/

Oi ( * USJgl cations All

NBSIR 78-1562

104 4 fl R 2 1

Interim Performance Criteria

for Solar Heating and Cooling

Systems in Residential

Buildings

Second Edition

Solar Technology Program

Building Economics and Regulatory Technology Division

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

U.S. Department of Commerce

Washington, D C. 20234

Department of Housing and Urban Development

Division of Energy, Building Technology and Standards

Washington, D.C. 20410 ff

-oc —

100

. U56

78-1562

JteAtonai Bursae of Standards MAY 1 4 1979

n^t a tc- fu.£

NBSIR 78-1562

u i :OCUDO

INTERIM PERFORMANCE CRITERIA

FOR SOLAR HEATING AND COOLING

SYSTEMS IN RESIDENTIAL

BUILDINGS

Second Edition

Solar Technology Program

Building Economics and Regulatory Technology Division

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

U.S. Department of Commerce

Washington, D.C. 20234

November 1978

Prepared for Department of Housing and Urban Development

Division of Energy, Building Technology and Standards

Washington, D.C. 20410

i/k LLi O. \ eg y\JLQ% , U L

'

- ' (

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

Dr. Sidney Harman, Under Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

ACKNOWLEDGMENTS

This document was prepared by the Solar Energy Program Team of the National Bureau of

Standards, Center for Building Technology. Team members who participated in the preparation

of this revision include:

John K. Holton, Project Leader

F. Eugene Metz

Elmer R. Streed

Leopold Skoda

Michael McCabe

Lawrence W. Masters

W. Douglas Walton (Center for Fire Research)

James R. Harris

David Waksman

Acknowledgment is also made of the helpful comments and suggestions received from

William Freeborne of the Department of Housing and Urban Development, and from Dubin-Bloome

Associates

1
FOREWORD

These interim performance criteria, developed for the Department of Housing and Urban

Development (HUD), are intended for use as a baseline document for criteria and standards

for the design, development, technical evaluation and procurement of the solar heating and

cooling systems to be used in residential 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 "residential criteria" document, represents the first revision

to the "Interim Performance Criteria for Solar Heating and Combined Heating/Cooling Systems

and Dwellings" published in January 1975. Its revision draws upon comments received and

experience gained in the use of two companion documents, the "Interim Performance Criteria

for Solar Heating and Cooling Systems in Commercial Buildings," NBSIR 76-1187 and the

"HUD Intermediate Minimum Property Standards Supplement, 1977 Edition, Solar Heating and

Domestic Hot Water Systems," 4930.2. Major changes or additions to the criteria and

evaluation statements contained in the original document are indicated by vertical lines in

the margins. Where an entire section has been significantly changed or reorganized,

notation appears at the beginning of the section.

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

program and as a basis for the preparation of definitive performance criteria in accordance

with the requirements of Section 8 of PL 93-409. Current plans of the Department of Energy

(DoE) and HUD call for preparation of the definitive performance criteria by December 1979.

It is also hoped that they will evolve into definitive performance criteria that can be used

to develop provisions for model state 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:

Chief , Solar Technology Program

National Bureau of Standards

Building 225, Room A-114

Washington, D.C. 20234

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 1960,

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 in 2 = 6.45 x 10

-4

meter"

1 ft 2 = 0.09290 meter z

Volume

1 in 3 = 1.639 x 10 -5 meter 3

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

Mass

1 ounce-mass (avoirdupois) = 2.834 x 10~z 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) = 1.055 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 (top

- 32)

Heat

1 Btu- in/h* f

2 • °F = 1.442 x 10 _1 W/m-K (thermal conductivity)

1 Btu/lbm <0 F = 4.184 x 10 3 J/kg-K (specific heat)

1 langley = 4.184 x 10 4 J/m^ = 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, the

Department of Housing and Urban Development (HUD) has utilized the services of the NBS

to develop this document containing interim performance criteria for the design and

evaluation of solar heating and cooling systems to be demonstrated by HUD in residential

construction.

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 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 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 residential 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 residential 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

The criteria given in this document for dwellings primarily consider aspects of planning and

design that are different from conventional buildings by reason of the solar energy systems

under consideration. The performance requirements of this document are consistent with the

requirements of the HUD MPS 4900.1, "Minimum Property Standards for One and Two Family Dwellings; MPS 4910.1, "Minimum Property Standards for Multi-Family Housing; MPS 4920.1, "Minimum

Property Standards for Care-Type Housing, and MPS 4930.2, "Intermediate Minimum Property

Standards Supplement for Solar Heating and Domestic Hot Water Systems."

* Definitions are given in the glossary of this document; see page 98.

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

not all cooling systems are combined with heating systems. *** (i.e., the HUD MPS, and recognized building codes and standards)

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 item

being addressed. The one or more criteria associated with each requirement state those con- siderations which are necessary to meet the requirement. Due to limitations in the stateof-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 only advisory.

The document is organized into chapters on the basis of the performance attributes listed

below.

1. Thermal 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 thermal 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.

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 designated use conditions. Corrosion and thermal degradation are typical durability /reliability

related items.

6. Operation and Servicing deals with the features of systems and their subassemblies

which allow them to 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.

v
7. Building and Site performance statements deal with the interactions between the

solar energy system and its surrounding environment, the building and site. These

performance statements 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.

For the purposes of this document, the various systems and subsystems, both active and passive,

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 (H/C) system or be completely separate from them. The term hot water

as used in this document includes both domestic hot water (DHW) and service

hot water (SHW). Service hot water may either be potable or non-potable

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, mechanical,

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 .

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 periodic 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.
TABLE OF CONTENTS

Page

Acknowledgments i

Foreword ii

SI Conversion Units iii

Introduction iv

1. THERMAL

1.1 H and C system performance. 1 1.2 HW system performance . 3 1.3 Collector performance ...... 4 1.4 Thermal storage performance 5 1.5 Component/system/space interactions 7 1.6 Energy transport performance 7 1.7 Control system performance 8 1.8 Auxiliary energy 10

2. MECHANICAL

2.1 Functional design 15

2.2 Leakage prevention 20

2.3 Collector orientation and location 2l

2.4 Heat transfer fluid quality 22 2.5 Subsystem isolation 24

2.6 Control subsystem design 24

2. 7 Operational verification 25

3. STRUCTURAL

3.1 Structural safety of H/C/HW system 28

3.2 Function and operation 3 3

4 . SAFETY

4.1 Health and safety 3 6 4.2 Fail-safe controls 36

4.3 Fire safety 37

4.4 Toxic and combustible fluids 40

4.5 Safety under emergency conditions 43

4.6 Protection of potable water and circulated air. 44

4.7 Protection from physical hazards. . 46

vii
Page

5. DURABILITY /RELIABILITY

5.1 Effects of external environment 50

5.2 Temperature and pressure resistance 54

5.3 Chemical compatibility of components 56

5.4 Components involving moving parts 58

6. OPERATION AND SERVICING

6. 1 Maintenance and servicing 60

6.2 Installation, operation and maintenance manual 61

6.3 Repair and service personnel 63

6.4 System monitoring 64

7. BUIDING AND SITE

7.1 Thermal design 65

7.2 Functioning of building and site 65

7.3 Mechanical and electrical functioning of building and site 66

7.4 Structural safety and serviceability of building and site elements 67

7.5 Safety of building and site 67

7.6 Durability and reliability of building and site 68

7.7 Maintainability of building and site 68

Appendix 1 70

Appendix 2 75

Appendix 3 81

Glossary 98

Abbreviations 103

viii
Chapter One

THERMAL

1.1

1.1.1

1 . 1.2

Requirement H and C system performance . H, C, and H/C 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.

Criterion Heating design temperatures . The heating system shall be designed

and facilities provided to maintain the indoor temperature limits

in occupied spaces for 97 1/2 percent winter outdoor design conditions

See chapter 23 reference [1]*, Section 615-3 of references [2, 3, 4],

for the geographic area in which the system is to be operated.

Evaluation Review of design parameters, HVAC equipment and heat loss calculations. A building load calculation procedure comparable in detail

at least to the modified degree-day method shall be used, see reference [1], Chapter 24 and reference [5], Chapter 43. 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 utilizing conventional energy, ambient air,

ground heat or stored thermal energy 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 controllable manner.

Comfort conditions combining the effects of dry bulb temperature, mean radiant temperature and relative humidity are presented in

ASHRAE Standard 55-74 [7]. Occupied spaces for sedentary activities in normal dress are usually designed for heating to maintain

a recommended indoor temperature of 70°F (21°C) dry bulb [2, 3, 6];

however, mean radiant temperature may be used on an equal basis to calculate comfort conditions. Minimum and maximum temperature and

humidity conditions are also specified in ASHRAE Standard 55-74

[7]. 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 compatable with their

functional use. Housing for the elderly and care-type facilities

may use other indoor design temperatures and design parameters

[3, 4].

The design requirements for a building utilizing passive solar

energy methods may require a higher level of detailed load analysis.

An example of the analysis considerations is presented in ASHRAE

Standard 90-75 [6]

,

Criterion Cooling design temperature . Where comfort air conditioning is re- quired or used, in occupied spaces, the cooling system shall be

designed and facilities provided to maintain the indoor temperature

for 21/2 percent summer outdoor design conditions. See chapter 23

reference [1], Section 615-5 of references [2, 3, 4] for the geographic area in which the system is to be operated.

Evaluation Review of design parameters, HVAC equipment and heat gain calculations

A procedure comparable in detail with the degree-hour method shall

be used, see reference [1], Chapter 25, reference [5], Chapter 43.

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)

.

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

1
Commentary

1.1.3 Criterion

Evaluation

Commentary

1.1.4 Criterion

Evaluation

Chapter One

THERMAL

Air conditioning equipment utilizing conventional energy, ambient

air, ground sink, or stored thermal energy may be used in con- junction with the solar system in an assist or auxiliary mode. The

use of evaporation, nocturnal radiation, dessication, 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 for cooling to maintain a recommended indoor temperature of

75°F (24°C) [2, 3, 6], Minimum and maximum temperatures are also

specified in the ASHRAE Standard 55-74 [7]. 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 care-type facilities and

housing for the elderly may use other indoor design temperatures

and design parameters [3, 4],

Relative humidity . If humidification is provided, it shall be designed and equipment provided to provide a relative humidity of no greater than 30 percent. If dehumidification is provided, it shall

be designed to provide a relative humidity of no less than 60 percent.

Review of design parameters and calculations made in accordance with

ASHRAE Standard 90-75 [6] to determine if the design relative humidity

lies within the comfort envelope defined in ASHRAE Standard 55-74 [7]

This criterion recognizes that some solar energy systems may be

designed for humidification or dehumidification purposes and that

in such cases, the limits established by Section 5 of ASHRAE

Standard 90-75 which recognize the energy expenditure required should

be used.

Building spaces with special functional requirements may use other

relative humidity design conditions. Design procedures have been

established to control relative humidity, see reference [1]

,

Chapter

7 and reference [8], Chapter 5. This control should be achieved as much as possible utilizing energy that would otherwise be rejected.

Thermal performance . The average yearly contribution of solar

energy to the operation of the H, C, and H/C systems shall be

specified in the design and shall result in a reduction (or comparative saving) in the average annual consumption of conventional

energy for the total building heating/cooling needs.

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 utilizing

correlation charts may be based upon monthly average climatic data

for sites where at least 10 years of weather data are available.

The prediction of system performance should reflect the cumulative

degradation in components resulting from environmental deterioration

or system wear.

2
Commentary

1.2 Requirement

1.2.1 Criterion

Evaluation

Commentary

Chapter One

THERMAL

Experimental verification of complete system performance may or may

not be practical for residential size systems prior to installation;

therefore, analytical simulation methods employing empirical subsystem or component performance can be used to calculate the performance over the full range of operating conditions when measured

performance data are not available.

Examples of analytical simulation methods for calculating system

performance are described fqr active systems in references [9, 10,

11, 12, 13, 14, 15, 16] and for passive systems in references [17,

18, 19, 20, 21, 22, 23, 24], Systems as actually installed may not

correspond exactly with predictive models, i.e., ducts that leak, flow

restrictions, uninsulated pipe or duct runs, or flow imbalances.

Sources of insolation data and data reduction methods are described in

references [25, 26, 27, 28, 29]. Performance factor definitions and

evaluation procedures are presented in references [30, 31]. Since

verification of the correlation of simulated versus actual perfor- mance has not been completed, simulation methods used to predict actual

performance should be considered with this understanding. It is

important to match system components, i.e., collectors, heat exchangers,

storage, auxiliary, etc., to building load for efficient performance.

In passive systems this will require careful design of storage and

control elements to prevent excessive space temperatures and non- colleption period heat losses. Such features may include aperture

insulation and shading devices.

For passive systems the determination of reduced energy consumption

may be based on a comparison with: a) the same building without

the solar aperture, or b) a reference building. Reference [31]

presents a discussion of these evaluation procedures. Data on actual operation of several passive systems is presented in

references [20, 21, 32, 33, 34].

HW system performance . The HW system shall be capable of collecting

solar energy and converting it into thermal energy which shall be

psed in combination with storage, if provided, and auxiliary energy

to supply an adequate amount pf hot pater at an acceptable temperature to meet the needs of the application.

Load. Single family and multifamily residential HW systems with

individual water heaters shall be capable of providing hot water at a tap temperapure of 140°F and wiph draw and recovery rates as shown

in Tables 1A-1 and 1A-2 in Appendix 1* For multifamily housing

pith central water heating, the domestic water heating capacities

shall be based upon ASHRAE design criteria in reference [5],

Chapter 37. The ipinimum daily usage shall be as indicated in Table

1A-3 in Appendix 1. For housing for the elderly and care-type

housing, temperatures are specified in Section 615-6.1 of MPS 4910.1

[3] and MPS 4920.1 [4], respectively.

Review of plans, specifications, and calculations.

Total energy requirements should be based upon actual use and

local water source temperature when known,

A residential HW design temperature of 140°F is required by the

HUD MPS [2, 3] and is necessary to meet some appliance operating

temperatures and varying demand and deterioration in system performance oyer time. The local source water temperature can vary

from 33 po 80°F with climate, region, and season. For guidance.

Table 1A-4 of Appendix 1 lists monthly average source water temperature for 14 cities. Tables 1A-1 qnd 1A-2 of Appendix 1 define

overall HW syspem draw and recovery rates, however, storage size

and auxiliary energy input must be determined for the type of solar

3
1.2.2 Criterion

Evaluation

Commentary

1.3 Requirement

1.3.1 Criterion

Evaluation

Commentary

Chapter One

THERMAL

system employed. For two tank systems these sizes may be appropriate for one of the tanks while for single tank systems storage

requirements are normally larger.

Thermal performance . 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 domestic hot water heating.

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 utilizing correlation

charts may be based upon monthly average climatic data for sites

where at least 10 year weather data are available.

When available, testing in accordance with proposed ASHRAE Standard

95-P [35] will provide a measure of solar contribution on a standard

solar day. Examples of analytical and design methods for active

systems are described in references [10, 11, 12, 13, 14, 17, 29,

36, 37], Thermosyphon system modeling is described in [23]. Since

verification of the correlation of simulated vs. actual performance

has not been completed, simulated methods used to predict actual

performance should be considered with this understanding.

TRNSYS computer studies evaluating the influence of (a) single

tank vs. double tank configuration, (b) stratified vs. mixed tank

performance, and (c) nominal vs. improved insulation on HW system

performance is available in references [38 Appendix A, 39]. A

further study concerning the effects of stratification is presented

in reference [40].

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 considered

during the design when known.

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 or excess heat dumping) where this function is included

in the design.

Thermal performance of component collectors . The solar collectors

shall collect or dissipate energy at their design values.

Review of drawings, calculations, and test data. Solar

collector panel performance data shall be generated using the

method described in ASHRAE Standard 93-77 [41] or any other comparable method demonstrated to have an overall limit of error of less

than + 5%.

Typical slope intercept curves for flat black and selective coated

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

and 1A-2 in Appendix 1 for liquid heat transfer fluids. Similar

data for collectors using air as the heat transfer fluid are shown

in Figures 1A-3 in Appendix 1.

4
Chapter One

THERMAL

1.3.2

1.4

1.4.1

The 93-77 standard test method provides the efficiency as a function

of inlet temperature, ambient temperature, and insolation for

collectors. The collector must have a single heat transfer fluid

inlet and outlet and must be separate from the thermal storage

device. Collectors with special geometric, optical, or thermal

characteristics may require additional data or other tests to fully

describe their thermal performance for all environmental and

operating conditions. Additional information on collector design,

performance, and operation is available [14; 29, Chapter 8 ; 42; 43;

44 ] • A method of calculating all day performance has been proposed

[ 45 ] and thermosyphon collectors are discussed in reference [23,

34] •

Criterion Thermal performance of combined collector-storage units . Combined

collectors shall collect or dissipate energy at their design values.

Evaluation Review of calculations, drawings, and test data.

Commentary Combined collectors may be active or passive. Consensus methods

to calculate or experimentally determine the performance of collectors combined with storage do not currently exist. However,

the performance of systems which employ combined collectors can be

predicted using analytical methods cited in section 1.1.4 and

preliminary procedures or approaches to predicting the performance

of mass storage wall collectors (Trombe wall) have been described

[ 32 ] . Flow resistance, dwell time and auxiliary energy requirements

may be significant factors in performance evaluation of active

combined collectors. Reference [46] discusses performance of one

type of combined collector /storage system.

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.

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 Review of drawings, calculations, and/or test data

The thermal storage design shall be evaluated using the procedure

prescribed in ASHRAE Standard 94-77 [47] or a comparable method

demonstrated to have an error of + 5% or less, where applicable.

In systems where storage cannot be separated analytically from

other components, total system performance must be evaluated.

Methods for this analysis and evaluation are cited in section

1.1.4. The evaluation of selected passive storage methods has

been reported in references [20, 32].

Commentary Minimum storage capacity for passive solar systems can be as low as

30-45'’ Btu/°F - ft of collector aperture for directly irradiated

mass. Indirectly heated storage mass may need to be 4 to 5 times

this amount. For active systems, in climate regions with small insolation, it is possible to have a satisfactory solar system with

little or no storage but a minimum of 50Q Btu/ft“ if collector is

a more usual minimum.

A number of factors are of importance in evaluating thermal storage:

adequate thermal capacity, sufficient heat transfer surface and

temperature gradients. ASHRAE Standard 94-77 measures the combined

effect of heat capacity, heat transfer surface and temperature

gradients

5
1.4.2 Criterion

Evaluation

Commentary

Chapter One

THERMAL

The standard is intended for use with both sensible and latent heat

(phase change) type storage media. However, additional tests may be

required to evaluate devices employing phase change phenomena.

Adequacy of heat transfer surface area is of concern primarily in

air systems and liquid systems employing heat exchange into storage.

For air systems, properly sized rock storage normally provides adequate surface area but other materials and configurations such as stacked brick may not. Rock storage comprised of uniformly sized

rock provides void space for air passage, turbulence and heat transfer. Rock sizes from 3/4 in. to 1 1/2 in. have been recommended [50]

but sizes up to 3 in. have been used.

In passive systems, the total required storage heat transfer capacity

is related to the amount of surface area that is directly irradiated

by the sun. It is important that directly irradiated surfaces be so designed that they are not insulated from the solar radiation (i.e.,

avoid rugs, wall hangings, etc.). This relationship is discussed in

reference [19]. In addition, the storage mass must have sufficient

thermal conductivity from the outside surface to the interior of the

storage

In air systems, pressure drop through storage is an important con- sideration. Insufficient flow resistance may result in flow short

circuiting and consequent loss of heat storage area. Large pressure

drops result in excessive operating energy. Dampers which do not

seal completely may cause partial bypassing of thermal storage and

hence a decrease in storage effectiveness.

Thermal stratification in both liquid and solid type storage devices

is generally desirable to improve collector performance. However,

stratification in liquid systems may reduce the total heat storage

capacity when the system is operated at maximum draw rates.

A discussion of the effects of stratification in liquid systems

is presented in references [38 Appendix A, 39, 40].

Thermal storage can be provided for hot or cold applications and

at a range of temperature in more than one container. Single vs. multi-tank configurations for HW systems are discussed in reference

[38 Appendix A] . The use of thermal storage in conjunction with

dampening of time and weather dependent loads on machines, electrical

peak shaving, and heat recovery should be considered.

Thermal losses . Thermal losses for the storage subsystem shall

not exceed the design values throughout the operating range for

the storage location and ambient temperature environment.

Review of drawings, calculations, and/or test data.

Thermal losses shall be evaluated using the procedures described

in ASHRAE Standard 94-77 [47] or a comparable' method demonstrated

to have an error of + 5% or less, where applicable.

Use of test methods such as ASHRAE 94-77 will give a measure of

thermal losses under operating conditions. This is of particular

concern with air systems when leakage may be difficult to detect and

significantly reduced systems performance may result. Also, reverse thermosyphoning from storage to collector during non-collection

periods can lead to significant thermal losses. Design configuration and/or check valves and dampers can reduce such losses.

6
Chapter One

THERMAL

Criteria for thermal losses from liquid storage tanks and piping

are presented in ASHRAE Standard 90-75 [6], Insulation greater

than these levels is desirable as loss fpom storage can greatly

deteriorate system performance. The effect of losses in HW systems

is discussed in reference [38 Appendix A], 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 energy losses from storage devices used solely for solar

HW thermal storage should be charged to the solar energy system.

Thermal losses from storage tanks used as part of the conventional

HW heating should be charged to the auxiliary heating system.

Care should be given to assure the continued effectiveness of

Insulation, particularly that located in exterior and underground

locations where the presence of water may lead to the soaking of

ipsulation which will result in thermal losses. Mechanical strength

of thermal insulation is also a concern. When movable insulation is

psed, as in passive systems, design consideration shall be given to potential structural damage. The compressive strength of insulation

used underneath storage vessels is most important as crushing of

insulation will reduce its thermal effectiveness. Mechanical

strength is also important in avoiding sagging, pulling away from

components and opening up at seams.

1.5 Requirement Component /sy stem/ 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

thq 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 in occupied spaces.

Evaluation Review of drawings, specifications, calculations, and

test data for compliance with the requirements of section 1.1. 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

pnd configurations may be necessary in designs where prior experience does not exist. In passive systems, calculations of over-heat

under heat, and frequency of temperature swing should be reviewed.

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

ducting, and storage containers will occur within or under a building structure. Over-heating and condensation can create

adverse conditions.

In direct gain passive systems in particular, excessive heat build

up may occur. This is often most severe during spring and fall.

•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.

1*6,1 Criteripn Energy Distribution . In spaces heated or copied using natural

energy distribution by radiation, convection, conduction and evaporation, distribution shall be at rates and in locations needed to meet

design system operating requirements.

7
Chapter One

THERMAL

1 . 6.2

1.6.3

1.7

Evaluation

Commentary

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Requirement

Commentary

Review of drawings, specification, calculations and test data.

The intent of this criterion is to recognize the need to carefully

study the means and paths of energy distribution in passive systems.

Such study should consider surfaces directly and indirectly heated

by the sun, paths of air movement and the variation in these on both

a daily and yearly cycle.

Thermal losses . Thermal losses, including air leaks, for the energy

transport subsystem shall not exceed the design values throughout

the operating range and ambient environment conditions.

Review of drawings, specifications, calculations, and test data.

Criteria for thermal losses in piping and ducts are presented in

ASHRAE Standard 90-75 [6]. Insulation greater than these levels

is desirable as thermal losses can greatly deteriorate system

performance. Variations in the thermal conductivity, specific

heat, and viscosity of the heat transfer medium with temperature

should be considered in the design, where applicable. Design data

and analytical procedures for thermal insulation and heat transfer

in building systems are available in the literature [1, 6, 48].

Thermal energy losses from piping or ducts associated with the

solar energy system 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. Pre-formed insulating

materials for pipes and round ducts and molded coverings for bends,

elbows and other fittings will help to reduce crushing in installation.

Electrical operating energy . The use of electrical operating

energy for the energy transport subsystem shall not exceed the

design values throughout the operating range.

Review of drawings, specifications, calculations, and test data.

The electrical operating energy required for fans, pumps, controls,

dampers, or valves can significantly influence the overall system

efficiency. These energy requirements should be accounted for in

the evaluation of the individual solar energy system and the H/C

distribution system. Operating energy for ancillary functions such

as freeze protection, excess heat dumping, and automatically operated

shades, shelters, drapes, louvers, or other mechanized controls should

be included.

Control system performance . The control subsystem shall provide for

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

Requirements for system performance monitoring are given in section 6.4.

8
Chapter One

THERMAL

1.7.1 Criterion Control of energy utilization. The control subsystem shall be

designed, and components provided, to control the flow of energy as specified in the system design.

Evaluation Review of schematic diagrams depicting the control subsystem and

their function during each operational mode.

Commentary Each control mode shall be clearly defined in terms of sensor type

and location, control device or activator location and position,

set points or control value and heat transfer fluid flow direction

if applicable. Typical system control modes include collector-tostorage, storage-to-load and collector protection from overheating

or freezing. A variety of methods may be used to prevent freezing

if a freeze tolerant design is not used. These methods are discussed in 2.1.17. Control priority should be given to modes which

use the least auxiliary energy. Draw from solar supply first then

utilize other modes based on their auxiliary energy consumption.

1.7.2 Criterion Circulation control. In the collector to storage/load loop, control

shall be designed to provide, when in the heating mode, for the circulation of heat transfer fluid only when useful energy can be collected.

Evaluation Review of drawings and specifications.

Commentary Circulation in liquid systems is typically limited to conditions when

the absorber plate temperature is about 10°F higher than the storage

or load use temperature to minimize circulation cycling. A larger

temperature differential may be used for air systems depending upon

the circulating fan electrical power requirements. In a liquid

thermosyphon system, if thermal storage is not elevated about 18

inches above the top of the collector, controls may be necessary

to stop reverse flow. Sensor locations are normally near the collector outlet and in the lower portion of the storage tank. Control

requirements for various system types are discussed in reference [29].

1.7.3 Criterion Manual adjustment. If manual control adjustments are required

during normal operation of the solar system, the control subsystem shall be designed to ensure that the safety of the system

and the building in which it is installed are not compromised by

failure to make these manual control adjustments.

Evaluation Review of drawings, specifications, and operating procedures.

Commentary The intent of this criterion is to assure that damage to the system

or building due to freeze-up or overheating will not occur if routine

procedures are not completed during periods of occupant absence.

Further coverage of freeze protection is given in section 1.8. These

provisions are not intended to restrict appropriate seasonal shutdown

manual controls. Control considerations for solar H and C applications

[14] and for HVAC equipment in general are discussed in references

[5, 8, 49].

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.

9
Chapter One

THERMAL

1.7.4 Criterion Inhabited space temperature control. Each H, C, or H/C system shall

be capable of providing occupied space temperature regulation by at

least one adjustable control or combination of controls and sensors capable of control within the range from 55°F to 85°F.

Evaluation Review of drawings and specifications.

Commentary Designs should allow for summer ventilation with preference given

to natural ventilation over mechancial methods. Controls may be

automatic or manual.

In certain multizone or multisystem applications, a priority

control may be needed to avoid simulataneous heating and cooling

of a common conditioned space. Localized controls for building

heating and cooling are discussed in reference [5]

1.7.5 Criterion Hot water temperature. The temperature control for the auxiliary

energy source shall be capable of adjustment over the range of

temperatures acceptable for the intended use.

Evaluation Review of drawings and specifications.

Commentary DHW tanks are typically equipped with a thermostat capable of

controlling heating over the temperature range of 120°-160°F.

Temperature control devices used with solar energy heated storage

tanks must be compatible with safety requirements and may require

the capability to cool the discharged water as well as heat it

(see Criterion 4.2.3).

1.8 Requirement Auxiliary energy. Auxiliary energy subsystems shall be lnfporsfpd

into the H/C/HW systems to the extent necessary to provide the

designed heating, cooling, and hot water. If auxiliary energy

control is not automatic, provisions shall be made to insure building

freeze protection during unoccupied periods.

Commentary Comparability of auxiliary energy with the solar system is critical

to efficient overall system operation. Methods for sizing auxiliary

systems are described in references [5, 6, 49].

Proper integration of auxiliary with the solar system also, requires

consideration. In heating and cooling systems it is important to be

able to isolate auxiliary from the solar side of the system so that

auxiliary energy is only used to condition the building. Normally,

it is undesirable to have auxiliary energy added into storage as it

will reduce collector efficiency. In HW systems, electric auxiliary

energy may be used in single tank configurations if stratification

can be preserved. In such cases collector efficiency can be maintained with a simple system. In HW systems with gas or oil auxiliary

it is normal to use a two tank configuration because stratification

is difficult to preserve in the auxiliary tank;

With absorption chillers it has been found to be less energy con- serving to have an electric boiler as back up to the solar system,

rather than a conventional vapor/compression machine.

10
Chapter One

THERMAL

1.8.1 Criterion

Evaluation

Commentary

1.8.2 Criterion

Evaluation

Commentary

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.

Review of plans, specifications, calculations, and

test methods.

The purpose of this criterion is to recognize the need for 100

percent back up operating capability with the auxiliary energy

subsystem when energy derived from solar radiation is not

available. Design heat loads are discussed by ASHRAE [1, 5, 6].

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.

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.

The use of solar energy should not compromise ventilation of the

building

11
Chapter One

THERMAL

References 1

1. ASHRAE Handbook of Fundamentals . 1977.*

2. HUD Minimum Property Standards, One and Two Family Dwellings , (No. 4900.1),

U.S. Department of Housing and Urban Development, Washington, DC (1973, revised 1976).+

3. HUD Minimum Property Standards, Multifamily Housing , (No. 4910.1), U.S. Department of

Housing and Urban Development, Washington, DC (1973, revised 1976).+

4. HUD Minimum Property Standards, Care-Type Housing , (No. 4920.1), U.S. Department of

Housing and Urban Development, Washington, DC (1973, revised 1976).+

5. ASHRAE Handbook/ Systems^ 1976.*

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

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

8. ASHRAE Handbook/Equipment, 1975.*

9. Duffie, J. A. and Beckman, W. A., Solar Energy Thermal Process , John Wiley and Sons,

New York, NY, 1974.

10. Beckman, W. A., Klein, S. A. and Duffie, J. A., S olar Heating Design - By the F-Chart

Method , Wiley-Interscience Publication, John Wiley and Sons, New York, NY, 1977.

11. F-Chart Computer Program Version 2.3 , Solar Engineering Laboratory, University of

Wisconsin, Madison, WI.

12. Klein, S. A., et. al. , TRNSYS - A Transient Simulation Program, Users Manual , Report 38,

Engineering Experiment Station, University of Wisconsin, Madison, WI, 1977.

13 . SOLCOST, Solar Energy Design Program for Non-Thermal Specialists, Users Guide for

CYBERNET , December 1977, Martin Marietta Aerospace, Denver Division, P.0. Box 179,

Denver, CO.

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

,

Los Angeles, CA, July 1975.

15. Proceedings of 1976 Annual Conference, American Section, International Solar Energy

Society, Winnipeg, Canada, August 1976, Volume 3, Solar Heating and Cooling of Buildings.**

16. Proceedings of 1977 Annual Meeting, American Section, International Solar Energy Society,

Orlando, FL, Volume 1, Solar Collectors and Heating and Cooling Systems.**

17. Passive Solar Heating and Cooling, Conference and Workshop Proceedings, Albuquerque,

NM, May 1976, Report No. LA-6637-C, Los Alamos Scientific Laboratory, Los Alamos, NM

87545.

18. Second National Passive Solar Conference, Proceedings, Philadelphia, PA, March 1978.**

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

47th Street, New York, NY 10017.

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

++National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161.

**American Section, International Solar Energy Society, P.0. Box 1416, Kileen, TX 76541.

12
Chapter One

THERMAL

19. Balpomb, J, D,, Hedstrom, J. C. and McFarland, R. D., Passive Solar Heating of

Buildings - Preliminary Results , Report No. LA-UR-77-1162 , Los Alamos Scientific

Laboratory, Los Alamos, NM 87544.

20. Stromberg, R. P. and Woodall, S. 0., Passive Solar Buildings: A Compilation of Data

and Results , Sandia Laboratories, SAND 77-1204, Albuquerque, NM, August 1977. -H21. "Research Evaluation of a System of Natural Air Conditioning," (Water-mass roof system),

California Polytechnic State University, January 1975, HUD Contract No. H 2026 R.

22. Arumf, F f N. ? "Thermal Inertia in Architectural Walls," Report sponsored by Department

pf Energy and thp National Concrete Masonry Association, NCMA, McLean, VA, 1977.

23. Bqughn, 4* ty. SDd Dougherty, D. A., "Experimental Investigation and Computer Modeling

of Solar Natural Circulation System," Proceedings of the 1977 American Section of ISES

Annual Meetfpg, Orlando, FL.

24. Request for Grant Application, H-8600, Passive Solar Residential Design Competition and

Demonstration, Division of Energy, Building Technology and Standards, PD&R, Department

of Housing and Urban Development, Washington, D.C. 20410, May 1978.

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

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

(Revised edition in ref erence 29 )

.

26. Bennett, I,, "Monthly Maps on Mean Daily Insolation for the United States," Solar Energy , Volume 9, p. 145, 1965.

2 7> Climatic Atlas of the United States , National Oceanic and Atmospheric Administration,

National Climatic Center, Federal Building, Asheville, NC 28801, June 1968.

28, Climatolpgical Data ~ National Summary , Published monthly. National Oceanic and

Atmospheric Administration, National Climatic Center, Federal Building, Asheville, NC

28801.

29, ASHRAR Applications of Solar Energy for Heating and Cooling of Buildings, 1977, GRP 170.*

30, Streed, R., McCabe, M., Waksman, D., Hebrank, J. , and Richtmyer, T. , 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

31, Ducas , W, , Streed, E. R. , Holton, J. K. and Angel, W. , "Thermal Data Requirements and

Performance Evaluation Procedures for Passive Buildings," Second National Passive Solar

Conference , Proceedings, Philadelphia, PA, March 1978.

32, Trombe, F., Robert, J. F., Cabanot, M. and Sesolis, B., "Concrete Walls to Collect and

Hold Heat,'1 Solar Age , August 1977.

33, Ohanessian, P, and Charters, W. S., "Thermal Simulation of a Passive Solar House Using

a Trombe-Michel Wall Structure," Solar Energy , Volume 20, p. 275, 1978.

34, Buckley, S., et. al., "Thermic Diode Solar Panels for Space Heating," Solar Energy , Volump 20, p. 495. ISES Solar Energy , Other papers published in Second National

Passive Solar Conference, Proceedings, Philadelphia, PA, March 1978.**

35, ASHRAE Standard 95-P, Method of Testing to Determine the Thermal Performance of Solar

Domestic Hot Water Systems .* (m preparation)

36, 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

Capactiy," Solar Energy , Volume 15, pp. 287-298, 1974.**

13
Chapter One

THERMAL

37.

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

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

Pretoria, South Africa, 1967.

38 . Intermediate Standards for Solar Domestic Hot Water Systems/HUD Initiative , NBSIR 77-1272, Prepared for HUD, Washington, DC, 1977.

39. Liu, S. I., Shik, K. and Wood B. D., "Experimental Validation of the Solar Simulation

Program TRNSYS for a Solar Domestic Hot Water Heating System," Proceedings of Systems

Simulation and Economic Analysis for Solar Heating and Cooling Conference, San Diego, CA,

June 1978.

40. Lavan, Z. and Thompson, J. , "Experimental Study of Thermally Stratified Hot Water

Storage Tanks," Solar Energy , Volume 19, p. 519, 1977.**

41. ASHRAE Standard 93-77, Methods of Testing to Determine the Thermal Performance of Solar

Collectors .

42. 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.+

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

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

44. 1977 Flat Plate Solar Collector Conference, Proceedings, Orlando, FL, March 1977,

Florida Solar Energy Center, Cape Canaveral, FL, FSEC-77-8.

45. Waksman, D., Streed, E. R. , Reichard, T. W. and Cattaneo, L. E. , Provisional Flat

Plate Solar Collector Testing Procedures: First Revision , NBSIR 78-1305A, June 1978,

National Bureau of Standards, Washington, DC 20234.

46. Jones, D. E., "System Performance Measurements for a Packaged Solar Space Heating System

Equipped with Air-Heating Collectors," Conference on Performance Monitoring Techniques

for Evaluation of Solar Heating and Cooling Systems, Washington, DC, April 1978,

Organized by the University of Utah, Mechanical Engineering Department, Salt Lake City, UT.

47. ASHRAE Standard 94-77, Methods of Testing Thermal Storage Devices Based on Thermal

Performance .

48. HUD Intermediate Minimum Property Standards Supplement, 1977 Edition, Solar Heating

and Domestic Hot Water Systems , (No. 4930.2), U.S. Department of Housing and Urban

Development, Washington, DC, 1977.

49. ASHRAE Handbook/Applications . 1974.*

50. Heating and Air Conditioning Systems Installation Standards for One and Two Family

Dwellings and Multifamily Housing Including Solar , SMACNA, 1977.
Chapter Two

MECHANICAL

2.1

2 , 1-1

2 . 1-2

2.1.3

Requirements

Commentary

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Functional design . The H/C/HW system shall be designed t he

capable of functioning under in-service flow rates, pres

temperatures, and other mechanical stresses.

A broad scope discussion of problems frequently encountered in

construction and operation of solar systems is present--: in

reference [1]

Equipment capabilities & applicable standards . Pumps, fans,

other components shall be sized to move the heat transfer fluid

through the collector, piping, and/or ducts at design fit v.- rat- All mechanical components shall conform to applicable local

nationally recognized codes and standards.

Review of drawings, specifications, historical performance, : test data, and design calculations. Systems or appli atims : do not lend themselves to engineering analysis may require

type tests to demonstrate compliance.

In order to transfer heat through the system/subsystc-.

,

of different transfer approaches such as gravity ; r uiiti n

,

combined forced and gravity circulation, or forced circul-::

may be used.

Eros ion- corrosion . Liquid piping and associated fittings

sized to carry the heat transfer liquid at design flow rate

out excessive erosion-corrosion.

Review of drawings, specifications, historical peri r- . previous test data, and design calculations.

Reference [2] provides recognized design practices : r : mination of limiting velocities for heat transfer : c. s . Chapter 36 of reference [3] also addresses this subject.

Operating conditions . Collectors, space heaters,

pumps, valves, regulating orifices, pressure regulators, . exchangers, and other fluid handling components shall S

of being operated over the pressure and temperature r

• pated in actual service without breakage, rupture, . . . or significant loss or gain in pressure that could impair

intended function.

Review of drawings, specifications, historical

previous test data, and design calculations. Svs: er-.s that do not lend themselves to engineering analysis shall

tested at the maximum and minimum service tempera: ;::vs . ipated fluid pressures. To show compliance with this : . :

• it is desirable that the design consist of components : covered by recognized standards, where available . by the manufacturer to be suitable for the pressure .

: - • and flow application.

Provisional tests described in test methods , 7.2 (no-flow 30 day degradation), 7.6 (thermal cvclicgl,

collector rupture and collapse), and '.12 (static press,

test) of NBSIR 78-1305A [4] are one means of assess-. : -c of these conditions on collectors.

Available codes and standards are listed by ASHRA1 , 3 1

15
Chapter Two

MECHANICAL

2.1.4 Criterion 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.

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, blowers, 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 [ 6 ]. Such reverse return methods may not

always be capable of coping with varying field conditions and

balancing valves, dampers or restrictors may be essential.

Consideration should be given to the effect of header arrangement

on collector array temperature rise.

Procedures for flow balancing of air system are presented in

reference [ 4 ].

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 and thermal storage fluids that can occur over the service temperature range shall be incorporated

into the system design. Expansion tanks shall be sized in accor- dance with the recommendations of ASHRAE.

Evaluation Review of drawings, specifications, and design calculations.

Commentary Water expands about 4 percent 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 Piping design. 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.

16
Chapter Two

MECHANICAL

Commentary Since the energy requirements of pumps 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 [8, 9],

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.

2.1.8 Criterion

A thermosyphon water heating system is an example where pipe sizing

for minimum pressure drop is essential as hot water circulation

results from the change in density of the fluid with temperature and

the movement of a heat transfer fluid by natural convection is

achieved by relatively low pressure differentials. Design considerations and equipment performance data is available [10, 11. 121

Duct design. Design of all air heating and air conditioning systems

shall be in accordance with applicable recommendations of ASHRAE

Chapter 25 [8], the National Environment Systems Contractors

Association (NESCA) [9], the Air-Conditioning and Refrigeration

Institute (ARI) [13], and/or Sheet Metal and Air-Conditioning

Contractors National Association (SMACNA) [12]. Installation shall

comply with National Fire Protection Association (NFPA) standards

90B , 31 and 54 [14],

Evaluation Review of plans and specifications.

Commentary Duct work should be designed for the shortest practical run and

elbows should be kept to a minimum. Unnecessary constructions

should be avoided. The use of turning vanes should be considered at

duct bends to reduce pressure losses. Low leakage dampers should be

selected and dampers should have position indicators to aid in monitor

ing the system.

Equal pressure loss in the collectors and storage is usually

recommended. The addition of ducts, filters, heat exchangers and

other appurtenances will establish the total pressure loss which

should be kept to a minimum in order to reduce blower operating

cost. Blowers sized near the center of their performance curves will allow for minor variations without replacement; however, sizing

shall also consider efficiency of operation. Standards for design,

sizing, construction and installation of ducts used with solar

energy systems are covered in sections 3 and 7 of reference [12].

2.1.9 Criterion Exhaust and vent 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. Similarly,

solar components shall not interfere significantly 5 either physically

or aer odynamically, with building vents, flues, and exhausts.

Evaluation Review of plans and specifications.

Commentary 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 from the flue

or vent.

17
Chapter Two

MECHANICAL

2.1.10 Criterion

Evaluation

Commentary

2.1.11 Criterion

Evaluation

Commentary

2.1.12 Criterion

Evaluation

Commentary

2.1.13 Criterion

Evaluation

Commentary

Thermosyphoning losses . Means shall be provided to prevent

undesired 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. System geometry, back draft dampers and check valves are some of the means used to prevent thermosyphoning. Some designs may

use thermosyphoning of energy from storage as a means of protection

from freezing.

Sound and vibration control . Piping, air ducts, and associated

fittings shall be designed to carry the heat transfer fluid at

design flow rates without excessive noise or vibrations which

could induce mechanical stress levels high enough to cause damage.

Pumps, fans, and compressors or other components involving moving

parts shall be balanced and/or mounted in a manner such that during

start-up operation or shutdown they do not induce excessive noise

or vibration that could cause damage.

Design practices to control sound and vibration shall be in

accordance with the applicable recommendations of ASHRAE [3, 8],

NESCA [9], ARI [13], and/or SMACNA [ 12 ]

Review the drawings and specifications, conduct a prototype inspection, and make sound and vibration measurements if deemed necessary.

Sound and vibration measurements, if required, shall be made in

accordance with the applicable recommendations of ASHRAE, as stipulated in Chapters 35 and 40 of reference [3].

Examples of possible sound and vibration are: a) lengths of piping

and connecting equipment that are resonant with pressure pulsation

frequency; b) vibration resulting from motors, pumps, fans, and

compressors which are not properly mounted; c) water hammer and

quick closing valves; d) wind excitation of piping by turbulence or vortex shedding; and e) ducting with excessive air velocities.

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 [15 ]

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 [ 16 ]

18
Chapter Two

MECHANICAL

2.1.14 Criterion

Evaluation

Commentary

2.1.15 Criterion

Evaluation

Commentary

2.1.16 Criterion

Evaluation

2.1.17 Criterion

Evaluation

Commentary

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.

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. These problems are especially severe in long runs and

with intersecting lines. Movement due to thermal changes can also

result in inadvertent dissimilar metals contact with other components and building elements, leading to corrosion problems.

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

insulated pipes or ducts shall be designed to avoid damaging the

insulation material.

Review of drawings and specifications.

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

sleeves or plates should be used to avoid damaging the insulation.

Care should also be taken that dielectric insulation of dissimilar

metals is not broken. Hangers must provide adequate support and

correct pitch of pipes to avoid liquids pockets remaining during

drain down conditions.

Flexible joints . All systems employing heat transfer fluids shall

be designed to be capable of accommodating flexing of plumbing and

fittings.

Review of drawings and specifications.

Freezing protection . System components including heat transfer

liquids shall be protected from damage by freezing at the lowest

ambient temperatures that will be encountered in actual use.

Review of drawings and specifications.

The intent 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. In air

systems, damper leakage can freeze water in air-to-water heat

exchangers. The intent of this criterion is not to restrict the

designer to the use of antifreeze solutions for liquid systems.

If automatic drain down is the freeze protection technique to be

used, automatic air vents, vacuum relief valves and drain down

valves should be protected from freezing. Rate of drain down

should be compared to rate of thermal losses so that ice blockages

will not form. Drain down systems are frequently designed to drain

at an outdoor temperature of about 38°F because of subcooling by

radiation losses and to refill at about 42°F to minimize cycling.

Such set points may be used but with the penalty of not collecting

useful energy when solar radiation is available at the time of cold

ambient temperatures. With drain down systems, flow rates with and

without siphon return will have to be considered in order to maintain flow rates through collectors to manufacturers' recommendations.

Both the oversizing of return lines to avoid siphon formation or the use of restrictors to insure it are ways to control flow.

19
2.2 Requirement

2.2.1 Criterion

Evaluation

Commentary

Chapter Two

MECHANICAL

The circulation of antifreeze heat transfer fluids at freezing

temperatures because of thermosyphoning, control or pump malfunction

may lead to freezing of domestic hot water at the heat exchanger

interface

Fail safe freeze protection methods are desirable since in the

event of power failure, freeze protection methods which require

electric power will be ineffective. Systems employing drain down

require control provisions to provide venting for draining and

refill and may require special provisions to prevent contamination

or corrosion of the heat transfer system during these operations

(see Criterion 2.1.10).

Continuous circulation of heat transfer fluid should not be used

for freeze protection due to the excessive energy loss this causes. Pulse circulation may be justified in very moderate climates where

freezing temperatures are infrequent. In addition, only in such warm climates can the use of electrical heating tapes or elements

be justified.

Designs which utilize vacuum insulation for protection can freeze

if this vacuum is lost due to leakage or for other reasons. Freeze

tolerant designs should be tested for reliability.

Other considerations of freeze protection are presented in sections

5.1.2 and 5.1.3.

A provisional test for evaluating the freeze resistance of solar

collectors under in-use conditions is described in test method 7.6

given in NBSIR 78-1305A [4].

Leakage prevention . Subsystem 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

Leak testing: liquid systems . Those portions of installed H/C/HW

systems which contain pressurized 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. Those portions

of the system designed to operate at atmospheric pressure shall be

filled with the heat transfer fluid and shall not leak when filled

for a minimum of 30 minutes.

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 gauge should be observed for this

period to determine whether the pressure drop is within allowable

limits. Provisional tests for evaluating the leakage and pressure

resistance of solar collectors are described in test methods 7.11

and 7.12 of NBSIR 78-1305A [4].

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

considered a standard test pressure [17]. 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 fluids such as silicones and hydrocarbons

have surface tensions less than water and special care must be

20
Chapter Two

MECHANICAL

2 . 2.2

2 . 2.3

2.3

Criterion

Evaluation

Commentary

Criterion

Evaluation

given to joints and connections. Some pipe dopes may not be com- patible with antifreezes and special thread sealers may be needed.

It is advisable to consult the fluid manufacturer for recommendations.

Some organic materials used for expansion tank diaphragms, valve

seats and sealants may be incompatible with glycols and may lead to leakage. Some leakage in valve and pump stuffing boxes and packing

glands may be a normal operating characteristic. Bleeder valves

of 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.

Leakage 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.

Review of drawings and specifications.

See Commentary for 2.2.1.

Leakage and over-pressure testing: air systems . All solar system

ducting and thermal storage components that operate at air pressures

of 0.10" wg or greater shall be capable of complying with the

requirements for leakage and pressure required for air ducts and

connectors by UL Standard 181 [18]. The complete air solar system

shall be constructed in accordance with SMACNA standards [12] for

air leakage and workmanship.

Review of drawings and specifications and testing per UL 181.

Provisional tests for evaluating the leakage and pressure resistance

of solar collectors are described in test methods 7.11 and 7.12 of

NBSIR 7 8-1305A [4]

Commentary This criterion is not intended to imply that each component be

tested in accordance with UL 181 [18] but only that component

construction and field installation provide assemblies that will

control air leakage. SMACMA [11] suggests a limit on duct leakage

of 5 percent. The criterion is intended to apply to active air solar

systems and not to passive systems.

Control of air leakage in active and passive air solar systems

both in and out of the system and also within the system at dampers

is very important to satisfactory system performance. It is of

greater importance in active air solar systems than in conventional

forced air heating systems for several reasons: (1) air pressure

in the system is usually higher, (2) there usually is more ducting,

(3) the system runs more hours, and (4) there may be more ducting

through unheated space. Although leakage to heated spaces during

the heating season may contribute to satisfaction of the load,

this represents a loss of control of the air stream and may com- promise total system operation. In particular, severe leakage at

the thermal storage unit can result in storage becoming almost

ineffective. Furthermore, leakage can result in space overheating.

To prevent excessive leakage, ducts should be sealed in accordance

with the SMACNA standard which keys sealing techniques to operating

pressure. To reduce internal leakage, low loss dampers will often

be necessary.

Requirement Collector orientation and location . The collector subsystem shall

be located, and oriented, as required by the design to capture

sufficient solar energy to meet functional requirement.

21
Chapter Two

MECHANICAL

2.3.1 Criterion

Evaluation

Tilt and azimuth . The collector shall be installed on a mount

capable of maintaining tilt and azimuth to design conditions.

Review of drawings and specifications.

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

continuously movable. Detailed information concerning orientation

is given by ASHRAE [19]. It is not the intent of this criterion

that the collector necessarily be reoriented or tilted after

initial installation.

Commonly used values for collector tilt are: latitude plus 10°-15°

for space heating systems and tilt equal to latitude for domestic

hot water systems. Deviations of + 15° from these values when

using conventional flat plate collectors will usually have little

effect [6] . Conventional flat plate collector orientation should

be such that the effective aperture generally faces south. However,

deviations to the east or west up to 20° may not result in a significant decrease in incident radiation [6]

Though passive apertures are usually vertical due to structural and

architectural considerations, these angles for glazing are still

desirable as they minimize reflective losses. Control of overheating is another factor which affects the choice of glazing angle for

passive systems.

2.3.2 Criterion Shading of collector . The location and orientation of the

collector shall be such that it is not shaded by external obstructions or mutual shadowing 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, buildings, and other portions of the collector.

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.

2.4

2.4.1

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 [20, 21, 22 , 23 ] . Consideration should also be given to partial shading of collectors which could cause unusual stress

concentrations and resulting glass breakage in an operating

collector.

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, or create a health hazard.

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

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

is known to exist, a suitable water treatment system as recommended

by the Water Quality Association shall be provided [24].

22
Chapter Two

MECHANICAL

The chemical composition of the heat transfer liquid shall be maintained at levels adequate to prevent unacceptable deposits on the

heat transfer surfaces, corrosion of the surfaces with which the

heat transfer liquid comes in contact, or loss of freeze resistance

by providing suitable devices or procedures.

Evaluation 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. The buildup of sludge may be

the result of decomposition of the heat transfer liquid, reactions

with additives within the liquid itself or reactions of the heat

transfer fluid with piping materials or extraneous impurities such

as pipe dope, solder flux, cutting oils or general system dirt.

To aid in preventing sludge (especially in the heat exchanger and

when antifreeze solutions are used), the system piping should be

thoroughly cleaned and flushed prior to the introduction of the

antifreeze mixture. Problems can develop when liquids such as "hard" water are used. Fluid viscosity at all operating conditions

must be properly matched by pump capacity and operating power, see Section 5.2.2. Antifreeze solutions may lose their freeze protection capability over time due to deterioration or the addition of

"make-up" water. Provisions for sampling the heat transfer liquid

without imparing system operation should be available.

2,. 4.2 Criterion Air quality. Adequate means shall be provided to prevent the

accumulation of dust, dirt or water that could result either in

a reduction of system efficiency or to deterioration of system

components

Evaluation Review of drawings and specifications.

Commentary The gravel used for rock bed 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 and/or heat exchangers

should also be considered.

2,5 Requirement

To facilitate rock bed washing, remove drain water that may have

leaked into the storage container, or to remove condensed moisture,

it may be desirable to construct rock storage containers with water

resistant interior surfaces and drainage provisions.

Subsystem isolation. Shutdown of the subsystems in one dwelling

unit shall not impair the distribution of energy to other dwelling

units of the building.

2.5.1 Criterion Shutdown in multifamily housing. The shutdown of the H/C/HW subsystems in one dwelling unit of a multifamily housing complex shall

not interfere with the operation of the subsystems in other dwelling

units

Evaluation Review of drawings and specifications.

Commentary This is to permit the shutdown of equipment in an individual dwelling

unit for repairs without impairing the operation of the equipment

in other dwelling units that are connected to the same central

system. Shutdown of the solar system shall not impair the distribution of energy to dwelling unit subsystems, nor safety provisions

as provided for in section 4.2.2.

23
Chapter Two

MECHANICAL

Isolation valves around pumps, heat exchangers and storage tanks

(where pressurized) will simplify repairs.

2.6 Requirement Control subsystem design. The control subsystem shall be designed

to operate the H/C/HW system in a safe and effective manner.

2.6.1 Criterion Temperature sensors. Temperature control sensors shall be protected

from detrimental extraneous heat flows.

Evaluation Review of drawings, specifications and system diagrams.

Commentary Problems of sensors giving erroneous readings of system operating

conditions have been experienced because of heating or cooling in the

immediate vicinity of the sensors due to extraneous heat flows.

Both degraded performance or system failure by freeze up can result

from the occurrence. Extraneous heat flows may result from solar

radiation, wind, ambient temperature and thermal gradients including

thermosyphoning. They may also be associated with storage tanks,

boilers, or hot or cold pipes when sensors are nearby.

Proper insulation of sensors will reduce their susceptibility to the influence of external heat flows. Proper placement of sensors

or use of check valves or backdraft dampers will reduce their

susceptibility to the influence of internal flows such as thermosyphoning

Proper installation (attachment, calibration, location) of sensors

is also critical in assuring proper performance.

2.6.2 Criterion Fluid flow control. Controls shall maintain the H/C/HW system

within the temperature and pressure operating limits as required

by the design.

Evaluation Review of drawings and specifications.

Commentary In systems which are not capable of withstanding thermal shock

created by filling hot collectors with cool fluids, control subsystems may be required to protect the system from cold filling.

Such controls would limit filling to cool periods. Requirements

for thermal shock resistance of components and materials are presented in section 5.2.1.

Control provisions may also be required for the dumping of heat

when temperatures and pressures approach unacceptable levels.

Under such conditions, deterioration of components may occur and/or

system function may be imparied due to such factors as boiling,

vapor locks, vacuum formation or pressure drops. Safety provisions

are presented in section 4.2.

2.6.3 Criterion Installation and maintenance. The control subsystem shall include

such provision for bypass, adjustment, or over-ride of manual or automatic controls as is required to facilitate installation,

start-up, operation, shutdown, and maintenance.

Evaluation Review of drawings, specifications and operating procedures.

Commentary Controls may be needed during installation, start-uo, and operation

to balance or adjust the svstem for proper operation. Controls mav be necessary to ensure the safety and durability of the svstem

and the building. Other controls may be required for tests or maintenance after the svstem has been in operation or for seasonal

shutdown.

24
Chapter Two

MECHANICAL

2.7 Requirement

2,7.1 Criterion

Evaluation

Commentary

Operational verification . On completion of installation, the

system shall be checked for adequate performance of all components

as well as the system as a whole.

Checkout . Inspection and testing shall be performed on the

installation to verify that the system and components are capable

of operating as specified in the design and the manuals defined in

section 6.2.

Visual inspection and testing in accordance with the procedures

specified in section 6.2.

Monitoring means may involve sensors and indicators or they may be

as simple as inspection.

Controls should be checked in operation to determine that subsystems

operate at the proper set points, that pumps and fans start and

stop properly and that fail safe devices work. Failure or improper

operation of sensors and controls have caused many problems. It

is recommended that means be provided during installation to allow

temperatures and flow rates to be checked during operation of the

system. Experience has shown that poor design and improper

installation of components is a major cause of system malfunction

and that a large proportion of mechanical failures are apparent

within a short period of operation. Incorrectly wired controls,

improper control set points, improper component location, reversed

components, improper sensor installation, etc., are examples of

such misapplications.

It is important to check distribution systems to assure that all areas intended to receive heating and cooling in the design receive

it in the actual installation. This is particularly important with

passive systems.

25
Chapter Two

MECHANICAL

References 2

1 . National Solar Heating and Cooling Demonstration Program Project Experience Handbook , Preliminary Draft, DOE/CS-0045/D, U.S. Department of Energy, September 1978.

2. National Standard Plumbing Code , as recommended by the National Association of PlumbingHeating-Cooling Contractors, Appendix B, 1971.

3. ASHRAE Handbook/Systems - 1976.

4. Provisional Flat Plate Solar Collector Testing Procedures , First Revision, NBSIR 78-1305A,

National Bureau of Standards, Washington, D.C., September 1977, PB 272 500.*

5. ASHRAE Hand book /Equipment - 1975.

6. Duffie, J. A. and Beckman, W. A., Solar Energy Thermal Processes , John Wiley and Sons,

New York, N.Y.

7. Testing, Balancing and Adjusting of Environmental Systems , Sheet Metal and AirConditioning Contractors National Association (SMACNA) , 8224 Old Court House Road,

Vienna, Va. 22180, 1974.

8. ASHRAE Handbook of Fundamentals - 1977.4-

9. The Standards and Manuals of the National Environmental System Contractors Association

(NESCA) , 150 Wilson Blvd. , Arlington, Va. 22209.

10. Baughn, J. W. and Dougherty, D. A., "Experimental Investigation and Computer Modeling of

Solar Natural Circulation System," Proceedings of the 1977 American Section of ISES

Annual Meeting, Orlando, Fla.

11. ASHRAE, Applications of Solar Energy for Heating and Cooling of Buildings , 1977,

GRP 170.4-

12 . Heating and Air-Conditioning Systems Installation Standards for One and Two Family

Dwellings and Multifamily Housing Including Solar , SMACNA, 1977.

13. Standard for Sound Rating of Room Fan-Coil Air-Conditioning (ARI 443-71) and Air Induction

Units (ARI 446-68), Air Conditioning and Refrigeration Institute, 1915 North Fort Myer

Drive. Arlington, Va. 22209.

14 . National Fire Codes , National Fire Protection Association, 470 Atlantic Avenue, Boston,

MA. 02210

15 . American National Standard, Water Hammer Arresters , ANSI A112.26.1, American National

Standards Institute, 1430 Broadway, New York, N.Y. 10018, 1969.

16. Windenburg, D. F. , "Vessels Under External Pressure," Mechanical Engineering , pp . 601-

607, January 1937.

17. ASME Boiler and Pressure Vessel Code, Section VIII, Subsection U99, Standard Hydrostatic

Test, American Society of Mechanical Engineers.

18. Factory Made Air Duct Materials and Air Duct Connectors , UL Standard No. 181, 1974.**

19 . ASHRAE Handbook/Applications - 1974.4-

+ American Society of Heating, Refrigerating and Air-Conditioning Engineer, 345 East 47th Street, New York, N.Y. 10017.

* Nationa! Technical Information Service, 5285 Port Royal Road, Springfield, Va. 22161. nderwriters Laboratories, Inc., 333 Pfingsten Road, Northbrook, 111. 60062.

26
Chapter Two

MECHANICAL

20. Tabor, H. , "Stationary Mirror System for Solar Collectors," Solar Energy , Vol. II,

pp. 3-4, July-October 1958.

21. Aronin, Jeffrey E. , Climate and Architecture , Reinhold, New York, N.Y. , 1953.

22. Libbey-Owens-Ford Co., Sun Angle Calculator , Libbey-Owens-Ford Co., Toledo, Ohio, 1975.

23. United Nations, Climate and House Design , United Nations Publication, New York, N.Y.,

1971.

24. Water Quality Association, 447 East Butterfield Road, Lombard, 111. 60148, 1974.

27
Chapter Three

STRUCTURAL

(Note: This chapter has been significantly reorganized from "Interim Performance Criteria

for Solar Heating and Combined Heating/Cooling Systems and Dwellings," Jan 1975)

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 wind, snow, operating, seismic, and thermal restraint loads are considered.

Typical failures that are to be avoided might include: the collapse of a frame supporting

solar collectors due to wind, snow, or earthquake; the leaking or collapse of an underground

thermal storage tank; the blowing off or fracture of a glass cover plate due to wind, the

impact of hail, or thermal stresses.

Note that these requirements apply to all elements of a solar system, not just those with a function of providing support for some other element. In this regard, there is an important

distinction made between conventional elements, those elements for which design and construction procedures are contained in existing building regulatory documents, and non-conventional

elements, those elements for which such procedures are not available. Elements made of

materials documented in existing 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 unusual

environment such as welded steel subjected to unusually high or low temperatures, or plastics

subject to high and low temperatures are examples of non-conventional elements. Elements

with a structural support function will generally be conventional, and the structural

requirements for these elements will usually be satisfied by the designer for the

particular installation. Elements with primary functions other than structural support

may frequently be non-conventional, and the structural requirements for these elements

will typically be satisfied by the manufacturer of the element.

3.1 Requirement Structural safety of H/C/HW system . The elements and connections

of the H/c/HW systems shall safely support all loads expected

during the design life of the systems without failure.

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

of the conventional elements and connections of the system shall

exceed the required design load U.

The resistance, R, of conventional elements shall be determined

by reference to Section 601 of the MPS [1, 2, 3].

The design load, U, shall be combined from the following loads

in accordance with Section 601-10 of the MPS:

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

601-3 of the MPS.

2. Live loads (L) shall include all static and dynamic loads

exerted by the operation of the solar energy system and all

applicable live loads from Section 601-4 of the MPS and all

appropriate maintenance loads. Surfaces that must support

maintenance personnel shall resist a single concentrated

load of 250 lbs. distributed over 4 square inch area at the most critical locations. This shall also include

vehicular loads as stipulated by AASHTO [ 4 ] on elements at or below grade subjected to traffic.

3. Snow and ice loads (S) shall include the snow loads stipulated

in Section 601-5 of the MPS and, for slender elements such as wires and slender pipes, the ice loads stipulated in Section

1 of Appendix 3.

4. Soil and water pressures (H) on buried elements shall be in

accordance with accepted principles of soil mechanics and

Section 601-8 of the MPS.

28
Evaluation

Commentary

Chapter Three

STRUCTURAL

5. Wind loads (W) shall be "Wind Loaas ' stipulated in Section

601-6 of the MPS.

6 Earthquake loads (E) shall be those stipulated in Section 601-2.2

and 601-9 of the MPS, For components and connections which

cannot be evaluated within the scope of the referenced provisions,

the value of "Cp" (horizontal force factor) shall be taken

as 1.0.

7. Constraint loads (T) caused by temperature changes, shrinkage,

moisture changes, normal functioning of the system, timedependent changes within the materials of the system, and by

differential movement of the supporting structure and foundation

settlement shall be taken as the most severe likely to be

encountered during the service life.

8. The load from ponding of water on large horizontal surfaces.

Review of design drawings, specifications, and calculations.

The intent of this criterion is that conventional elements and

systems continue to be designed in accordance with applicable

building code documents. Note that most of the loads in the

MPS are referenced from ANSI A58. 1-1972 [6].

There are circumstances in which common building materials cannot

be considered conventional because they are exposed to unusual

service conditions. See, for example, the discussion of structural

work in the commentary of section 3.1.2.

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 following paragraphs of commentary are numbered corresponding

to the loads listed under the criterion:

(2) The design live loads contained in the MPS for roofs constitute

minimum loading requirements needed primarily for human

safety while the building is undergoing maintenance. Resistance to these loads need not be required for collector panels

that are mounted on roofs without forming an integral part of

the roof if adequate access is provided for service and maintenance personnel. For collectors which form an integral

part of the roof, resistance to the design live roof loads

listed in the MPS should be required, because the roof will

need to be repaired from time to time and must support the

workman making the repairs.

(6) The value of "Cp" supplied for elements that are not specified

by the referenced provisions is consistent with conservative

values for elements appended to structures.

29
3.1.2 Criterion

Chapter Three

STRUCTURAL

(7) The possibility of stresses being imposed by thermal expansion

or contraction, wind movement, seismic loads, vibratory loads,

or foundation settlement need to be considered. Solar compoents 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.

Time dependent changes within materials of the system should

include consideration of materials degradation. Of particular

concern may be deterioration of plastics and organic materials,

corrosion and eletrolytic action between dissimilar metals

such as between a collector and its support. Materials

degradation is further discussed in Chapter 5.

(8) 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 excessive

deflections, providing slope to carry excess water away, providing drains to remove water, or providing overflow locations

to limit the depth of water.

Nonconventional elements, resistance to maximum load. The factored

resistance, R*, of the nonconventional elements of the system or a portion thereof shall exceed the factored load, U*.

R* shall be determined from Section 2 of Appendix 2 (reference [7]

presents detailed procedures for determining the resistance, R*,

of flat plate solar collectors) and U* shall be determined as follows

for additive loads, U* = 1.1 D + 1.5 (Q +

^F^)

for counteracting loads, U* = 1.6 Q

- 0.8 D

WHERE:

D = mean dead load, D, as stipulated in 3.1.1

_Q = mean maximum variable load, see below _

¥ F^ = mean transient load(s) acting simultaneously with Q

Q shall be any one of the following loads and F. shall include all

of the remaining loads: 1

1.25 L ) 1.2 S ) 1.0 H ) 0.85 W ) where L, S, H, W, E, and T are as stipulated

1.4 E ) in 3.1.1

1.0 T )

'F. shall be determined from the following table, or from a rational

analysis of the expected load combinations:

F.

l L S H w E T

V .1 0.65 0.25 rH o 0 0 1.0

30
Evaluation

Commentary

Chapter Three

STRUCTURAL

Constraint loads (T) shall be explicitly allowed for by considering

the extreme operating temperature range and by considering a differential foundation settlement of 2 inches in any horizontal

distance of 50 feet in addition to those conditions specified in

3.1.1, except that in cases where a particular foundation is

specifically designed to control differential settlements, the

differential settlements used for T should be those consistent

with the specified design. Uplift forces caused by a swelling of

expansion soils shall be calculated assuming a level of 0.9D for

gravity loads.

Review of design drawings, specifications, calculations, and

documentation of this resistance as described in section 2 of

Appendix 2. The provisional tests described in sections 7.7,

7.8, and 7.9 of NBSIR 78-1305A [7] provide one means of determining the effects of positive and negative live loads and

longitudinal loads on flat plate solar collectors and their moun t ing hardwar e

Considerable care is required to determine the resistance of

non-conventional elements. Section 2 of Appendix 2 gives

procedures for determining the nominal resistance from the

statistics of the random variables involved.

For experimental or analytical evaluation of structural response,

the selection of the 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. Reference

[7] gives detailed procedures for testing and rating flat plate

solar collectors.

In some circumstances, such as collectors framed in wood or attic

collectors, wood and cellulosic materials may be subject to sustained or cyclic elevated temperatures for extended periods of

time (years). Under such conditions, strength reduction of

structural members may be very significant and should be considered

[8, 9] . Uneven heating of such structural members may cause racking or twisting during the normal course of the day. This should

be accounted for in the design of the structure.

When physical testing is done to establish values for the resistance,

care should be taken to assure that all significant interactions

with other positions of buildings and environmental effects are properly accounted for. For example, when testing single stories

of high rise buildings, the effect of lateral drift above the

story in question should be added to the loads. Possible environmental factors that may be important include temperature, moisture,

ultraviolet light and atmospheric pollution. The resistance to long term sustained loads and to repeated loads are frequently

important, and fatigue is covered in section 5. A.

31
3.1.3 Criterion

Evaluation

Chapter Three

STRUCTURAL

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

safety against loading situations which have a suitably high probability of not being exceeded during the service life. Decisions

regarding structural safety are invariably made in the presence

of uncertainties which arise from basic randomness in many of the

resistance and load parameters as well as imperfect modeling and

information. Indeed, it is these uncertainties which motivate

and necessitate the use of safety factors in design. The recent

trend to use probabilistically derived resistance and load factors

in structural design represents an attempt to proportion members

and connections so that the probability of attaining any limit

state is acceptably small. The load factors represent present

day design practice of building structures and are similar to the load factors proposed for use in an innovative construction

[10]. 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 performance 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.

It should be noted that combining effects from several loads is

not always a simple task, and the formula given for combinations

in this document must be used with some judgment. For example,

it may be possible for some materials to relieve the effect of

constraint loads through creep or by yielding. Thus for some ductile materials, it would not be necessary to consider constraint

loads acting simultaneously with earthquake loads because the

structure would be expected to yield during the earthquake.

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.

Nonconvent ional elements, resistance to cyclic loads . Nonconventional elements shall be capable of resisting the expected

repeated loads without failure or visible cracking but in no case shall these repeated JLoads be taken as less than 500 cycles from

D to D + 1/2 Q where D and Q are defined in Criterion 3.1.2.

Physical simulation and testing or analysis based on available

test data.

Where physical simulation is used, the cyclic loading shall be

applied after reducing system slack by the prior application of one preloading cycle of D + Q.

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 pre

loading cycle, and it shall be less than 25 percent of the maximum

deflection in the first cycle.

32
Chapter Three

STRUCTURAL

Commentary

3.2 Requirement

3.2.1 Criterion

Even though the service load history cannot be simulated, the

imposition of the stipulated cyclic load is intended as a con- servative representation of service conditions. The residual

deflection limitation assures preservation of structural integrity

under cyclic loading.

Function and operation . The elements of the solar energy system

shall not impair the function or operation of the solar energy

system when exposed to structural loads.

Conventional elements, deflection limitations . The deflection

of conventional elements supporting the system elements shall not

exceed the limits of Section 601-11 of the MPS.

Evaluation Review of design drawings, specifications, and calculations.

Commentary Conventional deflection limitations are formulated to fulfill

many requirements. Where it can be demonstrated that Requirement 3.2 is satisfied, the empirical limit may be justifiably

modified

3.2.2 Criterion

Evaluation

Commentary

Nonconventional elements, deflection limitations . The deflection

of nonconventional elements supporting the system components shall

not exceed the following limitations:

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

measured after the element has sustained a superimposed load

of 0.2D + 1.5L for 24 hours shall not exceed the following

two limits:

, < 1.25s 0.2D + 1.5L

d

2 = ~I80~ X

L

where: s = span length

d^ = net deflection measured immediately after

application of the superimposed load

(b) The maximum residual deflection (d^) measured not more than

24 hours after removal of the superimposed load specified in

(a) shall meet the following conditions:

d^ = .25d2 or s/4000, whichever is greater

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.

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

except for very stiff systems. This guards against significant residual deflection increases in each cycle of loading that may lead to incremental collapse.

33
Chapter Three

STRUCTURAL

3.2.3 Criterion

Evaluation

Commentary

3.2.4 Criterion

Evaluation

Commentary

Where brittle components are attached to supporting elements,

particular attention shall be paid to Criterion 3.2.3, as it may

require more stringent limits on deflection.

Deflection compatibility . Under the effect of deflections caused

by the loads 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.

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 satisfied if it can be demonstrated that

deflections caused by the specified loads can be accommodated

by suitable details or adequate flexibility.

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.

Reference [ n] gives a range of limits on deflection depending

on circumstances that may be used for guidance in assessing

compatibility.

Hail damage . All system components and supporting structural

elements that will be exposed to the natural environment in

service shall resist, without excessive damage or major impairment of the functioning of the system, the impact of falling

hail as stipulated in Section 3 of Appendix 2.

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

hail resistance test described in Section 3 of Appendix 2.

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 completely prevent

punching or local cracking of nonstructural elements such as 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.

34
Chapter Three

STRUCTURAL

References 3

1. HUD Minimum Property Standards, One and Two Family Dwellings , (No. 4900.1), U.S.

Department of Housing and Urban Development, Washington, D.C. (1973, revised 1976)+

2. HUD Minimum Property Standards, Multifamily Housing, (No. 4910.1), U.S. Department

of Housing and Urban Development, Washington, D.C. (1973, revised 1976)+

3. HUD Minimum Property Standards, Care-Type Housing , (No. 4920.1) U. S. Department of

Housing and Urban Development, Washington, D.C. (1973 revised 1976)+

4. Standard Specification for Highway Bridges , AASHTO, Washington, D.C. 1973.

5. Uniform Building Code , 1976 Edition, International Conference in Building Officials,

Whittier, California 90601, 1976.

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

7. Provisional Flat Plate Solar Collector Testing Procedures, First Revision, NBSIR 78-1305A,

National Bureau of Standards, Washington, D.C. June, 1978.

8. Wood Handbook , 1974 p. 4-32-4-40, Forest Products Laboratory, Madison, Wisconsin.

9. MacLean, J.D., "Rate of Disintegration of Wood Under Different Heating Conditions,"

American Wood Preservers Association, 1951.

10. Performance Criteria Resource Document for Innovative Construction , NBSIR 77-1316,

National Bureau of Standards, Washington, D.C., November

1977.*

*

11. Building Code Requirements for Reinforced Concrete , ACI 318-71, American Concrete

Institute, Detroit, Michigan, 1971.

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

*National Technical Information Service, 5285 Port Royal Road., Springfield, VA 22161

35
Chapter Four SAFETY

4.1

4.1.1

4.1.2

4.2

4.2.1

Requirement

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Requirement

Criterion

Evaluation

Commentary

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

systems/subsystems and their components shall be in accordance

with nationally recognized standards for health and safety

including the HUD MPS 4900.1, 4910.1, 4920.1, and 4930.2 for

residential and care type housing [1, 2, 3, 4,].

Plumbing codes and standards . Plumbing materials and equipment

and their installation shall be in accordance with applicable

local and nationally recognized plumbing codes and standards.

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 [5] and with applicable standards of American National Standards Institute (ANSI),

National Electrical Manufacturer's Association (NEMA) , Underwriter's Laboratories (UL) and HUD. 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.

Fail-safe contro ls. 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 present a danger to the occupants or damage any of the components of the

system or the building. Safety devices when used shall meet the

requirements of Section 515 and 615 of the MPS [1, 2, 3].

Review of drawings, specifications, and design calculations.

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

could occur when cool heat transfer fluids are introduced into

collectors which have been exposed to solar radiation under noflow" conditions. Due to the possibility of large hydrostatic

head pressures on tanks that may be greatly in excess of pressures

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.

36
Chapter Four

SAFETY

4.2.2 Criterion Automatic pressure relief devices. Adequately sized and responsive

automatic pressure relief devices shall be provided in those parts of

the energy transport subsystem containing pressurized fluids. A

pressure relief device shall be provided in each portion of the subsystem where excessive pressures can develop. Each such section of

the system shall have a pressure relief device so that no section

can be valved off or otherwise isolated from a relief device.

Automatic pressure relief devices shall be set to open at not more than the maximum pressure for which the subsystem is designed.

Vented potable liquids shall be piped to suitable

drains. Non-potable or combustible liquids shall be handled in

accordance with Criterion 4.4.5.

Relief valves shall drain to locations acceptable to the local

administrative code authority. It is desirable to provide a means

of detecting when pressure relief has occured (i.e., when recharging is necessary)

Evaluation 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. Commentary Care should be taken in the design and layout of the fluid transport system to prevent conditions in which locally excessive

pressures are developed as a result of flow restrictions or air

locks. Large pressure drops due to flow of vapors or boiling

fluids should be considered in the selection and location of

pressure relief devices. Relief devices must be protected from

freezing as conditions can occur when pressure relief is needed

and exposed or otherwise chilled relief valves could be frozen.

Precautions must be taken to assure that heat transfer liquids do

not discharge on asphalt base roofing materials or other types of

roofing or locations which may be hazardous, cause structural

damage, building finish discoloration, or damage to plant materials.

4*2.3 Criterion Protection from scalding. Domestic hot water systems shall be

equipped with means for limiting temperature of the hot water

for personal use at fixtures to 140°F.

Evaluation Review of drawings and specifications.

Commentary This may be accomplished, for example, by the use of mixing valves

or by limiting solar energy input (heat dumping)

4.3 Requirement 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 including those of

HUD [1, 2, 3, 4] for the type of housing to which it is applied.

Commentary It is the intent of the requirement 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/or 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 such as passive system thermal control elements.

37
Chapter Four SAFETY

4.3.1 Criterion 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.

Evaluation 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 [7],

NFPA 90A [8] and 90B [9], NFPA 211 [10], NFPA 54 [11], NFPA 30 [6],

NFPA 31 [12], NFPA 256 [13] and the National Electrical Code [5],

and the HUD standards [1, 2, 3, 4]. 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.

Commentary

4.3.2 Criterion

Evaluation

Commentary

4.3.3 Criterion

The type of testing that should be performed to evalute the influence

of solar collectors on the fire resistance of roof assemblies is

described in test method 7.13 of NBSIR 78-1305A [14].

Currently, there are no standards that specifically address the fire

hazard of combustible materials used in the collector, thermal

storage or heat exchange portions of a solar air distribution system.

Flame spread classification of insulation . The flame spread classification index for all insulation materials except those installed

underground and outside the structure shall not exceed the following

values

Plastic Foam 75

Other Insulation Materials 150*

Insulation materials used for duct liners shall meet the requirements of either NFPA 90A [3] or 90B [9], whichever is applicable.

The ASTM E84 [15] flame spread test method shall be the basis for

evaluating the surface burning characteristics of the insulation

materials. Where materials with facings are to be used, the

surface burning characteristics of the faced material shall be

measured.

No single test is sufficient to provide a full estimate of perfor- mance of a product in a fire. Plastic foams and loose fill

insulation are difficult to evaluate in ASTM E84. The requirement

of flame spread classification of 75 maximum for plastic foams

will provide as much safety assurance as is possible with current

test methods. Such a classification shall not be construed as the

equivalent of "noncombustible . " Many insulation materials,

including those consisting of cellulose, plastic foam and fibrous

glass (containing organic binder) are combustible materials which

will burn and release heat, especially when exposed to continuous

large fire sources.

Areas of application . Materials used for thermal insulation shall

be in accordance with Criterion 4.3.2 and may be applied to the

following areas: walls, roofs, ceilings, floors, pipes, ducts,

vessels and equipment exposed to the external environment.

*The Consumer Product Safety Commission "Interim Safety Standard for Cellulose Insulation,"

Federal Register, Volume 43, No. 153, p. 35240, became effective on September 8, 1978 and

supersedes these requirements for cellulose insulation. Modifications to this standard

are under consideration by CPSC.

38
Chapter Four

SAFETY

4.3.4

4.3.5

Exposed plastic foam (untreated or fire-retardant treated) , Kraftasphaltic vapor barrier on mineral and organic fiber insulations,

and non-fire-retardant treated loose fill insulation shall not be

permitted in habitable areas unless fully protected from the

interior of the building by a thermal barrier having a finish

rating of not less than 15 minutes as determined by NFPA 251 [16].

Thermal barriers shall be installed in a manner such that they

will remain in place for a minimum of 15 minutes under the same

test conditions.

Installed insulation and vapor barriers shall not make contact

with pipes or pumps containing hot fluids, motors, fans, blowers,

and heaters, unless the insulation and/or the heat producing

appliances are specifically designed and rated for that purpose.

Evaluation Review of drawings and specifications.

Commentary Although a degree of material combustibility is allowed, the

intent is to allow insulating materials which are not more com- bustible (or flammable) than existing construction and insulation

materials, and to preclude any increased fire hazard due to the

retention of heat from energy dissipating objects. Electric circuit wires which are surrounded by substantial thermal insulation

may be subject to overheating. In areas where occupants are likely to be engaged in normal activities, the insulation should

perform its intended function without the increased risk of ignition, rapid flame spread and heat and smoke generation. Attention should be given to the requirements as they pertain to innovative insulation systems such as movable and fixed insulation

installed as part of passive systems. Insulation in concealed

spaces may be a particular fire problem due to its susceptibility

to smoldering and its unaccessibility for fire fighting.

Criterion Flame resistance permanency of insulation . Chemical retardant

insulations shall retain their flame resistance throughout their

service lifetime.

Evaluation

Criterion

Evaluation

Commentary

The procedures and equipment specified in ASTM C739-73, Section

10.4, "Flame Resistance Permanency" [17] shall be used in judging

the effect of aging on the permanence of any flame retardants used

during manufacture.

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 ordinances

and applicable HUD standards [1, 2, 3, 4],

Review of drawings and specifications. Testing to show compliance

in accordance with NFPA 251 [16] and applicable HUD standards

[1, 2, 3, 4].

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. Because of the

potential fire hazard, use of building elements and areas such

as walls, attics, crawl spaces, and as plenums may be subject

to restrictions in NFPA 90A [8], 90B [9], and local building

codes

39
Chapter Four

SAFETY

4.3.6

4.3.7

4.4

4.4.1

Criterion

Evaluation

Commentary

Criterion

Evaluation

Commentary

Requirement

Criterion

Evaluation

Commentary

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 2 inch nominal thickness or of non-combustible materials

providing equivalent protection. Firestopping may be included as

an integral part of the component where the component as installed

provides equivalent protection. Firestopping shall comply with

local codes and ordinances and applicable HUD standards [1, 2. 3,41.

Review of drawings and specifications

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.

Protection against auto-ignition of combustibles . Combustible

solids used in solar equipment and adjacent combustible solids

shall not be exposed to elevated temperatures which may cause ignition

Review of calculations, drawings, and specifications. Testing

to show compliance where necessary.

Exposure 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.

Such conditions may exist, for example, within active collectors

framed in wood or inside attic collectors. 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.

Clearances for HVAC equipment, ducting, and piping are discussed

in NFPA No. 89M [7] and 90B [ 9 ]. Where applicable, clearances

specified by a nationally recognized testing laboratory may be

used

Toxic and combus t ible fluids . Heat transfer fluids or thermal storage fluids which require special handling (e.g. toxic, combustible,

corrosive, explosive, etc.) shall not be used unless the systems in

which they are used are designed to avoid unreasonable hazards.

Toxic fluids . The use of toxic fluids shall comply with the

Federal Hazardous Substances Act [18] and the requirements of the

health authority having jurisdiction.

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. The toxicological effects of the fluid should be

evaluated at the elevated temperatures expected during system

operation as well as at ambient temperatures.

Toxic fluids are those having the capacity to produce personal

injury or illness to man through ingestion, inhalation, or absorption through any body surface [18]. A compilation of the toxicity

characteristics of materials used in solar systems has been

prepared [ 19]

40
4.4.2 Criterion

Evaluation

Commentary

4.4.3 Criterion

Evaluation

Chapter Four

SAFETY

Characteristics of the complete fluid mixture must be considered

in determining toxicity. For example, the addition of inhibitors

and/or buffers to anti-freeze/water mixtures or to water may

affect toxicity characteristics.

Combustible liquids . The storage, piping and handling of combustible liquids shall be in accordance with the Flammable and

Combustible Liquids Code NFPA No. 30 [6].

Review of drawings and specifications.

This section applies to those liquids which have met Criterion

4.4.3 for flash point.

Liquid flash point . The flash point of a liquid heat transfer

fluid shall equal or exceed each of the following temperatures:

A. 100°F;

B. 50°F above the design maximum flow temperature of the

fluid in the solar system;

C. (1) 200°F below the design maximum no-flow temperature

of the fluid attained in the collector provided

the collector manifold assembly is located outside

of the building and exposed to the weather and

provided that relief valves located adjacent to

the collector or collector manifold do not discharge directly into the building, or

(2) the design maximum no-flow temperature of the fluid

in all other manifold and relief valve configurations.

A "liquid heat transfer fluid" is defined as the operating or thermal storage liquid including water or other liquid base and

all additives at the concentration used under operating conditions.

The flash point shall be determined by the methods described in

NFPA No. 321 [20], "Basic Classification of Flammable and

Combustible Liquids." In systems using a gaseous heat transfer

fluid, a flammable gas shall not be used.

The design maximum flow temperature of the fluid is defined as the

maximum fluid temperature that will be obtained when the heat

transfer fluid is flowing through the system. The design maximum

no-flow temperature of the fluid is defined as the maximum fluid

temperature that will be obtained when the heat transfer fluid

is not flowing through the system. Generally, this temperature

will occur in the collector when it is receiving its maximum

level of solar radiation at maximum ambient temperature.

Review of drawings, specifications, design calculations and test

data for flash point and collector stagnation and operating temperatures. An acceptable way of determining the design maximum

flow temperature is by the limiting temperatures of control

devices or relief valves, or through theoretical or test analysis

of the system. A method of determining the maximum no-flow temperature is presented in test method 7.2 (section 7. 2. 5. 2) of

NBSIR 78-1305A [14] where the design maximum no-flow temperature

of the fluid is equal to the plate temperature at stagnation.

It should be noted that this method is not valid for collectors

with very low loss coefficients.

41
Commentary

4.4.4 Criterion

Evaluation

Commentary

4.4.5 Criterion

Evaluation

Commentary

Chapter Four

SAFETY

Flash point values listed in manufacturer's literature are frequently typical values and may be determined by an open cup

flash point test. Flash point values used should be based on actual measurement or certified minimum values determined by the

required closed cup flash point test method.

The flash point of aqueous solutions of organic materials depends

on the percentage of water in the mixture. In the case of

ethylene glycol, a flash point does not exist for certain percentages of ethylene glycol with water. When these mixtures are boiled and the vapors allowed to escape, the flash point of the

mixture usually will be reduced, ultimately approaching that of

the pure substance. Care should be taken that the flash point

of the solution is based on the anticipated percentage of water

during actual use of the liquid in the system and not necessarily

on the percentage as installed.

A further discussion of temperatures is presented in Appendix 3,

Section 1. Detection of toxic and combustible fluids . If heat transfer fluids

or thermal storage 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. These substances may be treated in a manner similar to antifreeze and gases when providing for tell-tale indicators. For

instance, antifreeze agents, such as ethylene glycol,- may be

treated with non-toxic dyes which distinguish them clearly.

Waste disposal . Systems utilizing other than air or potable water

as a heat transfer fluid or thermal storage fluid shall provide

for the catchment and/or harmless removal of these fluids from

vents, drains, re-charge points, or points of potable leakage

(i.e. leakage from components that would not normally be expected

to last the life of the system) as approved by local administrative code authority. Potable water shall be discharged to suitable

drainage systems connected to the building or site drains.

Review of drawings and specifications.

The discharge of toxic, corrosive, combustible, or explosive

fluids into sewers can create serious health and safety hazards

both within the community and at a considerable distance along

watercourses into which the sewers discharge. Safe disoosal of

these fluids requires, among other things, the consideration of

the fluid composition, its concentration and frequency of discharge

and the nature of the sewage treatment and disposal system available to the site. In some instances catchment of this discharge

and removal to specialized treatment facilities may be the only

acceptable disposal method. Under such conditions adequately

sized and protected catch basins must be provided.

42
Chapter Four

SAFETY

The leakage of toxic fluids into the ground could contaminate

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

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

leakage of combustible fluids may pose a fire hazard when exposed

to external ignition or heat loss.

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

life than the system, but which are replaced on a scheduled re- placement program which is more frequent than their design life

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

4.4.6 Criterion Identification. Drains and other designated fluid discharge or fill points in solar systems at which fluids requiring special

handling or high temperature or high pressure fluids may be discharged shall be labeled with a warning summarizing the identification and hazardous properties of the fluid, instructions

concerning the safe handling of the fluid, and emergency first

aid procedures.

Evaluation Review of specifications.

Commentary The original fluid containers will frequently be discarded after

the system is charged which could result in no record of the

fluid's properties being retained. The system drain is the point

at which the owner or service personnel are most likely to contact the heat transfer fluid and permanent labeling should be

retained at that point. Identification may be provided by

attaching a tag containing the required information such as may

be supplied by the heat transfer fluid manufacturer.

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

the H/C/HW systems shall not unduly hinder the movement of occu- pants 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 occu- pants of the building or emergency personnel to an extent greater

than that allowed by Sections 402 and 405 of the MPS [1, 2, 3, 4],

NFPA 101 [21] and local codes.

Evaluation Review of drawings and specifications.

Commentary The location of solar equipment on a roof could reduce the

usability of that roof for access or egress. Solar system components located remote from the building but near a means of egress

could block the means of egress if a fire occurs in the solar

system component.

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 [5] for electrical panels.

Evaluation Review of drawings and specifications.

43
Chapter Four

SAFETY

Commentary In large buildings, accessibility would normally be limited to qualified personnel; however, in small buildings, accessibility

to the tenants should be provided.

4.6 Requirement

In addition, controls which should only be adjusted by skilled

personnel should not be located in areas subjected to normal

occupant access. 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-organisms

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.

4.6.1 Criterion Contamination of potable water. 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

Evaluation Review of plans and specifications. The quality of the water

shall be in compliance with the National Interim Primary

Drinking Water Regulation [22].

Commentary 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.

4.6.2 Criterion Separation of circulation loops. Circulation loops of subsystems

utilizing non-potable heat transfer or thermal storage fluids

shall either be separated from the potable water system in such

a manner that a minimum of two physically separated walls or interfaces is maintained between the non-potable liquid and the

potable water supply or otherwise protected in such a manner that

equivalent safety is provided.

Evaluation Review of drawings and specifications.

Commentary Double wall heat exchanger designs are one way of meeting the

intent of this criterion. When double wall heat exchanger designs

consisting of two single wall heat exchangers in combination with

an intermediary potable heat transfer liquid are used, leakage

through one of the walls would result in a single wall configuration. Although this design is considered to meet the intent of

this criterion, there are several other designs that avoid this

problem.

The use of single wall configurations which' solely rely upon

potable water pressure to prevent contamination or extra thick

single walls are examples of constructions which are not con- sidered to meet the intent of this criterion.

When two walls are in intimate contact with one another, pitting

initiated through one wall can readily continue through the other

wall

When available, an ASME solar energy standard for heat exchangers

for heating and cooling, currently in preparation, will provide a consensus standard specifically tailored to solar applications.

44
Chapter Four

SAFETY

4.6.3

4.6.4

4.6.5

Criterion Identification of potable water and non-potable fluids . In systems

where dual fluid subsystems, one potable water and the other non- potable fluid, are installed each shall be identified either by

color marking or metal tags as required in ANSI A13. 1-1956 [23] or other appropriate methods.

In systems which are designed for the use only of non-potable,

non-toxic fluids, warning and description of such use restriction

shall be provided at all system fill and drain points.

Evaluation Review of drawings and specifications.

Commentary

Criterion

Evaluation

Commentary

Owner /occupants should be made aware that initially harmless

fluids may degrade during use through decomposition or interaction

with impurities in closed loop systems. There should be provisions for periodically monitoring the quality of these fluids to make owner/occupants aware of the potential for health hazard and

corrosive action posed by such degraded fluids

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.

Criterion

Evaluation

Commentary

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

are commonly used to prevent contamination of potable water

systems.

Contamination of air . Materials which come in direct contact

with air shall not affect the odor or biological quality of the

air in an occupied space in an undesirable manner. Solar systems

utilizing a heat source containing noxious fumes and serving an occupied area shall maintain a separation of the two streams in

such a manner that leakage will not contaminate the air in the

occupied space.

Review of drawings and specifications.

Special consideration should be given to the presence of fungus,

mold or mildew in air handling systems since such micro-organisms

are often allergenic. Filtering of air streams may be desirable

but such provisions in passive systems with low air velocities

may be impractical. Rock containing asbestos should not be used

due to the potential carcinogenic hazard. Cleanliness of the

rock storage medium is further covered in section 2.4.2.

Protection of air in occupied spaces from noxious fumes may be

accomplished by the use of suitable, non-corrodable heat exchangers

which maintain an absolute pressure in the secondary side higher

than in the primary side. An example of such an installation

would be an ammonia heat pipe which exchanges heat directly to an air stream.

45
Chapter Four

SAFETY

4.6.6

4.7

4.7.1

4.7.2

4.7.3

Criterion

Evaluation

Commentary

Requirement

Criterion

Evaluation

Commentary

Criterion

Evaluation

Criterion

Evaluation

Commentary

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

systems that come in contact with air being supplied to an occupied

area or with potable water and that operate under conditions that

promote the growth of fungi, mold or mildew shall not support such

growth

The materials shall be capable of withstanding exposure to fungus

as defined by either Method 20 of UL 181 [24] or Appendix D, Section

E of the MPS 4900.1 and 4910.1 [1, 2] . Review environmental and

design operating conditions.

Fungi can feed on some organic materials and generally thrive in

warm, moist environments. The potential for fungus growth in a rock storage container which becomes damp due to the failure of

waterproofing membrane around the container or other causes could

be a substantial problem requiring periodic maintenance. Use

of a fungicide in such maintenance could introduce another potential airborne hazard and other methods may be preferable.

Protection from physical hazards . The H/C/HW systems shall not

create a hazard to people greater than those found in conventional

buildings

Installation Arrangement . 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

building.

Review of calculations, drawings and specifications.

Some examples can be given of how the presence of solar components

might increase accident potential: (1) reflected rays from the

collector could be distracting to drivers on adjacent highways or annoying to the occupants of nearby buildings, and (2) the ground

around a storage unit might settle, creating a hazard because of

the uneven ground.

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 be suitably isolated.

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

Review of drawings and specifications.

Snow and ice . In areas which have a snow load of 20 pounds per

square foot or greater required by local codes, provisions should

be made over entrances and locations of pedestrian and vehicular

ways to restrain or deflect sliding snow and ice masses which may

slide off elevated solar system components.

Review of drawings and specifications.

Solar system components may often include smooth slippery surfaces

located in elevated positions at steep angles. These elements may

heat up rapidly and loosen masses of snow or ice which may slide

off. Means should be provided to prevent a hazard to people or property. Methods such as deflectors, restraints, low friction

materials, or design of "safe fall" areas (pedestrian or vehicular

routes located away from the building) should be considered.

46
Chapter Four

SAFETY

4.7.4 Criterion Lightning protection. As applicable, lightning protection shall

be provided in accordance with the NFPA No. 78 Lightning Protection Code [25]

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.

4.7.5 Criterion Glazing Materials. Solar panels with slopes less than 45° with

the horizontal and which extend lower than 6 feet above a walking

surface for unrestricted traffic adjacent to the panel shall be

safety glazed or otherwise protected against impact of persons

falling against the glazing. Panels with glazing materials meeting the impact and breakage requirements specified by the "Federal

Mandatory Standard for Architectural Glazing Materials," 16 CFR

Part 1201 [26], shall be considered safety glazed.

Glazing materials other than those specified above shall meet the

intent of the requirements for glazing in MPS Section 508-8

[1, 2, 3].

Evaluation Review compliance certification documents or test in accordance

with procedures specified in "Federal Mandatory Standard for

Architectural Glazing Materials" [26 ]

Commentary These criteria are intended to reduce the risk of injuries to people from accidental contact with solar glazing materials. It

is intended that they be applied to glazing materials in solar

systems only in those areas where there is a likelihood that

people might accidentally come in contact with the glazing, such

as installations on which children might climb or against which

a passerby may fall.

Traditionally, greenhouse type structures have been considered to provide adequate protection against the hazard of persons falling

against them. It is not the intent of this criterion to impose new requirements on greenhouses of conventional design when used

for solar applications.

Where large expanses of glazing are used, as in passive installations, the Federal safety standard for architectural glazing

materials [26] should be reviewed for its applicability with

respect to physical location and arrangement of the glazing and

exposure risk of persons nearby.

Potential safety hazards should be considered in areas exposed to falling limbs or other projectiles with regard to installation of

skylights, clearstory windows and collector arrays. Where safety

glazing is not employed, consideration should be given to provisions to restrain or deflect broken glass which may slide off

elevated solar system components over entrances and locations of

pedestrian and vehicular traffic ways.

Film-type glazing materials for the outermost cover plates, if

unsupported, may be unacceptable if they undergo large deflection

under load, e.g. a person's hand pushing against the glazing, may

present an opportunity for exposure of the film (and the person's

hand) to hot surfaces such as the absorber plate, see Criterion

4.7.2.

47
Chapter Four SAFETY

References 4

1. HUD Minimum Property Standards, One and Two Family Dwellings , (No. 4900.1),

U.S. Department of Housing and Urban Development, Washington, D.C. (1973, revised 1976).+

2. HUD Minimum Property Standards, Multifamily Housing , (No. 4910.1), U.S. Department of

Housing and Urban Development, Washington, D.C. (1973, revised 1976).+

3. HUD Minimum Property Standards, Care-Type Housing , (No. 4920.1), U.S. Department of

Housing and Urban Development, Washington, D.C. (1973, revised 1976).+

4. HUD Intermediate Minimum Property Standards Supplement, Solar Heating and Domestic Hot

Water Systems , (No. 4930.2), U.S. Department of Housing and Urban Development, Washington,

D.C. (1977).+

5. National Electric Code , NFPA, No. 70, 1978 (Also ANSI Cl, 1978)-

6. Flammable and Combustible Liquid Code , NFPA, No. 30, 1977.*

7. Clearances, Heat Producing Appliances , NFPA No. 89M, 1976.*

8. Air-Conditioning and Venting Systems , NFPA No. 90A, 1976.*

9. Warm Air Heating and Air Conditioning , NFPA No. 90B, 1976.*

10. Chimneys, Fireplaces and Vents , NFPA No. 211, 1977.*

11. Gas Appliances and Gas Piping Installation , NFPA No. 54, 1974* (also ANSI Z83.1, 1972).

12. Oil Burning Equipment , NFPA No. 31, 1974* (also ANSI Z95.1).

13. Fire Tests of Roof Coverings , NFPA No. 256, 1976* (also ASTM E108, 1975++, and UL 790).

14. Provisional Flat Plate Solar Collector Testing Procedures , First Revision, NBSIR 78-1305A,

National Bureau of Standards, Washington, D.C., June 1978.

15. Surface Burning Characteristics of Building Materials, Test for, ASTM E84-77, 1977. ++

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

1972* (also ASTM E119 and UL 263).

17. Flame Resistance Permanency , ASTM C739-73, Section 10.4, 1973. ++

18. "Federal Hazardous Substances Act," Code of Federal Regulations (CFR) Title 16,

Part 1500.

19. Searcy, J. Q. , ed.. Hazardous Properties and Environmental Effects of Materials Used in

Solar Heating and Cooling (SHAC) Technologies: Interim Handbook , SAND 78-0842, Sandia

Laboratories, Albuquerque, N.M. , June 1978.

20. Basic Classification of Flammable and Combustible Liquids , NFPA No. 321, 1976.*

21. Life Safety Code , NFPA No. 101, 1976.*

22. National Interim Primary Drinking Water Standards , 1977, Environmental Protection

Agency, Office of Water Supply, Stock Number 055-000-00157-0 .+

48
Chapter Four

SAFETY

23. Scheme for the Identification of Piping Systems , ANSI A13.1, 1975, American National

Standards Institute, 1430 Broadway, New York, N.Y. 10018.

24. Standard for Factory Made Air Duct Materials and Air Duct Connectors , UL 181,

Underwriters Laboratories, 333 Pfingston Road, Northbrook, 111. 60062, 1974.

25. Lightning Protection Code , NFPA No. 78, 1977.*

26. "Federal Mandatory Standard for Architectural Glazing Materials," 16 CFR 1201, Federal

Register, January 6, 1977.

27. Metz, F. E., and Orloski, M.J., "State-of-the-Art Study of Heat Exchangers Used With

Solar Assisted Domestic Hot Water Systems," NBSIR 78-1542, July 1978.**

* National Fire Protection Association (NFPA), 470 Atlantic Avenue, Boston, MA 02210. + Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.

**National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161.

-H-American Society for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103

49
Chapter Five

DURABILITY/RELIABILITY

5.1

5.1.1

Requirement Effects of external environment . The H/C/HW systems, their various

subassemblies and the building elements with which they interact

shall not be affected by external environmental factors to an extent

that will significantly impair their function during their design

life.*

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.

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.

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

conditions or engineering analysis. Where adequate information

is unavailable, testing using either the methodology outlined in

Section 2 of Appendix 3 or other methods which can be shown to meet the intent of the criterion shall be used.

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

particularly susceptible to solar degradation under prolonged

exposure. Components of particular concern include cover plates

(including films and coatings), absorber surfaces, collector

heat traps, collector insulation, outdoor exposed insulation and

its coatings, control insulation (shutters, shades, drapes, blinds,

etc.) and reflectors.

Care should be taken that coated cover plates that have a weather

side are properly installed. Some glazings are designed to be

recoated after a period of time due to weathering of the surface.

Transmittance of cover plates and emittance, and absorptance data

of absorber material are required to estimate the effects of degradation by solar radiation in reducing collector efficiency.

5.1.2 Criterion Moisture . Solar components, materials and the building elements

with which they interact shall not be adversely affected by

exposure to moisture in service to an extent that will significantly

impair their function during their design life.

Means shall be provided to prevent the penetration of water into

collectors, other solar hardware components hnd building elements.

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

conditions or engineering analysis. Where adequate information

is unavailable, methods which can be shown to meet the intent of

the criterion shall be used.

A provisional test described in test method 7.5 of NBSIR 78-1305A [l]

is one means of assessing rain penetration into solar collectors.

information concerning the properties of materials for solar applications is given in

Section 12 of Appendix 3.

50
Commentary

5.1.3 Criterion

Evaluation

Chapter Five

DURABILITY/ RELIABILITY

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

condensation forming on the underside of the cover plates or absorber surfaces is quite high. Desiccants in breather tubes

or plugs can be used to aid in the prevention of condensation.

The desiccants 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 collector temperatures increase.

A potential problem with collectors which are not hermetically

sealed is that, in industrial atmospheres, pollutants in condensate solution may cause permanent etching of the underside of the cover plates and absorber surfaces over a period of time. Such

etching can permanently reduce transmittance or absorptance. When

this possible condition exists, design consideration must be given

to avoid the problem.

The presence of moisture in rock storage bins due either to penetration of bin walls or the hygroscopic characteristics of

the rock itself can lead to adverse effects of thermal performance

(loss of energy in latent heat form) as well as moisture induced

deterioration of the container and the growth of fungus (see Section

4.6.5) .

Water leakage can occur with double glazed collectors such that

the space between the cover plates receives the leakage but not

the inner portion of the collector. Although this may not significantly reduce solar transmission it increases collector losses,

is subject to freezing and may have other detrimental effects.

The build up of moisture in building elements caused by the presence

of solar system components can result in the rotting of materials

and the growth of mold and fungus. More specifically, 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 on both the interior and exterior of

collector components leading to deterioration of absorber surfaces

and the creation of corrosion supportive conditions which may

affect collector performance. The provision of adequate ventilation

may be desirable.

Guidance for the waterproofing of exposed insulation both above

and below ground is given in the HUD MPS section 607-2 [2], and

also the ASHRAE Handbook of Fundamentals Chapter 17 [3]

Ice dams and snow build up . The design of solar buildings and

systems shall provide for the possibility of the formation of ice

dams and snow build up

Review of drawings and specifications.

51
Commentary

5.1.4 Criterion

Evaluation

Commentary

5.1.5 Criterion

Evaluation

Commentary

Chapter Five durability /reliability

In very cold climates, water flowing off a warn collector may

freeze on cold surfaces immediately below it (such as exposed

eaves) , thereby forming an ice dam which can cause water to back

up under roofing or into the collector itself. This may be

moderated by methods such as elimination of the cold surface or provision of an imprevious surface such as continuous flashing.

Snow sliding off a collector may pile up at the bottom and cover part of the collector. This would have a tendence to reduce the

efficiency of the collector and increase the possibility of

thermal breakage of glass in the collector. This may be moderated

by methods such as the provision of space below the collector for snow pile up or by the installation of heating cables.

A potential problem is the blockage of collector breathing tubes

which can lead to pressure build up and consequent cover plate

breakage

Soil related degradation . Solar components and materials 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

information is unavailable, testing using either the methodology

outlined in Section 3 of Appendix 3 or other methods which can

be shown to meet the intent of the criterion shall 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 . Solar components and materials that are exposed to airborne pollutants such as ozone, salt spray, SC^ or N0X

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

information is unavailable, testing using either the methodology

outlined in Section 4 of Appendix 3 or other methods which can be shown to meet the intent of the criterion shall be used.

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.

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 in the dry

condition or in the presence of moisture. Factors of concern

include surface erosion and consequent transmission loss of cover plate, deterioration of coupling hoses and exposed seals

and corrosion of metallic elements.

52
Chapter Five

DURABILITY/REUABILITY

5.1.6 Criterion Dirt retention and staining. The collector cover plate and

absorber surfaces shall not collect and retain dirt or stain

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 and stains by the cover plate and the effect of this 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 cover plates clean on the outside. In areas

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

periodic washing may be required to remove dirt and stain.

Accumulations of sap, leaves, branches, etc., can also degrade

collector performance.

In air collectors another problem may be significant, performance

reduction due to internal dirt accumulation from the system. In some collectors air flow is through absorber material and is con- tained by a cover plate. In such circumstances normal dirt build

up from air drawn from occupied spaces could cause a deterioration

of heat transfer ability and spectral properties of the absorber.

High temperatures could bake on such deposits. Filtering of such

air flow may be desirable. A similar situation may exist in

passive systems with air circulation (Tromb4 walls, air thermosyphons

etc.) where dirt deposits may occur on absorber or cover plate

surfaces. Because of the low air velocities involved, filtration

may be impractical and access for cleaning should be considered.

5.1.7 Criterion

Abrasive wear is expected to present a possible problem in areas subject to wind driven dirt and 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.

Fluttering by wind. Solar components and materials 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.

5 . 2 Requirement Temperature and pressure resistance. Solar components, materials,

and building elements with which they interact shall be capable of

performing their intended function for their design life xxhen

exposed to the temperatures and pressures that can be developed in

the system.*

*Maximum and minimum service temperatures are defined in Section 1 of Appendix 3

53
Chapter Five

DURABILITY/ RELIABILITY

5.2.1 Criterion

Evaluation

Commentary

Thermal degradation, shock, and cycling stresses . Solar components

materials, and building elements with which they interact shall not

thermally degrade to the extent that their function will be reduced

below design levels during their design life when exposed to maximum

and minimum service temperatures and pressures.

Solar components and materials shall be capable of withstanding the

stresses induced by thermal shock for their respective design lives.

The H/C/HW systems, their various subassemblies, and building elements

with which they interact 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. When adequate information is

unavailable for collector components, the "no-flow" aging procedure

described in test method 7.2 of NBSIR 78-1305A Til shall be used to evaluate thermal degradation. When adequate information for other

components is unavailable, testing using either the methodology

outlined in Section 5 of Appendix 3 or the methods which can be

shown to meet the intent of the criterion shall be used to evaluate

thermal degradation.

Provisional tests described in test method 7.3 (thermal shock/

water spray) and 7.4 (thermal shock/cold fill) of NBSIR 78-1305A [1] are means of assessing the effects of thermal shock on collectors.

A provisional test described in test method 7.6 of NBSIR 78-1305A

[l] is one means of assessing the effects of thermal cycling stresses

on collectors.

Physical restraints (including support conditions) that will be imposed

on the system in actual use shall be considered when testing is required.

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

particularly susceptible to thermal degradation under prolonged

exposure. Organic collector components of particular concern

include cover plates, absorbers, absorptive coatings, heat traps,

insulation, sealants, and enclosure frames. Storage containers,

piping, liners and coatings composed or organic materials are also

components of particular concern.

Another concern is the use, in rock bed thermal storage, of rocks

that dust when exposed to in-use temperatures due to decomposition.

Heat from collectors and other solar components can cause the

premature thermal degradation of adjacent building elements. This

degradation may be enhanced by the presence of moisture.

In addition to evaluating thermal degradation, this criterion is

intended to identify potential problems that may occur as a result

of differential thermal movement. Thermal compatiblity is especially

critical in the case of collectors which may contain large expanses

of glazing. If thermal expansion is cumulative in system or subsystem design, the test must be designed to reflect this condition.

Areas of concern include cover plate/frame, collector/support

,

collector/collector , collector /piping , reflective surface/substrate,

piping, coupling hoses, sensors, the bond of tube or coatings to absorber plate and warping or shrinkage of cover plate or absorber.

54
Chapter Five

5.2.2 Criterion

DURABILITY/ RELIABILITY

Deterioration of fluids or phase change materials. Except when

such changes are allowed by the design of the system, fluids or phase change materials shall not freeze, give rise to excessive

precipitation, otherwise lose its homogeneity, boil, change

absorptivity or change pH or viscosity beyond the design ranges

when exposed to their maximum and minimum service temperature and

pressure during their design life.

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

conditions or engineering analysis. Where adequate

information is unavailable, testing using either the methodology

outlined in Section 6 of Appendix 3 or other methods which can be

shown to meet the intent of the criterion shall be used.

Commentary 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 balance 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 may cause precipitation to occur which may lead

to a build up of solids in pump seals and valve seats which may

lead to malfunction.

Viscosity changes in heat transfer fluids may lead to pumping

problems, if not considered in the design such as excessive pumping

power requirements or overheating due to heat transfer fluid

thickening

When heat transfer fluids are used as absorbers a bleaching of the

fluid may significantly reduce system performance.

Standardized methods to evaluate the durability of phase change

thermal storage materials due to temperature cycling have not been

developed. Evidence of the ability of a phase change material to remain stable through a number of cycles representative of a specified portion of its design life would be useful.

5.2.3 Criterion 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.

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

conditions or engineering analysis. Where adequate

information is unavailable a provisional test described in test

method 7.2 of NBSIR 78-1305A [1] or a test method described in

Appendix D of NBSIR 77-1437 [4] or other methods which can be

shown to meet the intent of the criterion may be used.

Commentary If the results of the no-flow test procedure (procedures 7.2 of

NBSIR 78-1305A [1]) indicate an outgassing problem then the test

procedure outlined in Appendix D of NBSIR 77-1437 [4] may be used

to evaluate components of the collector to determine which com- ponent(s) is at fault.

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

cover plate transmissivity or other changes in the optical

properties of collector components.

55
5.3 Requirement

5.3.1 Criterion

Evaluation

Commentary

5.3.2 Criterion

Evaluation

Chapter Five

DURABILITY/ RELIABILITY

Material problems that have been observed in the field include the

outgassing of gaskets and sealants, absorptive coatings, and

insulation.

Chemical compatibility of components . Materials used in the solar

system, its various subassemblies and the building elements with

which they interact shall have sufficient chemical compatibility to prevent corrosive wear and deterioration that would significantly

shorten their intended service life under in-use conditions.

Deterioration of gaskets, sealants, and polymeric coupling hoses . Gaskets, sealants, and polymeric coupling hoses either dry or 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.

Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Acceptability of gaskets and

sealants shall be determined by the methods outlined in ASTM D 3667-78 [5] and in Appendix B and C of NBSIR 77-1437 [4]. Where

adequate information is unavailable, coupling hoses may be tested

using either the methodology outlined in Section 7 of Appendix 3 or other methods which can be shown to meet the intent of the

criterion.

Gaskets, sealants, polymeric coupling hoses, and similar organic

materials frequently swell when exposed to liquids and, thus, may

lose their ability to function.

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 harden the hose beneath the clamp, causing it to lose resiliency and begin to leak. Further tightening of the clamps

will temporarily stop leakage but further hardening will occur with

the end result being a hard non-resilient ring under the clamp

which can no longer be tightened to prevent leakage. Silicone

rubber hoses and EPDM's, if properly vulcanized, tend to maintain

their resiliency with no tendency to take a thermal set. The

silicone rubber hoses, however, tend to be so pliable that screwtype clamps with perforated bands should not be used as it is

possible to extrude the material through the perforations in the

band. If this material is used, smooth band clamps should be

utilized

Materials/transf er fluid compatibility . Materials designed to be

used in contact with heat transfer fluids shall not be corroded or otherwise adversely affected 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. Acceptability of gaskets and

sealants shall be determined by the methods outlined in Appendix

B of NBSIR 77-1437 [4]. Where adequate information is unavailable,

materials may be tested using the methodology outlined in

Section 8 of Appendix 3 or other methods which can be shown to meet the intent of the criterion.

56
Chapter Five

DURABILITY/RELIABILITY

Commentary

5.3.3 Criterion

Evaluation

Commentary

5.3.4 Criterion

Evaluation

Commentary

Corrosion of metals by heat transfer fluids could be a serious

problem in solar energy systems. Society of Automotive Engineers

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

provides guidance in preventing corrosion. Experience indicates

that tight closed loop systems help to prevent corrosion.

Any use of inhibitors should be keyed to the characteristics of

all elements of the energy transport system to which it is exposed

including collectors, piping, connectors, tanks, pumps, valves,

heat exchangers, etc. With non-toxic heat transfer fluids, any

inhibitors should be selected to maintain the desired fluid

properties, see section 4.4.1. Further discussion is included in

reference [6]

Compatability 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

information is unavailable, testing using either the methodology

outlined in Section 9 of Appendix 3 or other methods which can be

shown to meet the intent of the criterion shall 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.

The use of corrosion inhibitors or dielectric fittings that electrically isolate dissimlar 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.

Attention should be paid to all elements of a solar system when

considering compatibility of dissimilar materials. This should

include energy transport system, structural support and connections,

fabricated parts, and roofing materials.

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 solar components or building elements that would significantly impair their ability

to perform their intended function over their design life.

Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Where adequate

information is unavailable, testing using either the methodology

outlined in Section 10 of Appendix 3 or other methods which can be

shown to meet the intent of the criterion shall be used.

Salts such as those that can be leached by moisture from some types

of glass fiber and mineral wool insulation or from ogranic component

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. Corrosion of solar components

can also be caused by substances leached from roofing materials.

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

Evaluation

Commentary

5.4 Requirement

5.4.1 Criterion

Evaluation

Commentary

Chapter Five

DURABILITY/ RELIABILITY

Effects of decomposition products . Chemical decomposition products

that are expelled from solar components or building elements under

in-use conditions shall not cause the degradation of solar components or building elements to the extent that would significantly

impair their ability to perform their intended function over their

design life.

Documentation of satisfactory long-term performance under in-use

conditions or engineering analysis. Where adequate

information is unavailable, testing using either the methodology

outlined in Section 11 of Appendix 3 or other methods which can

be shown to meet the intent of the criterion shall be used.

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.

Heat transfer fluids, including inhibited water, may decompose and cause scale build up which may cause deterioration of performance. This

is particularly true of hot water heaters where supply water is

heated directly in the collector and dissolved solids (calcium

salts) precipitate.

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.

Wear and fatigue . Check valves, pressure regulators, pumps, electrical switches, collector tracking mechanisms, insulation movement mechanisms and assemblies, 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.

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.

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 fluids and their additives.

Many of the components described in the criteria involve the use

of conventional components in unusual applications. A record of

satisfactory performance in the conventional application may not

be sufficient to adequately predict performance in the solar

application and careful evaluation may be desirable.

In some applications, less expensive components which are easily

replaced but have shorter expected lifespans may be more desirable

than more reliable but more costly components.

58
Chapter Five

DURABILITY/ RELIABILITY

References 5

1. Provisional Flat Plate Solar Collector Testing Procedures , First Revision,

NBSIR 78-1305A, National Bureau of Standards, Washington, D.C., June 1978.

2. HUD Minimum Property Standards, One and Two Family Dwelling , (No. 4900.1),

U.S. Department of Housing and Urban Development, Washington, D.C. (1973, revised

1976). +

3 . ASHRAE Handbook of Fundamentals - 1977.*

*

4. Solar Energy Systems - Standards for Rubber Seals , NBSIR 77-1437, National Bureau of

Standards, Washington, D.C., March 1978.**

5. Standard Specification for Rubber Seals Used in Flat Plate Solar Collectors , ASTM

D 3667-78 1978. ++

6. Metz, F.E., and Orloski, M.J., "State-of-the Art Study of Heat Exchangers Used with

Solar Assisted Domestic Hot Water Systems, NBSIR 78-1542, July 1978.**

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

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

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

**National Technical Information Service, 5285 Port Royal Rd . , Springfield, VA 22161.

-H-American Society for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103.

59
Chapter Six

OPERATION AND SERVICING

6.1 Requirement Maintenance and servicing. The H/C/HW systems shall be designed,

constructed and installed to provide sufficient access and

appurtenances for general maintenance, convenient servicing, and

monitoring of system performance.

6.1.1 Criterion 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, or building element. Individual collectors

in an array shall be replaceable or repairable without disturbing

non-adjacent collectors in the array.

Evaluation Review of drawings and specifications.

Commentary 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.

Access to storage units may be necessary. Rock storage and liquid

storage in both active and passive systems may require access for

cleaning or replacement. Collector glazings which require periodic

recoating will need access. Isolation valves may be necessary for

the repair or replacement of system components.

Information on access provisions is provided in Reference [1].

6.1.2 Criterion Misuse. Solar components shall be located where the potential for

their misuse is minimized.

Evaluation Review of building plans indicating occupant access and 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 potential misuse or vandalism.

6.1.3 Criterion Draining and filling of fluids. To facilitate system or subsystem

maintenance and repair, subsystems employing fluids shall be capable of being filled and drained by appropriate personnel.

Evaluation Review of drawings, specifications, and mairttenance instructions.

Commentary In systems employing hazardous fluids it may be desirable to arrange

drain and fill provisions so that this work may be accomplished

only by skilled maintenance personnel using appropriate equipment.

An example of this would be domestic hot water systems using an ethylene glycol/water mixture for the heat transfer fluid.

6.1.4 Criterion Flushing of liquid subsystems. Suitable connections shall be provided for the flushing (cleaning) of liquid energy transport

subsystems

Evaluation Review of drawings and specifications.

Commentary The recommendations of the system manufacturer for cleaning agents

compatible with the materials of the system should be followed.

60
Chapter Six

OPERATION AND SERVICING

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.

6.1.8 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, walkways, ladder supports, safety

belt slips, 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 equipment.

6.1.9 Criterion Protection. Protection shall be provided for the system during

maintenance in accordance with manufacturers instructions.

Evaluation Review of maintenance manual.

Commentary System may require special protective measures during shut-down

for maintenance such as protection for collectors or controls.

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

Commentary This manual may consist in whole or in part of a series of instruction sheets provided by the various subsystem and component manufacturers. It may be a single manual, or installation instructions

may be separate from operation and maintenance.

Its size and complexity should be consistent with the need for

descriptive information. The simplest passive system may warrant

no more than an attached label or tag.

61
Chapter Six

OPERATION AND SERVICING

6.2.1 Criterion Installation instructions. The instructions shall include Dhvsical.

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.

The instructions shall be available at the installation site or from normally accessable sources.

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 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 system, 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 sequence of operation,

flow diagrams, and wiring diagrams. The manual shall include a tabulation of those specific performance requirements which are dependent upon specific maintenance procedures. The maintenance

procedures, including ordinary, preventive and minor repairs, shall

be cross-referenced for all subsystems and organized into a maintenance schedule. The manual shall describe operation procedures

for all parts of the system including those required for implementation of specified planned changes in mode of operation.

The manual should specify temperature, pressure, and flow conditions

which are expected to occur at the access points required in

Criterion 6 . 4 .to facilitate operational checks and troubleshooting

Evaluation

The manual shall describe start-up and shutdown procedures.

Review of maintenance and operating instructions.

Commentary One of the most common sources of malfunction in large systems

is expected to be in the control subsystem. These malfunctions

are not always complete failures but more often a matter of

adjustment. Control subsystem malfunctions are not usually

obvious unless testing at specified points is conducted.

For package systems, it would be desirable to have start-up and

shutdown procedures indicated on a simple label.

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.

62
Chapter Six

OPERATION AND SERVICING

Evaluation Review of maintenance plan.

Commentary This criterion is applicable to both active and passive systems.

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.

Commentary 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., available for the system.

6,2.5 Criterion Maintenance hazards. The manual shall provide warning against

hazards that could arise in the operation and/or maintenance of

the system and shall fully describe the precautions that shall

be taken to avoid these hazards.

Evaluation Review of maintenance and operating instructions.

Commentary Some systems contain toxic and/or combustible 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.

Indications of hot valves and discharge points should be given.

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, HC and HW systems. The H, C, HC and HW systems

shall be capable of being serviced with a minimum amount of special

equipment by the appropriate existing trades (HVAC, plumbing, etc.)

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.

6.4 Requirement System monitoring. Provision shall be made for system monitoring

in accordance with the specifications of the installation, operation and maintenance manual.

6.4.1 Criterion Minimum operating information. Provisions shall be made to indicate

to the user when either the collector loop or the auxiliary energy

system is operating.

Evaluation Review of drawings, specifications and operating instructions.

Commentary A minimum level of information is essential to the user to assure

that the solar system is functioning as intended. Monitoring

means may involve sensor and indicators or they may be as simple

as observation and awareness of appropriate radiant temperatures

and air movement

63
Chapter Six

OPERATION AND SERVICING

6.4.2 Criterion 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.

Evaluation Review of drawings and specifications for the location of test

fittings and electrical contacts.

Commentary Adequately located test fittings will permit system monitoring and

expedite the maintenance and repair of equipment.

1) Uniform Mechanical

References 6

Code, International Conference of Building Officials, 5360 South

Workman Mill Road, Whittier, California 90601, 1973

64
Chapter Seven

BUILDING AND SITE

(Note mance

7.1

7.1.

7.2

7.2

This chapter has resulted from the consolidation of chapters 7-13 of "Interim PerforCriteria for Solar Heating and Combined Heating/Cooling Systems and Dwellings," Jan. 1975.)

Requirement Thermal design . The building and site shall utilize materials,

designs, and construction methods appropriate for their intended

use

Criterion Energy conservation . The dwelling total energy usage including

factors related to microclimate, site, exterior envelope, illumination, H/C energy distribution, and HW shall be designed for

overall efficiency including use of solar energy.

The dwelling design shall take into account the interaction

between dwelling energy usage and the solar energy system.

Evaluation Review of calculations, drawings, and specifications.

Commentary A well designed solar energy system should include a building

which is energy conserving since collector area and sizing of

other solar hardware components is proportional to the building

load requirements. ASHRAE Standard 90-75 [1] sets forth requirements for the design of the exterior envelope of new buildings for

effective use of energy. Insulation to levels greater than those

specified in 90-75 is normally desirable in solar buildings to minimize heating load. In the case of passive buildings it may

be desirable to tailor the design to the optimum use of glazed

areas, thermal mass, insulation, ventilation and other appurtenances

for heating, cooling and illumination. In such cases, the provisions of Section 10 (Energy Requirements for Building Designs

Based on Systems Analysis) and 11 (Requirements for Buildings

Utilizing Solar, Wind or Non-Depleting Energy Sources) of 90-75

may be applied.

There are several aspects that may be considered in the design of

buildings that conserve energy. One consideration is site design

where building energy consumption can be conserved by managing the

microclimate and, therefore, modifying its effect on the building,

for example, wind deflection. For a study identifying climate

design regions and their impact on residential design, see reference [2]

A second consideration is the exterior envelope of the

building where energy can be conserved by modifying factors such

as: color, thermal conductivity, orientation, shading, surface

area and weather tightness. A third consideration is the mass of

the building which can exert considerable influence on the building's thermal behavior. A fourth consideration is space planning.

For example, placing residential living areas on the south side

and storage or corridor areas on the north, coordinate space use with natural temperature variations. Which combination of options

is chosen and how effective the selection will be is dependent on design conditions and design goals.

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

.1 Criterion Space use. A location shall be provided for solar subsystems that

will not significantly impair the use of required exterior or interior spaces.

Evaluation Review of site and building drawings showing the location of solar

subsystems

65
Chapter Seven

BUILDING and SITE

Commentary 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.

7.2.2 Criterion 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.

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 if it can- not be healed naturally without further deterioration. Several

examples can be cited that could cause such conditions to exist:

(1) if 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.

7.2.3 Criterion Interaction. The interaction of building and site with solar

systems and components shall be in accordance with applicable

criteria of Chapter 1.

Commentary Applicable criteria include: 1.1.1, 1.1.2, 1.1.3, 1.2.1, 1.3.2,

1.4.2, 1.5.1, 1.6.2, 1.7.4, 1.8.1, and 1.8.2.

7.3 Requirement Mechanical and electrical functioning of building and site. The

mecahnical and electrical operation of the building or site shall

not be adversely affected by the H/C/HW systems.

7.3.1 Criterion Interaction. The interaction of building and site with solar

systems and components shall be in accordance with applicable

criteria of Chapter 2.

Commentary Applicable criteria include 2.1.3, 2.1.7, 2.1.8, 2.1.9, 2.1.11

thru 2.1.17, 2.2.2, 2.2.3, 2.3.1, 2.3.2, 2.4.1, 2.4.2,

and 2.5.1.

66
Chapter Seven

BUILDING and SITE

7.4 Requirement Structural safety and serviceability of building and site elements.

The structural safety and serviceability of building and site

shall not be impaired by the H/C/HW systems.

7.4.1 Criterion Loads. Building and site elements shall be capable of carrying

the increased loads imposed by solar components.

Evaluation Review of structural drawings, specifications, and design calculations taking into consideration the loads set forth in Chapter

3, Structural.

Commentary All possible loading conditions, such as those created by thermal

distortion, empty storage tanks exposed to wind or hydrostatic

forces, alternate or adjacent span loading of panels, or combinations of live and dead loads should be checked. The addition of

solar 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.

7.4.2 Criterion Penetration of structural members. When penetrations are required

in structural members to accommodate passage of solar components,

those structural members shall be designed so that compliance with

the MPS is maintained.

Evaluation Review of structural and mechanical drawings.

Commentary 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

7 . 5 Requirement Safety of building and site. The safe operation of the building

or site shall not be affected by the H/C/HW systems.

7.5.1 Criterion Protection from thermal deterioration. Building materials adjacent

to solar equipment shall not be exposed to elevated temperatures

that result in adverse physical, chemical, mechanical, or thermal

changes that result in the creation of a safety hazard.

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/or fire

resistance ratings pf; the building elements,

7.5.2 Criterion Interaction. The interaction of building and site with solar

systems and components shall be in accordance with applicable

criteria of Chapter 4.

Commentary Applicable criteria include: 4.1.1, 4.1.2, 4.2.2 thru 4.3.7,

4.4.2, 4.4.4, 4.4.5, 4.4.6, 4.5.1, 4.5.2, 4.6.1 thru 4.6.5, and

4.7.1 thru 4.7.5.

67
Chapter Seven

BUILDING and SITE

7.6 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.

7.6.1 Criterion Exterior penetrations. Openings in the exterior enclosure of the

building through which connections, piping, ducting, and/or

wiring are passed shall be made weather resistant and moisture

proof

Evaluation Review of drawings and specifications.

Commentary Particularly with collector supports, the penetration should either

be accessible for maintenance or the assembly should be built tightly

to the roof and flashed and caulked as necessary for watertightness.

Reference [3] provides guidance for waterproofing penetration.

7.6.2 Criterion Interaction. The interaction of building and site with solar

systems and components shall be in accordance with applicable

criteria of Chapter 5.

Commentary Applicable criteria include: 5.1.2, 5.1.3, 5.2.1, 5.3.3, 5.3.4,

5.3.5, and 5.4.1.

7.7 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.

7.7.1 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 Roof maintenance may be difficult if collector installations are

not designed for this need. 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.

7.7.2 Criterion Interaction. The interaction of building and site with solar

systems and components shall be in accordance with applicable

criteria of Chapter 6.

Commentary Applicable criteria include: 6.1.1 thru 6.1.6, 6.1.9, 6.2.1,

and 6.2.3.

68
References 7

Chapter Seven

BUILDING and SITE

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

2. Loftness, V., "Identifying Climatic Design Regions and Assessing Climatic Impact on Residential Building Design," AIA/RC, Technical Paper I, Winter 1977.

3. "A Manual of Roofing Practice," National B.oofing Contractors Association, 1970 (71).

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

47th Street, New York, New York 10017.

69
APPENDIX 1

Table 1A-1 Direct Fired Water Heater Capacities. [1, 2 ]

pm 0A3 ' roewr on oXS ELECT. OIL "CAS Efficr; TUL UX3- "ELECT Oil

Number of Bedrooms 1 2 3 -• Storage (gal) 20 20 30 30 30 30 30 40 30 — — —

1 to Input (Btuh 1-1/2 or lew) 27K 2.5 70K 36K 3.5 70K 36k 4.5 70K -- -- -- *tha Draw (gph) 43 30 89 60 44 89 60 58 89 — — —

Recovery

(gpM

23 10 59 50 14 59 30 18 59 — — —

Number of Bedrooms 2 2 4 5 3torage (gal) 30 40 30 40 50 30 40 50 30 50 66 30

- Input (Btuh 36k 4.5 70K 36K 5.5 70K 38k 5.5 70K 47K 5.5 70K

Draw (gph) 60 58 89 70 72 89 72 72 89 90 88 89 Recovery

(gph)

30 18 59 30 22 59 32 22 59 40 22 59

Number of Bedrooms 3 U s

5

Storage (gal) 40 50 30 50 66 30 50 66 30 50 80 40

3 to Input (Btuh 3-l/2 or lew) 3bK 5.5 70K 38k 5.5 70K 47K 5.5 70K 50K 5.5 70K

Baths Draw (gph) 72 72 89 82 88 89 90 88 89 92 102 99 Recovery

(gph)

32 22 59 32 22 59 40 22 59 42 22 59

Note: Storage capacity, input and the reoovery requirements indicated in the Table are typical and may vary with each individual manufacturer. Any combination of these requirements to produce the

1 hour draw stated will be satisfactory. Recovery is based on 100 P water temperature rise.

Kaample: For a 3-bedroom, 2 bath residence there are three choices as follows: A 40 gal storage/30 gph recovery gas heater; a 50 gal storage/22 gph reoovery electrlo heater; or a 30 gal storage/59 gph reoovery oil heater; or at. equivalent combination which will produce at least a 70 gph total draw.

Table 1A-2 Indirect Fired Water Heater Capacities. [1, 2]

NUMBER OF BATHROOMS 1 to 1-1/2 2 to 2-1/2 3 to 3-1/2 NUMBER OF BEDROOMS 2 3 4 3 4 5 3 4 5 6 TANK TYPE INDIRECT BOILER-CONNECTED

I-W-H rated gal in 3 hr

100 F degree rise

40 40 66 66 66 66 66 66 66 66

WATER HEATER CAPACITIES

(180 F BOILER WATER - INTERNAL OR EXTERNAL

CONNECTION)

Manufacturer rated gal.

in 3 hr 100 F deg rise

49 49 75 75 75 75 75 75 75 75

Tank capacity in gals. 66 66 66 66 66 82 66 82 82 82

TANKLESS TYPE INDIRECT

BOILER- CONNECTED WATER

HEATER CAPACITIES

(200 F BOILER WATER - INTERNAL OR EXTERNAL

CONNECTION)

I-W-H rated gpu.

100 F deg rise

2.75 2.75 3.25 3.25 3.25 3.75 3.25 3.75 3.75 3.75

Manufacturer rated, draw

in 5 min. 100 F deg rise

15 15 25 25 25 35 25 35 35 35

Note: Heater capacities and inputs are minimum allowable. Variations in tank size are permitted when

recovery is based on 4 gph/kw @ 100 F rise for electrical, AGA recovery ratings for gas heaters,

and 1BR ratings for steam and hot water heaters.

70
APPENDIX 1 Cont

Table 1A-St Daily Hot Water usage (140°F) for Solar System Design

Category One and two Family Units

and Apartments up to 20

* Units

Apts, of [3]

20-200 Units

Apts, of over 200

[3]

Units

No. of People 2 3 4 5 6 — —

No. of Bedrooms 1 2 3 4 5 — —

Hot Water/Unit

(gal /day)

40 55 70 85 100 40 35

Table 1A-4 Monthly Temperature (tm) in °F at Source for City Water in 14 Selected Cities [4]

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

1 . Phoenix Ri, Re, W 48 48 50 52 57 59 63 75 79 69 59 54

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

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

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

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

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

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

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

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

10. Salt Lake City W, C 35 37 38 41 43 47 53 52 48 43 38 37 11. Seattle Ri 39 37 43 45 48 57 60 68 66 57 48 43

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

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

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

Abbreviations: C-creek, L-lake , Re-reservoir, Ri-river, W-well.

* Assumes 20 gal. per person for first 2 people and 15 gal. per person for additional

family members.

71
EFFICIENCY

APPENDIX 1 Cont

100 r- Double Glazed, Flat Plate, Flat Black Paint Antiref lective Double Glazed, Flat Plate, Black Chrome Selective Surface Single Glazed, Flat Plate, Black Chrome Selective Surface

Sipgle Glazed, Evacuated Tube, Concentric Selective

Absorber, no rear reflector Linear Fresnel Lens, Tracking-concentrating, Black Chrome Selective Surface

Single Glazed, Flat Plate, Flat Black Paint Single Glazed, Trickle Type

t4 ~ t

,

Figure 1A-1 Typical Thermal Efficiency Curves for Liquid

Collectors Based on Collector Aperture Area

ti _ t a

Figure 1A-2 Typical Thermal Efficiency Curves for Liquid

Collectors Based on Collector Gross Frontal Area

72
COLLECTOR

EFFICIENCY

APPENDIX 1 Cont.

Figure 1A-3 Typical Thermal Efficiency Curves for Flat Plate

Collectors Using Air as the Working Liquid, Based on Collector Gross Frontal Area [5]

(Q indicates flow rate in standard cubic feet per

minute (scfm) per unit collector area)

73
References Appendix 1

1. HUD Minimum Property Standards, One and Two Family Dwellings , (No. 4900.0),

U.S. Department of Housing and Urban Development, Washington, DC (1973, revised 1976).

2. HUD Minimum Property Standards, Multifamily Housing , (No. 4910.1), U.S. Department of

Housing and Urban Development, Washington, DC (1973, revised 1976).

3. Werden, R. G. and Spielvogel, L. G. , "Part II Sizing of Service Water Heating Equipment

in Commercial and Institutional Buildings," ASHRAE Transactions , Volume 75, PII, 1969,

p. i.v.1.1.

4. Data from Handbook of Air Conditioning System Design , pp. 5-41 through 5-46, McGraw-Hill

Book Company, New York, NY, 1965.

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

Los Angeles, CA, July 1975.

74
(Note: This appendix has resulted from the reorganization of chapter 2 of "Interim Perfor- mance Criteria for Solar Heating and Combined Heating/Cooling Systems and Dwellings," Jan. 1975.)

Section 1

Commentary

Section 2

APPENDIX 2

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 2A-1 (see reference [12]) 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 2A-1 with documented information of the

accumulation of ice recorded for major ice storms [1] and ice

loads considered in the design of steel transmission pole

structures [ 2] 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 factored resistance,

R*, of nonconventional elements is defined as follows:

R* = (J) Rm

where

R = mean, or best estimate, of the resistance expected

under service conditions.

(J) = resistance factor which depends on the coefficient

of variation (c.o.v.) in resistance V^, and the

ductility, u, as follows:

Design Resistance Factor, j)

V

R

U

2 or less 5 or more

0.10 0.70 0.78

0.20 0.50 0.63

0.30 0.35 0.48

For intermediate values of and u, (J) may be obtained by linear

interpolation.

R^, V^, and u shall be determined as indicated in the following

paragraphs.

Where adequate existing test data on the various material

properties comprising the system is available, evaluation of the mean resistance, R , shall be performed using engineering analysis.

Where adequate test data is unavailable, system elements and subassemblies shall be evaluated in the laboratory using simulated

static load levels consistent with the specified load combinations.

75
APPENDIX 2 Cont

76

FIGURE

2A-1

Mean

Annual

Number

of

Days

with

Glaze

(Freezing

Rain)

[1]
APPENDIX 2 Cont.

Section 3

Commentary

V

R

shall be determined as:

V

R

- + ?

F + VP ll/2 2 °- 10

Where

is the c.o.v. in material strength relevant to the limit

state of the component considered (i.e., yield or tensile

strength, compression strength, etc.)

Vp is the c.o.v. attributable to fabrication, arising from

dimensional variations in components and tolerances in

the assembly of those components. Vp shall not be taken

to be less than 0.05

Vp is the c.o.v. associated with the ability to predict the

component capacity when all variables in the corresponding

analytical model are precisely known. Vp shall not be

taken to be less than 0.05

Coefficients of variation shall be determined in accordance with

standard methods of statistical analysis using existing test data

on materials comprising the system and laboratory tests conducted

during the development and acceptance stages for innovative

structural elements and subassemblies.

The ductility factor, u, is defined as the ratio of maximum

obtainable deflection to yield deflection for structures with

load-deformation relations (not stress-strain relations) that

exhibit a relatively definite yield point. For structures that

do not have such relations, the ductility factor, u, shall be

computed from an "effective" function (Figure 2A-2) consisting

of 2 straight lines. The first line is drawn through the origin

and a point of the actual function at which the resistance is 60

percent of its maximum load value (P ) . The second line is a horizontal line ending at the ultimate deflection (d ), 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 (dy e ) 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 = d / d u ye

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 2A-3

and the velocity is the terminal velocity shown in Table 2A—1.

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

[ 3 ] indicating that a representative hail storm area is generally

one order of magnitude smaller than the regions for which statistical information is compiled.

77
APPENDIX 2 Cont.

| The impact from the vertical terminal velocity is used as a

I measure of the effect of hail falling with or without horizontal

I wind. It is possible that a larger impact could occur on sur- faces sloped from 30° to 60° if the maximum particle diameter

occurred simultaneously with a high horizontal wind velocity

perpendicular to the 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.

Reference [4] describes the general NBS Hail Resistance Test,

and Reference [

5' ] describes a similar test directly applicable

to flat plate solar collectors.

EFFECTIVE RESISTANCE FUNCTION

FIGURE 2A

Determination

of the

Ductility Factor

ft =

A | + A 3

- A2 + A 4

Diameter

in

Weight

gm lb

Terminal

Velocity

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

TABLE 2A-i

Values of Weight

and Terminal

Velocity, Computed

for Smooth Ice

Spheres

78
Sean

annual

number

6f

day&

with

hail

APPENDIX 2 Cont

79

FIGURE

2A-3

Mean

Annual

Number

of

Days

with

Hail

[1]
References Appendix 2

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

2. "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.

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

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

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

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

5. Provisional Flat Plate Solar Collector Testing Procedures , First Revision,

NBSIR 78-1305A, National Bureau of Standards, Washington, D.C., June 1978.

80
(Note: This appendix has been significantly revised from "Interim Performance Criteria

for Solar Heating and Combined Heating/Cooling Systems and Dwellings," January 1975.)

APPENDIX 3

Section 1 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 at which

a system and its components are designed to operate, either with or without the flow of heat transfer fluid. The minimum service

temperature refers to the minimum temperature at which a system and

its components are designed to operate, 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 fluid 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 no useful

energy can be removed from 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 at maximum ambient temperature and the heat

transfer fluid is not flowing through the collector (design

maximum no-flow temperature). 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 at maximum ambient temperature and the heat transfer

fluid is flowing through the system (design maximum flow temperature)

A way of determining this temperature is by the limiting temperature

of control devices or relief valves or through theoretical or test

analysis of the system. The design maximum no-flow temperature

that will occur at various locations in the collector can be calculated by use of an analytical model and appropriate environmental

conditions. Typical examples of this type of information are shown

in Figures 3A-1 to 3A-4.

Figures 3A-1 through 3A-4 are intended to provide assistance in

establishing the maximum no-flow temperature of critical components

for four "typical" collector designs. Cover plate and absorber

plate temperatures are plotted as a function of ambient temperature

for exposure to a solar radiation flux of 340 Btu/ft^-hr (1070 W/m^).

Dataare shown for collectors with one and two cover plates with

two cover glass materials (a typical window glass material and a more transparent glass material with a low iron oxide content)

and with spectrally flat and selective black absorber coatings.

The calculations were performed with a transient thermal analysis

computer program using finite difference techniques . \j The calculations were based on the folio-wing assumptions: 1) a glass cover plate thickness of 1/8 in; 2) air space thickness of 3/8 in

between both cover plates and between the absorber surface and the

inner cover plate; 3) zero edge and back losses; 4) incident solar

radiation is normal to the collector; and 5) the following properties of the glass cover plates:

—Ramsey, J. W. , Borzoni, J. T. and Holland, T. H. , "Development of Flat Plate Solar

Collectors for the Heating and Cooling of Buildings," NASA CR-134804, June 1975.

81
APPENDIX 3 Cont.

Conventional Glass Low Iron Oxide Glass

absorptance

extinction coeff.

index of refrac.

thermal cond.

transmittance

emittance

= 0.06

= 0.70 per in

= 1.52

= 0.589 Btu/(ft*h-°F)

= 0.86

= 0.86

absorptance

extinction coeff.

index of refrac.

thermal cond

transmittance

emittance

= 0.02

=0.20 per in

= 1.52

= 0.589 Btu/ (f t’h* °F)

= 0.90

= 0.86

It should be noted that the exposure conditions represent typical

maximum conditions and that a higher solar radiation flux can be

experienced under some atmospheric conditions or by the use of

external reflectors. It is recommended that the temperature of

critical components be experimentally established for particular

collector designs whenever possible.

Section 2 Test Methodology: Criterion 5.1.1, Components or materials shall

be tested using at least one of the following aging procedures and

appropriate evaluation procedures.

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.

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 subject 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.

82
APPENDIX 3 Cont.

Q

£

a.

e©

,a

(Jj 9J*|SiWlU»i

k»3

IS

Ib®

a.E

a?

E

83

Figure

3A1

Maximum

No

Flow

Temperatures

at

Various

Locations

Figure

3A-2

Maximum

No

Flow-Temperatures

at

Various

Locations

in

a

Collector

with

a

Flat

Black

Absorber

(Absorpin

a

Collector

with

a

Selective

Absorber

(Absorptivity

=0.9,

Emissivity

=

0.9)2

and

Two

Glass

tivity

=0.9,

Emissivity

=0.1)

and

Two

Glass

Cover

Plates

(I

=

340

Btu/Hr.ft

,

no

wind)

Cover

Plates

(i=

3

40

Btu/Hr.ft

2

,

no

wind)
APPENDIX 3 Cont

(do) »Jiu*jaduaai

(J0 ) ajmejaduiai

84

Figure

3A-3

Maximum

No

Flow-Temperatures

at

Various

Locations

Figure

3A-4

Maximum

No

Flow-Temperatures

at

Various

Locations

in

a

Collector

with

Flat

Black

Absorber

(Absorpin

a

Collector

with

a

Selective

Absorber

(Absorptivity

-

0.9,

Emissivity

=

0.9)

and

One

Glass

tivity

=

0.9,

Emissivity

=

0.1)

and

One

Glass

Cover

Plate

(I

-

340

Btu/Hr.ft

,

no

wind)

Cover

Plate

(I

=

340

Btu/Hr.ft“,

no

wind)
APPENDIX 3 Cont.

Evaluation

Aging Procedure 3

ASTM reference methods for Aging Procedure 3 include:

D1006-73

D1014-66 (1973)

D1435-75

D1828-70

G7-77

Gll-72

G24-73

Conducting Exterior Exposure Tests of Paints

on Wood

Conducting Exterior Exposure Tests of Paints

on Steel

Outdoor Weathering of Plastics

Atmospheric Exposure of Adhesive Bonded

Joints and Structures

Atmospheric Environmental Exposure Testing

of Non-Metallic Materials

Effects of Outdoor Weathering on Pipeline

Coatings

Conducting Natural Light Exposure Under Glass

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 1300 Btu/ft 2 (350 Langleys).

Evaluation procedures shall be selected to measure the effect of

the aging procedures on important properties of the components or materials

Absorber coatings and polymeric cover plate materials shall be

evaluated before and after aging for optical properties, i.e.

absorptance, emittance and transmittance, as appropriate, using

the following ASTM methods:

E408-71 Total Normal Emittance of Surfaces Using

Inspection Meter Techniques

E424-71 (Method A) Solar Energy Transmittance and Reflectance

of Sheet Materials

Other evaluation procedures shall be used, as appropriate. The

following ASTM procedures are illustrative of the types of procedures that may be used:

Physical Deterioration

D659-74 Evaluating Degree of

of Exterior Paints

Resistance of Chalking

D660-44 (1970) Evaluating Degree of

of Exterior Paints

Resistance of Checking

D661-44 (1975) Evaluating Degree of

of Exterior Paints

Resistance of Cracking

D714-56 (1974) Evaluating Degree of Blistering of Paints

Tensile Strength

C297-61 (1970)

D638-76

D897-72

Tension Test of Flat Sandwich Construction

in Flatwise Plane

Tensile Properties of Plastics

Tensile Properties of Adhesive Bonds

85
APPENDIX 3 Cont.

Flexure Strength

Flexure Testing of Glass (Determination of

Modulus of Rupture)

Flexure Test of Flat Sandwich Constructions

Flexural Properties of Plastics and

Electrical Insulating Materials

C158-72

C393-62 (1970)

D790-71

Evaluations should be performed on both aged and unaged specimens

to establish a basis of comparison.

Commentary The tests 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.

Section 3

Section 4

Test Methodology: Criterion 5.1.4. Testing of non-ferrous metals

shall be performed for a period of 500 hours at the maximum service

temperature. 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. 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.

The resistivity values below give

tionship between soil corrosivity

Resistivity, ohm-cm

Below 500

500 - 1,000

1,000 - 2,000

2,000 - 10,000

above 10,000

The resistivity of the soil shall be

unprotected ferrous metals are to be

be buried in soil shall be resistant

evaluated by ASTM D2017-71.

a rough indication of the relaand resistivity.

Soil Corrosivity

very corrosive

very corrosive

moderately corrosive

mildly corrosive

progressively less corrosive

5,000 ohm-cm or greater if

buried in the soil. Wood to

to natural decay when

Test Methodology: Criterion 5.1.5 . 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.

86
APPENDIX 3 Cont.

Section 5

A. Resistance to Ozone

Coupon specimens of components shall be exposed for 21 days

to an ozone atmosphere of 50+5 pphm/volume in a test chamber

at 23 + 2°C (73.4 + 3.6°F). After 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." Specimens should be stressed to simulate service conditions

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.

B. Resistance to Salt Spray

Coupon specimens of components shall be evaluated in accordance

with ASTM Standard Method B117-73. After exposure for 21 days

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 specimens before and after exposure.

C . Resistance of SO? and N0X

Coupon specimens of components are to be supported vertically

in a closed chamber having openings for gas inlet and outlet

and maintained at a temperature of 23 + 2°C (73.4 + 3.6°F) for

a period of 21 days. An amount of (SO 2 or N0X ) equivalent to

1 percent of the volume of the test chamber shall be introduced into the chamber each working day. A small amount of

water is to be maintained at the bottom of the chamber

Test Me t hodology: Criterion 5.2. 1. Complete components or coupon

specimens shall be subjected to heat aging for a period of 21 days

at the maximum service temperature. Components and materials

stressed in normal use should be stressed during the exposure.

They shall be evaluated using evaluative procedures described in

Section 2 of this Appendix.

When evaluated after exposure to the maximum service temperature,

there shall be no significant signs of cracking, crazing, or blistering and there shall be no significant change in optical

properties of absorber and cover plate materials. Also, the

specimens shall exhibit no significant loss of strength as a result of the aging.

87
APPENDIX 3 Cont

Section 6

Section 7

Section 8

Section 9

Test Methodology: Criterion 5.2.2. All fluids shall be subjected

to the two tests below:

Test 1 - Expose the fluids to their maximum service temperature

for a period of 21 days. The fluids shall contain

turnings of the metal to be used in service in quantities

of 10 g of metal turnings to 100 cc of fluid. Fluid

aeration shall be included in fluids to be used in "open"

systems. Fluid aeration need not be included for "closed"

system usage. The test must be repeated for all metal

materials that are present in the system.

Test 2 - Expose the fluids to their minimum service temperature

for a period of 24 hours.

At the completion of test 1, inspect the fluids visually for signs

of undesired changes such as excessive precipitation or boiling.

Also, before and after test 1, measure the pH and the viscosity of

the fluid and evaluate the infrared spectrum of the fluid to ensure

fluid stability. After the tests, the fluids shall not exhibit

changes that would significantly impair their ability to function.

At the completion of test 2, examine the fluid for an indication

of freezing.

Test Methodology: Criterion 5.3.1 . 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.

Test Methodology: Criterion 5.3.2 . Coupon specimens, or entire

components, shall be immersed in the heat transfer fluid for a period of 42 days. 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 for materials

used in pressurized systems or ASTM D2570-73, Simulated Service

Corrosion Testing of Engine Coolants for materials used in systems

at atmospheric pressure, 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.

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 42 days 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.

88
APPENDIX Cont

Adjoining Dissimilar Materials Not Used in Contact with the Transfer Fluid

Test specimens consisting of dissimilar materials in direct contact with one another shall be subject to the test as described

in Section 4 , resistance to SO 2 and N0X.

Section 10 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.

Section 11 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 ser- vice temperature of the components 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 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.

89
APPENDIX 3 Cont

Section 12 Materials Tables

TABLE 3A-2 Usually Acceptable and Unacceptable Use Conditions for Metals in Direct

Contact with Heat Transfer Liquids in Open Systems

Usually Unacceptable Use Conditions 1 / Usually Acceptable Use Conditions —

Aluminum

1.

When in direct contact with untreated

tap water with pH <5 or >9.

2.

When in direct contact with aqueous

liquid containing less electro positive

metal ions, such as Copper or iron or halide ions

3. When specific data regarding the behavior of a particular alloy are not available, the velocity of aqueous liquid shall not exceed 4 ft/sec.

4. When in direct contact with a liquid

which is in contact with corrosive fluxes.

1. When in direct contact with distilled

or deionized water which contains

appropriate inhibitors and does not contact copper or iron.

2. When in direct contact with distilled

or deionized water which contains

appropriate inhibitors and a means of removing heavy metal ions obtained

from contact with copper or iron.

3. When in direct contact with stable

anhydrous organic liquids.

Copper

1. When in direct contact with aqueous

liquid containing high concentrations

of chlorides, sulfates or liquid which

contains hydrogen sulfide.

2. When in direct contact with chemicals

that can form copper complexes such as ammonium compounds

3. When in direct contact with an aqueous

uid having a velocity greater than 4 ft/sec

4. When in direct contact with a liquid

which is in contact with corrosive fluxes.

1. When in direct contact with distilled,

deionized or low chloride, low sulfate

and low sulfide tap water.

2. When in direct contact with stable

anhydrous organic liquids.

2 /

5. When in contact with an aqueous liquid

with a pH lower than 5.

6. When the copper surface is initially

locally covered with a copper oxide film

or a carbonaceous film.

7.

When operating under conditions conducive

to water line corrosion.

Steel

1. Wien in direct contact with untreated

tap, distilled or deionized water with

pH <8 or >12.

2. When in direct contact with a liquid

which is in contact with corrosive fluxes.

3. When in direct contact with an aqueous

liquid having a velocity greater than

6 ft/sec. U

4. When operating under conditions conducive

to water line corrosion.

1. When in direct contact with distilled,

deionized or low salt content water which contains appropriate corrosion

inhibitors

2. When in direct contact with stable

anhydrous organic liquids.

3. When adequate cathodic protection of the steel is used (practical only for storage tanks)

90
APPENDIX 3 Cont.

TABLE 3A-2 (Contd.)

Usually Unacceptable Use Conditions Usu 1 11

Acceptable Use Conditions 1 /

Stainless Steel

1. When the grade of stainless steel selected is not corrosion resistant in the anticipated heat transfer liquid.

2. When in direct contact with a liquid

which is in contact with corrosive

fluxes

1. When the grade of stainless steel se- lected is resistant to pitting, crevice

corrosion, intergranular attack and stress corrosion cracking in the anticipated use conditions.

2. When in direct contact with stable

anhydrous organic liquids.

Galvanized Steel

1. When in direct contact with aqueous

liquid containing copper ions.

2. Wnen in direct contact with aqueous

liquid with pH <8 or >12.

3. When in direct contact with aqueous

liquid with a temperature >55°C.

1. When adequate cathodic protection of

the galvanized parts is used (practical

only for storage tanks)

2. When in contact with stable anhydrous

organic liquids.

Brass and Other Copper Alloys

Binary copper-zinc brass alloys (CDA 2 XXX series) exhibit generally the same behavior

as copper when exposed to the same conditions. However, the brass selected should

resist dezincification in the operating conditions anticipated. At zinc contents of 15% and greater, these alloys become increasingly susceptible to stress corrosion.

Selection of brass with a zinc content below 15% is advised. There are a variety of other copper alloys available, notably copper-nickel alloys, which have been developed

to provide improved corrosion performance in aqueous environments.

“The use of suitable antifreeze agents and buffers is acceptable provided they do not promote

corrosion of the metallic liquid containment system. The use of suitable corrosion inhibitors for specific metals is acceptable provided they do not promote corrosion of other

metals present in the system. If thermal or chemical degradation of these compounds occurs,

the degradation products should not promote corrosion.

2 /The flow rates at which erosion/corrosion becomes significant will vary with the conditions

of operation. Accordingly, the value listed is approximate.

TABLE 3 A-3 Usually Acceptable and Unacceptable Use Conditions for Metals in

Direct Contact with Heat Transfer Liquids in Closed Systems .

Usually Unacceptable Use Conditions Usually Acceptable Use Conditions 1/

Aluminum

1. When in direct contact with untreated

tap water with pH <5 or >9.

2. When in direct contact with liquid

containing copper, iron or halide ions.

3. When specified data regarding the behavior

of a particular alloy are not available,

the velocity of aqueous liquid shall not exceed 4 ft/sec.

1. When in direct contact with distilled

or deionized water which contains

appropriate corrosion inhibitors.

2. When in direct contact with stable

anhydrous organic liquids.

91
APPENDIX 3 Cont.

TABLE 3A-3 (Contd.)

Usually Unacceptable Use Conditions 1 Usually Acceptable Use Conditions —

Copper

1.

When in direct contact with an aqueous liq^/l.

uid having a velocity greater than 4 ft/sec

When in direct contact with untreated

tap, distilled or deionized water.

2.

When in contact with chemicals that can form copper complexes such as ammonium compounds

2. When in direct contact with stable

anhydrous organic liquids.

3.

When in direct contact with aqueous

liquids which do not form complexes

with copper.

Steel

1. When in direct contact with liquid

having a velocity greater than 6 ft/sec.—

2. When in direct contact with untreated

tap, distilled or deionized water with

pH <8 or >12.

Stainless

1 . When in direct contact with untreated

tap, distilled or deionized water

with pH >8 or <12.

2. When in direct contact with stable

anhydrous organic liquids.

3. When in direct contact with aqueous

liquids of pH >8 or <12.

Steel

1. When the grade of stainless steel selected

is not corrosion resistant in the anticipated heat transfer liquid.

2. When in direct contact with a liquid

which is in contact with corrosive fluxes.

1. When the grade of stainless steel

selected is resistant to pitting,

crevice corrosion, intergranular attack

and stress corrosion cracking in the anticipated use conditions.

2. When in direct contact with stable

anhydrous organic liquids.

Galvanized Steel.

1. When in direct contact with water with 1. When in contact with water of pH >8 pH <8 or >12. but <12.

2. When in direct contact with an aqueous

liquid with a temperature >55°C.

Brass and Other Copper Alloys

Binary copper-zinc brass alloys (CDA 2XXX series) exhibit generally the same behavior

as copper when exposed to the same conditions. However, the brass selected shall resist dezincification in the operating conditions anticipated. At zinc contents of 15% and greater, these alloys become increasingly susceptible to stress corrosion.

Selection of brass with a zinc content below 15% is advised. There are a variety of other copper alloys available, notably copper-nickel alloys, which have been developed

to provide improved corrosion performance in aqueous environments.

1/The use of suitable antifreeze agents and buffers is acceptable provided they do not promote corrosion of the metallic liquid containment system. The use of suitable corrosion

inhibitors for specific metals is acceptable provided they do not promote corrosion of other metals present in the system. If thermal or chemical degradation of these compounds

occurs, the degradation products should not promote corrosion.

2 /The flow rates at which erosion/corrosion becomes significant will vary with the conditions

of operation. Accordingly, the value listed is approximate.

92
TABLE

3

A-4

Properties

of

Typical

Cover

Plate

Materials—

APrEITDIX 3 Cont

e -h ca D 4-1 U

E o

U Cl

<u B

id a id X O H

"8 -8 O rH O »- O Ifl O 0) o d o a

<r c o E C H 4)

Cd -M

TJ

a) O rH o cd o a) 'd’ s

c

cd

Cd O <D O U CL C o e

C O 0)

•H C

cn a)

ti m

AJ to C I

I OJ o

C -H H

cd u a -h x xu ^

cd u

e

*-< C

'

< 0) X

<u cd

cd o

.X r—

cd o

0) QJ

CQ -

<u in > r- O CT>

M-* T3

<U C

(X h-l

93

Clarkson,

C.

W.

,

Herbert,

J.

S.,

"Transparent

Glazing

Media

for

Solar

Energy

Collectors,"

paper

presented

at

U.S.

Section-ISES

Meeting,

Ft.

Collins,

Colorado,

August

71-23,

1974.
TABLE 3A-5 Characteristics of Absorptive Coatings^/

APPENDIX 3 Cent.

Property

Material^'''"*

2/ Absorptance—

a Emittance

e

a

e* Breakdown

Temperature

°F (°C)

Comments

Anodic Aluminum .94-. 96 .3-.

May Be Influenced By

Moisture

Black Chrome .87-. 93 .1 v9

Alkyd Enamel .90 .9 1 Durability Limited at High

Temperatures

Black Acrylic

Paint

.92-. 97 .84-. 90

Black Inorganic

Paint

.89-. 96 .86-. 93 vl

Black Silicone! Paint

.86-. 96 .83-. 89 ^1 Silicone Binder

PbS/Silicone

Paint

.94 .4 2.5 662 (350) Has a High Emittance for Thicknesses >10pm

Flat Black

Paint

.95-. 98 .89-. 97 vl

Ceramic Enamel .93 .84 1.1 Stable at High Temperatures

Black Zinc .90 .1 9

Copper Oxide over Aluminum

.93 .11 8.5 392 (200)

Black Copper

over Copper

.85-. 90 .08-. 12 7-11 842 (450) Patinates with Moisture

Black Chrome

over Nickel

.92-. 96 .07-. 12 8-13 842 (450) Stable at High Temperatures

Black Nickel

over Nickel

.93 .06 15 842 (450) May be Influenced by Moisture

at Elevated Temperatures

Ni-Zn-S over Nickel

.96 .07 14 536 (280)

Black Iron over Steel.90 .10 9

^These valves were obtained from the following references:

G. E. McDonald, "Survey of Coatings for Solar Collectors", NASA TMX-71730, paper presented at Workshop on Solar Collectors for Heating and Cooling of Buildings, November 21-23, 1974,, New York City.

G. E. McDonald, "Variation of Solar-Selective Properties of Black Chrome with Plating Time", NASA TMX-71731 , May 1975.

S. W. Moore, J. D. Balcomb, J. C. Hedstrom, "Design and Testing of a Structurally Integrated Steel Solar Collector Unit Based on Expanded Flat Metal Plates", LA-UR-74-1093 , paper presented at U. S. Section-ISES Meeting, Ft. Collins, Colorado, August 19-23, 1974.

D. P. Grimmer, S. W. Moore, "Practical Aspects of Solar Heating: A Review of Materials Use in Solar Heating Applications", paper presented at SAMPE Meeting, October 14-16, 1975, Hilton Inn.

R. B. Toenjes, "Integrated Solar Energy Collector Final Summary Report", LA-6143-MS, Los Alamos Scientific Laboratory, Los Alamos, New Mexico, November 1975.

G. L. Merrill, "Solar Heating Proof-of-Concept Experiment for a Public School Building", Honeywell

Inc., Minneapolis, Minnesota National Science Foundation Contract No. C-870.

D. L. Kirkpatrick, "Solar Collector Design and Performance Experience", for the Grover Cleveland

School, Boston, Massachusetts, paper presented at Workshop on Solar Collectors for Heating and Cooling of Buildings, November 21-23, 1974, New York City. —

2 /Dependent on thickness and vehicle to binder ratio.

94
APPENDIX 3 Cont.

TABLE 3A-6

1 / Properties of Typical Absorber Substrate Materials—

Material Aluminum Copper Mild Carbon

Steel

Stainless

Steel

Property

Elastic Modulus,

Tension

psi x 10^

10 19 29 28

Density

lbs/cu. in.

0.098 0.323 0.283 0.280

Expansion Coefficient

(68-212°F)

in/ in/°F x 10 6

13.1 9.83 8.4 5.5

Thermal Conductivity

(77-212°F)

Btu/hr-ft 2 - °F/ft

128 218 27 12

Specific Heat

(212 °F)

Btu/lb • °F

0.22 0.09 0.11 0.11

1/ Typical values: standard specifications or manufacturer's literature should be

consulted for specific types or alloys.

95
APPENDIX 3 Cont

TABLE 3A

Thermal Storage Unit Containers^

Container

Usage Above BelowTransfer MediaPressure

Conditions

3/ Recommended—

Container Standard Protective

Coating

Recommended

Coating

Standard Material Ground Ground Air Liquid High Low 2/ Compliance Ext . Int

Compliance

Aluminum X X X X X ANSI B96.1

1973

- -

Concrete X X X X X X IAPMO PS I (1966)

X X Ext. MPS

609-7.3

Int. TTP-95A(3)

27 May 66

Earth X X X Vapor Barrier

Materials as per ASTM E154.68

Vapor Barrier Covering of Solids RequiredMPS 507.2.2

Plastics X X X X X MIL-T-52777 4/

21 Feb 1974

- -

Steel X X X X X X AWWA D-100

(1967)

X X Ext. MPS

609-7.4 5/

Ext. 6 Int. AWWA D10

(1964)

Wood X X X X NWTI S-75^ - -

1/ Thermal Storage Unit - any container, space, or device which has the capacity to store transfer media

(liquid or solid) containing thermal energy for later use.

2/ Low pressure systems are those subjected to atmospheric pressure only, i.e. vented.

3/ When applicable, ASME Boiler and Pressure Vessel Code, Section VIII may be used.

4J Refers to fiber reinforced polyester containers

5/ In lieu of interior galvanized, glass-lined or stone-lined tanks.

6 / "Specifications and Recommended Practice for Wood Tanks and publication S-75, National Wood Tank Institute, 848 Eastman Continuous Stove

Street, Chic Ago, Wool Pipe,"

Li, 1)0622, !')!'.

06
APPENDIX 3 Cont

97
GLOSSARY

Absorptance: The ratio of the amount of radiation absorbed by a surface to the amount of

radiation incident upon it (for terrestrial applications, usually calculated for air mass 2 characteristics)

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: An air gap in a potable water distribution system is 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. (NSPC)*

Auxiliary energy subsystem: Equipment utilizing energy other than solar both to supplement

the output provided by the solar energy system as required by the design conditions and to provide full energy backup requirements during periods when the solar H or DHW systems are inoperable. It may be integrated directly into the solar energy system, or it may be com- pletely separate from it and contain its own means for delivery of heating, cooling and/or

hot water to the building.

Backflow: The flow of water or other liquids, mixtures or substances into the distribution

pipes of a potable supply of water from any source or sources other than its intended source.

Backflow preventer: A device or means to prevent backflow into the potable water system.

Chemical compatibility: The ability of materials to remain in contact with each other without chemical interaction, such as electrolytic action or plasticizer migration.

Collector, combined: The collector and storage are constructed and operated such that they

functionally perform as one unit and the thermal performance of the individual components

cannot be meaningfully measured.

Collector, component: Collector that is not thermally integrated with the storage or building. The collector performance can be thermally characterized as an individual com- ponent with a moving heat transfer fluid.

Collector efficiency (ASHRAE 93-77): The amount of energy removed by the transfer fluid

per unit of gross collector area during the specified time period divided by the- total

solar radiation incident on the collector per unit area during the same test period, under

steady state or quasi-steady state.

Collector subsystem: The assembly used for absorbing solar radiation, converting it into

useful thermal energy and transferring the thermal energy to a heat transfer fluid. It includes the entire collector array, with its one or more collector units, together with

manifolding and interconnections.

Combustible liquid: Combustible liquid shall mean any liquid having a flash point at or above 100°F (37.8°C) (NFPA 321).

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).

*National Standard Plumbing Code

98
Contaminants (hazardous) : Materials (solids or liquids or gases) which when added unintentionally (or intentionally) to the potable water supply cause it to be unfit for human or animal consumption. (ASSE 1013)

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 or building.

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. 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.

Creep: A time-dependent deformation resulting from sustained loads which can be influenced

by factors such as temperature and solar radiation.

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.

* Design maximum flow temperature: The maximum temperature that will be obtained in a component when the heat transfer fluid is flowing through the system.

Design 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.

Dielectric fitting: An insulating or non-conducting fitting used to isolate electrochemically dissimilar materials.

Ease of ignition: The flame exposure time required to produce sustained flaming of a representative specimen of material from a controlled impinging flame source.

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: Those portions of an H/C/HW system which contain heat transfer

fluids and transport energy throughout the system.

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) Structural deflections under design loads that cause significant performance

degradation of the component or subsystem.

Flammable liquid: Any liquid having a flash point below 100°F (37.8°C) and having a vapor

pressure not exceeding 40 pounds per square inch absolute (2068.6 mm) at 100°F (37.8°C)

(NFPA 321).

Flash point: The minimum temperature of a liquid at which sufficient vapor is given off to form an ignitible mixture with the air near the surface of the liquid or within the vessel

used as determined by appropriate test procedure and apparatus as specified in NFPA 321.

Flow condition: The condition obtained when the heat transfer fluid is flowing through the

collector array under normal conditions.

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.

99
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. 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 non-potable depending

on its intended use.

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.

Manual of Acceptable Practices (MAP): A HUD document providing information and guidance to assist in the use of the MPS.

Maximum service temperature: The maximum temperature at which a system and its components

are designed to operate 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 at which a system and its components

are designed to operate either with or without the flow of heat transfer fluid.

MPS 4900.1

MPS 4910.1

MPS 4920.1

MPS 4930.2

Hot Water Systems."

FHA "Minimum Property Standards for One and Two Family Dwellings."

FHA "Minimum Property Standards for Multifamily Housing."

FHA "Minimum Property Standards for Care-Type Housing."

FHA "Intermediate Property Standards Supplement - Solar Heating and Domestic

"No-flow" condition: That condition obtained when the heat transfer fluid is not flowing

through the collector array due to shutdown or malfunction and the collector is exposed to the amount of solar radiation that it would receive under normal operating conditions.

Heat transfer fluid may be in the collector but it is not flowing.

Operating energy: The conventional energy required to operate the H/C/HW systems,

excluding the auxiliary energy which supplements the solar energy collected by the systems

(e.g. the electrical energy required to operate the energy transport and control subsystems).

Outgassing: The emission of gases by materials and components usually during exposure to elevated temperature or reduced pressure.

Pitting: The process by which localized material loss is caused in materials or components

by erosion or chemical decomposition.

Physical compatibility: The ability of materials and components in contact with each

other to resist degradation by physical actions such as differential thermal expansion.

Plasticizer migration: The movement of plasticizers used in plastic materials. These

plasticizers may concentrate in a narrow boundary area or migrate to another material in

connection with the specimen.

Potable water: Water free from impurities present in amounts sufficient to cause disease

or harmful physiological effects and conforming in its bacteriological and chemical quality

to the requirements of the Public Health Service Drinking Water Standards or the regulations

of the public health authority having jurisdiction. (BOCA)

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.

100
pphm: Parts per hundred million.

Premature failure: Failure that occurs before the design lifetime.

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 with 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.

Safety glazing materials: Glazing materials so constructed, treated or combined with other

materials as to minimize the likelihood of cutting and piercing injuries resulting from

human contact with these glazing materials.

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 having a terrestrial

wavelength range (air mass 2) from 0.3 to 2.4 micrometers (300-2400 nanometer).

Solar energy system, active: A system which may include collectors, thermal storage, heat

transfer fluid and load, and which utilizes solar energy or environmental energy sinks for

heating or cooling and in which all energy flows are by forced means (pumps or fans).

Solar energy system, hybrid: A system which may include collectors, thermal storage, heat

transfer fluid and load, and which utilizes solar energy or environmental energy sinks for

heating and cooling and in which at least one energy flow is by forced means and at least

one is by natural means.

Solar energy system, passive: A system which may include collectors, thermal storage, heat

transfer fluid and load, and which utilizes solar energy or environmental energy sinks for

heating and cooling and in which all energy flows are by natural means (conduction, convection, radiation, or evaporation)

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 time 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 such as complete collector

array or storage unit.

System: The complete assembly of subsystems and components necessary to supply heating/

cooling and/or hot water to the building.

Tap temperature: The temperature at which hot water is discharged from an outlet at the

point of use.

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.

101
Toxic fluids: Gases or liquids which are poisonous, irritating and/or suffocating, as classified in the Hazardous Substances Act, Code of Federal Regulations, Title 16, Part 1500.

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 non-linear distribution of flexural

stresses

UV: Ultra-violet radiation, that part of the terrestrial solar energy between 0.3 and 0.4

micrometers (300-400 nanometers).

Vertical penetrations: The vertical passage of a utility chase, pipe, duct, etc., through

a fire-rated structural assembly.

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 summer design temperature: The outdoor air temperature will be higher than

the stated value not more than 73 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 will be lower than

the stated values for not more than 54 hours per year (2 1/2% of the 2,160 hours in

December, January and February).

102
ABBREVIATIONS

AASHTO

AGA

ANSI

ARI

ASHRAE

ASME

ASTM

DOE

ERDA

FM

HUD

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

Department of Energy

Energy Research and Development Administration

Factory Manual

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 Association

Occupational Safety and Health Association

Society of Automotive Engineers

Sheet Metal and Air-Conditioning Contractor's National Association

Uniform Building Code

Underwriters Laboratories, Inc.

103
-

'
NBS-114A (REV. 7-73)

U.S. DEPT. OF COMM. 1. PUBLICATION OR REPORT NO. 2. Gov’t Accession

BIBLIOGRAPHIC DATA No. Sheet NBSIR 78-1562

3. Recipient’s Accession No.

4 . TITLE AND SUBTITLE

Interim Performance Criteria for Solar Heating and

Cooling of Residential Buildings

5. Publication Date November 1978

6. Performing Organization Code

744.00

7. AUTHOR(S)

John K. Holton

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. 7446500 (Task F)

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Division of Energy, Building Technology § Standards

Office of Policy Development and Research

Department of Housing and Urban Development

Washington, D.C. 20410

13. Type of Report & Period Covered

Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) The interim performance criteria, developed for the Department of Housing and Urban

Development, is a baseline document for criteria and standards for the design, development, technical evaluation and procurement of the solar heating and cooling systems to

be used in residential 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 "residential criteria" document, represents the first

revision to the "Interim Performance Criteria for Solar Heating and Combined Heating/

Cooling Systems and Dwellings" published in January 1975, Its revision draws upon

comments received and experience gained in the use of two companion documents, the

"Interim Performance Criteria for Solar Heating and Cooling Systems in Commercial

Buildings," NBSIR 76-1187, and the "HUD Intermediate Minimum Property Standards Supplement, 1977 Edition, Solar Heating and Domestic Hot Water Systems," 4930,2,

These interim criteria are intended primarily for use in the solar residential demonstration program and as a basis for the preparation of definitive performance criteria

in accordance with the requirements of Section 8 of PL 93-409,

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 KX1 Unlimited 19. SECURITY CLASS

(THIS REPORT)

21. NO. OF PAGES

1 | For Official Distribution. Do Not Release to NTIS

UNCLASSIFIED

113

| | Order From Sup. of Doc., U.S. Government Printing Office Washington, D.C. 20402. SD Cat. No. Cl^,

20. SECURITY CLASS

(THIS PAGE)

22. Price

|X 1 Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151 UNCLASSIFIED

$ 6 ®50

USCOMM-DC 29042- P 74
'