0

SC=0 .

****** 4.0

4.0

4.0

SC=0.

******

6.0

6 .0 5.0

SC=0.

******

8.0

8 .0

6 . 0

U=0. 84

SC = 1 .0 ******

10.0

10.0

6 . 0

SAVI NGS-TO- I NVESTMENT RATIOS FOR SOLAR SCREENS (COST= $1.0/SQ. FT.. U=0.84

HEATING ENERGY **************

GAS

OIL STEAM

SC=0 .

******

2 . 8

2 . 8 2 . 4

SC=0.

******

2 . 6

2 . 5

2 . 3

SC=0.

******

2 . 3 2 . 3

2 . 2

SC=0 .

******

1 . 7

1 . 7

1 . 8

SC=0 .

******

1 . 2

1 . 2

1 . 5

SC = 1 .0 ******

1 . 1

1 . 1

1 . 5

10 YEAR PRESENT WORTH FACTOR = 9 . 5 ( GAS ) MATERIAL & INSTALLATION COST = $ 42000.

.0( 01 L ) , 8 . 1 ( STEAM ) ,

. 1 ( ELEC)

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $3.0/50. F^. U=0. 84

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 ************** ****** ****** ****** ******

GAS 12.0 13.0 18.0 >30.0

OIL 12.0 14.0 18.0 >30.0

STEAM 15.0 17.0 19.0 >30.0

SC=0.

******

; 30.0

>30.0

>30 .

SC=1 .0 ******

>30.0

>30.0

/30 .0

SAVINGS-TO-INVESTMENT PATIOS FOP SOLAR SCREENS '.COST= I3.0/SQ. FT. U=0. 84 > HEATING ENERGY **************

GAS

OIL STEAM

SC=0.

******

1 . 3

1 . 2

1 . 1

SC=0.

******

1 . 2

1 . 1

1 . 1

SC=0.

******

1 .0

1 .0

1 .0

SC=0 .

******

. 8

. 8

. 9

SC=0.

******

. 6

. 7

. 7

SC = 1 .J *****

. 6

. 7

. 7 20 YIAR PRESENT WORTH FACTOR = 1 5 . 6 ( GAS

MATERIAL 4 INSTALLATION COST = $126000.

14.5(OIL). 12.2(STEAM>. 11.4(ELEC)

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $5.0/SO. FT.. U=>7.84)

HEATING ENERGY SC=0.1 SC=0.2 ************** ****** ******

GAS >30.0 >30.0

OIL >30.0 >30.0

STEAM >30.0 >30.0

SC=0.

******

>30.0

>30.0

>30.0

SC=0.

******

>30.0

>30.0

>30.0

SC=0.

******

>30.0

>30.0

>30.0

SC = 1 .0 ******

> 30 .

>30.0

^30 . 0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $6.0/SQ. FT.

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4

*************** ****** ****** ******

GAS .7 .6 -S OIL S .6 .6 STEAM .6 -6 -"^

SC=0.

******

. 5

. 5

. 5

SC-0.

******

. 4

. 4

. 4

U=0 . 84 ) SC= 1 . 0 ******

. 4

. 5

. 4

30 YEAR PRESENT WORTH FACTOR

MATERIAL & INSTALLATION COST

19. 8 (GAS)

$252000

20.g(OIL), 14.7{STEAM). 12.7(ELEC)
uj J Lj o I- q: t-H o HH K > e:oq(-id

95
cDf-Lij<rE:

96

98
Q. LU ObJ 2: f99
Table 12a. Cost-effectiveness for San Jose U = 0.50, Summer-only

Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.50)

HEATING ENERGY SC»0.1 SC=0.2 SC=0.4 SC-0.6 SC=0.8 SC-1.0

*••««« *«4>**« GAS 4960. 5216. 4896. 3942. 2099. -250. OIL 3255. 4023. 4532. 4168. 2654. 445.

STEAM 2545. 3527. 4381. 4263. 2885. 734.

ASSUMPTIONS: ELECTRICITY COST . $.062/KWH

HEATING FUEL COST = $.023(GAS). .038(0IL). . 045 ( STEAM ) /KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (C0ST> $1.0/50. FT.. U=0.50)

HEATING ENERGY SC=0.1 50=0.2 SC«0.4 SC=0.6 SC=0.a SC=1.0

• •«*•••••»-*• «««««• 4t*«r«« GAS 12.0 11.0 11.0 15.0 >30.0 >30.0

OIL >30.0 18.0 12.0 14.0 25.0 >30.0

STEAM >30.0 25.0 13.0 13.0 26.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST. SI.O/SQ. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

««*«*••*«***•« •««•«* GAS .9 1.0 .9 .8 .4 OIL .7 .8 .9 .8 .5 .1 STEAM .4 .7 .8 .8 .6 .2

10 YEAR PRESENT WORTH FACTOR = 9.2(GAS). 8.0(0IL). 8.7(STEAM). 8.3(ELEC) MATERIAL <S INSTALLATION COST = $ 42000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST^ $3.0/S0. FT.. U=0.50)

HEATING ENERGY SC^O.I SC=0.2 SC=0.4 SC=0,6 SC=0.8 SC=1.0

*•«••«•••««•«« **»•«• •#«««« **«««« GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (C0ST= $3.0/S0. FT.. U=0,50)

HEATING ENERGY SC^O.1 SC=0.2 SC»0.4 SC»0.6 SC=0.8 SC=1.0

«*««*« GAS .4 .5 .5 .4 .2 OIL .2 .3 .4 .4 .3 .1 STEAM .2 .3 .4 .4 .3 .1

20 YEAR PRESENT WORTH FACTOR = 14.3(GAS), 14.8(0IL), 13.6(STEAM). 12.4(ELEC) MATERIAL & INSTALLATION COST = $126000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $6.0/S0. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC-0.4 SC=0.6 SC=0.8 SC=1.0

• •••*.•»*•• «««**« «•»««* GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST=i $6.0/S0. FT., U=0.50)

HEATING ENEROr SC-0. 1 SC=0.2 SC-0.4 SC=0.6 SC=0.8 SC=1.0

*«••*•••*•.•• «•«*•« ****** ******

GAS .3 .3 .3 .2 .1 OIL .1 .1 .2 .3 .2 .1 STEAM .1 .2 .2 .3 .2 .1

30 YEAR PRESENT WORTH FACTOR - 17.3(GAS), 21.3(0IL). 16.2(STEAM). 14.5(ELEC) MATERIAL & INSTALLATION COST » $252000.

100
Table 12b. Cost-effectiveness for San Jose U = 0.84, Summer-only

Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS {U=0.84)

HEATING ENERGY SC»0.1 SC»0.2 SC»0.4 $C=0.6 30=0.8 SC-1.0

•••***•*•*••*• •••**« •••«*« •«•••« •••••• ••••«• GAS 3407. 3637. 3658. 3098. 1978. 117. OIL 878. 1599. 2510. 2652. 2068. 5l6.

STEAM -175. 750. 2031. 2466. 2105. 682.

ASSUMPTIONS: ELECTRICITY COST = $.062/KWH

HEATING FUEL COST « $.023(GAS). .03a{0IL). . 045 ( STEAM ) /KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST« $1.0/S0. FT.. U»0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC»0.4 SC=0.6 SC=0.8 SC^I.O «•****••««•*• *••*•« ••**•« *••»«• ••»«•• GAS >30.0 27.0 21.0 29.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST. $1.0/S0. FT., U=0.84)

HEATING ENERGY SC«0.1 SC=0.2 SC«0.4 SC=0.6 SC=0.8 SC»1.0

*•**«•*••«*••« •«•««* «««*«« «»••«• GAS .6 .6 .7 .6 .4 .0 OIL .2 .3 .5 .5 .4 .1 STEAM .1 .4 .5 .4 .1

10 YEAR PRESENT WORTH FACTOR » 9.2(GAS). 8.0(OIL). 8.7(STEAM). 8.3(ELEC) MATERIAL & INSTALLATION COST x $ 42000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $3.0/S0. FT.. U=0.84)

HEATING ENERGY SC»0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

••••••*«••«••• ««•.«. *««•«« *««««• GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30 0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (C0ST= $3.0/SQ. FT.. U=0.84)

HEATING ENERGY SC=O.I SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ••**••*••••• «•*«*« GAS .3 .3 .3 .3 .2 .0 OIL .1 .2 .2 .2 .1 STEAM .0 ,2 .2 .2 .1

20 YEAR PRESENT WORTH FACTOR » 14.3(GAS). 14.8(0IL). 13.6(STEAM), 12.4(ELEC) MATERIAL & INSTALLATION COST « $126000.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS {C0ST= $6.0/S0. FT.. U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.a SC=1.0

««««•*«*•««««• •*«•«« ••«•*• GAS >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

OIL >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO- INVESTMENT RATIOS FOR SOLAR SCREENS (COST* $6.0/S0. FT.. U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SCxO.4 SC=0.6 SC=0.8 SC=1.0

•***•« «....• «•«*•< »»•*.» »«,.*• ••*••> GAS .2 .2 .2 .2 .1 .0 OIL ----

---- .1 .1 -1 STEAM .0 .1 .1 .1 -0

30 YEAR PRESENT WORTH FACTOR = 17.3(GAS). 21.3(0IL). 16.2(STEAM). 14.5(ELEC) MATERIAL & INSTALLATION COST " $252000.

101
Table 12c. Cost-effectiveness for San Jose U = 0.50, All-year Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

****•**:******** ****** ****** ****** ****** ****** ******

GAS 15770. 13869. 9702. 5799. 1810. -2429.

OIL 14822. 13157. 9449. 6022. 2500. -1281.

STEAM 14427. 12861. 9344. 6115. 2788. -802.

ASSUMPTIONS: ELECTRICITY COST = $.062/KWH

HEATING FUEL COST = $.023(GAS), .038(OIL), . 04 5 ( S TEAM ) / KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $1.0/SQ. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 3.0 4.0 5.0 9.0 >30.0 >30.0

OIL 3.0 4.0 5.0 9.0 26.0 >30.0

STEAM 4.0 4.0 5.0 8.0 27.0 >30.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $1.0/SQ. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.5 SC=0.8 SC=1.0 ************** ****** ****** ****** ****** ****** ******

GAS 3.1 2.7 1.9 1.1 .4 OIL 2.9 2.6 1.9 1.2 .5 STEAM 2.8 2.5 1.8 1.2 .5

10 YEAR PRESENT WORTH FACTOR = 9 . 2 ( GAS ) . 3.0(OIL). 8.7(STEAM), 8.3(ELEC)

MATERIAL & INSTALLATION COST = $ 42000.

PAY-BACK PERIODS (YEARS) FOP SOLAP SCREENS (C0ST= S3.0/SQ. FT.. U=0.50>

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

 >r ** ******* ****** ****** ****** ****** ****** ******

GAS 1(7.0 12.0 23.0 >30.0 >30.0 >30.0

OIL 11.0 13.0 26.0 >30.0 >30.0 >30.0

STEAM 12.0 14.0 26.0 >30.0 >30.0 >30.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= S3.0/SO. FT., U=O.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.3 SC=1.0 ************** ****** ****** ****** ****** **-*r** ******

GAS 1.5 1.3 .9 .6 .2 OIL 1.4 1.3 .9 .6 .3 STEAM 1.4 1.2 .9 .6 .3 20 YEAR PRESENT WORTH FACTOR = 14.3(GAS). 14.3(0ILi, 13.6(STEAM), 12.4(ELEC)

MATERIAL & INSTALLATION COST = 112600(7.

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= S6.0/SQ. FT.. U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0

************** ****** ****** ****** ****** ****** ******

GAS >30.0 >30.0 >30.0 >30.0 >30.0 ^30.0

OIL >30.0 >30.0 >30.0' >30.0 >30.0 >30.0

STEAM >30.0 >30.0 >30.0 >30.0 >30.0 >30.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= SG.0/SQ. FT., U=0.50)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.G SC=0.8 SC=1.0

************** ****** ****** ****** ****** ****** ******

GAS .9 .8 .6 .3 .1 OIL .8 .7 .5 .4 .2 .0 STEAM .8 .7 .5 .4 .2 30 YEAR PRESENT WORTH FACTOR = 1 7 . 3 ( GAS ) , 21.3(OIL). 16.2(STEAM), 14.5{ELEC)

MATERIAL ^ INSTALLATION COST = $252000.

102
Table 12d. Cost-effectiveness for San Jose U = 0.8A, All-year Cooling

FIRST YEAR ENERGY SAVINGS (DOLLARS) FOR SOLAR SCREENS (U=0.84)

HEATING ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.6 SC=0.8 SC=1.0 ************** ****»« «««*«* ****** ****** ******

GAS 14701. 13037. 9426. 6053. 2732. -714. OIL 12784. 11391. 8325. 5511. 2736. -151.

STEAM 11985. 10705. 7867. 5286. 2738. 34.

ASSUMPTIONS

ELECTRICITY COST = $.062/KWH

HEATING FUEL COST = $.023(GAS) .038(OIL) ,045(STEAM)/KWH

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST- S1.0/SQ. FT, U=0. 84 > HEA-ING ENERGY

GAS

OIL STEAM

SC=0 .

******

3.0

4 . 0

4.0

SC=0.

******

4 .0

4 . 0 5.0

SC=0.

******

5 .0 6.0

6.0

SC=0.

6

******

9.0

9 .0 10.0

SC=0.

8

******

>30.0

>30.0

•30.0

SC= 1 .0 ******

>30.0

>30. 0 >30. 0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= I1.0/SQ. FT. U=0. 84

)

HEATirU ***** r : ENERGY

r ***** * GAS

OIL :team

SC=0.

******

2 . 8 2 . 5

2 . 3

SC=0,

2 . 5

2 . 3 2.0

SC=0 .

******

1 . 3

1 . 6

1 . 5 10 YEAR PRESENT WORTH FACTOR = 9 . 2 ( GAS

)

MATERIAL & INSTALLATION COST = S 42000.

SC=0.

6

******

1 . 2

1 . 1

1 .0

8 . 0 ( 0 I L

SC=0.

8

******

. 5

. 5

. 5 3.7(STEAM)

SC=1 .0 ******

8 .

.0 ELEC )

PAY-BACK PERIODS (YEARS) FOR SOL SC=0 .

SCREENS {COST= $3.0/SO. FT.. U=0.34)

HEATING ENERGY **************

GAS

OIL STEAM

SC=0.

******

11.0

14.0

16.0

14.0

18.0

20 . 0

SC=0.

****** 27.0

>30.0

>30.0

SC=0.

6

******

>30.0

>30.0

>30.0

SC=0.8

******

> 30 .

0

>30.0

>30.0

SC= 1 .0 ****** >30.0

>30.0

>30.0

SAVUJGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= $3.0/SQ. FT. HEATIIIG ENERGY SC=0.1 SC=0.2 SC=0.4 SC=0.5 SC=0.3 ************** ****** ****** ****** ****** *****.< GAS 1.4 1.2 .9 .6 .3 OIL 1.2 1.0 .8 .5 .3 STEAM 1.1 1.0 .7 .5 .3U=0 . 34

)

SC = 1 .0 ******

.0

20 YEAR PRESENT WORTH FACTOR

MATERIAL & INSTALLATION COST

14.3' GAS

)

$1 26000.

1.!.8{0IL). 13.6(STFAM). 12.4^ELEC)

PAY-BACK PERIODS (YEARS) FOR SOLAR SCREENS (COST= $e.0/SO. FT.. U=0.S4)

HEATiriG ENERGY

 :** ********

GAS

OIL

STEANL

SC=0.

****** >30.0

>30.0

>30.0

SC=0 .

****** >30.0

>30.0

>30.0

SC=0.

*****>< >30.0

>30.0

>30.0

SC=0.

5

******

>30.0

>30.0

>30.0

SC=0.

8

******

>30.0

>30.0

>30.0

SC= 1 .0 ****** >30.0

>30. er >30.0

SAVINGS-TO-INVESTMENT RATIOS FOR SOLAR SCREENS (COST= S6.0/SO. FT., U=0.84)

HEATING ENERGY **************

GAS

OIL STEAM

;C=0 .

t « * * * *

. 8

. 6

. 7

SC=0.2

******

. 7

. 5

. 6

SC=0.

******

. 5

. 4

. 4

SC=0.6

******

. 3

. 3

. 3

SC=0.8

******

SC=1 .0 ******

30 YEAR PRESENT WORTH FACTOR = 1 7 . 3 ( GAS ) . 21.3(0IL)

MATERIAL & INSTALLATION COST = $252000.

103

16.2<STEAM). 14.5(ELEC)
I
NBS-114A IREV. 2-6C) U.S. DEPT. OF COMM. 1. PUBLICATION OR 2. Performing Organ. Report No. 3. Publ 1 cation D ate BIBLIOGRAPHIC DATA

REPORT NO. May 198A SHEET (See /nstructionsj NBS BSS 161

4. TITLE AND SUBTITLE

Effectiveness of Solar Shading for an Office Building

5. AUTHOR(S)

S. Treado, J. Barnett, W. Remmert

6. PERFORMING ORGANIZATION (If joint or other than NBS. see in struct/on sj 7. Contract/Grant No. NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234

Final

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

Design and Construction Division, General Services Administration, Washington, DC

20407; Naval Facilities Engineering Command, U.S. Navy, Washington, DC 20350;

Directorate of Civil Engineering, U.S. Air Force, Washington, DC 20330; and Office

of Chief of Engineers, U.S. Army, Washington, DC 20310.

10. SUPPLEMENTARY NOTES

Library of Congress Catalog Card Number: 84-601038

[^J Document describes a computer program; SF-185, PIPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most si gnificant information. If document includes a significant

bibliography or literature survey, mention it here) The impact of solar shading of windows on building energy consumption, energy

costs and occupant comfort is examined for a typical office building. Measurements of the solar and thermal performance characteristics of three solar screens are reported. Using the DOE-2 computer program, annual building energy

simulations were performed for seven tlimatic locations in the United States.

Thirteen combinations of window thermal transmittance and shading coefficient

are examined for each location. The analysis includes separate evaluations for

buildings with all-year cooling and summer-only cooling. The percentage of

occupied hours when overheating occurs in perimeter office areas is presented.

A life-cycle cost analysis is used to determine payback periods and savings-toinvestment ratios for three combinations of shading device first cost and

expected life. The evaluation assumes that any shading devices are fixed, and

that daylighting is not used to offset interior lighting requirements.

The results indicate that solar shading can reduce building energy consumption

and improve comfort conditions in buildings with significant cooling loads. The

optimum shading device characteristics vary with climatic location. Solar

shading is more beneficial to buildings which are cooled all year, than buildings

with summer-only cooling.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

building energy analysis; cooling loads; heating loads; solar screens; solar

shading; window management; windows.

13. AVAILABILITY

Unl imited

I I For Official Distribution. Do Not Release to NTIS

[X] Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

111

15. Price

USCOMM-DC 6043-P80

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