NBSIR 76-1187

Interim Performance Criteria

for Solar Heating and Cooling

Systems in Commercial

Buildings

Center for Building Technology

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

November 1976

Prepared for Energy Research and Development Administration

Division of Solar Energy

Washington, D. C. 20545

NBSIR 76-1187

INTERIM PERFORMANCE CRITERIA

FOR SOLAR HEATING AND COOLING

SYSTEMS IN COMMERCIAL

BUILDINGS

Center for Building Technology

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

November 1976

Prepared for Energy Research and Development Administration

Division of Solar Energy

Washington, D. C. 20545

U.S. DEPARTMENT OF COMMERCE, Elliot L. Richardson, Secretary

Edward O. Vetter, Under Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director
....

. ,

'
ACKNOWLEDGMENTS

The preparation of this interim document has been a joint effort of members of the Solar

Energy Program Team at the National Bureau of Standards. Team members who participated in

the preparation of this document include:

Typing and editing was performed by Leslie Suddueth and Mary Lou Miller.

Valuable comments regarding this document have also been received from Alwin Newton, P.E.,

Consulting Engineer; Andrew Parker, Mueller Associates, Inc.; and Richard Rittleman,

Burt Hill and Associates.

The helpful suggestions and review comments received from Carl W. Conner, ERDA, and

William Freeborne, HUD, are also gratefully acknowledged.

David Waksman

Elmer Streed

Larry Masters

Leopold Skoda

Paul Brown

Robert Dikkers

John Holton

James Harris

Richard Crenshaw

William Walton

Robert Beausoleil

i
FOREWORD

These interim performance criteria will be used for the design, development, technical

evaluation and procurement of the solar heating and cooling systems to be used in

commercial buildings during the solar heating and cooling demonstration program authorized

by Public Law 93-409, the "Solar Heating and Cooling Demonstration Act of 1974".

This second edition of the "commercial criteria" document, prepared by the National

Bureau of Standards (NBS) , represents the first revision to the document prepared by

the National Aeronautics and Space Administration (NASA)* in February 1975. Major changes

to the criteria and evaluation statements contained in the original NASA document are indicated by vertical lines in the margins. Where an entire section has been significantly

changed or reorganized, a notation appears at the beginning of the section.

These interim criteria are intended primarily for use in the solar demonstration program.

However, it is hoped that they will evolve into definitive performance criteria that can be used to develop provisions for model and local building codes as well as Federal

specifications. Comments related to the usability of this document and suggested

modifications are encouraged and should be sent to the following address:

Manager, Solar Energy Program

National Bureau of Standards

Building 225, Room A-114

Washington, D.C. 20234

Interim Performance Criteria for Commercial Solar Heating and Combined Heating/Cooling

Systems and Facilities, NASA, Marshall Space Flight Center, Document No. 98M1001,

February 28, 1975

ii
SI CONVERSION UNITS

In view of the present accepted practice in this country for building technology, common

U.S. units of measurement have been used throughout this document. In recognition of

the position of the United States as a signatory to the General Conference of Weights

and Measures, which gave official status to the metric SI system of units in I960,

assistance is given to the reader interested in making use of the coherent system of

SI units by giving conversion factors applicable to U.S. units used in this document.

Length

1 in = 0.0254 meter (exactly)

1 ft = 0.3048 meter (exactly)

Area

1 in2 = 6.45 x 10 -4 meter2 1 ft 2 = 0.09290 meter2

Volume

1 in 3 = 1.639 x 10~ 5 meter 3

1 gal (U.S. liquid) = 3.785 x 10 -3 meter 3

Mass

1 ounce-mass (avoirdupois) = 2.834 x 10 -2 kilogram

1 pound-mass (avoirdupois) = 0.4536 kilogram

Pressure or Stress (Force/Area)

1 inch of mercury (60°F) = 3.377 x 10 3 pascal

1 pound-force/inch2 (psi) = 6.895 x 10 3 pascal

Energy

1 foot-pound-force (ft-lbf) = 1.356 joule

1 Btu (International Table) = 1.005 x 10 3 joule

1 Kilowatt-hour = 3.600 x 10 6 joule = 3.412 x 10 3 Btu

Power

1 watt = 1 x 10 7 erg/second

1 btu/hr = 0.2929 watt

Temperature

to c = 5/9 (t #F - 32)

Heat

1 Btu-in/h-ft 2 - °F = 1.442 x 10

_1 W/m-K (thermal conductivity)

1 Btu/lbm - °F = 4.184 x 10 3 J/kg-K (heat capacity)

1 langley = 4.184 x 104 J/m2 = 1 cal/cm2 = 3.69 Btu/ft 2

iii
INTRODUCTION

Background

Public Law 93-409, the Solar Heating and Cooling Demonstration Act of 1974, provides for

"demonstration within a three-year period of the practical use of solar heating technology, and .... the development and demonstration within a five-year period of the

practical use of combined heating and cooling technology." Under the provisions of the

Act, in February 1975, the NASA developed a first edition of this document containing

interim performance criteria for the design and evaluation of solar heating and cooling

systems to be demonstrated in commercial buildings. Since that time, responsibility

for further development of the document has been assumed by the NBS. This second edition

of the "commercial criteria" represents the first revision to the NASA document. It is

expected that this document will be updated periodically as data and information are gained

from the demonstration program.

Obj ectives

These interim criteria have the following objectives:

1. To provide designers, manufacturers and evaluators with the technical

performance criteria that will be used for the commercial solar

heating and cooling demonstration program.

2. To establish technical performance levels that will be used for the

evaluation and procurement of systems, subsystems and components*

for the commercial solar heating and cooling demonstration program.

3. To provide a basis for the development of more definitive performance

criteria at a later date.

Scope

The interim performance criteria given for hardware related items including space heating

systems, hot water systems, space cooling systems, or combinations thereof**, and their

various subsystems, components, and materials are intended to:

1. establish minimum levels for health and safety that are consistent

with those presently established for conventional systems used

in commercial applications,

2. ensure that the proposed heating, cooling, and hot water systems,

or combinations thereof, are capable of providing levels of

performance consistent with those provided by conventional systems

used in commercial applications.

3. verify that proposed systems, subsystems, and components are capable of providing their design performance levels, and

4. ascertain that the systems, subsystems, and components are durable,

reliable, readily maintainable and generally constructed in accordance

with good engineering practice.

*Definitions are given in the glossary to this document; see page 84.

**Although not specifically mentioned in PL 93-409, it is recognized in this document

that not all cooling systems are combined with heating systems.

iv
The interim performance criteria are intended to be flexible in order to allow freedom

of design and encourage innovation in keeping with the intent of Public Law 93-409.

\ Organization and Format

This interim document is organized on the basis of performance criteria dealing with

heating and cooling systems and their integration into buildings.

Performance statement entries are presented in the Requirement, Criterion, Evaluation and

Commentary format. The Requirement is a qualitative statement giving the user need or expectation for the item being addressed. It is a general statement of what the system or

its subassemblies shall be able to do. The Criterion is generally a quantitative statement

giving the level of performance required to meet the application or expectation for the ^.tem being addressed. The one or more criteria associated with each requirement state those

considerations which are necessary to meet the requirement. Due to limitations in the

state-of-the-art, a quantitative statement is not always contained in each criterion in

this document. In addition, quantitative statements have been intentionally omitted in some criteria where these values will be provided by the designer. The Evaluation sets

forth the methods of test and/or other information upon which an evaluative judgment of

compliance with a criterion will be based. It states the standards, inspection methods,

analyses, review procedures, historical documentations, and/or methods which may be used

in evaluating whether or not the system and its subassemblies as designed comply with the

criterion. It is expected, in many cases, that the review of documentation of in-use

performance, or professional judgment, will be used as evaluative tools in lieu of testing.

The Commentary provides background for the reader and presents the rationale behind the

selection of specific data presented in the Requirement, Criterion or Evaluation. The

commentary is intended for information purposes, and is therefore not mandatory.

The document is divided into two parts. The first part, Systems and Components, deals

with interim performance criteria for heating, cooling and hot water systems and their

subassemblies. The second part, Building and Sites , presents performance criteria

dealing with the interactions between the solar energy system and its surrounding

environment, the building and site. These performance criteria provide for integrating the

building and site with the system and its components without seriously degrading the

environment or impairing the normal function of the building and its components.

Both parts of the document are organized on the basis of the first six performance

attributes listed below. An additional attribute, Visual Characteristics, is considered

under Building and Site .

1. Functional performance statements are used to evaluate the ability of

systems and their subassemblies to operate and provide their rated

output. The ability of the solar heating system to maintain the building

at a specified temperature under a given set of outdoor conditions is an example of a functional consideration.

2. Mechanical performance statements treat the mechanical design and

performance of the solar energy systems and their subassemblies.

Factors such as the ability of the system to withstand normal design

service conditions, e.g., pressure and temperature, are considered

under this category.

3. Structural performance statements deal with the ability of systems and

subassemblies to maintain their structural integrity under in-service

and extreme conditions. Factors such as wind, snow and seismic

loads are considered under this category.

V
4. Safety deals with the mitigation of hazards that could result in property

damage or injury and death. Hazards such as those due to fragile,

toxic and/or flammable materials are considered under this category.

5. Durability/Reliability relates to the ability of systems and their subassemblies to perform designed functions for a specified interval under

actual use conditions. Corrosion and thermal degradation are typical

durability/reliability related items.

6. Maintainability deals with the ease with which systems and their subassemblies can be maintained in good operating condition for extended

periods of time. Routine scheduled maintenance, corrective maintenance,

replacements, and repairs are considered under this category.

Accessibility is an important maintainability consideration.

7. V isual Characteristics deals with the relationship of the solar installation to the building and the site with regard to visual compatibility.

For the purposes of this document the various systems and subsystems treated in this

document are defined as follows:

The heating (H) system is the complete assembly of subsystems and components

necessary to convert solar energy into thermal energy and use this energy

in combination with auxiliary energy, where required, for space heating purposes.

The cooling (C) system is the complete assembly of subsystems and components

necessary to convert solar energy into thermal energy and use this energy in

combination with auxiliary energy, where required, for space cooling purposes.

(Where cooling is required, nocturnal radiation, evaporative cooling, and/or

other means may be used in combination with, or in lieu of, heat actuated

space cooling.)

The hot water (HW) system is the complete assembly of subsystems or components

necessary to convert solar energy into thermal energy and use this energy in

combination with auxiliary energy, where required, to provide hot water in the

building. It may either be integrated directly into the H, C, or combined H

and C (HC) systems or be completely separate from them. The term hot water as used in this document includes both domestic hot water (DHW) and commercial service

hot water (SHW) . The commercial service hot water may either be potable or nonpotable depending on its intended use.

The term H/C/HW system is used when a requirement or criterion is applicable to the individual H, C or HW systems or any combination thereof.

The energy transport subsystem includes those portions of the H/C/HW systems

which transport energy throughout the systems. Heat transfer from the collector

to storage and from storage to the point of use is accomplished through the energy

transport subsystem.

The control subsystem comprises all of the devices and their electrical,

pneumatic or hydraulic auxiliaries used to regulate the processes of collecting,

transporting, storing and utilizing energy in response to the thermal, safety

and health requirements of the building occupants or building.

The auxiliary energy subsystem utilizes conventional energy sources to back up and/or supplement the output provided by the solar energy system.

The collector subsystem serves the primary function of absorbing solar energy,

converting it into useful thermal energy, and transferring the thermal energy to a heat transfer fluid. It consists of the entire collector array, with its one or more collector units, together with associated manifolding and interconnections.

vi
The storage Subsystem serves the primary function of storing thermal energy so that

it can be used when required. Specific designs may utilize more than one heat

storage temperature (e.g. dual temperature storage) and may also employ cold storage

in all or part of the storage subsystem.

This document is not final in nature. With the present state-of-the-art, there will

be a need for frequent updates to readjust levels of acceptability for both systems and

components. A major reason for including a commentary in the presentation is to assure a workable process of updating these interim performance criteria by establishing the basis

for selection of performance levels and methods of evaluation so that, when questions arise

as to the basis for a particular criterion, the reader will have available the rationale

behind the criterion.

% vii
TABLE OF CONTENTS

SYSTEMS AND COMPONENTS

1. FUNCTION

1.1 H and C system performance

1.2 HW system/subsystem performance

1.3 Collector performance

1.4 Thermal storage performance

1.5 Component /system/ space interactions

1.6 Energy transport performance

/ 1.7 Controls and instrumentation

1.8 Auxiliary energy

2 . MECHANICAL

2.1 System design conditions

2.2 Mechanical stresses

2.3 Leakage prevention

2.4 Collector adjustments

2.5 Heat transfer fluid quality

3 . STRUCTURAL

3.1 Structural loading and resistance

3.2 Function and operation

Appendix

4 . SAFETY

4.1 Health and safety . . 4.2 Fail-safe controls

4.3 Fire safety

4.4 Toxic and flammable fluids

4.5 Safety under emergency conditions

4.6 Protection of potable water and circulated air ...

4.7 Excessive surface temperatures

1

2

4

7

7

7

8

9

12

14

16

16

17

19

2224

31

31

32

34

35

35

37
5. DURABILITY/RELIABILITY

j 5.1 Effects of external environment 39 5.2 Temperature and pressure resistance 42

5.3 Chemical compatibility of components 44

5.4 Components involving moving parts 45

Appendix 47

6. MAINTAINABILITY

6.1 Accessibility for maintenance and servicing 64

6.2 Installation, operation, and maintenance manual 65

6.3 Repair and service personnel 66

BUILDINGS AND SITES

7 . FUNCTION

7.1 Design 68

7.2 Adequate space 68

7.3 Functioning of building and site 69

8 . MECHANICAL

8.1 Mechanical and electrical functioning of H/C/HW systems 72 8.2 Mechanical and electrical functioning of building and site 72 8.3 Mechanical and electrical functioning of connections 73

9 . STRUCTURAL

9.1 Structural integrity of H/C/HW systems 75 9.2 Structural integrity of building and site elements 75 9.3 Structural connections 76

10 . SAFETY

10.1 Safety of building and site 77

11. DURABILITY/RELIABILITY

11.1 Durability and reliability of H/C/HW systems 79 11.2 Durability and reliability of building and site 79 11.3 Durability and reliability of connections 79

ix
12 . MAINTAINABILITY

12.1 Maintainability of H/C/HW systems 80

12.2 Maintainability of building and site 80

12.3 Maintainability of connections 81

13. VISUAL CHARACTERISTICS

13.1 Visual characteristics of building and site 82

GLOSSARY 83

ABBREVIATIONS 88

x
CHAPTER ONE - FUNCTION

Systems and Components

1.1 Requirement H and C system performance . H, C, and HC systems shall be capable

of collecting solar energy and converting it into useful thermal

energy. This thermal energy and auxiliary energy, as required,

shall be used to meet the total energy needs for building

heating/cooling.

1.1.1 Criterion Heating design temperature. The heating system shall maintain

the design indoor temperature for 97 1/2 percent winter outdoor

design conditions [1]* for the geographic area in which the

system is to be operated.

Evaluation Review of calculations and design parameters for compliance with

ASHRAE Standard 90-75 [2]. The design load shall be evaluated

and used on the same time basis as the solar energy system

calculations (i.e., hourly, daily or monthly).

Commentary Heating equipment may be used in conjunction with the solar

energy system in an assist or auxiliary mode. Passive techniques

should be designed to collect, store, or distribute the thermal

energy in a usable manner.

Occupied spaces for sedentary activities in normal dress are usually designed to maintain a recommended indoor temperature

of 72°F (22°C) dry bulb [2]. Indoor design temperatures have

not been specified in this criterion because they vary depending

on when and how a space is used. Spaces intended to be used as part of a passive system may be designed for temperature fluctuations. Buildings with special functional requirements such

as hospitals, housing for the elderly, laboratories, etc., may

use other indoor design temperatures and design parameters.

Additional details for design procedures utilizing energy con- serving methods are available [3, 4, 5].

1.1.2 Criterion Cooling design temperature. Where comfort air conditioning is

required or used, the cooling system shall maintain the design

indoor temperature for 2 1/2 percent summer outdoor design con- ditions for the geographic area in which the system is to be

operated.

Evaluation Review of calculations and design parameters for compliance with

ASHRAE Standard 90-75 [2]. The design load shall be evaluated

and used on the same time basis as the solar energy system

calculations (i.e., hourly, daily or monthly).

Commentary Air conditioning equipment may be used in conjunction with the

solar system in an assist or auxiliary mode. The use of evaporation, nocturnal radiation, or other passive techniques should be

designed to operate in conjunction with devices which collect,

store, or distribute the converted thermal energy in a controllable

manner

.

Occupied spaces for sedentary activities in normal dress are usually designed to maintain a recommended indoor temperature of

78°F (25.5°C) [2]. Indoor design temperatures have not been

specified in this criterion because they vary depending on when and how a space is used. Spaces intended to be used as part

of a passive system may be designed for temperature fluctuations

compatible with their functional use. Buildings with special

functional requirements such as hospitals, housing for the elderly,

Numbers in brackets represent references given at the end of each chapter

1
CHAPTER ONE - FUNCTION

Systems and Components

laboratories, etc., may use other indoor design temperatures

and parameters. Additional details for design procedures

utilizing energy conserving methods are available [3, 4, 5].

1.1.3 Criterion Relative humidity. If humidification is provided, it shall be

designed to a maximum relative humidity of 30 percent. If

dehumidification is provided, it shall be designed to a minimum relative humidity of 60 percent.

Evaluation Review of design parameters and calculations made in accordance

with ASHRAE Standard 90-75 to determine if the design relative

humidity lies within the comfort evelope defined in ASHRAE

Standard 55-74 [6].

Commentary Building spaces with special functional requirements may use other relative humidity design conditions. Design procedures

have been established to control relative humidity [1, 4].

This control should be achieved as much as possible utilizing

energy that would otherwise be rejected.

1.1.4 Criterion Solar contribution. The average yearly contribution of solar

energy to the operation of the H, C, or HC systems shall be

specified in the design and shall result in a reduction in the

average annual consumption of conventional energy for the total

building heating/cooling needs.

Evaluation Engineering review of analytical methods, drawings, test data and

calculations. Analytical predictions or correlations based upon

measured or simulated performance including the heating and

cooling loads, solar subsystem or component performance and the

climatic conditions shall be utilized to predict the percentage

of average monthly and yearly total energy requirement to be

provided by solar energy and auxiliary energy and to determine

the operating energy and thermal losses. Hourly or daily input

data intervals are required for simulation calculations. Predictions based upon correlation charts may be based upon monthly

average climatic data for sites where at least 10 years of

weather data are available.

Commentary Experimental verification of complete system performance is

usually not practical for commercial size systems prior to installation; therefore, analytical methods employing empirical

subsystem or component performance are used to calculate the

performance over the full range of operating conditions.

Examples of analytical methods are described in references [7,

8, 9, 10]. Sources of insolation data and data reduction methods

are described in references [11, 12, 13, 14, 15]. Performance

factor definitions and evaluation procedures are presented in

reference [16].

1.2 Requirement HW system/subsystem performance. The HW system shall be capable

of collecting solar energy and converting it into thermal energy

which shall be used in combination with storage, if provided, and

auxiliary energy to supply an adequate amount of hot water at an acceptable temperature to meet the needs of the application.

|

1.2.1 Criterion Draw and temperature design output. The HW system shall be

capable of providing hot water at the design temperature draw

and recovery rate.

Evaluation Engineering review of plans, specifications, and calculations.

Total energy requirements should be based upon actual use, local

water source temperature, and required hot water discharge

temperatures

2
CHAPTER ONE - FUNCTION

Systems and Components

Commentary Typical methods for estimating potable hot water requirements

have been described by ASHRAE [3]. The amount of hot water

required will vary with climatic and application requirements.

Potable hot water temperatures required can vary from 105°F to 180°F but a delivery temperature greater than 110°F must be used

for domestic use and is recommended for calculations if the

exact outlet temperature is not specified. Geographic and

seasonal variations in source water temperature can be significant as shown in Table 1.2-1 and local values should be used.

Table 1.2-1

Source and Monthly Temperature (t^) in °F at Source for City Water

in 14 Selected Cities (Data is for 1973) Unless Otherwise Noted

[7]

City Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

1 . Phoenix 48 48 50 52 57 59 63 75 79 69 59 54

2. Miami 70 70 70 70 70 70 70 70 70 70 70 70

3. Los Angeles 50 50 54 63 68 73 74 76 75 69 61 55

4. Albuquerque 72 72 72 72 72 72 72 72 72 72 72 72

5. Las Vegas 73 73 73 73 73 73 73 73 73 73 73 73

6. Denver 39 40 43 49 55 60 63 64 63 56 45 37

7. Ft. Worth 56 49 57 70 75 81 79 83 81 72 56 46

8. Nashville 46 46 53 66 63 69 71 75 75 71 58 53

9. Washington, DC 42 42 52 56 63 67 67 78 79 68 55 46

10. Salt Lake City 35 37 38 41 43 47 53 52 48 43 38 37

11. Seattle 39 37 43 45 48 57 60 68 66 57 48 43

12. Boston 32 36 39 52 58 71 74 67 60 56 48 45

13. Chicago 32 32 34 42 51 57 65 67 62 57 45 35

14. New York City 36 35 36 39 47 54 58 60 61 57 48 45

. 2.2 Criterion

Evaluation

Commentary

Non-tap temperature design output . Other commercial applications

using potable (non-tap) or non-potable HW systems shall meet the

temperature criteria as specified in ASHRAE [2] [3], as applicable.

Engineering review of plans, specifications, and calculations.

Total energy requirements should be based upon actual demand and

temperature requirements when available.

Tables estimating the demand at 140°F for various buildings

and utilization temperatures have been prepared by ASHRAE [3]

for use if the exact demand and the outlet temperature are not

known.

3
CHAPTER ONE - FUNCTION

Systems and Components

1.2.3 Criterion Solar contribution. The average yearly contribution of solar

energy to the operation of the HW system shall be specified in

the design and shall result in a reduction in the average annual

consumption of conventional energy for hot water heating.

Evaluation Engineering review and analysis of drawings, test data, and calculations. Analytical predictions or correlations based upon

measured or simulated performance including at least the source water temperature, hot water requirements, HW system performance,

and the climatic conditions shall be utilized to predict the percentage of average monthly and yearly total energy requirements

to be provided by solar energy and auxiliary energy from conventional energy sources. Hourly or daily input data intervals are required for simulation calculations. Predictions based upon

correlation charts may be based upon monthly average climatic

data for sites where at least 10 year weather data is available.

Examples of analytical and design methods are described in

references [10, 15, 17, 18].

Commentary The effectiveness of solar hot water systems is influenced by

the correlation between the daily withdrawal schedule and the

availability of solar energy. These parameters should be con- sidered during the design when known.

1.3 Requirement Collector performance. The solar collectors shall absorb solar

energy and convert it into useful thermal energy. The collectors

shall be capable of dissipating thermal energy (i. e., nocturnal

reradiation) where this function is included in the design.

1.3.1 Criterion Thermal performance of discrete collectors. The solar collectors

shall collect or dissipate energy at their design values.

Evaluation Engineering review of drawings, calculations, and test data.

Solar collector panel performance data shall be generated using

the method described in ASHRAE Standard 93-P (in preparation) [19] or any other comparable method demonstrated to have an overall

limit of error of less than + 5%.

Commentary Typical slope intercept curves for flat black and selective coated

absorber panels with one and two covers are shown in Figures 1.3-1

and 1.3-2 for air and water heat transfer fluids, respectively.

The 93-P test method will provide the efficiency as a function of

operating temperature, ambient temperature, and insolation for

collectors with a definable aperture or interception area. The

collector must have a single heat transfer fluid inlet and outlet

and must be separate from the thermal storage device. Collectors

with other geometric, optical, or thermal characteristics may

require additional or other tests to fully describe their thermal

performance for all environmental and operating conditions.

Additional information on collector design, performance, and

operation is presented in reference [10, 15, 20, 21].

1.3.2 Criterion Thermal performance of combined active collector-storage units or passive collectors. Combined active or passive collectors shall

collect or dissipate energy at their design values.

Evaluation Engineering review of calculations, drawings, and test data.

Commentary Consensus methods to calculate or experimentally determine the

performance of combined or integral systems do not currently exist

4
CHAPTER ONE - FUNCTION

Systems and Components

Figure 1.3-1 Thermal Efficiency Curves For Typical Flat Plate

Collectors Using Air As The Working Fluid [20]

5
COLLECTOR,

CHAPTER ONE - FUNCTION

Systems and Components

Ti - T a °Fhrft 2

I

1 Btu

Figure 1.3-2 Thermal Efficiency Curves For Typical Flat Plate

Collectors Using A Liquid Heat Transfer Fluid [19]

6
CHAPTER ONE - FUNCTION

Systems and Components

However, combined system performance can be predicted using the

analytical methods cited in Paragraph 1.1.4 and preliminary procedures or approaches to predicting the solar fraction of the total

energy supplied by passive systems have been described [22].

Comprehensive coverage of collector technology has been published

[21].'

1.4 Requirement Thermal storage performance. When included in the design, the

storage subsystem shall be capable of providing its rated output

under design loads and the required output for all part load

conditions during which the solar energy system contributes heat.

The storage of thermal energy from sources other than solar may

be utilized when feasible.

1.4.1 Criterion Storage capacity and rate. The storage subsystem shall provide

sufficient heat transfer rates and thermal energy capacity to absorb and store energy at the maximum design collection rate.

Evaluation -Engineering review of drawings, calculations, and/or test data.

The thermal storage design shall be evaluated using the procedure prescribed in NBSIR 74-635 [23] (currently under revision

for publication as ASHRAE Standard 94-P [24]), or a comparable

method demonstrated to have an error of + 5% or less.

Commentary Criteria for thermal losses from liquid storage tanks and piping

are presented in ASHRAE Standard 90-75 [2], Thermal energy lost

within the building envelope during the heating season may be

credited to the solar energy system. Conversely, thermal losses

during the cooling season must be considered in the design as adding to the cooling load.

Thermal storage can be provided for hot or cold applications and

at a range of temperature in more than one container. The use of

thermal storage in conjunction with heat recovery, electrical peak

shaving, and dampening of time and weather dependent loads on machines should be considered.

1.5 Requirement Component/system/space interactions. The presence of system

components shall not significantly affect the efficient operation

of the H/C/HW systems or the habitability of the occupied spaces.

1.5.1 Criterion Heat or humidity transfer effects. Heat or humidity transfer from

the collector, thermal storage, piping, or other elements shall not

interfere with the efficient operation of the H/C/HW systems or cause loss of control of temperature, humidity, or other controlled

conditions

.

Evaluation Engineering review of drawings, specifications, calculations, and test data. A thermal analysis including calculations of the heat

transfer and condensation rates from storage containers, piping,

and other thermally insulated components or test data on equivalent material and configurations may be necessary in designs

where test data does not exist.

Commentary It is realized that some heat transfer from insulated piping and

storage containers will occur within or under a building structure.

Over-heating and condensation can create adverse conditions.

1.6 Requirement Energy transport performance. The energy transport subsystem

shall transfer the required thermal energy between the operating

subsystems at or above the design efficiency under full load

conditions

.

7
CHAPTER ONE - FUNCTION

Systems and Components

1.6.1 Criterion Thermal losses . Thermal losses for the energy transport subsystem

shall not exceed the design values throughout the operating

range

Evaluation Engineering review of drawings, specifications, calculations, and

test data.

Commentary

1.6.2 Criterion

Evaluation

Commentary

1.7 Requirement

1.7.1 Criterion

Evaluation

Commentary

1.7.2 Criterion

Evaluation

Commentary

Criteria for thermal losses in piping and ducts are presented in

ASHRAE Standard 90-75 [2], Variations in the thermal conductivity, specific heat, and viscosity of the heat transfer medium

with temperature should be considered in the design. Design data

and analytical procedures for thermal insulation and heat transfer

in building systems are available in the literature [1, 2, 4].

Thermal energy lost within the building envelope during the heating

season may be credited to the solar energy system. Conversely,

thermal losses during the cooling season must be considered in the

design as adding to the cooling load.

Electrical operating energy . The use of electrical operating energy

for the energy transport subsystem shall not exceed the design

values throughout the operating range.

Engineering review of drawings, specifications, calculations and

test data.

The electrical operating energy required for fans, pumps, controls, or valves can significantly influence the overall system efficiency.

These energy requirements should be accounted for in the evaluation

of overall system performance.

Controls and instrumentation . The control subsystem shall provide

for the safe and proper operation of the H/C/HW systems.

Installation and maintenance . The control subsystem shall include

such provision for manual bypass, adjustment, or over-ride of

automatic controls as is required to facilitate installation,

startup, operation, shutdown, and maintenance.

Review of drawings, specifications, and operating procedures.

Provision of manual controls may be needed during installation,

startup, and operation to balance or adjust the system for proper

operation. Other manual controls may be required for tests or maintenance after the system has been in operation or for seasonal

shutdown. Control considerations have been discussed [10]. Controls

should be considered for collector-to-storage, storage-to-load and

collector protection from overheating or freezing.

Manual adjustment . If manual control adjustments are required

during normal operation of the system/subsystem, the control

subsystem shall ensure that the safety and durability of the

system and the building in which they are installed are not com- promised by failure to perform these manual control adjustments

for a reasonable period of time. The time period, as well as any

contingent environmental conditions, shall be stipulated by the

designer

Review of drawings, specifications, and operating procedures.

These provisions are not intended to restrict appropriate seasonal

shutdown manual controls. Control considerations for solar H and

C applications [10] and for HVAC equipment in general are discussed in references [3, 4, 25].

8
CHAPTER ONE - FUNCTION

Systems end Components

1.7.3

1.7.4

1.8

1 . 8.1

1 . 8.2

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Requirement

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Demonstration systems may require various degrees of attention for

periodic adjustments. The use of main valves and duct dampers with

visual position indicating devices is encouraged.

Inhabited space temperature control . Each H, C, or HC system

shall be capable or providing occupied space temperature regulation by at least one adjustable automatic control or combination

of controls and sensors set to control within the range from

55°F to 85°F.

Review of drawings and specifications.

In certain multizone or multisystem applications, a priority control may be needed to avoid simultaneous heating and cooling of

a common conditioned space. Localized controls for building

heating and cooling are discussed in reference [3],

Hot water temperature . Potable water storage tanks providing

hot domestic water directly to the hot water distribution system

shall be equipped with instantaneous automatic temperature controls capable of adjustment from the lowest to the highest

acceptable temperature settings for the intended use.

Review of drawings and specifications.

Location and adjustment of the HW controls can influence the use

of auxiliary energy.

Auxiliary energy . The auxiliary energy subsystem shall be

integrated into the systems to the extent necessary to automatically provide the designed heating, cooling, and hot water.

Design heat loads . The auxiliary energy subsystem shall be

designed to meet the peak heating and hot water loads as specified

in Criteria 1.1.1 and 1.2.1.

Engineering review of plans, specifications, calculations, and test methods.

The purpose of this criterion is to back up the systems used in the

Demonstration Program with 100 percent operating capability with

the auxiliary energy subsystem when energy derived from solar

radiation is not available. Design heat loads are discussed by

ASHRAE [1, 2, 3].

Design cooling load . The portion of the yearly total (latent and

sensible) cooling load provided by the auxiliary energy subsystem

shall not exceed the design values specified in Criteria 1.1.2

and 1.1.3.

Engineering review of drawings, specifications, calculations,

and test data.

The design of the cooling system must carefully consider the type

and amount of auxiliary energy used to ensure that a saving in

conventional energy is realized with the solar cooling system.

9
CHAPTER ONE - FUNCTION

Systems and Components

' References

1. ASHRAE Handbook of Fundamentals - 1972.*

2. ASHRAE Standard 90-75, Energy Conservation in New Building Design , 1975.*

3. ASHRAE Handbook and Product Directory - 1973 Systems.*

4. ASHRAE Handbook and Product Directory - 1974 Applications.*

5. Energy Conservation Design Guidelines for New Office Buildings , Second Edition, July

1975, General Services Administration (3F1) , Washington, D.C. 20407.

6. ASHRAE Standard 55-74, Thermal Environmental Conditions for Human Occupancy, 1974.*

7. Solar Heating and Cooling of Buildings - Phase 0 , National Science Foundation Reports,

NSF/RA/N-74-021B, NSF/RA/N-74-022B, and NSF/RA/N-74-023B , Washington, D.C., May 1974.

8. Duffie, J. A. and Beckman, W. A., Solar Energy Thermal Process , Wiley-InterScience

Publication, John Wiley and Sons, New York, 1974.

9. Klein, S. A., etal, "A Method of Simulation of Solar Processes and Its Applications,"

Solar Energy, Vol. 17, p. 29, 1975.

10. Extended Abstracts , International Solar Energy Congress and Exposition (ISEC&E), Los

Angeles, California, July 1975.

11. Liu, B. Y. H. and Jordan, R. C. , "Availability of Solar Energy for Flat-Plate Solar Heat

Collectors," Chap. 1, Low Temperature Engineering Application of Solar Energy , 1967

(revised edition being prepared by ASHRAE see reference 15).*

12. Bennett, I., "Monthly Maps of Mean Daily Insolation for the United States," Solar Energy , Vol. 9, p. 145, 1965.

13. Climatic Atlas of the United States , U.S. Department of Commerce, June 1968.

14. Climatological Data - National Summary, published monthly, National Climatic Center,

Federal Building, Asheville, North Carolina 28801.

15. ASHRAE Publication, "Applications of Solar Energy for Heating and Cooling of Buildings,"

(in preparation).*

16. Streed, E. R. , etal, "Thermal Data Requirements and Performance Evaluation Procedures

for the National Solar Heating and Cooling Demonstration Program," NBSIR 76-1137,

August 1976, National Bureau of Standards, Washington, D.C. 20234.

17. Gutierrez, G., Hincapie, F., Duffie, J. A. and Beckman, W. A., "Simulation of Forced

Circulation Water Heaters; Effects of Auxiliary Energy Supply, Load Type and Storage

Capacity," Solar Energy , Vol. 15, p. 287-298, 1974.

18. Chinnery, D. N. W. , Solar Water Heating in South Africa , NBRI Bulletin 44, Council for

Scientific and Industrial Research Report 248, p. 1-79, UDC 694, 4.551.521.1 (680),

Pretoria, South Africa, 1967.

19. ASHRAE Standard 93-P, "Method of Testing for Rating Solar Collectors Based on Thermal

Performance," (in preparation).*

*American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 345 East

East 47th Street, New York, N.Y. 10017.

-(-Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

10
CHAPTER ONE - FUNCTION

Systems and Components

20. Hill, J. E., Streed, E. R. , Kelly, G. E. , Geist, J. C. and Kusuda, T. , "Development of

Proposed Standards for Testing Solar Collectors and Thermal Storage Devices," NBS

Technical Note 899, February 1976, Catalog No. C13.46:899.+

21. Workshop on Solar Collectors for Heating and Cooling of Buildings , Proceedings,

National Science Foundation, NSF/RA-N-75-019 , May 1975.

22. Balcomb, J. D. and Hedstrom, J. C. , "Simulation Analysis of Passive Solar Heated

Buildings - Preliminary Results," Report No. LA-UR-76-89, Los Alamos Scientific

Laboratory, Los Alamos, New Mexico 87544.

23. Kelly, G. E. and Hill, J. E. , "Method of Testing for Rating Thermal Storage Devices

Based on Thermal Performance," NBSIR 74-635, National Bureau of Standards, Washington,

D. C. May 1975.

24. ASHRAE Standard 94-P, "Method of Testing Thermal Storage Devices for Thermal

Performance," (in preparation) .

25. ASHRAE Handbook and Product Directory - 1975 Equipment.*

*American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 345

East 47th Street, New York, N.Y. 10017

+Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

11
CHAPTER TWO - MECHANICAL

Systems and Components

2.1

2 . 1.1

2 . 1.2

2.1.3

2.1.4

Requirements

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Criterion

System design conditions . The H/C/HW systems shall be capable of

functioning at their design flow rates, pressures and temperatures.

Equipment capabilities & applicable standards . Pumps , fans , or other components shall be sized to move the heat transfer fluid

through the collector, piping, and/or ducts at design flow rates.

All mechanical components shall conform to applicable local

and nationally recognized codes and standards.

Review of drawings, specifications, historical performance,

previous test data, and design calculations. Systems or applications that do not lend themselves to engineering analysis

may require prototype tests to demonstrate compliance.

In order to transfer heat through the system/subsystem, a number

of different transfer approaches such as gravity circulation,

combined forced and gravity circulation, or forced circulation

may be used.

Noise or erosion-corrosion . The piping or ducts and associated

fittings shall be sized to carry the heat transfer fluid at design flow rates without excessive noise as prescribed by

reference [1] or erosion-corrosion.

Review of drawings, specifications, historical performance,

previous test data and design calculations.

Reference [2] provides organized design practices for transfer fluid

limit velocities in piping systems. In air ducts, the velocities

normally should not exceed the recognized values of ASHRAE or Sheet

Metal and Air Conditioning Contractors National Association (SMACNA)

Operating conditions . Collectors, space heaters, water heaters,

pumps, valves, regulating orifices, pressure regulators and other

fluid handling components shall be capable of being operated over

the pressure and temperature ranges anticipated in actual service

without breakage, rupture, binding, galling, or significant loss

or gain in pressure that could impair their intended function.

Review of drawings, specifications, historical performance,

previous test data and design calculations. Systems or components

that do not lend themselves to engineering analysis shall be

tested at the maximum and minimum service temperatures with

anticipated fluid pressures. To show compliance with this

criterion it is desirable that the design consist of components

that are covered by recognized standards, where available, and

are specified by the manufacturer to be suitable for the pressure,

temperature, and flow application.

Available codes and standards are listed by ASHRAE [3]

Fluid flow in collectors . When an array of collectors is

connected by manifolds, provision shall be incorporated in the

manifolds and/or collectors to maintain the design flow rate of

the heat transfer fluid through each collector.

12
CHAPTER TWO - MECHANICAL

Systems and Components

Evaluation Review of drawings, specifications, historical performance,

previous test data, and design calculations or testing to determine that each collector will receive its design flow rate.

Commentary Because of friction and variation in velocity head in manifolding,

flow rates may be inadequate through collectors remote from the

pump or other fluid supply source. This can result in inefficient

collector operation. The provision of flow regulating devices

is one means of correcting for this problem. Another method is

the use of reversed supply and return headers for parallel arrays

of collectors with graduated header sizes to compensate for changes

in flow rate [4],

Consideration should be given to the effect of header arrangement

on collector array AT.

2.1.5 Criterion Entrapped air. When liquid heat transfer fluids are used, the

system shall provide suitable means for air or gas removal from

high points in the piping system.

Evaluation Review of drawings and specifications.

Commentary Except for expansion tanks and air chambers where trapped air is

required, trapped air in piping systems and collectors can impede the flow of liquids through piping, reduce heat transfer

potential and otherwise reduce overall system efficiency. The

freezing of exposed air vent fittings has been known to occur and

create trapped air conditions in solar piping systems. The

potential buildup of vapor which could create air pockets and thus

block or restrict the flow of heat transfer fluids should be

considered

.

2.1.6 Criterion Thermal expansion of fluids. Adequate provisions for the thermal

expansion of heat transfer fluids that can occur over the service

temperature range shall be incorporated into the system design.

Expansion tanks shall be sized in accordance with the recommendations

of ASHRAE.

Evaluation Review of drawings, specifications, and design calculations.

Commentary Water expands about 4% in volume when heated from 40°F to 200°F,

Other heat transfer fluids will have different coefficients of

volume expansion. Means should be provided in the system design

to contain this additional fluid volume without exceeding the

operating pressure of the system or resulting in spillage.

2.1.7 Criterion Pressure drops. Pressure drops shall not exceed the limits

specified in the design. Pipe sizing shall be in accordance

with recognized methods.

Evaluation Review of drawings, specifications, and design calculations.

Commentary Since the energy requirements of pumps and fans are a function

of the system flow resistance, pressure drops should be kept as low as practical. The unnecessary use of fittings such as bends,

tees, globe valves, reducers, or obstructions to flow should be

avoided by careful arrangement of piping runs. Accepted practices

for plumbing design are discussed in standard plumbing guides [5]

[6]. It is possible to design solar energy systems that consume

more conventional energy than the systems that they replace because

of high operating power requirements.

13
CHAPTER TWO - MECHANICAL

Systems and Components

i

2.1.8 Criterion

Evaluation

Commentary

2.1.9 Criterion

Evaluation

2.1.10 Criterion

Evaluation

Commentary

2.2 Requirement

2.2.1 Criterion

Evaluation

Commentary

2.2.2 Criterion

i Air transport system . Design of all air heating and air conditioning systems shall be in accordance with applicable recommendations

of ASHRAE, National Environmental Systems Contractors Association

(NESCA) , or Air-Conditioning and Refrigeration Institute (ARI) . In- stallation shall comply with National Fire Protection Association

(NFPA) standards 90B, 11 and 54.

Review of plans and specifications.

Duct work should be designed for the shortest practical run and

elbows should be kept to a minimum. Constrictions should be

avoided

Air discharge openings . Air discharge openings through roofs or exterior walls shall not be located such that their exhaust will

cause the deposition of grease, lint, condensation or other

deleterious materials on solar optical components.

Review of plans and specifications.

|| Thermosyphoning losses . Means shall be provided to prevent un- desired loss of thermal energy from storage through thermosyphoning

action.

Review of drawings and specifications.

Significant losses of energy from storage can occur through this

mechanism. Some designs may use thermosyphoning of energy from

storage as a means of protection from freezing.

Mechanical stresses . Mechanical stresses that arise within the

system shall not cause damage to or malfunction of the system or

its components

Vibration stress levels . Vibrations in piping, ducts, instrumentation

lines, and control devices shall be controlled to reduce stress

levels below those that could cause fatigue and subsequent component

damage

Review of drawings, specifications, historical performance, and

previous test data for adequate piping and equipment supports.

! Examples of possible vibration sources in piping are as follows:

a. Lengths of piping and connecting equipment that are resonant

with pressure pulsation frequency.

il b. Vibration resulting from motors, pumps, fans, and compressors

which are not properly mounted.

c. Water hammer and quick closing valves.

d. Expansion and contraction of piping on hangers.

e. Wind pulsations on certain lengths and diameters of piping

supported by loose hangers or supports.

Vibration from moving parts . Pumps, fans and compressors or other components involving moving parts shall be balanced

and/or mounted in a manner that will avoid vibration that

could cause damage or excessive noise.

14
I CHAPTER TWO - MECHANICAL

Systems and Components

i

t

2.2.3

2.2.4

2.2.5

Evaluation

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Criterion

Evaluation

Review of drawings and specifications. Prototype inspection and

testing if deemed necessary. The equipment supporting structure

shall not have natural frequencies within + 20 percent of the

operating speeds. The equipment when mounted and placed in

operation should not exceed a self-excited vibration velocity of

0.10 inches per second when measured with a vibration meter on

the bearing caps of the machine in the vertical, horizontal, and

axial directions or measured at the equipment mounting feet if the

bearing caps are concealed [7] .

Water hammer . When a liquid is used as the transfer fluid and

quick closing valves are employed in the design, the piping system

shall be able to control or withstand potential "water hammer".

Water hammer arresters shall be in compliance with applicable codes.

Review of drawings, specifications, and/or design calculations.

Pressure rises resulting from water hammer may damage piping and

equipment. It can be minimized by piping system design, or the use of water hammer arresters [8, 9].

Vacuum relief protection . Closed storage tanks and piping located

at elevations above the system served shall be protected against

collapsing pressure if subjected to vacuum. Such components

shall be designed to withstand such pressures or have vacuum

relief protection.

Review of drawings and specifications.

Possible collapse of large diameter tanks and piping from

atmospheric pressure is an important design consideration [10].

Thermal changes . The system components and assemblies shall be

designed to allow for the thermal contraction and expansion that

will occur over the service temperature range.

Review of drawings, specifications and calculations.

Commentary Piping and other components may experience changes in dimensions

as a result of temperature changes. Such changes can result in

excessive stresses within the piping, piping supports, structure,

pumps, compressors, and solar collectors if means are not incorporated

in the piping system design to allow for the thermal movement.

2.2.6 Criterion Pipe and duct hangers . Pipe and duct hangers used to support

insulated pipes or ducts shall be designed to avoid damaging

the insulation material.

Evaluation Review of drawings and specifications.

Commentary If pipe or duct hangers are installed over the insulation material,

plates should be used to avoid damaging the insulation.

2.2.7 Criterion Flexible joints . All systems employing heat transfer fluids shall

be designed to be capable of accommodating flexing of plumbing

and fittings.

Evaluation Review of drawings and specifications.

15
CHAPTER TWO - MECHANICAL

Systems and Components

2 . 3 Requirement Leakage prevention. System assemblies containing heat transfer

fluids shall not leak to an extent greater than specified in

the design when operated at all conditions within the design

operating range.

2.3.1 Criterion Leak testing. Those portions of installed H/C/HW systems which

contain liquid heat transfer fluids and are not directly connected

to the potable water supply shall not leak when pressures of not

less than 1-1/2 times their design pressure are imposed for a minimum of 15 minutes

Evaluation Review of specifications and testing. The test pressure shall be

applied for a period of time necessary to inspect each joint for

leakage. The temperature of the water shall be within 5°F of

the ambient atmosphere. A pressure gage would be observed for

this period to determine whether the pressure drop is within

allowable limits.

Commentary A hydrostatic test pressure of 1 1/2 times the design pressure is

considered a standard test pressure [11]. For most applications,

clear water is used. If the water temperature is not approximately

that of the ambient atmosphere, sweating will result and proper

examination will be difficult. In addition, the use of hot

liquids can result in the swelling of packings and joint materials,

thus concealing leaks. Some leakage in valve and pump stuffing

boxes and packing glands may be desirable. Bleeder valves or petcocks should be provided at the highest point or points in the

system to permit venting of all air in the piping during the

filling operation.

2.3.2 Criterion Pressure test: potable water. Those portions of installed H/C/HW

systems that are directly connected to the potable water supply

system shall not leak when tested in accordance with applicable

local and nationally recognized codes and standards.

Evaluation Review of drawings and specifications.

Commentary See Commentary for 2.3.1.

2. A Requirement Collector adjustments. The collector subsystem shall be capable

of being located, oriented, and tilted as required by the design

to capture sufficient solar energy to meet functional requirements.

2.4.1 Criterion Orientation and tilt. The collector shall be installed on a mount capable of maintaining tilt and orientation to design

conditions

Evaluation Review of drawings and specifications.

Commentary Collectors can either be fixed, require seasonal adjustment, or be

continuously movable. Detailed information concerning orientation

and tilt is given by ASHRAE [3]. It is not the intent of this

criterion that the collector necessarily be reoriented or tilted

after initial installation.

16
CHAPTER TWO - MECHANICAL

Systems and Components

2.4.2 Criterion Mutual shadowing. Collectors shall be installed so that mutual

shadowing is minimized and does not exceed design limits.

Evaluation Review of drawings (site and system) , specifications and calculations .

Commentary Data are available for calculating shading angles with respect

to the time of day and year [12].

2.5 Requirement Heat transfer fluid quality. Provision shall be made to maintain

the quality of the heat transfer fluid at a level that does not

impair its heat transfer function.

2.5.1 Criterion Liquid quality. The systems shall have filters or other means

to prevent contamination by foreign substances that could impair

the flow and quality of the heat transfer fluid beyond acceptable

limits

Evaluation

- When make-up water is of such a quality that excessive corrosion

is known to exist, a suitable water treatment system as recom- mended by the Water Quality Association shall be provided [13].

Review of piping drawings and specifications.

Commentary The piping in some solar collectors and heat exchangers may have

small cross sections in which blockage by dirt, scale, pieces

of gasket material, pieces of packing, or other foreign matter

in the heat transfer fluid could occur.

2.5.2 Criterion Air quality. Adequate means shall be provided to prevent the

accumulation of deposits of dust or dirt that could result either

in a reduction of system efficiency, or in the creation of a health

hazard when air from the system is admitted into occupied spaces.

Evaluation Review of drawings and specifications.

Commentary The gravel used for rockbed storage with air systems should be

selected for size and freedom from dirt and dust. The use of

smooth and washed material and of filtered air is desirable.

The possibility of dirt buildup in collectors should also be

considered

2.5.3 Criterion Fluid treatment. Suitable devices and procedures shall be provided

to assure that the chemical composition of the heat transfer fluid

is maintained at levels adequate to prevent unacceptable deposits

on the heat transfer surfaces or corrosion of the surfaces with

which the heat transfer fluid comes in contact.

Evaluation Review of drawings and specifications.

Commentary Problems can develop when fluids such as "hard" water are used.

2.5.4 Criterion Freezing protection. System components shall be protected from

damage by the freezing of heat transfer liquids at the lowest

ambient temperatures that will be encountered in actual use.

Evaluation Review of drawings and specifications.

Commentary The purpose of this criterion is to insure that rupture or other

damage to solar collectors and associated piping and equipment

will not occur from expansion of water if it freezes. The intent

of this criterion is not to restrict the designer to the use of

antifreeze solutions. If automatic draindown is the freeze

protection technique to be used, automatic air vents and/or vacuum

relief valves should also be protected from freezing.

17
CHAPTER TWO - MECHANICAL

Systems and Components

References

1. ASHRAE Handbook and Product Directory - 1973 Systems.

2. National Standard Plumbing Code , as recommended by the National Association of

Plumbing-Heating-Cooling Contractors, Appendix B, pp. 10-11, 1971.

3. ASHRAE Handbook and Products Directory , 1974 Applications .+

4. Duffie, John A., and Beckman, William A., Solar Energy Thermal Processes , John Wiley

and Sons, New York, N.Y.,, pp. 261-264, 1974.

5. King, R. C. and Crocker, S., Piping Handbook , 5th ed. , McGraw-Hill Book Company,

New York, Chapter 3, p. 130.

6. Marks, L. S., Mechanical Engineers Hahdbook , 6th ed., McGraw-Hill Book Company,

Section 12, p. 102, 1958.

7. "Vibration Isolation," Section 1515, Public Buildings Service Guide Specifications,

April 1970, PBS: 401515, General Services Administration, Washington, D.C. 20405.

8. American National Standard, Water Hammer Arresters, ANSI A112.26.1, 1969, American

Society of Mechanical Engineers.

10. Windenburg, D. F. , "Vessels Under External Pressure," Mechanical Engineering , pp. 601-607, January 1937.

11. King, R. C. and Crocker, S., Piping Handbook , 5th ed., Chapter 7, p. 291, McGraw-Hill

Book Company, New York, 1967.

12. Tabor, H. , "Stationary Mirror Systems for Solar Collectors," Solar Energy , Vol. II, pp. 3-4, July-October 1958.

13. Water Quality Association - 447 East Butterfield Road, Lombard, Illinois 60148, 1974

+American Society of Heating, Refrigerating and Air Conditioning Engineers, 345 East 47th

Street, New York, N.Y. 10017

18
CHAPTER THREE - STRUCTURAL

Systems and Components

( Note: This chapter has been significantly reorganized ) The performance requirements and criteria in this chapter deal with the ability of

systems and elements to maintain their structural integrity under in-service and extreme

conditions. Factors such as thermal, operating, wind, snow and seismic loads are con- sidered in this chapter. Typical failures that are to be avoided might include the

fracture of a glass collector surface due to restraint from incompatible thermal

expansion, due to the impact of hail, or due to unequal stress caused by partial shading,

or the collapse of a rack supporting solar collectors due to wind, snow, or earthquake.

Performance requirements for building structures and the interaction of solar systems

with building structures are included in Chapter 9.

There is an important distinction made between conventional elements, those elements for

which design and construction procedures are contained in common building regulatory

documents, and non-conventional elements, those elements for which such procedures are

not available. Elements made of materials documented in common building regulatory

documents, such as structural steel, aluminum, timber, glass, masonry, concrete, etc.,

that will be exposed to service conditions that are normally considered in such documents

are examples of conventional elements. New materials, such as a new alloy of aluminum,

or conventional materials exposed to an environment not normally considered, such as welded

steel subjected to unusually high or low temperatures, are examples of non-conventional

elements

3.1 Requirement Structural loading and resistance . The structural elements

and connections of the H/C/HW systems shall support the ultimate

loads expected during the service life of the systems without

failure.

3.1.1 Criterion Conventional elements, load and resistance . The resistance,

R, of the conventional elements of the system shall exceed

the required design load U.

The resistance, R, of conventional elements and systems shall

be determined by reference to the local building code or to one of the three model codes [l, 2, 3] or the MPS [4] if no local code is in effect.

The design load, U, includes the following:

1. Dead loads (D) shall be the "Dead Loads" stipulated in

Section 2 of ANSI A58.1 [5].

2. Live loads (L) shall include all applicable "Live Loads"

stipulated in Section 3 and "Snow Loads" stipulated in

Section 7 of ANSI A58.1, static and dynamic loads exerted

by the operation of the solar energy system, ice loads

as stipulated in Section 1 of the Appendix to this chapter

on slender elements such as wires and slender pipes,

vehicular loads as stipulated by AASHTO [6] on elements

at or below grade subjected to traffic, and all soil and

water pressures on buried elements in accordance with

accepted principles of soil mechanics.

3. Wind Loads (W) shall be "Wind Loads" stipulated in

Section 6 of the ANSI A58.1 [5].

4. Earthquake loads (E) shall be those stipulated in Section

8 of the ANSI A58.1 [5], or the provisions of the Uniform

Building Code (UBC) [2]. For components and connections

which cannot be evaluated within the scope of the referenced

provisions, the value of "Cp" shall be taken as 1.0.

19
CHAPTER THREE - STRUCTURAL

Systems and Components

5. Constraint loads (T) caused by temperature changes,

shrinkage, moisture changes, normal functioning of the

system, time-dependent changes within the materials of the

system, and by differential foundation settlement shall

be taken as the most severe likely to be encountered

during the service life.

The above loads shall be combined to obtain the total design

load, U, as stipulated in Section 4 of ANSI A58.1 [5].

Evaluation Review of design drawings, specifications, and calculations.

Commentary Conventional elements and systems are those for which design

and construction procedures are currently specified in common building regulatory documents. The intent of this criterion

is that such elements continue to be designed in accordance

with these documents.

It is recognized that some elements will be designed using

the ultimate resistance and factored loads while others will

be designed using an allowable resistance and unfactored loads.

The loads presented are those expected to occur in the projected

lifetime of the installation. Particular attention should be

given to the load caused by the thermal cycling of the system,

both under normal conditions and "no-flow" conditions.

The value of C p supplied for elements that are not specified

by the UBC is consistent with conservative values for elements

appended to structures.

3.1.2 Criterion Nonconventional elements, resistance to maximum load . The

resistance, R, of the nonconventional elements of the system or

a portion thereof shall exceed the required ultimate load, U:

U 1 R = Rm ^ Cu where

Rn, = mean resistance

0 = variability factor as defined in Section 2 of the Appendix

to this chapter

Cu = ductility factor as defined in Section 2 of the Appendix to this chapter

U = a^D + a£ (a 3 L + a 3 Q + a 4

T)

Q

= W or E

D, L, W, E, and T as defined in Criterion 3.1.1

aq = 1.3 if D acts alone or adds to the effect of other loads or 0.9 if D counteracts other loads

a£ = 1.0 if one of L, Q, or T is acting, or 0.75 if two of L, Q, or T are acting, or 0.6 if L, Q, and T all act

33 = 1.7 or 0 a4 = 1.3

Constraint loads (T) shall be explicity allowed for by con- sidering a differential foundation settlement of 2 inches in

any horizontal distance of 50 feet in addition to those con- ditions specified in 3.1.1, except that in cases where a particular foundation is specifically designed to control

20
CHAPTER THREE - STRUCTURAL

Systems and Components

Evaluation

Commentary

3.1.3 Criterion

Evaluation

differential settlements, the differential settlements used

for T should be those consistent with the specified design.

Uplift forces caused by a swelling of expansive soils shall

be calculated assuming a level of 0.9D for gravity loads.

Review of design drawings, specifications, calculations, and

documentation of the resistance as described in section 2 of

the Appendix to this chapter.

The intent of the criterion is to provide a minimum level of

safety against loading situations which have a suitably low

probability of occurrence during the service life. The load

factors represent present day design practice of building structures and are similar to the load factors proposed for use in the

NBC of Canada [7], These factors will also produce ultimate

loads comparable to those presently used in the design of steel

,and concrete structures. Adoption of a similar level of perfor- mance requirements for the H/C/HW systems will permit the designer

to explore the potential use of system components as structural

elements in addition to their primary heating and/or cooling

function.

Due to economic considerations in foundation design, the

assumption is usually made that the conventional structures are capable of accommodating a reasonable amount of differential

settlement. The prescribed foundation settlement is consistent

with observed performance of conventionally designed foundations

and represents the threshold at which structural damage occurs. This criterion is relaxed when special precautions are used

in foundation design to control differential settlements.

Nonconventional elements, resistance to cyclic loads . Nonconventional structural elements shall be capable of resisting

the following repeated loads without failure and without a residual deflection in excess of 25 percent of the maximum

deflection measured in the first cycle of load application:

(1) 100 cycles from 1.0 D to 1.0 D to + 0.5 L

(2) 1000 cycles from 1.0 D to 1.0 D + 0.5 W

(3) 1000 cycles from 1.0 D to 1.0 D + 0.5 T

Where D, L, W, and T are as defined in 3.1.1, except that

only thermal constraint loads need be included in T.

Physical simulation and testing or analysis based on available

test data.

The cycle loading (1) and (2) shall be assumed to be applied

after reducing system slack by the prior application of one preloading cycle of the following loads:

for (1) from (ID) to (ID + 1L)

for (2) from (ID) to (ID + 1W)

for (3) from (ID) to (ID + IT)

21
CHAPTER THREE - STRUCTURAL

Systems and Components

3.1.4

3.1.5

3.2

3.2.1

Commentary

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Cyclic loading shall commence only after deflection

recovery from the preloading cycle is substantially complete.

The residual deflection shall be taken as the difference

between the deflection measured 24 hours after removal of the

superimposed cyclic load and the residual deflection, if any,

not recovered from the preloading cycle.

Even though the service load history cannot be simulated* the

imposition of the stipulated cyclic loads is intended as a conservative representation of service conditions. The

residual deflection limitation assures preservation of

structural integrity under cyclic loading.

Ponding . Horizontal surfaces of all elements exposed to the

exterior environment shall be designed to prevent failure due

to ponding.

Review of drawings and analysis based on documented strength

and stiffness properties or physical simulation and testing.

Ponding is defined as the retention of water due to the

deflection of horizontal surfaces. Measures to resist ponding

include providing sufficient stiffness to prevent failure,

providing slope to carry excess water away, providing drains

to remove water, or providing overflow locations to limit the

depth of water.

Hail damage . All system components and supporting structural

elements that will be exposed to the natural environment in

service shall be designed to resist, without excessive damage

or major impairment of the functioning of the system, the

impact of falling hail as stipulated in Section 3 of the Appendix

to this chapter.

Evaluation will be based on analysis using known structural

information on the physical characteristics of the system

components or on physical simulation and testing using the NBS

hail resistance test described in the NBS Building Science Series

23 [8].

In cases where protective measures are provided to prevent

impact of hail on system components, such as the use of screens

or deflectors, these protective measures shall be included in the test specimen.

It is not the intent of this criterion to prevent punching or local

cracking of nonstructural elements such as glass cover plates

of collector panels under hail impact, but rather to control

damage by keeping it at a level which would not create a major

curtailment in the functioning of the system, premature

failure or hazards created by excessive shattering of glazed

elements

Requirement Function and operation . The structural elements of the solar

energy system shall not impair the function or operation

of the solar energy system when exposed to service loads.

Criterion Resistance to damage . Under the effect of deflections caused

by loads D, L, W, and T as defined in Criterion 3.1.1, in

addition to the anticipated creep deflections, the system as

a whole or any component, connection or support thereof, shall

not suffer permanent damage which would require replacement

or repair, or which would impair its intended function during

its service life.

22
CHAPTER THREE - STRUCTURAL

Systems and Components

Evaluation Evaluation of documentation of data for design, tests,

installations. Evaluation and/or testing of components

and elements where deemed essential. Determination of

compliance with generally accepted standards and engineering

and trade practices, where applicable.

The criterion is deemed satisfactory if it can be demonstrated that deflections caused by the specified loads

can be accommodated by suitable details or adequate

flexibility.

Commentary The intent of this criterion is to provide for the proper

functioning of the system under service loading conditions

without breakdown or permanent impairment beyond levels

comparable to conventional heating and cooling systems.

Criterion ' Nonconventional elements, deflection limitations. The

deflection of nonconventional structural element? supporting

the system components shall not exceed the following limitations

(a) With the full dead load (1.0 D) in place, the

maximum deflection due to a superimposed load of

0.2 D + 1.5 L, sustained for 24 hours shall not

exceed

1.25s 0.2D + 1.5L

180 L where s = span length

(b) The maximum residual deflection measured not more

than 24 hours after removal of the superimposed load

specified in (a) shall not exceed:

0.25s

180

Evaluation Analysis and/or physical simulation, including tests on prototype support structure. Deflections shall be

measured in a direction normal to the span and shall

include the deflection of the supporting members.

One preloading cycle is permitted, provided that loading

in the actual test does not commence before deflection

recovery from the preloading cycle is substantially complete.

Commentary Loads lower than required ultimate loads should not cause

large, irrecoverable deformations. It is not unreasonable

to require non-conventional structures to resist the

stipulated superimposed loads without resulting in significant

residual deformations. The limitations in part (a) implies

deflection limitation of s/180 under service live load

(1.0 L) with an additional 25 percent allowance for creep.

Part (b) requires 75 percent elastic recovery of deflection.

This guards against significant residual deflection

increases in each cycle of loading that may lead to incremental

collapse.

23
CHAPTER THREE - STRUCTURAL

Systems and Components

Section 1

Commentary

Section 2

APPENDIX

Ice loads . The radial thickness of ice around the circumference of exposed wires, slender pipes, and similar

members shall be based on the annual frequency of occurrence of glaze shown in Figure A-l (see reference [9])

and shall be computed as follows:

Mean number of

days with glaze under 1 1-4 4-8 over 8

Thickness of ice

(inches) 0 1/2 3/4 1.0

The map of Figure A-l with documented information of the

accumulation of ice recorded for major ice storms [9] and

ice loads considered in the design of steel transmission

pole structures [10] have been utilized to relate thickness

of ice to frequency of occurrence of such storms. This

assumption is made in view of a lack of statistical data

on accumulation of ice and should result in a generally

conservative practice even though it is recognized that

thickness of ice cannot be solely expressed in terms of

rate of occurrence.

Resistance of nonconventional elements . The resistance, R,

of nonconventional elements is defined as follows:

R = Rro 0 Cu where

Rflj = mean resistance

0 = variability factor which shall be such that

approximately 95% of the system or portions

thereof exceed Rm 0 in resistance. For normal

distribution of resistance, 0=1- 1.65v.

v = coefficient of variation of resistance with

respect to Rm.

Cu = coefficient for ductility = (u + 7)/12, but not more than 1.0 for loadings not including earthquake,

and equal to 1.0 for loadings including earthquake.

u = ductility factor for loading condition U, as defined

in the following paragraphs.

Where adequate existing test data on the various material

properties comprising the system is available, evaluation

of the resistance will be performed using engineering analysis.

Where adequate test data is unavailable, system elements and

subassemblies will be evaluated in the laboratory using

simulated static load levels consistent with the specified

load combinations.

24
CHAPTER THREE - STRUCTURAL

Systems and Components

25

FIGURE

A-l

MEAN

ANNUAL

NUMBER

OF

DAYS

WITH

GLAZE

(FREEZING

RAIN)
CHAPTER THREE - STRUCTURAL

Systems and Components

The ductility factor will be evaluated as follows: For

an ideal elastoplastic (elastic-perf ectly plastic) resistance function (plot of applied load as ordinate and

deflection as abscissa) , the ductility factor is defined

as the ratio of ultimate deflection to yield deflection

(u = du / dy) . For an actual (nonlinear) function, the

ductility factor shall be computed from an "effective"

function (Fig. A-2) . The effective function consists

of 2 straight lines. The first line is drawn through

the origin and a point on the actual function at which

the resistance is 60 percent of its maximum load

value (Pu) . The second line is a horizontal line ending

at the ultimate deflection (du ) , which shall not exceed

that where the resistance function falls below 95 percent of its maximum load value. The horizontal line

is located so that the area under the 2 lines forming

the effective function is equal to the area under the

actual function up to the point of ultimate deflection.

Effective yield deflection (dye ) shall be taken as the

deflection at the point of intersection of the 2 lines,

which is at a resistance level termed "effective yield

resistance." The ductility factor is based on the

effective resistance function: u = du / dye

.

For experimental or analytical evaluation of structural response, the selection of system components shall

be done in a manner representing the least margin of

safety to the system but consistent with its interaction

with structural systems to which they are attached.

Test loads applied to the system components shall result

in the most critical conditions encountered in service.

Additional eccentricities of loading caused by drift due

to lateral loads and anticipated differential foundation

settlements shall be provided for in tests of supporting

structural elements of the system. The effects of service

history caused by fatigue, sustained load, temperature,

moisture, ultraviolet light or other environmental factors

shall be provided for in tests.

Section 3 Hail loads . The design hail load shall be taken from the

perpendicular impact of falling hail particles with

a diameter (in inches) equal to 0.3d where d is the mean

annual number of days with hail determined on the basis

of the map shown in Figure A-3 and the velocity is the

terminal velocity shown in Table A-l.

Commentary The correlation of hail size with mean annual number of

days with hail is based on studies on the probability of

exceedance of a given particle size as a function of

frequency of occurrence of hail, a twenty year recurrence

interval reflecting the life expectancy of the system and

observations of statistical data [11] indicating that a representative hail storm area is generally one order of

magnitude smaller than the regions for which statistical

information is compiled.

The impact from the vertical terminal velocity is used

as a measure of the effect of hail falling with or without

horizontal wind. It is possible that a larger impact

could occur on surfaces sloped from 30° to 60° if the

maximum particle diameter occurred simultaneously with

a high horizontal wind velocity perpendicular to the

26
APPLIED

LOAD

CHAPTER THREE - STRUCTURAL

Systems and Components

surface. It may be overly conservative for particles

over 1.5" impacting on near vertical surfaces. However,

due to the lack of information on this phenomenon and the

low probability of its occurrence, it is assumed that the

terminal velocity gives the best measure of impact force

consistent with the present state of the art.

EFFECTIVE RESISTANCE FUNCTION

FIGURE A- 2 DETERMINATION OF THE DUCTILITY FACTOR

27
Sean

annual

number

6f

day&

with

'hail

CHAPTER THREE - STRUCTURAL

Systems and Components

1

n

28

FIGURE

A-3

MEAN

ANNUAL

NUMBER

OF

DAYS

WITH

HAIL
CHAPTER THREE - STRUCTURAi

Systems and Components

TABLE A-l

Values of weight and terminal velocity,

computed for smooth ice spheres

• Terminal

Diameter Weight Velocity

in gm lb ft/sec

1/2 0.98 0.002 51

3/4 3.30 0.007 62

1 7.85 0.017 73

1 1/4 15.33 0-.034 82

1 1/2 26.50 0.058 90

1 3/4 42.08 0.093 97

2 62.81 0.138 105

2 1/4 89.43 0.197 111

2 1/2 122.67 0.270 117

2 3/4 163.28 0.360 124

3 211.98 0.467 130

29
CHAPTER THREE - STRUCTURAL

Systems and Components

References

1. Basic Building Code/1975 , Building Officials and Code Administrators International, Inc.,

Chicago, Illinois 60637, 1975.

2. Uniform Building Code , 1976 Edition, International Conference of Building Officials,

Whittier, California 90601, 1976.

3. Standard Building Code , 1976 Edition, Southern Building Code Congress International, Inc.,

Birmingham, Alabama 35222, 1976.

4. HUD Minimum Property Standards, One and Two Family Dwellings (No. 4900.1) (1973, revised

1974) and HUD Minimum Property Standards, Multi-Family Housing (No. 4910.0) (1973),

U.S. Department of Housing and Urban Development, Washington, D.C.

5 . Building Code Requirements for Minimum Design Loads in Buildings and Other Structures , American National Standards Institute, ANSI A58.1 - 1972.

6. Standard Specifications for Highway Bridges , AASHT0, Washington, D.C. 1973.

7. Allen, D. E., "Limit States Design - A Probabilistic Approach," Canadian Journal of

Civil Engineering , Vol. 2, 1975.

8. Greenfield, H., Hail Resistance of Roofing Products , Building Science Series 23,

National Bureau of Standards, Washington, D.C., August 1969.

9. Baldwin, J. L. , Climates of the United States , U.S. Department of Commerce, 1973.

10. "Design of Steel Transmission Pole Structures," Task Committee on Steel Transmission

Poles of the Committee on Analysis and Design of Structures, Journal of the Structural

Division , American Society of Civil Engineers, December 1974.

11. Mathey, R. G. , Hail Resistance Tests of Aluminum Skin Honeycomb Panels for the

Relocatable Lewis Building , Phase II, NBS Report 10193, 1970.

30
CHAPTER FOUR - SAFETY

Systems and Components

4.1

4.1.1

4.1.2

4.1.3

4.2

4.2.1

Requirement

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Requirement

Criterion

Evaluation

Health and safety . The design and installation of the H/C/HW

systems and their components shall be in accordance with

applicable local and nationally recognized codes and standards

for health and safety.

Plumbing codes and standards . Plumbing materials and equipment

and their installation shall be in accordance with applicable

local and nationally recognized plumbing codes,

Review of drawings and specifications. Testing to show compliance

where necessary.

Suitable standards are available for conventional equipment.

Unique, innovative installations may require special consideration.

Electrical codes and standards . Electrical materials and equipment and their installation shall be in accordance with applicable

local and nationally recognized electric codes [1] and with

applicable standards of American National Standards Institute

(ANSI), National Electrical Manufacturer's Association (NEMA)

,

and Underwriter's Laboratories (UL) . Electrical components,

wiring, switching, and protective devices shall be approved or listed by a nationally recognized testing laboratory.

Review of drawings and specifications. Testing to show compliance

where necessary.

Suitable standards are available for conventional equipment.

Unique installations may require special consideration.

Safety and health standards . The design and installation of the

H/C/HW systems and their components shall comply with the

Occupational Safety and Health Standards (OSHA) [2].

Review of drawings and specifications. Inspection of construction site.

The OSHA Standards apply to both construction practices and to the system as installed.

Fail-safe controls . The H/C/HW systems shall be fail-safe for

operation under all anticipated conditions (normal and "no-flow")

and in the event of damage to system components or a power

failure.

System failure prevention . The control subsystem shall be

designed so that, in the event of a power failure, or a failure

of any of the components in the system, the temperatures and/or

pressures developed in the H/C/HW systems will not damage any of

the components of the system or the building or present a danger

to the occupants. The safety devices shall meet the requirements

of one or more of the following organizations: American Gas

Association (AGA) , American Society of Mechanical Engineers (ASME)

,

Factory Mutual (FM) , National Board of Boiler and Pressure Vessel

Inspectors (NBBPVI) , or Underwriter's Laboratories (UL)

Review of drawings, specifications, and design calculations.

31
CHAPTER FOUR - SAFETY

Systems and Components

Commentary

4.2.2 Criterion

Evaluation

Commentary

4.3 Requirement

4.3.1 Criterion

Evaluation

The excessive pressure and temperatures that can build up on collectors under "no-flow" conditions are an important consideration. Consideration should be given to the thermal shock which

could occur when cool heat transfer fluids are introduced into

collectors which have been exposed to solar radiation under

"no-flow" conditions. Due to the possibility of large hydrostatic head pressure on tanks that may be greatly in excess of

pressure elsewhere in the system, care should be taken in the

selection of the location of safety devices. In systems which

are not capable of withstanding the maximum temperatures to which they will be exposed (i.e. under "no-flow" conditions) it

is essential that some means of protection such as energy dumping

be provided.

Automatic pressure relief devices . Adequately sized and responsive automatic pressure relief devices such as valves and venting

systems shall be provided in those parts of the energy transport

subsystem containing pressurized fluids. Automatic pressure

relief valves shall be set to open at not less than 25 percent in excess of working pressure and at not more than maximum pressure

for which the subsystem is designed. Vented non-combustible,

potable liquids shall be piped to suitable drains. Non-potable

or combustible liquids shall be handled in accordance with

Criterion 4.4.1.

Relief valves shall drain to locations acceptable to the local

administrative code authority.

Review of drawings and specifications and/or determination that

methods, devices, and materials to be used are approved by a recognized testing and evaluation agency as being suitable for

the proposed use.

For large systems, special consideration should be given to venting the excessive pressures caused by exposure fires.

Guidelines for calculating vent size are contained in NFPA 30

[3].

Fire safety . The design and installations of the H/C/HW systems

and their components shall provide a level of fire safety con- sistent with applicable codes and standards.

Fire codes and standards . Assemblies and materials and their

installations shall be in accordance with local and nationally

recognized codes and standards for fire safety.

Review of drawings and specifications for conformance with the

local and nationally recognized codes and standards for fire

safety including but not limited to applicable sections of

NFPA 89M [4], NFPA 90A and 90B [5], NFPA 211 [6], NFPA 54 [7],

NFPA 30 [3], NFPA 31 [8], NFPA 256 [9], and the National

Electric Code [1]. In cases where sufficient engineering information is not available, testing to show compliance may be

required. Potential heat, rate of heat release, ease of ignition,

and smoke generation will be considered in assessing the potential

fire hazards.

32
CHAPTER FOUR - SAFETY

Systems and Components

Commentary It is the intent of this criterion to (1) prevent the use of

materials, equipment, and fluids which present a fire hazard

greater than that allowed for conventional systems, (2) provide

proper clearance and venting of heat build-up for those system

components that operate at elevated temperatures, and (3) give

consideration to the combustibility of materials adjacent to high temperature components in determining the clearance and/ot

insulation required.

Special consideration should be given to the fire safety features

of innovative system designs particularly those utilizing insulation in a way which may present a greater hazard than with

conventional designs.

4.3.2 Criterion Penetrations through fire-rated assemblies. Penetrations

through fire-rated walls, partitions, floors, roofs, etc. shall

not reduce the fire resistance required by local codes and ordi- nances .

Evaluation Review of drawings and specifications. Testing to show compliance

in accordance with NFPA 251 [10].

Commentary It is the intent of this criterion to (1) prevent the passage of

system components through fire-rated assemblies from adversely

affecting the fire endurance rating of the assembly in terms

of premature collapse of structural elements and (2) ensure that

proper techniques are employed in constructing these components

so that adequate protection can be provided.

4.3.3 Criterion Firestopping. H/C/HW system components that are integral parts

of assemblies which normally require firestopping shall be firestopped on all sides. Firestopping shall be wood blocking of

minimum two-inch nominal thickness or of non-combustible materials

providing equivalent protection.

Evaluation Review of drawings and specifications.

Commentary It is the intent of this criterion to prevent H/C/HW system com- ponents from reducing the effectiveness of firestopping. For

example, in the case where a solar collector is an integral part

of a wood framed wall which would normally be firestopped between

studs, firestopping shall be required in the wall above and below

the solar collector.

4.3.4 Criterion Protection against auto-ignition of combustibles. Combustible

solids used in solar equipment shall not be exposed to elevated

temperatures which may cause ignition.

Evaluation Review of calculations, drawings, and specifications. Testing to show compliance where necessary.

Commentary Exposure of cellulosic materials as well as other combustible

materials over an extended period of time result in the material

reaching and surpassing its auto-ignition temperature. The most

commonly accepted ignition temperature of wood is 392°F.

However, studies have indicated that wood may ignite when

exposed to a temperature of 212°F for prolonged periods of time.

The ignition temperatures of plastics may be above or below those

of cellulosic materials.

33
CHAPTER FOUR - SAFETY

Systems and Components

4.4

4.4.1

4.4.2

4.4.3

Requirement

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Toxic and flammable fluids . Heat transfer fluids which require

special handling because of their degree of toxicity, excessive

pressure, high temperature, and/or flammability shall not be used

unless the systems in which they are used are designed to avoid

exposing the occupants of the building to hazards.

Fluids requiring special handling . Liquids defined as flammable

according to NFPA 321 [11] and flammable gases shall not be used

in H/C/HW systems. Liquids defined as combustible according to NFPA 321 [11] require special handling. Toxic fluids shall have

a usage profile that precludes the possibility of evoking an adverse toxicological response in man as determined by the health

authority having jurisdication. The use of toxic fluids shall

comply with the Federal Hazardous Substances Act [12]. All toxic

fluids require special handling.

When evaluating the toxicological properties of fluids, special

consideration should be given to the effect of a system failure

on the occupants. The evaluation should include the effects from

contacting both the liquid directly and the vapor given off by

the liquid. In addition, toxicological effects of the fluid

should be evaluated at ambient temperature as well as the elevated

temperatures expected during system operation.

Toxic fluids are those having the capacity to produce personal

injury or illness to man through ingestion, inhalation, or absorption through any body surface [12].

Liquid flash point . Liquids used in solar-powered equipment shall

not be heated to temperatures greater than 100°F below their

flash points under either operating or "no-flow" conditions. The

flash point of liquids used in industrial applications as defined

by NFPA 101 [13] may be lower subject to the approval of the

authority having jurisdiction.

Testing in accordance with NFPA 321, "Classification of Flammable

Liquids" [11]

It is the intent of this criterion to minimize the possibility

of ignition of hot heat transfer and thermal storage liquids

when either leakage or intentional liquid release (e.g. pressure

relief or drainage) occurs.

Detection of toxic and combustible fluids . If heat transfer

fluids that require special handling are used, means shall be

provided to indicate a failure of the fluid transfer system

(e.g. leakage, pump failure, or activation of relief valves) and

the provision of warning when leaks occur. The extent of warning

(i.e. whether solely maintenance personnel, or all of the occupants of a building) shall be determined on the basis of the

degree of hazard presented by the fluid used and the type of

occupancy.

Review of drawings and specifications. Testing of detection and

warning system (s)

It is common practice to relate toxicity and flammability ratings

to the level of hazard created at ambient temperatures. Heat

transfer fluids which do not present a hazard at ambient temperatures may be hazardous at the temperatures developed in the

system.

34
CHAPTER FOUR - SAFE i t Systems and Components

4.4.4 Criterion Provision of catch basins. Adequately sized and protected catch

basins shall be provided, when liquids requiring special handling

are used, to collect and store the overflow from pressure relief

valves, liquids drained from the system when it is being serviced, potential leakage (i.e. leakage from components that

would not normally be expected to last the life of the system),

and accidental drainage.

Evaluation Review of drawings and specifications.

Commentary The leakage of toxic liquids into the ground could contaminate

ground water. In addition, leakage of some heat transfer liquids

can damage roofing, sealants, and other building materials. Some

components (for example, connector hoses) which have a shorter

life than the system, but which are replaced on a scheduled

replacement program which is more frequent than their design

life may be considered in aggregate, to last the life of the

' system. The leakage of combustible liquids may pose a fipe

hazard when exposed to external ignition or heat sources.

4.5 Requirement Safety under emergency conditions. In the event of emergencies,

the H/C/HW systems shall not unduly hinder the movement of occupants of the building or emergency personnel. Life safety

hazards which could occur as a result of failures of the above

systems shall not be greater than those imposed by conventional

systems

.

4.5.1 Criterion Emergency egress and access. The design and installation of the

H/C/HW systems shall not impair the emergency movement of occupants of the building or emergency personnel to an extent greater

than that allowed by NFPA 101 [13], where applicable.

Evaluation Review of drawings and specifications.

Commentary The location of exits and passageways as related to the H/C/HW

systems is an important consideration.

4.5.2 Criterion Identification and location of controls. Main shutoff valves and

switches should be conspicuously marked and placed in locations

that are readily accessible to those personnel who would normally

be expected to operate them in the event of an emergency. These

valves and switches shall be located in the same manner as specified in 240.24 of NFPA 70 [1] for electrical panels.

Evaluation Review of drawings and specifications.

Commentary In large facilities, accessibility would normally be limited to qualified personnel; however, in smaller commercial facilities,

accessibility to the tenants should be provided.

4.6 Requirement Protection of potable water and circulated air. No material, form

of construction, fixture, appurtenance or item of equipment shall

be employed that will support the growth of micro-ogranisms or introduce toxic substances, impurities, bacteria or chemicals

into potable water and air circulation systems in quantities

sufficient to cause disease or harmful physiological effects.

35
CHAPTER FOUR - SAFETY

Systems and Components

4.6.1 Criterion

Evaluation

Commentary

4.6.2 Criterion

Evaluation

Commentary

4.6.3 Criterion

Evaluation

4.6.4 Criterion

Evaluation

Commentary

4.6.5 Criterion

Evaluation

Commentary

Contamination by materials . Materials which come in direct

contact with potable water shall not affect the taste, odor, or physical quality and appearance of the water in an undesirable manner

Review of plans and specifications for compliance with the 1962

Edition of the Public Health Service Drinking Water Standards

[14].

This criterion is not intended to preclude using dyes suitable

for ingestion as a means for the detection and warning of leaks

in the system.

Separation of circulation loops . Circulation loops of subsystems utilizing non-potable heat transfer liquids shall be

separated from the potable water system in such a manner that

a minimum of two walls or interfaces is maintained between the

non-potable liquid and the potable water supply.

Review of drawings and specifications.

In double wall heat exchangers consisting of a heat exchange

coil containing a non-potable liquid and a heat exchange coil

containing a potable liquid immersed in an intermediary potable

liquid intended to conduct heat between the two coils, leakage

through one of the coil walls would result in a single wall con- figuration. There are several heat exchanger designs that avoid

this problem.

Identification of non-potable and potable water . In buildings

where dual liquid systems, one potable water and the other non- potable liquid, are installed each system shall be identified

either by color marking or metal tags as required in ANSI A13.1-

1956 [15] or other appropriate methods.

Review of drawings and specifications.

Backflow prevention . Backflow of non-potable fluids into the

potable water systems shall be prevented.

Review of drawings and specifications. Inspection of assembled

systems

Pollution of the potable water supply can occur by way of backflow caused by back pressure and/or backsiphonage within a cross connection between the potable supply and non-potable fluid in

the system. The former type of backflow can occur, for example,

from elevated tanks or pumps. The latter can occur when the

potable water supply system is under vacuum such as might occur with a broken street water main.

Piping arrangements, backflow prevention devices, and/or air gaps

are commonly used to prevent contamination of potable water

systems

Growth of fungi . Components and materials used in the H/C/HW

systems shall not promote the growth of fungi, mold, or mildew.

The design shall be capable of withstanding exposure to fungus

as defined by Method 508 of MIL-STD-810 [16].

Special consideration should be given to the presence of fungi

in air handling systems since such micro-organisms are frequently

allergenic

36
CHAPTER FOUR - SAFETY

System* and Components

4.7 Requirement

4.7.1 Criterion

Evaluation

Fungi can feed on some organic materials and generally thrive in warm, moist environments. They can be killed by sufficiently low

wavelength ultraviolet radiation but much of this radiation may

be absorbed by the earth's atmosphere. The potential for fungus

growth in a rock storage container which becomes damp due to the

failure of waterproofing membrane around the container could be

a substantial problem requiring periodical maintenance with a fungicide. In addition, there is a high potential for fungus

growth occurring under collectors that are applied over a building

watertight membrane and it may be possible for fungi to grow pn

both the interior and exterior of collector components and possibly affect the collector performance.

Excessive surface temperatures . Contact with heated exterior

surfaces of the H/C/HW systems shall not create a hazard to people

.

Protection from heated components . Subassemblies of the H/C/HW

systems that are accessible, located in areas normally subjected

to public traffic and which are maintained at elevated temperatures

shall either be insulated to maintain their surface temperatures

at or below 140°F at all times during their operation or suitably

isolated. Any other exposed areas that are maintained at hazardous temperatures shall be identified with appropriate

warnings

.

Review of drawings and specifications.

37
CHAPTER FOUR - SAFETY

Systems and Components

References

1. National Electric Code , NFPA, No. 70, 1975 * (also ANSI Cl, 1975).

2. "Occupational Safety and Health Regulations ," CFR Title 29, Chapter XVII, Part 1910 and

Part 1926.

3. Flammable and Combustible Liquid Code , NFPA, No. 30, 1973.*

4. Clearances, Heat Producing Appliances , NFPA No. 89M, 1971.*

5. Air-Conditioning and Venting System, NFPA, No. 90A, 1975 and Warm Air Heating and AirConditioning , NFPA, No. 90B, 1973.*

6. Chimneys, Fireplaces and Vents , NFPA; No. 211, 1972.*

7. Gas Appliances and Gas Piping Installation , NFPA, No. 54, 1974 * (also ANSI Z 83.1, 1972).

8. Oil Burning Equipment , NFPA, No. 31, 1974* (also ANSI Z 95.1).

9. Fire Tests of Roof Coverings , NFPA, No. 256, 1970* (also ASTM E108 1975, American

Society for Testing and Materials, 1916 Race Street, Philadelphia, Pa. 19103 and UL

790) .

10. Standard Methods of Fire Tests of Building Construction and Materials , NFPA, No. 251,

1972* (also ASTM E119 and UL 263).

11. Classification of Flammable Liquids , NFPA, No. 30, 1973.*

12. "Federal Hazardous Substances Act," CFR Title 16, Part 1500.

13. Life Safety Code , NFPA, No. 101, Boston, Mass., 1973.*

14. The Public Health Service Drinking Water Standards , 1962, U.S. Department of Health,

Education and Welfare.+

15. "Scheme for the Identification of Piping Systems," ANSI A13.1, 1975.

16. Military Standard, MIL-STD-810C, 10 March 1975, Military Standard for Environmental

Test Methods.

*National Fire Protection Association (NFPA), 470 Atlantic Avenue, Bostop, Mass. 02210.

+Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

38
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

5 . 1 Requirement Effects of external environment. The H/C/HW systems and their

various subassemblies shall not be affected by external environmental factors to an extent that will significantly impair their

function during their design life.

5.1.1 Criterion Solar degradation. Components or materials shall not be

adversely affected by exposure to sunlight in service to an extent that will significantly impair their function during

their design life.

a. When components or materials are exposed to UV

radiation with or without an intermittent

water spray at their maximum service temperature,

there shall be no signs of excessive deterioration such as cracking, crazing, embrittlement,

etching, loss of transmittance, loss of adhesion,

changes in permeability, loss in flexural strength,

or any other changes that would significantly

affect the performance of the components in the

system.

b. The collector shall be capable of providing its rated

output after exposure t:o levels and intensities of

solar radiation and temperatures that are equivalent

to those that would be expected in actual use over

the life of the collector.*

Evaluation Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Where adequate existing

information is unavailable, testing using either the methodology

outlined in Section 03 of the Appendix given at the end of this

chapter or other methods which can be shown to meet the intent

of the criterion.

Commentary The transmittance, emittance, and absorptance data required to estimate the effects of degradation by solar radiation in

reducing collector efficiency are available for most

materials currently being used in collectors.

5.1.2 Criterion Moisture. Components or materials shall not be adversely

affected by exposure to moisture in service to an extent that

will significantly impair their function during their design

life

.

Evaluation Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Where adequate existing

information is unavailable, methods which can be shown to meet

the intent of the criterion will be used.

*Use temperatures are defined in Sections 01 and 02 of the Appendix given at the end of

this chapter.

39
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

Commentary

5.1.3 Criterion

Evaluation

I

Commentary

5.1.4 Criterion

Evaluation

Moisture can exhibit itself in several forms, e.g. rainfall,

melting snow and ice, or condensation. The intent of this

criterion is to ensure adequate performance of components or materials that are expected to be exposed to moisture in service.

Some components, such as collector insulation, are usually

intended to be used in low moisture environments; however, it is

still possible for them to be periodically exposed to moisture

from condensation. Such components would not usually be expected

to meet the intent of this criterion if moisture exposure could

not occur, e.g. in collectors that are hermetically sealed. If flat plate collectors are not hermetically sealed, the likelihood

of condensate forming on the underside of the cover plates is

quite high. Dessicants in breather tubes or breather plugs can

be used to maintain a dry environment. The dessicants should be

located in such a way that they are not in contact with the

collector plate and it is desirable that they be capable of

regeneration by solar energy as the collector builds temperature.

One additional potential problem with collectors which are not

hermetically sealed is that, in industrial atmospheres, the

introduction of dilutants in condensate solution may cause permanent etching of the underside of the cover plates over a period

of time. Such etching can permanently reduce the transmittance.

When this possible condition exists, design considerations must

be given to avoid the problem.

Soil related degradation . Components that are intended to be

buried in soils shall not degrade under in-use conditions to an extent that their function will be impaired during their design

life.

Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Where adequate existing

information is unavailable, testing using either the methodology

outlined in Section 04 of the Appendix given at the end of this

chapter or other methods which can be shown to meet the intent

of the criterion will be used.

This criterion is primarily intended to protect metallic components from soil corrosion. It may be possible to protect some metallic components with the use of sacrificial anodes. Other

components such as wood or plastics may also be degraded by

contact with soil.

Airborne pollutants . Components that are exposed to airborne

pollutants such as ozone, salt spray, SO^, NO^, or HC1 with or without the presence of moisture shall not be adversely affected

by these factors to the extent that will significantly impair

their function during their design life.

Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Where adequate existing

information is unavailable, testing using either the methodology

outlined in Section 05 of the Appendix given at the end of this

chapter or other methods which can be shown to meet the intent of

the criterion will be used.

40
CHAPTER FIVE - CURABILITY / RELIABILITY Systems and Components

The maximum pollutant levels in the areas where the system will

be installed shall be used to determine the pollutant levels

required for testing. If components are to be used in areas where they are not exposed to any or all of these pollutants,

tests that are not applicable need not be conducted.

Commentary Ozone concentrations in normal dry air have been reported to range from 1-5 pphm/volume. However, concentrations of 100

pphm/volume have been reported during very smoggy conditions.

Ozone is known to degrade some organic materials but it has

little effect on inorganic materials other than metals.

The effects of solar radiation in combination with airborne

pollutants may also be an important consideration.

5.1.5 Criterion Dirt retention on cover plate surface. The collector cover plate surface shall not collect and retain dijrt to an extent

that would significantly impair the function of the collector

during its design life.

Evaluation Engineering analysis, documentation of satisfactory long-term

performance under in-use conditions and review of plans and

specifications.

Commentary The possible collection and retention of dirt by the cover plate

and the effect of retained dirt on the collector performance may

be significant. The retention of dirt may be affected by the

tilt angle of the collector. Rainfall and snow melt are generally

sufficient to keep the collector cover plates clean. In areas

of low rainfall or because of the nature of the cover plate

surface, periodic washing may be required to remove dirt.

5.1.6 Criterion Abrasive wear. The ability of the collector to function at its

rated capacity shall not be significantly impaired by the

abrasive wear to which its surface will be subjected during its

design life.

Evaluation Engineering analysis, documentation of satisfactory long-term

performance under in-use conditions, and review of surface hardness specifications for cover plate materials.

Commentary Test methods which are currently available for measuring abrasion

resistance are believed to be too stringent for testing organic

collector cover plates. Abrasive wear is expected to present a possible problem in areas subject to wind driven sand. Also,

abrasive wear of cover plates resulting from periodic cleaning

or scrubbing may have a significant effect on the ability of the cover plates to transmit sunlight.

5.1.7 Criterion Fluttering by wind. Components that are subject to fluttering

by wind shall not degrade under in-use conditions to an extent

that will significantly impair their function during their

design life.

Evaluation Documentation of satisfactory long-term performance under in-use

conditions, engineering analysis, or testing using an experimental verification procedure which can be shown to meet the

intent of the criterion.

Commentary Thin films that increase in brittleness at low temperatures may

be particularly susceptible to degradation by fluttering by wind.

41
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

5.2

5.2.1

Requirement Temperature and pressure resistance . Components shall be capable

of performing their intended function for their design life when

exposed to the temperatures and pressures that can be developed

in the system.

Criterion Thermal degradation . Components shall not thermally degrade to the extent that their function will be reduced below design

levels during their design life when exposed to in-use

temperatures

Evaluation Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. When adequate existing

information is unavailable for collector components, the "no-flow"

aging procedure described in Part B, Method 1 of Appendix

Section 03, given at the end of this chapter, will be used.

When adequate existing information for other components is

unavailable, testing using either the methodology outlined in

Section 06 of the Appendix or other methods which can be shown

to meet the intent of the criterion will be used.

5.2.2

5.2.3

Commentary Some organic components which may be used in the system may be

particularly susceptible to thermal degradation under prolonged

exposure. Collector components of particular concern include

organic cover plates, absorptive coatings, insulation, sealants,

and enclosure frames.

Criterion Deterioration of fluids . Except when such changes are allowed by

the design of the system, fluids shall not freeze, give rise to excessive precipitation, otherwise lose its homogeneity, boil or change pH. or viscosity beyond the design ranges when exposed to its intended range of service temperature and pressure.

Evaluation Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Where adequate existing

information is unavailable, testing using either the methodology

outlined in Section 07 of the Appendix given at the end of this

this chapter or other methods which can be shown to meet the

intent of the criterion will be used.

Commentary

Criterion

Evaluation

Thermal cycling may cause precipitation to occur. Systems may be

pressurized to prevent boiling. Although boiling can be prevented

by pressurization, excessive temperatures can break down some constituents of the fluid to form organic acids. Buffers can counter the pH imbalance but only until they are exhausted.

Changes in pH can be accepted but when the allowable range is

exceeded, the transfer fluid or at least the buffers must be

renewed. This can be an acceptable maintenance requirement.

Thermal cycling stresses . The H/C/HW systems and their various

subassemblies shall be capable of withstanding the stresses

induced by thermal cycling for their respective design lives.

Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Where adequate existing

information is unavailable for collector components, the

"no-flow" aging procedures, described in Part B, Method 1 of

Appendix Section 03, given at the end of this chapter will be used.

Where adequate existing information is unavailable for other

components, testing using the methodology outlined in Section 08

of the Appendix given at the end of this chapter or other methods

which can be shown to meet the intent of the criterion will be

used

42
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

Physical restraints that will be imposed on the system in actual

use shall be considered when testing is required.

Commentary This criterion is intended to identify potential problems that

may occur as a result of differential thermal movement. Thermal

compatibility is especially critical in the case of collectors

which may contain large expanses of glazing. If thermal expansion is cumulative in the system or subsystem design, the tests

must be designed to reflect this.

5.2.4 Criterion Leakage. Those portions of systems which contain heat

transfer fluids shall not leak when tested at a pressure

equal to 150% of the working pressure of the system over the

entire range of service temperatures.

Evaluation Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Where adequate existing

information is unavailable, testing using either the methodology

outlined in Section 09 of the Appendix given at the ppd of phis

chapter or other methods which can be shown to meet the intent

of the criterion will be used.

Commentary This criterion is intended to evaluate materials which may creep

or become brittle within the range of expected service temperatures

The joints near coupling hoses are a potential source of leakage.

The selection of coupling hoses and clamps is quite critical.

Many failures have been noted due to the clamping of hoses with

screw or spring-type clamps, exposing the hose to high temperatures which tend to vulcanize the area beneath the clamp, causing

it to lose resiliency and begin to leak. Further tightening of

the clamps will temporarily stop leakage but further vulcanizing

will occur with the end result being a hard non-resili^nt ring

under the clamp which can no longer be tightened to prevent

leakage. Silicone rubber hose is one of the few materials which

have been tested and tend to maintain their resiliency with no tendency to take a thermal set. The silicone rubber hoses,

however, tend to be so pliable that screw-type clamps with perforated bands should not be used as it is possible to extrude the

material through the perf ormations in the band. If this material

is used, smooth band clamps should be utilized.

5.2.5 Criterion Transmission losses due to outgassing. Outgassing of volatiles

that will reduce collector performance below specified design

values shall not occur when the collector is exposed to the

maximum service temperature and pressure that will occur in

actual service.

Evaluation Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Where adequate existing

information is unavailable, testing using either the "no-flow"

aging procedure described in Part B, Method 1 of Appendix

Section 03 given at the end of this chapter or other methods

which can be shown to meet the intent of the criterion will be

used

Commentary Outgassing from components inside the collector could lead to deposits on the underside of the collector cover plates which

may reduce the transmissivity of the cover plates.

43
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

5.3

5.3.1

I

5.3.2

I

5.3.3

1

Requirement Chemical compatibility of components . Materials used in the

systems and their various subassemblies shall have sufficient

chemical compatibility to prevent corrosive wear and deterioration that would significantly shorten the intended service life

of components under in-use conditions.

Criterion Deterioration of gaskets, sealants, and polymeric coupling hoses . Gaskets, sealants, and polymeric coupling hoses in direct contact with fluids shall not be adversely affected by contact with

these fluids to an extent that will significantly impair their

ability to function during their design life.

Evaluation Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Where adequate existing

information is unavailable, testing using either the methodology

outlined in Section 10 of the Appendix given at the end of this

chapter or other methods which can be shown to meet the intent

of the criterion will be used.

Commentary

Criterion

Evaluation

Gaskets, sealants, polymeric coupling hoses, and similar organic

materials frequently swell when exposed to liquids and frequently

lose their ability to function.

Materials/transfer fluid compatibility . Materials designed to be

used in contact with heat transfer fluids shall not be corroded

by these fluids to the extent that their function will be significantly impaired under in-use conditions during their design life

Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Where adequate existing

information is unavailable, testing using either the methodology

outlined in Section 11 of the Appendix given at the end of this

chapter or other methods which can be shown to meet the intent

of the criterion will be used.

Commentary

Criterion

Evaluation

Corrosion of metals by heat transfer fluids could be a serious

problem in solar energy systems. Society of Automotive Engineers

(SAE)* Report J447a (1964), "Prevention of Corrosion of Metals,"

provides guidance in preventing corrosion.

Compatibility of dissimilar materials . Non-isolated dissimilar

materials shall not be degraded to the extent that their function

will be significantly impaired under in-use conditions during

their design life.

Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Where adequate existing

information is unavailable, testing using either the methodology

outlined in Section 12 of the Appendix given at the end of this

chapter or other methods which can be shown to meet the intent of

the criterion will be used. Dissimilar materials used in contact

with heat transfer or other fluids shall be tested to reflect

this condition. Where protective finishes are normally provided,

they shall be used on the specimens tested.

*Society of Automotive Engineers, Inc. Two Pennsylvania Plaza, New York, NY 10001.

44
CHAPTER FIVE - DURABILITY / RELIABILITY Systems and Components

Commentary The use of corrosion inhibitors or dielectric fittings that electrically isolate dissimilar materials may be desirable. In the case of plastics, plasticizer migration may be a concern. The

presence of pinholes in protective coatings may drastically

accelerate corrosive action.

5.3.4 Criterion Corrosion by leachable substances. Chemical substances that can be leached by moisture from any of the materials within the system

shall not cause corrosive deterioration of any other components

that would significantly impair the ability of those components

to perform their intended function over their design life.

Evaluation Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Where adequate existing

information is unavailable, testing using either the methodology

outlined in Section 13 of the Appendix given at the end of this

chapter or other methods which can be shown to meet the intent

of the criterion will be used.

Commentary Salts such as those that can be leached by moisture from some types of glass fiber and mineral wool insulation or frojn organic

components may cause corrosion of system components that are in

close proximity. Chlorides or sulfates that may be leached are

of particular concern in regard to metallic corrosion.

5.3.5 Criterion Effects of decomposition products. Chemical decomposition

products that are expelled from components under in-use conditions shall not cause the degradation of other components within

the system to the extent that they would significantly impair

their ability to perform their intended function over their

design life.

Evaluation Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Where adequate existing

information is unavailable, testing using either the methodology

outlined in Section 14 of the Appendix given at the end of this

chapter or other methods which can be shown to meet the intent

of the criterion will be used.

Commentary Components and materials, such as gaskets, sealants, coatings,

etc., may yield degradation products during their service life

without impairing their function or aesthetic properties.

These degradation products could significantly impair the

performance of other components in the system.

5.4 Requirement Components involving moving parts. Components that involve

moving parts shall, with normal maintenance, be capable of

performing their intended function without excessive wear

or deterioration for their design life.

5.4.1 Criterion Wear and fatigue. Check valves, pressure regulators, pumps,

electrical switches and similar components shall be capable of

operating under in-use conditions for their intended life spans

without exhibiting wear or fatigue that would reduce their performance below specified levels.

45
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

Evaluation

Commentary

Documentation of satisfactory long-term performance under in-use

conditions, engineering analysis, or testing using an experimental verification procedure which can be shown to meet the

intent of the criterion. Either the number of cycles that would

be expected in actual service under in-use conditions or an accelerated procedure shall be used for experimental verification.

In some applications, less expensive components which are readily replaced but have shorter expected lifespans may be more desirable than more reliable but more costly components.

Inclusion of the heat transfer fluid during tests of components

with moving parts may be helpful. In particular, very hard

crystalline precipitates may be formed from some types of heat

transfer f luids ^and their additives.

46
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

APPENDIX

Section 01 - Temperature Conditions

Many of the criteria given in this chapter contain references to the maximum or minimum

service temperatures in specifying the temperature at which testing should be performed.

The maximum service temperature is the maximum temperature to which a component will be

exposed in actual service, either with or without the flow of heat transfer fluid. The

minimum service temperature refers to the minimum temperature to which a component will be

exposed in actual service, with or without the flow of heat transfer fluid.

The minimum service temperature to which a component in the system will be exposed will

generally occur when 1) no solar radiation is falling on the collector, 2) the heat transfer

is not flowing through the system, and 3) the ambient air temperature is at its lowest

level. The no-flow condition mentioned above assumes the flow of the heat transfer fluid

will be stopped when solar radiation is not falling on the collector to avoid pumping out heat energy. However, if the flow of fluid is not stopped at night, the minimum service

temperature of some components may occur as nocturnal radiation and/or evaporative cooling

takes place.

The maximum service temperature, to which the collector and components that are in intimate

contact with it will be exposed, will generally occur when the collector is receiving its

maximum level of solar radiation and the heat transfer fluid is not flowing through the

collector component. Other components, such as those in the storage subsystem, will

generally reach their maximum temperature when the collector is receiving its maximum level

of solar radiation and the heat transfer liquid is flowing through the system. The maximum service temperature that will occur at various locations in the collector under no-flow

conditions can be calculated if the ambient temperature, the intensity of insolation, the

number of cover plates, the back and edge losses, and the absorptivity and emissivity of

the absorbent surface and other related factors are known. The type of information that is

required to determine the maximum service temperature in various locations of collectors

under no-flow conditions is shown in Section 02 of this Appendix.

Section 02 - Typical Figures Showing the Maximum "No-Flow" Temperatures in Various

Collector Locations of Specific Collector Designs

Figures A-l through A-4 are intended to provide assistance in identifying the maximum

service temperatures at various locations in the collector under no-flow conditions. The

five curves on each figure represent the maximum service temperature for each side of two cover plates and the surface of the absorber. The calculations used to generate the

graphs assumed: 1) a glass cover plate thickness of 0.125 inches, 2) air space thickness

of 0.1875 inches both between cover plates and between the absorbent surface and the lower

cover plate, 3) zero edge losses, and 4) the incident solar radiation is normal to the

collector

Section 03 - Test Methodology: Criteria 5. 1.1. a and 5.1.1.b

Part A - Test Methodology: Criterion 5. 1.1.

Components or materials shall be tested using at least one of the three aging procedures

and appropriate evaluation procedures as described, beginning on page 52.

The surfaces of components or materials shall be visually inspected before and after aging

to ensure that no signs of excessive deterioration, such as dimensional changes, cracking,

chalking, or other visually detectable changes which could significantly affect the performance of the components in the system, are present. In addition, other evaluation procedures shall be used, as necessary, to evaluate performance.

47
TEMPERATURE,

CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

1-300 BTU/HR FT2 -STILL AIR-PLAT BLACK ABSORBER-ZERO HEAT REMOVAL FROM THE COLLECTOR

Figure A-l. Temperatures at Various Locations in a Collector with a Flat Black

Absorber and Two Glass Cover Plates (Absorptivity = 0.9,

Emissivity = 0.9, I = 300 Btu/Hr. ftp)

48
TEMPERATURE,

CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

1=250 BTU/HR FT2-STILL AIR—FLAT BLACK ABSORBER-ZERO HEAT REMOVAL FROM THE COLLECTOR

OUTDOOR AIR TEMPERATURE, ”F

•Figure A-2 Temperatures at Various Locations in a Collector with a Flat

Black Absorber and Two Glass Cover Plates (Absorpitivity = 0.9,

Emissivity = 0.9, I = 250 Btu/Hr. ft.

2

)

49
TEMPERATURE,

CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

Figure A-3 Temperatures at Various Locations in a Collector with a Selective

Absorber and Two Glass Cover Plates (Absorptivity = 0.9,

Emissivity = 0.1, I = 300 Btu/Hr. ft. 2)

50
TEMPERATURE,

CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

Figure A-4 Temperatures at Various Locations in a Collector with a Selective

Absorber and Two Glass Cover Plates (Absorptivity = 0.9,

Emissivity = 0.1, I = 250 Btu/Hr. ft. 2)

51
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

Aging Procedure 1

ASTM reference methods for Aging Procedure 1 include G26-70 Operating Light and Water

Exposure Apparatus (Xenon-Arc Type) for Exposure of Non-Metallic Materials, and D2565-75,

Operating Xenon Arc-Type (Water-Cooled) Light and Water Exposure Apparatus for Exposure

of Plastics.

Expose components or materials to simulated solar radiation (such as xenon arc radiation)

for a period of 2,000 equivalent sun hours. The exterior surfaces of components which are exposed to rainfall in service shall be subjected to a water spray for a period of 5 minutes during each 60 minutes of the light exposure. For components not exposed to rainfall under normal operating conditions, the water spray shall not be included in the

procedure.

Aging Procedure 2

Expose components or materials to concentrated natural solar radiation using machines such

as those referenced in ANSI Z97. 1-1975, paragraph 4.3.2, for a period of 2,000 equivalent

sun hours. The exterior surfaces of components which are exposed to rainfall in service

shall be subjected to a water spray for a period of 8 minutes during each 60 minutes of

sunlight exposure. For components not exposed to rainfall under normal operating conditions, the water spray shall not be included in the procedure.

Aging Procedure 3

ASTM reference methods for Aging Procedure 3 include:

G7-69T

D1828-70

D1014-66 (1973)

D1006-73

G24-73

Gll-72

D1435-69

Atmospheric Environmental Exposure Testing of Non-Metallic

Materials

Atmospheric Exposure of Adhesive Bonded Joints and Structures

Conducting Exterior Exposure Tests of Paints on Steel

Conducting Exterior Exposure Tests of Paints on Wood

Conducting Natural Light Exposures Under Glass

Effects of Outdoor Weathering on Pipeline Coatings

Outdoor Weathering of Plastics

Expose components and materials to solar radiation outdoors for twelve months . The

average daily flux of the solar radiation, as obtained by averaging the daily fluxes over

the twelve month period of outdoor exposure, shall be at least 1,500 Btu/ft^.

Evaluation Procedures

Evaluation procedures shall be selected to measure the effect of the aging procedures on important properties of the components or materials. The following ASTM evaluative

techniques for organic coatings shall be used:

D714-56 (1974)

D659-74

D660-44 (1970)

D661-44 (1975)

Evaluating Degree of Blistering

Evaluating Degree of Resistance

Exterior Paints

Evaluating Degree of Resistance

Exterior Paints

Evaluating Degree of Resistance

Exterior Paints.

of

to

to

to

Paints

Chalking of

Checking of

Cracking of

52
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

Evaluation techniques, in addition to those related to visual inspection, shall also be

used. The methods below represent the types of evaluative techniques that should be used

where applicable:

Vapor Transmission

E96-66 (1972) Water Vapor Transmission of Materials in Sheet Form

C355-64 (1973) Water Vapor Transmission of Thick Materials

Tensile Strength

D638-72 Tensile Properties of Plastics

D897-72 Tensile Properties of Adhesive Bonds

C297-61 (1970) Tension Test of Flat Sandwich Constructions in

Flatwise Plane

Flexure Strength

D790-71 Flexural Properties of Plastics

C393-62 (1970) Flexure Test of Flat Sandwich Constructions

Evaluations should be performed on both aged and unaged specimens to establish a basis of

comparison.

Commentary

The test are intended to permit estimations to be made of the effect of solar radiation in

degrading collector components and in reducing the collector efficiency. The 2,000 equivalent sun hours test time is considered to be equivalent to approximately 12 months of actual

solar exposure with an average exposure time of 6 hours per day. The fact that the intensity of solar radiation varies with time of the day and time of the year should be considered

in establishing the length of the exposure.

Part B - Test Methodology: Criterion 5.1.1,b

Method 1 involves the exposure of the collector to solar radiation at an actual test site

and measuring the decrease in collector efficiency as a result of the exposure. State-ofthe-art collector test methods are referenced in Criterion 1.3.1. Method 1 also includes

visually inspecting collector components after the aging procedure to ensure that undesirable

changes have not occurred.

Method 2 involves measuring the deterioration of the windows and the absorbent surfaces

separately by means of small scale laboratory tests and then incorporating this information

into a model developed by ASHRAE which can be used to calculate collector efficiency. The

test procedure for Method 2 is given below.

Method 1 for Evaluating the Effects of Solar Degradation on the Performance of the Collector

Test Specimens

The test specimen shall consist of the entire collector as it would be used in actual

service

53
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

Aging Procedure

2 Expose the collector to solar radiation having an average daily flux of 1,500 Btu/ft at the tilt angle under "no-flow" conditions for 30 days. At least one 4 hour period during

the 30 day exposure shall have a minimum solar flux of 300 Btu/ft^/hr. The 30 day "no-flow"

exposure must be performed on a complete collector without transfer liquid (if liquid is

the transfer medium). The angle of collector exposure shall be + 10° of that used in

service. For tracking collectors, the exposure angles shall be the same as those used in

service

Evaluation Procedure

Test the collector before and after aging fpr thermal efficiency. State-of-the-art test methods are referenced in Criterion 1.3.1.

The test specimens shall exhibit no significant change in performance as a result of the

aging procedure. Components shall not exhibit changes that would significantly impair

their function when visually inspected after the aging procedure.

Method 2 for Evaluating the Effects of Solar Degradation on the Performance of the Collector

(Primarily for spectrally selective materials)

Test Specimens

Test specimens shall consist of specimens of the materials to be tested.

Specimens of window materials for aging and evaluating shall consist of the number of

windows used in the collector spaced and aligned as they would be in the collector.

Aging Procedure

Specimens shall be exposed to simulated solar radiation* with the spectral intensity in the

300 to 450 nm wavelength range equivalent to the air mass 2 solar spectrum (such as Xenon

arc radiation) for a period of 1,000 hours at the maximum temperature to which they will be

subjected in actual service. For collector windows, the exterior surfaces of the components

shall be subjected to a water spray for a period of 5 minutes during each 60 minutes of the

light exposure. For components not normally exposed to rainfall as secondary collector

windows and absorbent coatings, the water spray shall not be included in the procedure.

Test Procedures**

Collector Windows

1. Measure the total spectral transmittance (including both diffuse and

normal radiation) of the windows from 300 to 1,820 nm.

2. Expose the windows to the aging procedure described above.

3. Repeat step 1.

4. Calculate the solar transmittance (t) determined from transmittance

measurements from 300 to 1,820 nm for both unaged and aged specimens

using the procedure described under Calculations .

*Specimens shall be mounted perpendicular to the incident radiation.

**0ther less sensitive test procedures which are directly integrating are given in

ASTM E424-71 and E434-71.

54
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

Absorbent Surface

Part A

1. Measure the directional reflectance of the absorbent surface in the

infrared spectral range from 3 to 20 ym (3,000 - 20,000 nm)

(Maximum of .5 ym increments.)

2. Expose the absorbent surface to the aging procedure described above.

3. Repeat step 1.

4. Convert the reflectance values to emittance (e) assuming an opaque

coating where: Emittance = 1 - Reflectance.

5. Calculate the total emittance from 3 to 20 ym for both unaged and

aged specimens using the procedure described under Calculations .

Part B

1. Measure the directional reflectance of the absorbent surface from

300 to 1,820 nm. (Maximum 1,000 nm increments.)

2. Expose the abosrbent surface to the aging procedure described above.

3. Repeat step 1.

4. Convert the reflectance values to absorptance assuming an opaque

coating where: Emittance = Absorptance = 1 - Reflectance.

5. Calculate the solar absorptance (a) from 300 to 1,820 nm for both

unaged and aged specimens using the procedure described under

Calculations .

Calculations

Transmittance

1. Multiply the measured value of transmittance of both aged and unaged

window specimens over the wavelength range from 300 to 1,820 nm by

the value of solar energy (watts/cm^/nm) at the same wavelengths as read from Figure A-5 . (Maximum of 100 nm increments.)

2 2. Plot energy (watts/cm /nm) versus wavelength curves for both aged

and unaged specimens.

3. Integrate, from 300 to 1,820 nm, the area under the curve of

Figure A-5 and record the area (Eq.q) .

4. Integrate, from 300 to 1,820 nm, the area under the energy versus wavelength curve for unaged specimens and record the area (Eq^).

5. Integrate, from 300 to 1,820 nm, the area under the energy versus wavelength curve for aged specimens and record the area (Eq^).

6 . Divide Eq^ by Eq^q to obtain the solar transmittance, 13 , as measured for the unaged window specimen.

7. Divide Eq^ by ET1 to obtain the solar transmittance, t^, as measured for the aged window specimen.

8 . Incorporate T 2 and T 3 into the appropriate equations used in

the method to determine the collector efficiency in Criterion 1.3.1.

55
SPECTRAL

IRRADIANCE-WATTS/CM

2

/NM

CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

WAVELENGTH (nm)

Figure A-5 Spectral Irradiation at Air Mass 2.0

56
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

Total Emittance*

The total emittance of surfaces can vary with temperature because of the change in energy

spectral distribution with temperature according to the Planck Radiation Law. The

influence of environmental effects on the total emittance can be determined from spectral

emittance data by the following procedure:

1. List the spectral emittance and the spectral energy (watts/cm^/ym) of

a black body in at least 0.5 ym wavelength intervals over the wavelength range of 3.0 to 20.0 ym for each temperature. Use a maximum

of 10°C temperature intervals over the temperature range of collector

operation (nominally from 38 to 121°C (100 to 250°F) . Calculate

the product of these two values for each wavelength interval.

2. Plot the data obtained from step 1 as a function of wavelength for

both aged and unAged specimens and for each temperature. Plot the

spectral energy distribution for a black body for each temperature

used

3. Integrate, from 3.0 to 20.0 ym, the area under the black body

curve for each temperature and record the area (E £ g)

4. Integrate, from 3.0 to 20.0 ym, the area under each energy-emittance

curve for unaged specimens and record the area (E

e ^) for each

temperature.

5. Integrate, from 3.0 to 20.0 ym, the area under each energy-emittance

curve for aged specimens and record the area (E £ 2) for each

temperature

6. Divide Ee i by E£ b for each temperature to obtain cl for each unaged

specimen and Ee 2 by E£ b to obtain £2 for each aged specimen.

7. Incorporate el and e2 into the appropriate equations used in the

method to determine collector efficiency in Criterion 1.3.1.

Absorptance

1. Multiply the value of absorptance of both aged and unaged absorbent

surface specimens at various wavelengths from 300 to 1,820 nm by the

value of solar energy (watts/cm^/nm) at the same wavelengths as read

from Figure A-5

2 2. Plot energy (watts/cm /nm) versus wavelength curves for both aged

and unaged specimens.

*Total hemispherical emittance can be deterined by means of calorimetric techniques.

Total normal emittance can be measured with a portable emissometer.

57
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

3. Integrate, from 300 to 1820 nm, the area under the curve of Figure A-5

and record the area (E ).

Otp

4. Integrate, from 300 to 1820 nm, the area under the energy versus wavelength

curve for unaged specimens and record the area (E , )

al

5. Integrate, from 300 to 1820 nm, the area under the energy versus wavelength

curve for aged specimens and record the area (E^) .

6. Divide E^ by E to obtain the solar absorptance, al, for the unaged window

specimen? 1 a

7. Divide E^ by E^ to obtain the solar absorptance, a. 2 , for the aged window

specimen.

8. Incorporate al and a2 into the appropriate equations used in the method to determine collector efficiency in Criterion 1.3.1.

Transmittance or Reflectance by ASTM Method E 424-71

An alternate calculation method to those presented above is presented in ASTM Method

E 424 for transmittance and reflectance. In ASTM E 424, solar energy transmittance or reflectance is calculated by integration using the solar energy distribution for sea

level and air mass 2.0. Table A-l contains twenty selected ordinates for use in the

calculations

Table A-l Twenty Selected Ordinates

Reflectance at Sea Level*

for Evaluation of Solar Transmittance or

Ordinate Wavelength Ordinate Wavelenj

Number (nm) Number (nm)

1 390 11 745

2 444 12 786

3 481 13 831

4 511 14 877

5 543 15 959

6 574 16 1026

7 606 17 1105

8 639 18 1228

9 669 19 1497

10 705 20 1722

Extracted from ASTM Method E 424.

58
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

Section 04 - Test Methodology: Criterion 5.1.3

Testing of non-ferrous metals shall be performed for a period of 500 hours at the maximum

service temperature to which the components will be subjected in actual use. During the

duration of the test, coupon specimens shall be partially immersed in aqueous solutions

having a pH equivalent to that found in soil specimens taken from the sites where the

systems are intended to be used. ASTM G31-72 may be useful in performing immersion tests. Testing of ferrous metals shall be by either the four probe technique or the soil box

technique [1]. Both techniques measure soil resistivity. If the probe technique is used,

probe spacing shall be adjusted to measure the soil resistivity at the depth at which the

ferrous member is to be buried. Similarly, soil box samples shall be obtained from that

depth. These tests shall not be carried out when the soil is frozen but shall be performed

when the soil contains its maximum moisture content.

I The resistivity values below give a rough indication of the relationship between soil

corrosivity and resistivity.

Resistivity, ohm-cm Soil Corrosivity

Below 500

500 - 1,000

1,000 - 2,000

2,000 - 10,000

Above 10,000

very corrosive

very corrosive

moderately corrosive

mildly corrosive

progressively less corrosive

The resistivity of the soil shall be 5,000 ohm-cm or greater if unprotected ferrous metals

are to be buried in the soil. Wood to be buried in soil shall be resistant to natural

decay when evaluated by ASTM D2017-71.

Section 05 - Test Methodology: Criterion 5.1.4

This section contains test methods to determine the resistance of components to airborne

pollutants. Following the test, specimens shall exhibit no signs of deterioration that

would significantly impair their performance.

Resistance to Ozone

Coupon specimens of components shall be exposed for 500 hours to an ozone atmosphere of 50+5 pphm/volume in a test chamber at 23 + 2°C (73.4 + 3.6°F).

The specimens shall be exposed under conditions which simulate in-use

conditions. After the exposure, the surfaces of the specimens shall be

visually examined for signs of deterioration such as cracking, blistering,

or dimensional changes using a microscope with an eye-piece micrometer at 20X magnification. An ozone test chamber is described in ASTM D1149-64

(1970), "Accelerated Ozone Cracking of Vulcanized Rubber."

The extent of change of the specimens as a result of the exposure shall be

determined by comparing the exposed specimens to control specimens or by

comparing the characteristics of the same specimens before and after

exposure.

[1] "Control of Pipeline Corrosion,” A. W. Peabody, National Association of Corrosion

Engineers, 2400 South Loop West, Houston, Texas

59
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

Resistance to Salt Spray

Coupon specimens of components shall be evaluated in accordance with ASTM

Standard Method B117-73. After exposure for 500 hours, the specimens

shall be visually examined for signs of deterioration such as cracking,

crazing, blistering, or pitting. The extent of the change as a result of

the exposure shall be determined by comparing the exposed specimens to control specimens or by comparing the characteristics of the same speci- mens before and after exposure.

Resistance to SO 2 , N0X , and HC1

Coupon specimens shall be immersed for 500 hours in aqueous solutions containing

100 ppm of H2 SO 3 , HNO 3 and HC1 on a one component per test solution basis

so that one half the specimen is in the solution. During the immersion,

the temperature of the test specimen shall be cycled repetitively as follows:

one hour at the maximum service temperature, one hour at 23 + 2°C (73.4 +

3.6°F), one hour at the minimum service temperature and one hour at 23 +

2°C (73.4 + 3.6°F). Sufficient time shall be provided between each of the

above cycles to allow the specimens to equilibrate at the test temperature.

Test solutions shall not be heated above their boiling points or cooled

below their freezing points during the tests and the concentrations of the

solution shall be maintained at the desired levels. After exposure, the

specimens shall be visually examined for signs of deterioration such as cracking, crazing, blistering, or pitting. The extent of change of the

specimens as a result of the exposure shall be determined by comparing the

exposed specimens to control specimens or by comparing the same specimens

before and after exposure. ASTM D1654-74 may be useful in evaluating properties of coated metal specimens. Also ASTM Gl-72 and G31-72 may be useful

in performing tests.

Section 06 - Test Methodology: Criterion 5.2.1

Complete components or coupon specimens shall be subjected to heat aging for a period of

500 hours at the maximum service temperature to which they will be exposed in actual service.

Components and materials stressed in normal use should be stressed during the exposure.

They shall be visually inspected both before and after aging.

When visually evaluated after exposure at the maximum service temperatures, there shall be no significant signs of cracking, crazing, blistering, or other deterioration. Also, the

specimens shall exhibit no significant loss of strength as a result of the aging.

Section 07 - Test Methodology: Criterion 5.2.2

All fluids shall be subjected to the three tests below:

Test 1 - Expose the fluids to their maximum service temperature for a period

of 500 hours.

Test 2 - Expose the fluids to their minimum service temperature for a period

of 500 hours.

Test 3 - Subject the fluids to 100 cycles of cooling and heating with each

cycle consisting of the following steps:

a. Cooling to the minimum service temperature over a period

of two hours.

b. Holding at the minimum service temperature for two hours.

60
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

c. Heating to the maximum service temperature over a period

of two hours.

d. Holding at the maximum service temperature for two hours.

Periodically, during each test and at the completion of each test, inspect the fluids

visually for signs of undesired changes such as freezing, excessive precipitation, boiling,

or formation of gas bubbles. Also, before and after each test, measure the pH and the

viscosity of the fluid and evaluate the IR spectrum of the fluid to ensure fluid stability.

Boiling tests shall be conducted at service pressures. After the tests, the fluids shall

not exhibit changes that would significantly impair their ability to function.

Section 08 - Test Methodology: Criterion 5.2,3

Subject samples of each subassembly of the system, which would normally undergo or be

affected by thermal cycling to 100 cycles of cooling and heating with each cycle consisting

of the following steps: '

a. Cooling to the minimum service temperature over a period of two hours.

b. Holding at the minimum service temperature for two hours.

c. Heating to the maximum service temperature over a period of two hours.

d. Holding at the maximum service temperature for two hours.

During the test, the specified minimum or maximum temperature shall be maintained only on

the collector plate so that the plate will be the heat source. The temperature of other

components shall be permitted to vary as the temperature of the plate changes. Strain

induced into the specimens during the test shall be measured.

After every third cycle and at the end of the test, visually inspect the components for

signs of thermal incompatibility.

After exposure to the repeated cycles at the maximum and minimum service temperatures, there

shall be no significant signs of cracking, crazing, loss of adhesion, or other deterioration.

Section 09 - Test Methodology: Criterion 5.2.4

Joints and system components which contain heat transfer fluids shall be static pressure

tested with the heat transfer fluids at a fluid pressure equal to 150% of the working

pressure that would occur in the component. Testing shall be performed concurrently for

a period of 500 hours at the minimum service temperature and a period of 500 hours at the

maximum service temperature.

During and following the pressure tests, visual inspections shall be made to identify

evidence of leaks. Also, the pressure of the fluid shall be monitored to detect changes

due to leakage.

Section 10 - Test Methodology: Criterion 5.3.1

I

Test the components for 100 hours at the maximum service temperature using ASTM D471-75.

Components shall be stressed to simulate service conditions.

At the end of each test, visually inspect the components for signs of cracking, swelling,

or other dimensional changes or loss of adhesion to adjoining components.

61
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

Section 11 - Test Methodology: Criterion 5.3.2

Coupon specimens, or entire components, shall be immersed in the heat transfer fluid for a period of 1000 hours. During the test, the temperature of the fluid surrounding the

specimens shall be cycled repetitively as follows: 20 hours at the maximum service temperature followed by cooling to minimum service temperature and reheating to the maximum

service temperature over a four hour period. Appropriate modifications including flow rate

and degree of fluid aeration shall be included in the test. Protective coatings shall form

a part of the test specimen if they are used in the actual system. Testing shall be

followed by visual inspection. Standard TM-01-71, Autoclave Corrosion Testing of Metal in

High Temperature Water, of the National Association of Corrosion Engineers of ASTM D2570-73,

Simulated Service Corrosion Testing of Engine Coolants, may be used in the evaluation of

metals

Following the test, the test specimens shall not show signs of pitting, crevices, erosion,

or exhibit other signs of general corrosive deterioration with the exception of discoloration.

Section 12 - Test Methodology: Criterion 5.3.3

Adjoining Dissimilar Materials Used in Contact with the Transfer Fluid

Test specimens consisting of dissimilar materials in direct contact with one another shall

be immersed in the heat transfer fluid for a period of 1000 hours at the maximum service

temperature according to ASTM D1384-70 (1975). During the test, the heat transfer fluid

shall be circulated to simulate flow rate and degree of fluid aeration. This shall be

followed by visual observation. Protective coatings shall be used when they form a part

of the component.

Adjoining Dissimilar Materials Not Used in Contact with the Transfer Fluid

Test specimens consisting of dissimilar materials in direct contract with one another shall

be subjected to 100 cycles of heating and cooling in air containing 100 ppm sulfate. Each

cycle shall consist of:

a. Heating to the maximum service temperature over a period of two hours.

b. Holding at the maximum service temperature and a relative humidity of

90% or greater for 18 hours.

c. Cooling to the minimum service temperature over a period of two hours.

d. Holding at the minimum service temperature for two hours.

Following the exposure, visually inspect the specimens for signs of corrosion.

At the completion of the above tests, specimens shall not show signs of pitting or exhibit

other signs of corrosive deterioration with the exception of discoloration.

Section 13 - Test Methodology: Criterion 5.3.4

Expose components containing leachable substances and components that may be affected by

the leachable substances in water or steam for a period of 500 hours at the maximum service

temperature. At the end of the exposure, visually inspect the component that may have been

affected by the leachable substance for signs of deterioration such as pitting, cracking,

or dimensional changes

62
CHAPTER FIVE - DURABILITY / RELIABILITY

Systems and Components

Section 14 - Test Methodology; Criterion 5.3.5

The evaluation shall consist of two stages. In the first stage, components shall be heated

to their maximum service temperature for two hours and the composition of the decomposition

products, if any, shall be determined. Analysis for organic materials could be by infrared

spectroscopy or chromatography. Standard wet chemical techniques could be used for

inorganic substances.

The second stage of the evaluation shall be performed if the amount and types of decomposition products are significant. The second stage shall consist of subjecting components,

that would be exposed to the decomposition products in actual service, to the decomposition

products in a test chamber for 100 hours at the maximum service temperature of the com- ponents being tested. The concentration of the decomposition products shall be the maximum

concentration expected in actual service. During the exposure, moisture shall be added to the test chamber to maintain a relative humidity of 90% or greater.

After the exposure, test Specimens shall be visually examined for signs of degradation

such as cracking, corrosion, and swelling or other dimensional changes.

63
CHAPTER SIX - MAINTAINABILITY

Systems and Components

6.1 Requirement

6.1.1 Criterion

Evaluation

Commentary

6.1.2 Criterion

Evaluation

Commentary

6.1.3 Criterion

Evaluation

6.1.4 Criterion

Evaluation

Commentary

Accessibility for maintenance and servicing . The H/C/HW systems

shall be designed, constructed, and installed to provide

sufficient access for general maintenance, convenient servicing,

and monitoring of system performance.

Access for system maintenance . All individual items of equipment and components of the H/C/HW systems which may require

periodic examination, adjusting, servicing and/or maintenance

shall be accessible for inspection, service, repair, removal or replacement without dismantling of any adjoining major piece of

equipment or subsystem. Individual collectors in an array shall

be replaceable or repairable without disturbing non-adjacent

collectors in the array.

Review of drawings and specifications.

Accessibility as a function of component life is an important

consideration. Some manufactured collector systems and many

individually designed systems are done in such a way that

sequential installation is necessary. This can make it very

difficult to replace an individual collector without disturbing

the entire array.

Information on access provisions is provided in Reference [1].

Access for system monitoring . Appropriate access for sensors

shall be provided for inspecting and checking essential system

parameters, e.g. temperature, pressure, and critical voltages.

Review of drawings and specifications for the location of test fittings and electrical contacts.

Adequately located test fittings will permit system monitoring

and expedite the maintenance and repair of equipment.

Draining and filling of liquids . To facilitate system or subsystem maintenance and repair, subsystems employing liquids

shall be capable of being conveniently filled and drained.

Review of drawings and specifications.

Flushing of liquid subsystems . Suitable connections shall be

provided for the flushing (cleaning) of liquid energy transport

subsystems

Review of drawings and specifications.

The recommendations of the system manufacturer for cleaning

agents compatible with the materials of the system should be

followed

64
CHAPTER SIX - MAINTAINABILITY

Systems and Components

6.1.5 Criterion Filters. Filters shall be designed and located so that they can be cleaned or replaced with minimum disruption to the system and

adjacent equipment. Cleaning frequencies shall be specified by

the system manufacturer in the maintenance manual.

Evaluation Review of drawings and specifications.

6.1.6 Criterion Water shut off. The HW system shall be valved to shut off from

the cold water supply.

Evaluation Review of drawings and specifications.

6.1.7 Criterion Impairment of operation. The functional capability of the

H/C/HW systems shall not be impaired to a greater extent than

conventional systems when system repairs or modifications are being made.

Evaluation Engineering review of specifications and drawings.

Commentary Equipment that requires preventive maintenance shall be provided with complete instructions to maintain proper and

efficient operation of component, subsystem, and system.

6.2 Requirement Installation, operation, and maintenance manual. A manual* shall

be provided containing instructions for the installation, operation, and maintenance of the H/C/HW systems and/or subsystems

and components

6.2.1 Criterion Installation instructions. The instructions shall include

physical, functional, and procedural requirements for H/C/HW

subassembly and component installation.

These instructions shall describe the interconnection requirements of the various subsystems and components and their interface requirements with the building and site.

Evaluation Review of installation instructions.

Commentary It is not the intent of this criterion to require the provision

of complete, detailed system installation specifications. Such

specifications would normally be project specific and part of

the procurement process.

6.2.2 Criterion Maintenance and operation instructions. The manual shall com- pletely describe the H/C/HW systems, their breakdown into

subsystems, their relationship to external systems and elements,

their performance characteristics, and their required parts and

procedures for meeting specified capabilities.

The manual shall list all parts of the systems, by subsystem,

describing as necessary for clear understanding of operation,

maintenance, repair, and replacement, such characteristics as shapes, dimensions, materials, weights, functions, and performance

characteristics. The manual shall include a tabulation of those

specific performance requirements which are dependent upon

specific maintenance procedures. The maintenance procedures,

* The manual may consist in whole or in part of a series of instruction sheets provided by

the various subsystem and component manufacturers.

65
CHAPTER SIX - MAINTAINABILITY

Systems and Components

including ordinary, preventive and minor repairs, shall be cross- referenced for all subsystems and organized into a maintenance

cycle. The manual shall fully describe operation procedures for

all parts of the system including those required for implementation of specified planned changes in mode of operation. The

manual shall provide warning against hazards that could arise

in the maintenance of the system and shall fully describe precautions that shall be taken to avoid these hazards.

The manual should specify temperature, pressure, and flow

conditions which are expected to occur at the access points

required in Criterion 6.1.2 to facilitate operational checks and

troubleshooting.

Evaluation Review of maintenance and operating instructions.

Commentary

/ One of the most common malfunctions in large systems is expected

to be in the control system operation. These malfunctions are not always complete failures but more often a matter of adjustment. Control system malfunctions are not usually obvious unless

testing at specified points is conducted.

Some systems contain toxic and/or flammable materials that could

result in the poisoning of maintenance personnel or result in

fires or explosions when repairs involving soldering or welding

are involved. In addition, toxic fumes can be given off.

6.2.3 Criterion Maintenance plan. The manual shall include a comprehensive plan

for maintaining the specified performance of the H/C/HW systems

for their design service lives.

The plan shall include all the necessary ordinary maintenance,

preventive maintenance and minor repair work, and projections

for equipment replacement

Evaluation Review of maintenance plan.

6.2.4 Criterion Replacement parts. Parts, components, and equipment required for

service, repair, or replacement shall be commercially available

from the system or subsystem manufacturer or supplier.

Evaluation Review of specifications for the availability of parts.

Cemmentary This criterion is intended to preclude long periods of system

downtime due to the need for the repair or replacement of parts

It would be desirable to have a minimum one-year's supply of

consumable parts and potential early failure items, such as fan

belts, bearings, etc., in hand for the system.

6 . 3 Requirement Repair and service personnel. The H/C/HW systems shall be

designed in such a manner that they can be conveniently repaired

by qualified service personnel.

6.3.1 Criterion Servicing of H, C, and HC systems. The H, C, and HC systems

shall be capable of being serviced with a minimum amount of

special equipment by a trained HVAC service technician using a service manual.

Evaluation Review of drawings, specifications, and service instruction

manuals

Commentary The complexity and design of certain components may require

their removal and replacement for repair of the system.

66
CHAPTER SIX - MAINTAINABILITY

Systems and Components

6.3.2 Criterion Servicing HW system . The HW system shall be capable of being

serviced with a minimum amount of special equipment by a qualified plumber using a service manual.

Evaluation Review of drawings, specifications, and service instruction

manuals

I

i

I

Reference

1. Uniform Mechanical Code , International Conference of Building Officials, 5360 South

Workman Mill Road, Whittier, California 90601, 1973.

67
CHAPTER SEVEN - FUNCTION

Buildings and Sites

7 . 1 Requirement Design. The buildings and sites shall utilize materials, designs,

and construction methods appropriate for their intended use.

7.1.1 Criterion Design-Habitable buildings. The design of habitable and publicly

used buildings shall be done by registered Architects and/or

Engineers. The design of these buildings shall conform to state

and local building codes and regulations.

Evaluation Review of calculations, drawings, and specifications, and review

of Architect and Engineer credentials.

Commentary A well designed solar energy system should include a building

which is energy ^conserving. The codes and standards in most

states do not completely address energy conservation; and

upgrading in this particular way may be desirable.

There are several approaches that should be considered for the

design of buildings that conserve energy. One approach considers

the site where energy can be conserved by managing the microclimate and, therefore, modifying its effect on the building.

A second approach considers the exterior envelope of the building

where energy can be conserved by modifying factors such as: color, thermal conductivity, orientation, texture, surface area

and weather tightness. A third approach considers the mass of the

building and the objects around the building. Through careful

selection of materials, the rate at which energy is stored and

released can be managed, e.g., energy stored during the day and

released at night can reduce the thermal load on the building in

either a cooling cycle or a heating cycle depending on whether

the energy is released inside or outside of the building. Which

combination of options is chosen and how effecitve the selection

will be is dependent on design conditions and design goals.

7.1.2 Criterion Passive use of solar energy. Consideration shall be given in the

building and site design to the passive utilization of solar

energy, wherever practical.

Evaluation Review of calculations, drawings, and specifications.

Commentary Savings can be realized when normally provided components of the

building and site can be given an additional use in the H/C/HW

systems. Considering the building itself as a system for capturing,

storing, and utilizing solar energy can provide opportunities for

reductions in the building heating or cooling requirements.

7.2 Requirement Adequate space. The building site shall provide space to adequately accommodate the H/C/HW systems.

7.2.1 Criterion Collector. The building and site shall provide sufficient space

for the installation of the solar collectors.

Evaluation Review of site and building drawings showing the area provided

for the solar collector and calculations showing the space

needed for the collector.

Commentary This criterion does not require that the solar collector be

separate from other solar components, but only intends to establish that adequate surface areas have to be provided if the

68
CHAPTER SEVEN - FUNCTION

Buildings and Sites

7 . 2.2

7.3

7 . 3.1

7 . 3.2

collecting element is installed on the building or site. The

slope and area of the collectors is a complicated problem and

requires consideration of factors, such as the following: climatic

region, collector orientation and tilt angles, collector exposure

to wind, amount of energy to be supplied or released by collector,

collector mounting (free-standing or integrated with the building) , efficiency of the collector, and shading of the collector.

Criterion Storage . Where thermal storage is required, the building and/or

site shall provide sufficient space for the installation of the

storage subsystem.

Evaluation Review of site and building drawings showing the space provided

for thermal storage and calculations showing the volume required

for storage.

Commentary This criterion does not mean that, where required, storage should

-be separate from other solar components, it is intended only to ensure that a sufficient volume is provided for storage. The

amount of storage required will vary with such factors as: heat

capacity, storage medium, climatic region, amount of energy to be supplied or released by the collector, efficiency of the

collector, heat losses in the system, and design load of the

H/C/HW systems.

Requirement Functioning of building and site . The use and habitability of

the building and site shall not be substantially impaired by

the H/C/HW systems.

Criterion

Evaluation

Commentary

Criterion

Space use . A location shall be provided for solar subsystems

that will not significantly impair the use of required exterior

or interior spaces.

Review of site and building drawings showing the location of

solar subsystems.

The space provided for the solar subsystems should be in addition

to that normally required. Solar subsystems should not reduce or increase humidity, temperature, or radiation beyond acceptable

levels or interfere with required headroom or circulation space.

Heat storage areas that are incorporated within the building

should be properly insulated to prevent undesirable overheating

of adjacent rooms. System subassemblies located on the site

(e.g., collector or storage units) should not unduly interfere

with trash removal, furniture moving, the servicing of mechanical

equipment, or the normal movement of people and vehicles. The

operation of solar equipment should not create noise levels

which would impair the comfort levels of occupied spaces during

the day or at night. Since a collector may reflect a large

percentage of the incident solar radiation at high incidence

angles, the possibility of reflecting solar rays onto areas where people congregate should be investigated. Solar subsystems

such as storage should be used as positive design elements

that add to rather than subtract from the aesthetic quality of a space.

Impact on environment . A site location shall be provided for the

solar subsystems which will not significantly degrade the

immediate natural environment and site.

Evaluation Review of drawings and a report on the negative effects of the

building and its solar subsystems on drainage, vegetation,

microclimate, and wildlife.

69
CHAPTER SEVEN - FUNCTION

Buildings and Sites

Commentary This criterion does not require that existing conditions should

be maintained but that environmental degradation of the site and

the immediate area around the site should be prevented it if

cannot be healed naturally without further deterioration.

Several examples can be cited that could cause such conditions

to exist: (1) runoff from a large collector is not collected

and carried away in a drainage system it could, for certain soil

conditions, cause excessive erosion, (2) if the reflected rays

from a collector or the shade created by a collector killed

existing vegetation and prevented the growth of new vegetation,

large areas of soil might be exposed to excessive runoff, and

(3) if the installation of solar equipment is poorly planned or implemented, it can result in the unnecessary cutting down of

trees or in other conditions which would kill vegetation such as compaction, sunburn, drying, grade change, root pruning, or lack of support.

7.3.3 Criterion View. The location of solar components shall not unnecessarily

block interior or exterior views of the site unless they are intended as an integrated part of that view.

Evaluation Review of site and building drawings.

Commentary Even well-designed components can be undesirable obstructions

to attractive views of the building or site, unless they are integrated into the view.

70
CHAPTER SEVEN • FUNCTION

Buildings and Sites

General References

1. Aronin, Jeffrey F. , Climate and Architecture , New York, N.Y., (1953).

2. Fitch, James Marston, American Building: The Environmental Forces that Shape It , Houghton Mifflin Co., Boston, Mass., (1972).

3. Fitch, James Marston, "Buildings Designed for Climate Control in the United States of

America," Weather and the Building Industry , Research Conference Report No. 1,

Building Research Advisory Board of National Research Council, Washington, D.C., (1950).

4. Givoni, B., Man, Climate and Architecture , Elsevier Publishing Co., New York, N.Y.,

(1969)

5. Knowles, Ralph L., Energy and Form , MIT Press, Cambridge, Mass., (1974).

6. Koenigsberger , Rugersoll, Mayhew, Szokolay, Manual of Tropical Housing and Building : Part 1 Climatic Design , Longman Group Limited, London, (1973).

7. Olgyay, Aladar, "Solar Control and Orientation to Meet Bioclimatic Requirements,"

Architectural Forum, (March 1954), pp. 38-46.

8. Olgyay, Victor, Design with Climate , Princeton University Press, Princeton, N.J.,

(1963).

9. Robinette, Gary 0., Plants/People/and Environmental Quality , U.S. Department of

Interior, National Park Service in Association with American Society of Landscape

Architects Foundation, Government Printing Office, Washington, D.C. (1972).

10. AIA Research Corporation Solar Dwelling Design Concepts , prepared for U. S. Department

of Housing and Urban Development, Office of Policy Development and Research* (June 1976).

(Available from Superintendent of Documents, U. S. Government Printing Office, Washington, D. C., 20402, Stock No. 023-000-00334-1)

11. Steadman, Philip, Energy Environment and Building , Cambridge University Press,

Cambridge, Mass., (1975).

12. The House Beautiful Climate Control Projects , Bulletin of the American Institute of

Architects, September 1949 - January 1952.

13. Total Environmental Action, Solar Energy Home Design in Four Climates , Total

Environmental Action, Harrisville, N.H. , (1975).

14. United Nations, Climate and House Design , United Nations Publication, New York, N.Y.

,

(1971).

71
CHAPTER EIGHT - MECHANICAL

Buildings and Sites

8.1

8 . 1.1

8 . 1.2

Requirement Mechanical and electrical functioning of H/C/HW systems . The

building and site elements shall not prevent the proper mechanical

and electrical functioning of the H/C/HW systems.

Criterion Blockage of mechanical equipment . Buildings and planting

arrangement shall be coordinated with the installation of solar

components to avoid interference with their mechanical function.

Evaluation Review of building and site drawings showing the location of

solar system subassemblies, vegetation, fences, walls, and any

other objects which might affect the operation of the H/C/HW

systems

/ Commentary Existing vegetation and future growth of that vegetation can become a problem in the functioning of mechanical equipment, air

intakes and vents. For example, plants might block and, therefore,

reduce the efficiency of a fan or a compressor-condenser unit.

On the other hand, vegetation can also be used to advantage as a sunshade to reduce the cooling load.

Criterion Shading of collector . The location provided for the collector

shall not be shaded more than the specified period allowed for in

the design.

Evaluation Review of calculations or drawings estimating the area of the

collector shaded by objects such as mechanical equipment,

chimneys, vents, snow, trees, and buildings. Consideration shall

be given to the latitude of the site, the height of the object

above the collector, the azimuth angle of the object relative to the collector and the cut-off angles at which solar energy can be

efficiently collected throughout the year.

Commentary In locating trees in order to minimize the amount of shade falling

on the collector, the designer may not be able to effectively use

shade trees to improve the microclimate. Data are available for

calculating shading angles as a function of the time of day and

year [1, 2, 3, 4]. Consideration should also be given to partial

shading of collectors which could cause unusal stress concentrations and resulting glass breakage in an operating collector.

8.1.3 Criterion Sensor location . A location shall be provided for interior and

exterior control sensors (if sensors are required by the solar

technology being used) which will allow the detection of appropriate changes in the system and the environment without

unnecessary interference from factors such as shade, drafts,

thermal radiation, and vibrations.

Evaluation Review of drawings showing the location and elevation of control

sensing equipment. If sensing equipment is located on the

exterior of a building, exterior elevations showing the location

of control sensing equipment shall be provided.

8.2 Requirement Mechanical and electrical functioning of building and site . The

mechanical and electrical operation of the building or site shall

not be adversely affected by the H/C/HW systems.

72
CHAPTER EIGHT - MECHANICAL

Buildings and Sites

8 . 2.1

8 . 2.2

8.2.3

8.3

8.3.1

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Requirement

Criterion

Evaluation

Space for installation . Where portions of the solar subsystem

and particularly the energy transport subsystem are installed

within floors, walls, ceilings, or utility chases, adequate

space shall be provided for installations.

Review of the drawings showing the layout of the energy transport

subsystem and typical architectural sections for walls, floors,

and roof.

A preferred location for piping and ducts in walls may be within

interior walls rather than in exterior walls. This is particularly

true for those pipes and ducts delivering hot water, heating or cooling to the building so that losses and gains, therefore,

will be contained within the conditioned space. Provisions should

be made when using solar heating/cooling systems (using lower

working temperatures than conventional systems) for additional

space to include the larger ductwork and piping required under

these circumstances.

Exhaust and venting . The location provided for solar components

shall not interfere aerodynamically or physically with the

venting of the building plumbing systems or the exhaust of

mechanical systems to the extent that their intended function is

significantly impaired.

Review of drawings showing the location of solar components,

plumbing vents, and mechanical exhausts.

The wind conditions created around chimneys, flues, plumbing

vents, mechanical exhausts and condensers by the presence of

solar components should be examined for possible interference

with the mechanical operation of such elements. Flues and vents

should be located either far enough from higher elements (such

as roof mounted solar equipment) or extended far enough above

them to insure continuous outward flow frpm the flue or vent.

Utilities . The location and installation of solar components

shall not interfere with the safe operation of existing or proposed utility systems.

Review of utility plan and site plan.

Underground potable water piping serving an array of solar

collectors installed remote from the building if in proximity to sewers or sewage facilities, could allow contamination of the

potable water system. A horizontal separation of at least 10

feet from a septic tank drainage field apd 12 inches from a sewer

line is common practice for pipes carrying potable water.

Mechanical and electrical functioning of connections . The

connections between the H/C/HW systems and the building or site shall function mechanically or electrically as intended.

Plumbing connection . Plumbing connections between the solar com- ponents and water service or waste disposal systems shall be in

accordance with applicable nationally recognized and local

plumbing codes.

Review of drawings, details, and specifications related to plumbing connections.

73
CHAPTER EIGHT - MECHANICAL

Buildings and Sites

8.3.2

8.3.3

Commentary

Criterion

Evaluation

Particular attention should be given to making sure that

plumbing connections are dimensionally coordinated, that pipe

sizes and threads are compatible, and that changes in direction

do not unduly restrict the flow of fluid.

Electrical connections . Electrical connections between the

solar components and the electrical system of the building and

site or electrical service to the building and site, shall be in

accordance with applicable local and nationally recognized codes,

as specified in Criterion 4.1.2.

Review of drawings, details, and specifications related to electrical connections.

Commentary

Criterion

Evaluation

It is possible for improperly installed electrical connections to overload the electrical service and for electrical connections

that are not mechanically secure to create a fire hazard.

Duct connections . Duct connections between the solar components

and the mechanical system shall be in accordance with ASHRAE and

SMACNA standards.

Review of drawings, details, and specifications related to duct

connections

References

1. Aronin, Jeffery R^>, Climate and Architecture , New York, N.Y. (1953), p. 28-114.

2. ASHRAE, Handbook of Fundamentals , American Society of Heating, Refrigerating and

Air-Conditioning Engineers, Inc., New York, N.Y. (1972), p. 406.

3. Libbey-Owens-Ford Co., Sun Angle Calculator , Libbey-Owens-Ford Co., Toledo, Ohio

(1975).

4. United Nations, Climate and House Design , United Nations Publication, New York, N.Y.

(1971).

74
CHAPTER NINE - STRUCTURAL

Buildings and Sites

Requirement

Criterion

Evaluation

Commentary

Requirement

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Structural integrity of H/C/HW systems . The building or site

shall not reduce the structural integrity of the H/C/HW systems

below allowable design values.

Movement in adjacent structures . The locations provided for the

installation of solar components shall take into account possible

movements in adjacent structures which could impair tbe intended

performance capability of the solar systems.

Review of site and building drawings.

The possibility of stresses being imposed by thermal expansion or contraction, wind movements, seismic loads, vibratory loads, or foundations settlement need to be considered. Solar components

- vary in their ability to withstand the effect on their performance

of differential settlement. For example, a rock storage bin

can probably settle a great deal without affecting its performance;

however, a plumbing connection may be able to withstand very

little differential settlement.

Structural integrity of building and site elements . The structural

integrity of building and site elements shall not be impaired by

the H/C/HW systems.

Loads . in addition to basic design loads, building and site

elements shall be capable of carrying the increased loads imposed

by solar components.

Review of structural drawings, specifications, and design calculations taking into consideration the loads set forth in Chapter 3,

Structural (Systems and Components)

All possible loading conditions, such as those created by empty

storage tanks exposed to wind, alternate op adjacent span loading

of panels, or combinations of live loads along with dead loads

should be checked. The addition of solap components to an existing structure may require detailed investigation of the

existing structure and shall be based on the latest engineering

practices and applicable codes.

Penetration of structural members . When penetrations are required

in structural members to accommodate passage of solar components,

the structural design should reflect such additional requirements.

Structural members shall be designed so that compliance with

state and local building codes and regulations is maintained.

Review of structural and mechanical drawings.

This criterion is intended to prevent holes which are cut for

the installation of pipes, ducts, conduit wires, and other

mechanical equipment from reducing the required strength of

structural members.

75
CHAPTER NINE - STRUCTURAL

Buildings and Sites

9 . 3 Requirement

9.3.1 Criterion

Evaluation

Commentary

9.3.2 Criterion

Evaluation

Structural connections . Structural connections between solar

components and the building or site elements shall be capable of

carrying imposed loads.

Structural connections . Structural connections between solar

components and the building or site elements shall be capable of

transmitting sustained loads as specified in the design.

Review of structural drawings, connection details, specifications,

and design calculations.

This criterion deals not only with the connections of major

structural elements but with brackets or other supports used for

mounting solar components on a building. Allowable stresses and

design criteria for solar components supporting structures shall

be in conformity with accepted engineering practice and applicable

codes. This criterion is intended to insure that the local area

around the connection of a solar component is structurally

designed. Criterion 9.2.1 is intended to insure that those loads are carried by the building and site elements.

Brittle components . Where required, brittle elements of the

solar components shall be attached by devices or other means

capable of accommodating the maximum movement that would occur in

normal use.

Review of structural connection details and specifications.

76
CHAPTER TEN - SAFETY

Buildings and Sites

10 . 1 Requirement Safety of building and site. The safe operation of the building

or site shall not be affected by the H/C/HW systems.

10.1.1 Criterion Fire. The location of solar components shall not be detrimental

to the fire safety of the building or site.

Evaluation Review of calculations, drawings, and specifications.

Commentary When solar components are located on the site, circulation paths

should be checked to see that interference with the movement of

fire fighting equipment or with the emergency evacuation of a building is not jeopardized. When system components are mounted

on the building or made an integral part of the building, the

fire safety of the building's occupants must be maintained. This

will require that attention be given to the effects of "no flow"

temperatures on adjacent parts of a building, use of roofs by fire

fighters for gaining access, venting, and rescuing people from

fires

10.1.2 Criterion Protection against auto-ignition of combustibles. Combustible

solids adjacent to solar equipment shall not be exposed to elevated temperatures which may cause ignition.

Evaluation Review of calculations, drawings, and specifications. Testing

to show compliance where necessary.

Commentary Heating of cellulosic materials as well as other combustible materials over an extended period of time may result in the material

reaching and surpassing its auto-ignition temperature. The most

commonly accepted ignition temperature of wood is 392°F. However,

studies have indicated that wood may ignite when exposed to a temperature of 212°F for prolonged periods of time. The ignition temperature of plastics may be above or below those of cellulosic

materials. Clearances for HVAC equipment, ducting, and piping are discussed in NFPA No. 89M. Where applicable, clearances specified

by a nationally recognized testing laboratory may be used.

10.1.3 Criterion Protection from thermal deterioration. Building materials adjacent

to solar equipment shall not be exposed to elevated temperatures

that can result in adverse physical, chemical, mechanical, or thermal changes.

Evaluation Review of calculations, drawings, and specifications.

Commentary Building materials exposed to elevated temperatures may be

subject to hardening, softening, melting, blistering, buckling,

and other adverse changes which may reduce the structural and

fire resistance ratings of the building elements.

10.1.4 Criterion Accidents. The location provided for solar components shall not

increase the accident potential to a greater extent than would be

expected for a conventional non-solar facility.

Evaluation Review of calculations, drawings, and specifications.

Commentary Several examples can be given of how the presence of solar com- ponents might increase accident potential: (1) snow and ice

accumulations on the collector could present a hazard to pedestrians

77
CHAPTER TEN - SAFETY

Buildings and Sites

below, (2) reflected rays from the collector could be distracting

to drivers on adjacent highways or annoying to the occupants of

nearby buildings, and (3) the ground around a storage unit might

settle, creating a hazard because of the uneven ground.

10.1.5 Criterion Lightning protection . Lightning protection shall be provided in

accordance with the NFPA No. 78 Lightning Protection Code [1]

Evaluation Review of calculations, drawings, and specifications.

Commentary There is some evidence to suggest that solar arrays, particularly

solar arrays with plastic covers, increase the electrostatic

potential between ground and air, and could induce increased

lightning hazard in areas of high lightning incidence.

Reference

1. Lightning Protection Code , NFPA, No. 78, 1975, National Fire Protection Association

(NFPA), 470 Atlantic Avenue, Boston, Mass. 02210.

78
CHAPTER ELEVEN - DURABILITY / RELIABILITY

Buildings and Sites

11 . 1 Requirement Durability and reliability of H/C/HW systems. The building and

site shall not reduce the durability or reliability of the H/C/HW

systems to an extent that would significantly impair their intended

function.

11.1.1 Criterion Vegetation. The location of plant materials shall consider the

effects that their sap, roots, growth or decay could have on the

durability and reliability of the H/C/HW systems.

Evaluation Review of site plans showing the location and type of existing

and proposed plant materials and the location of the solar com- ponents .

11.2 Requirement Durability and reliability of building and site. The durability

and reliability of the building and site elements shall not be

reduced by the H/C/HW systems to an extent that would significantly

impair their intended function.

11.2.1 Criterion Chemical corrosion. Solar components shall not cause corrosion of

the building or site elements to an extent that would significantly

impair their intended performance.

Evaluation See Evaluation: Criterion 5.3.4.

11.2.2 Criterion Heat and moisture. Roof mounted system components shall not cause a buildup of heat or moisture that would cause excessive deterioration

of the roofing system or other components of the buildings.

Evaluation Review of drawings, specifications, and calculations for potential

temperature buildup caused by solar subsystems.

Commentary The presence of the collector can cause abnormal heat rises which

could cause thermal degradation and the buildup of moisture which

could cause rotting or the growth of mold and fungus. The provision

of adequate ventilation may be required. Venting to interior mechanical

areas or other generally unoccupied areas within the building may be

acceptable in order to minimize heat loss caused by venting.

11.2.3 Criterion Exterior penetrations. Openings in the exterior enclosure of the

building through which piping, ducting, and/or wiring are passed shall

be made weather resistant and moisture proof.

Evaluation Review of drawings and specifications.

11.3 Requirement Durability and reliability of connections. The connections between

the H/C/HW systems and the building that are exposed to external

environmental factors shall not undergo changes that will impair

their expected performance.

11.3.1 Criterion Material compatibility. Connector materials between solar components

and the building and site shall be chemically and physically compatible

under in-use conditions.

Evaluation See Evaluation: Criterion 5.3.2.

79
CHAPTER TWELVE - MAINTAINABILITY

Buildings and Sites

12 . 1 Requirement Maintainability of H/C/HW systems. The building or site shall

not prevent the practical maintainability of the H/C/HW systems, nor shall the systems prevent the practical maintainability of the

building or site.

12.1.1 Criterion Accessibility. The design shall make adequate provision for

accessible maintenance.

Evaluation Review of site and building drawings.

Commentary Solar components should be accessible without trespassing on adjoining property and should not be located unnecessarily under

buildings or roads, behind mechanical equipment or in other

places which are inaccessible for maintenance without disassembling any major structural or mechanical elements. There should

be sufficient room around components to permit their examination,

adjusting, servicing, and/or maintenance. Accessibility for

repair, maintenance and replacement should reflect the expected

life of the component and frequency of routine maintenance

required. An element with a shorter maintenance cycle or life

expectancy should be more accessible than one that has a longer

maintenance cycle or life expectancy.

12.1.2 Criterion Misuse. Solar components shall be located where the potential

for their misuse is minimized.

Evaluation Review of site plans showing the location of recreational

facilities, protective screening, roads, sidewalks, and solar

subsystems.

Commentary The proximity of system components to playgrounds and sidewalks

should be examined to minimize the potential misuse or vandalism.

In addition, equipment which should only be adjusted by skilled

personnel should not be located in areas subjected to normal

pedestrian traffic.

12,1.3 Criterion Permanent maintenance accessories. Permanent maintenance accessories such as hose bibs, drains, and ladder supports necessary

for the maintenance of the H/C/HW systems shall be provided.

Evaluation Review of maintenance plans and drawings and specifications showing

type and the location of drains, ladder supports, safety belt clips,

and other permanent maintenance accessories relative to the location

of solar equipment.

Commentary Drains, hose bibs, and surfaces for supporting ladders or other

equipment may be needed to service the solar eauipment.

12 . 2 Requirement Maintainability of building and site. The practical maintainability

of the building or site shall not be significantly impaired by

the H/C/HW systems.

80
CHAPTER TWELVE - MAINTAINABILITY

Buildings and Sites

12.2.1 Criterion Accessibility. The location of the solar components shall not

impair accessibility needed to maintain the building or site.

Evaluation Review of maintenance plans, site plans, and building drawings.

Commentary The location of underground elements should be examined both to ensure that they can be maintained without trespassing on adjoining property and to ensure that they do not prevent digging,

truck access, etc., necessary to maintain the facility or site.

12.2.2 Criterion Ice dams. The presence of a solar component shall not create the

potential for significant ice damming which might cause roof

leakage

Evaluation Review of roof drawings and details for roof-installed solar

components

Commentary Ice sliding off a collector, for example, can create a dam behind

which water could accumulate and cause roof leakage.

12 . 3 Requirement Maintainability of connections. The connections between the H/C/HW

systems and building or site shall be maintainable.

12.3.1 Criterion Accessibility. Connections which require maintenance shall be

accessible without disassembling major portions of the solar

components, the building or the site elements.

Evaluation Review of maintenance plans and building drawings and specifications

81
CHAPTER THIRTEEN - VISUAL CHARACTERISTICS

Buildings and Sites

13 . 1 Requirement Visual characteristics of building and site. Consideration shall

be given to the effects on the visual characteristics of the

existing and proposed environment caused by the installation of

a solar energy system.

13.1.1 Criterion Building. The effects of the solar subsystems on the mass,

scale, grid pattern, texture, and color of the building shall be

considered.

Evaluation Review of site and building drawings, models, and renderings.

/ 13.1.2 Criterion Neighborhood. Consideration shall be given to the relationship

between the solar energy system and its building and site with

the surrounding neighborhood.

Evaluation Review of site plans, elevations, photographs of neighboring

buildings, models, and renderings of the solar energy system

installed on the building and site, and the surrounding neighborhood.

82
GLOSSARY

Absorptance - The ratio of the amount of radiation absorbed by a surface to the

amount of radiation incident upon it.

Absorptivity - The capacity of a material to absorb radiant energy.

Air chamber - A closed section of pipe or a container filled with air entrapped

at atmospheric pressure which when mounted in a water supply line absorbs the

pressure surges caused by the rapid opening and closing of valves.

Air gap separation - The unobstructed vertical distance through the free atmosphere between the lowest opening from any pipe or faucet supplying water to a tank, plumbing fixture, or other device and the flood level rim of the receptacle.

Auxiliary energy subsystem - Equipment utilizing conventional energy sources to supplement the output provided by the solar energy system. It may be integrated

directly into the solar energy system, or it may be completely separate from it,

and contain its own means for delivery of heating, cooling and/or hot water to the building.

Back pressure - A form of backflow caused by a pump, elevated tank, boiler,

or other means that could create pressure within the system greater than the

supply pressure of a fluid.

Backflow - The reverse flow of liquids, gases, or substances into the distributing pipe

lines of a potable supply of water. Backflow may occur under two conditions - pressure

greater than atmospheric (see "Back pressure") , and pressure that is subatmospheric

(see "Backsiphonage")

Backs iphonage - A form of backflow due to a negative or subatmospheric pressure.

Cathodic protection - The process of providing corrosion protection against

electrolytic reactions that could be deleterious to the performance of the protected material or component.

Chemical compatibility - The ability of materials and components in contact with each

other to resist mutual chemical degradation, such as that caused by electrolytic action

or plasticizer migration.

Climate - The prevailing or average weather conditions of a geographic area or region as shown by temperature and meteorological changes over a period of

years

Collector efficiency (instantaneous) - The amount of energy removed by the

transfer fluid per unit of aperature (entrance window area) over a 15-minute

period by the total incident solar radiation onto the collector for the 15-minute

period.

Collector subsystem - The assembly used for absorbing solar radiation, con- verting it into useful thermal energy, and transferring the thermal energy to a heat transfer fluid.

Control subsystem - The assembly of devices and their electrical, pneumatic

or hydraulic auxiliaries used to regulate the processes of collecting, transporting,

storing and utilizing energy in response to the thermal, safety, and health

requirements of the building occupants

Cooling (C) system - The complete assembly of subsystems and components necessary to convert solar energy into thermal energy and use this energy in combination with auxiliary energy, where required, for space cooling purposes.

Cooling degree days - The number of degrees that the daily mean temperature is

above 65 degrees F.

83
Combustible solids - This term as used herein means cellulosic materials, such as wood,

paper and many fibrous materials (except asbestos and some of the synthetic fibers) as defined in Section 5 of the NFPA Fire Protection Handbook, 13th Edition.

Component - An individually distinguishable product that forms part of a more complex

product (i.e. subsystem or system)

Creep - A time-dependent deformation caused by sustained loads. (See "Sustained load.")

Cross-connection - Any connection between a potable water system and non-potable

source or system through which backflow can occur. (See "Backflow.")

Cyclic load - A service load whose magnitude and/or direction are subject to time dependent variation.

Design life - The period of time during which an H/C/HW system is expected

to perform its intended function without requiring major maintenance or replacement.

Dielectric fitting - An insulating or nonconducting fitting used to isolate electrochemically dissimilar materials.

Hot water (HW) system - The complete assembly of subsystems or components

necessary to convert solar energy into thermal energy and use this energy in

combination with auxiliary energy, where required, to provide hot water in the

building.

Ease of ignition - The flame exposure time required to produce sustained flaming

of a representative specimen of material from a controlled impinging flame source.

Electrical distribution subsystem - All electrical conductors and equipment installed

in an H/C/HW system including supply conductors for operation of the systems.

Emittance - The ratio of the radiant energy emitted by a body to the energy

emitted by a black body at the same temperature.

Energy transport subsystem - That portion of an H/C/HW system which contains

heat transfer fluids and transports energy throughout the system.

Environmental impact statement - A report of any effects that the system or its building could have on the site and its surroundings.

Expansive soil - A soil which exhibits an increase in volume with an increase in

moisture content.

Failure (structural) - Failure of a structure or any structural element is

defined as one of the following:

(a) Sudden, locally-increased curvature, major spalling, or structural collapse.

(b) The inability of the structure to resist a further increase in load.

(c) An increase in deflection of no less than the maximum allowable deflection

under service load conditions, occurring during any 10-minute period after

application of the superimposed load without increase in the applied load.

Fluid requiring special handling - Fluid having a degree of toxicity such that it

is categorized as a "highly toxic substance" or a "toxic substance" as defined

by paragraphs 191.1 (e) and (f) of the Hazardous Substances Act, Regulations,

Part 191, Chapter 1, Tile 21 (A); fluid having a degree of flammability such that

it is categorized as a "flammable substance" or an "extremely flammable substance" as defined by the application of the Tagliabue Open-Cup Flash Point Test

(stated in the Act)

84
Heat actuated cooling - The use of thermal energy to initiate a thermodynamic

cycle which results in lowering the temperature of a heat transfer fluid, which

in turn is used to lower the indoor air temperature.

Heat capacity - The amount of heat necessary to raise the temperature of a given mass one degree.

Heat transfer medium - A fluid used in the transport of thermal energy.

Heating degree days - The number of degrees that the daily mean temperature is

below 65 degrees F.

Heating (H) system - The complete assembly of subsystems and components

necessary to convert solar energy into thermal energy and use this energy in

combination with auxiliary energy, where required, for heating purposes.

Heating and cooling (HC) system - The complete assembly of subsystems and

components necessary to convert solar energy into thermal energy and use this

energy in combination with auxiliary energy, where required, for combined

heating and cooling purposes.

Humidity, relative - The ratio of the actual partial pressure of water vapor

present to the pressure of saturated water vapor at the same temperature and

barometric pressure.

In-service conditions - The conditions to which a solar H/C/HW system

and its components will be exposed during their operational lifetimes.

Load factors - Multipliers by which design loads are increased in order to obtain

the loads to be used in ultimate strength design of structural elements.

Maximum "flow" temperature - The maximum temperature that will be obtained

in a component when the heat transfer fluid is flowing through the system.

Maximum "no-flow" temperature - The maximum temperature that will be obtained

in a component when the heat transfer fluid is not flowing through the system.

Maximum service temperature - The maximum temperature to which a component

will be exposed in actual service, either with or without the flow of heat

transfer fluid.

Metastable precipitation - The precipitation of solid matter from a solution under

conditions where such precipitation is marginally stable.

Minimum service temperature - The minimum temperature to which a component

will be exposed in actual service, either with or without the flow of heat

transfer fluid.

Outgassing - The process by which materials and components expel gases.

Passive solar energy system - An assembly of collectors, thermal storage device(s)

and transfer media which converts solar energy into thermal energy and in

which no energy in addition to solar is used to accomplish the transfer

of thermal energy. The prime elements in a passive system are usually some form

of thermal capacitance and solar energy control.

Pipe friction - Pipe wall roughness or duct wall roughness. Such roughness

causes the loss of energy in the form of heat.

Pitting - The process by which localized wear is caused in materials or components

by erosion or chemical decomposition.

85
Plasticizer migration - The process by which plasticizers used in plastics

migrate within the specimen and either concentrate in a narrow boundary area

or migrate to another material in connection with the specimen.

Ponding - The retention of water due to deflection of horizontal surfaces.

Potential heat - The difference between the heat of combustion of a representative

specimen of material and the heat of combustion of any residue remaining after

exposure to a simulated standard fire, determined by combustion calorimetric

techniques

pphm - Parts per hundred million.

Rate of heat release - A method of measuring the relative combustibility of

materials by determining the rate at which heat is released by the material,

determined by calorimetric techniques.

/ Residual deflection - The portion of the displacement of an element in a structure

which is not recovered after the removal of the action causing that displacement.

Resultant velocity of hail - The velocity resulting from a hailstone falling at its

terminal velocity and acted on by a wind force.

Sensors - Devices (such as pressure transducers, thermocouples, flowmeters,

etc.) used to sense individual parameters.

Service loads - Loads which are expected during the service life of a structure

and upon which the design of the structure is based.

Shading angles - Angles that the sun makes in both elevation and azimuth that cause shadows

Significant (deterioration, loss, etc.) - Deterioration that either

results in a decrease in performance greater than that allowed for

in the design or in the creation of a hazard.

Solar degradation - The process by which exposure to sunlight deteriorates the

properties of materials and components.

Solar energy - The photon energy originating from the sun's radiation in the

wave-length region from 0.3 to 2.7 micrometers.

Solar time - The hours of the day as reckoned by the apparent position of the sun. Solar noon is that instant on any day at which the sun reaches its maximum altitude

for that day. Solar time is very rarely the same as local standard time in any

locality.

Storage subsystem - The assembly used for storing thermal energy so that it can be used when required.

Subsystem - A major, separable, functional assembly of a system.

Sustained load - A load that is sustained over a period of time.

Tap temperature - The temperature at which potable hot water is discharged

from an outlet at the point of use.

Temperature, dry-bulb - The temperature of a gas or mixture of gases

indicated by an accurate thermometer after correction for radiation.

Temperature, wet bulb - The temperature at which liquid or solid water, by

evaporating into air, can bring the air to saturation adiabatically at the same temperature

86
Terminal velocity of hail - The maximum vertical velocity reached by a hailstone

occurring when the drag force on the hailstone is equal to the force exerted by

gravity on its mass.

Toxic fluids - Gases or liquids which are poisonous, irritating and/or suffocating,

are classified in the Hazardous Substances Act, Part 191, Chapter I, Title 21.

Transmittance - The ratio of the radiant flux transmitted through and emerging

from a body to the total flux incident on it.

Ultimate strength design - A method of proportioning structures or members for

failure at a specified multiple of working loads, and assuming nonlinear distribution of flexural stresses.

Utility plan - A drawing showing location of electrical lines, gas lines, water, etc.

Vertical penetrations - The-vertical passage of a utility chase, pipe, duct, etc.,

through a fire-rated structural assembly.

Water hammer - A term used to indicate that destructive forces, exemplified

by the pressure surges and attendant pounding noises and vibration which develop

in a pipe system when a column of noncompressible liquid flowing through a pipe

line at a given pressure and velocity is stopped abruptly.

Water hammer arrester - A manufactured device, other than an air chamber,

containing a permanently sealed cushion of gas or air, designed to provide

protection against excessive shock pressure without maintenance.

Working stress design - A method of proportioning structures or members for

prescribed working loads at stresses well below the ultimate, and assuming

linear distribution of flexural stresses.

Zero hardness - A property of softened water such that no calcium or magnesium

can be found in it by ordinary analytical methods.

2 1/2 percent design summer temperature - The outdoor air temperature will be

higher than the stated value not more than 88 hours per year (2 1/2% of the 2,928

hours in June through September)

97 1/2 percent winter design temperature - The outdoor air temperature wT i.ll be

lower than the stated values for not more than 65 hours per year (2 1/2% of the

2,160 hours in December, January and February).

87
ABBREVIATIONS

AASHTO

AGA

ANSI

ARI

ASHRAE

ASME

ASTM

EKDA

FMHUD

NACE

NASA

NBBPVI

NBC of Canada

NBS

NESCA

NEMA

NFPA

OSHA

SAE

SMACNA

UBC

UL

(Code Groups, Associations, and Gov’t. Agencies)

American Association of State Highway and Transportation

Officials

American Gas Association

American National Standards Institute

Air-Conditioning and Refrigeration Institute

American Society of Heating, Refrigerating, and

Air-Conditioning Engineers

American Society of Mechanical Engineers

American Society for Testing and Materials

Energy Research and Development Administration

Factory Mutual

Department of Housing and Urban Development

National Association of Corrosion Engineers

National Aeronautics and Space Administration

National Board of Boiler and Pressure Vessel Inspectors

National Building Code of Canada

National Bureau of Standards

National Environmental Systems Contractor's Association

National Electrical Manufacturer's Association

National Fire Protection Associations

Occupational Safety and Health Administration

Society of Automotive Engineers

Sheet Metal and Air-Conditioning Contractor's National

Association

Uniform Building Code

Underwriter's Laboratories, Inc.

88
'

NBS-114A (REV. 7-73) '

(J.s DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 76-1187

2. Gov’t Accession

No.

3. Recipient’s Accession No.

4. TITLE AND SUBTITLE

Interim Performance Criteria for Solar Heating

and Cooling Systems in Commercial Buildings

5. Publication Date November 1976

6. Performing Organization Code- 465. 00

7. AUTHOR(S)

Solar Energy Program Team, Center for Building Technology

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 4656505, Task 2

11. Contract/Grant No.

E(49-l) - 3800

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Energy Research and Development Administration

20 Massachusetts Avenue, N.W.

Washington, D.C. 20545

13. Type of Report & Period Covered

Interim

14. Sponsoring Agency Code

i 15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most significant information. It document includes a significant

bibliography or literature survey, mention it here.) Public Law 93-409, the Solar Heating and Cooling Demonstration Act of 1974, provides

for "demonstration within a three-year period of the practical use of solar heating

technology, and .... the development and demonstration within a five-year period

of the practical use of combined heating and cooling technology." Under the provisions

of the Act, in February 1975, the NASA developed a first edition of this document containing interim performance criteria for the design and evaluation of solar heating

and cooling systems to be demonstrated in commercial buildings. Since that time,

responsibility for further development of the document has been assumed by the NBS

This second edition of the "commercial criteria" represents the first revision to the

NASA document. It is expected that this document will be updated periodically as data

and information are gained from the demonstration program.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Buildings; cooling; heating; hot water; performance criteria; solar energy; standards.

18. AVAILABILITY [X Unlimited 19. SECURITY CLASS

(THIS REPORT)

21. NO. OF PAGES

1

' For Official Distribution. Do Not Release to NTIS

UNCL ASSIFIED 100

Order From Sup. of Doc., U.S. Government Printing Office Washington, D.C. 20402. SD Cat. No. 03

20. SECURITY CLASS

(THIS PAGE)

22. Price

1 Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151 UNCLASSIFIED 45-00

USCOMM-DC 29042-P74
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