c. 2 i»

NBS BUILDING SCIENCE SERIES 147

Performance Criteria for Solar

Heating and Cooling Systems

in Residential Buildings

Prepared for:

U.S. DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT

OFFICE OF POLICY DEVELOPMENT AND RESEARCH o ^

U.S. DEPARTMENT OF COMMERCE • NATIONAL BUREAU OF STANDARDS '^''^
NATIONAL BUREAU OF STANDARDS

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

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

the Institute for Computer Sciences and Technology.

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Engineering — Building Technology — Fire Research — Chemical Engineering^

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

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National Bureau of Standard;

Library, £-01 Admin. Bidg.

OCT 2 5 1982

NBS BUILDING SCIENCE SERIES 147

Performance Criteria for Solar Heating and

Cooling Systems in Residential Buildings

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

Washington, DC 20234

Prepared for: -

, U.S. Department of Housing and Urban Development

Office of Policy Development and Research

Building Technology Division

Washington, DC 20410

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

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Issued September 1982
Library of Congress Catalog Card Number: 82-600581

National Bureau of Standards Building Science Series 147

Natl. Bur. Stand. (U.S.), Bldg. Sci. Ser. 147, 236 pages (Sept. 1982)

CODEN: BSSNBV

U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 1982

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

Price $7.50

(Add 25 percent for other than U.S. mailing)
TABLE OF CONTENTS

Page

ACKNOWLEDGMENTS Iv

FOREWORD V

INTRODUCTION 1 TERMINOLOGY 7

1. SITE AND BUILDING 1-1

2. THERMAL 2-1

3. MECHANICAL 3-1

4. SAFETY AND HEALTH 4-1

5. DURABILITY/ RELIABILITY 5-1

6. OPERATION AND SERVICING 6-1

APPENDIX A A-a

DURABILITY/RELIABILITY SECTIONS (Sec. 1 thru Sec. 10) A-1

REFERENCES A-21

APPENDIX B B-a

MATERIALS TABLES B-1

TECHNICAL REVIEW ITEMS B-8

REFERENCES B-1

ABBREVIATIONS B-1

SI CONVERSION UNITS B-1

COMPOSITE INDEX I-l

ill
ACKNOWLEDGMENTS

This document was prepared by the Center for Building Technology staff

of the National Bureau of Standards. Members who participated in the

preparation of these performance criteria include:

F. Eugene Metz (Former project leader)

John K. Holton (Former project leader)

Thomas H, Boone

Leopold F. Skoda

Michael F . McCabe

Elmer P. Streed

Lawrence W. Masters

Elizabeth J. Clark

Paul W. Brown

W. Douglas Walton (Center for Fire Research)

David Waksman

Thomas K. Faison

Belinda C. Reeder

Robert D. Dikkers ^

'

Acknowledgment is also made of the helpful comments and suggestions

received from William Freeborne and David Moore of the Department of

Housing and Urban Development, David E. Cassel and the staff of Mueller

Associates. Special thanks is given to Leslie Suddueth, Ulesia Gray,

and Brenda Thompson for their patience and excellent job of typing this

document as well as many early drafts. Thanks is also given to Walter

E. Shipp for preparing the composite index to the document.

The buildings drawn on the cover are representative of projects that were

built under the HUD Solar Residential Demonstration Program. They are located in Washington State; Shelton, Connecticut; Shenandoah, Georgia;

and Palo Alto, California. They demonstrate applications of passive and

air and liquid active systems.

iv
FOREWORD

The Solar Heating and Cooling Demonstration Act of 1974 (Pub. L. 93-409)

authorized a five-year program for research, demonstration, and market

development of solar heating and cooling systems in residential and com- merical buildings. As part of this program, the Act directed the Secretary

of the Department of Housing and Urban Development (HUD), utilizing the

services of the Director of the National Bureau of Standards (NBS) , to

develop and publish Interim Performance Criteria for solar heating and

cooling systems and buildings within 120 days of enactment, and to use these criteria in the selection of solar systems and demonstration projects. The Interim Criteria were published on January 1, 1975. The Act

further directed (HUD), utilizing the services of NBS and information

developed in the demonstration program, to develop and publish "definitive

performance criteria" as soon as feasible.

In the period from 1975 through 1979, HUD awarded 783 grants to support

demonstrations of solar heating, cooling, and domestic hot water systems

in 12,423 dwelling units. A number of these projects were equipped with

sophisticated instrumentation systems to measure the solar system performance. In addition, operating, maintenance, and repair information was collected from many more projects. This information has been used by HUD

and NBS to evaluate the effectiveness of the original Interim Performance

Criteria and to develop new, more precise criteria for solar system performance, thereby meeting the requirements of Section 8 of the Act.

Extensive use also has been made of technical information developed from

concurrent Department of Energy solar research, development, and

demonstration activities.

These Performance Criteria are not intended to be used as mandatory

standards governing the procurement or acceptability of solar systems

proposed for HUD or other Federal solar activities. Instead, the document

will serve as a technical reference and resource for the solar industry,

the building industry, and Federal, State, and local agencies concerned

with assessing the design and performance of solar systems in buildings.

For example, HUD relies on HUD 4930.2, the Intermediate Minimum Property

Standards (IMPS) Supplement for Solar Heating and Domestic Hot Water

Systems to control the quality of solar systems proposed for use in HUDassisted housing programs. These IMPS are based on the performance

requirements of the original Interim Performance Criteria; further

revisions will reflect the new Performance Criteria requirements.

The document is intended to establish minimum levels of performance with

regard to health and safety and the various aspects of technical performance. The criteria for health and safety put primary emphasis on compliance with existing codes and standards. The criteria on thermal

and mechanical performance, durability/reliability, and operation/servicing present performance requirements considered to be representative of

acceptable levels. By the use of performance language in the document,

it is believed that sufficient latitude has been provided to allow the

V
innovation and flexibility that is essential for the stimulation of a viable solar industry at this time and in the future.

In developing these criteria, several sources have been utilized:

° Performance criteria developed by the National Bureau of Standards

(NBS) for the Department of Housing and Urban Development (HUD)

and the Department of Energy (DoE).

- "Interim Performance Criteria for Solar Heating and Combined

Heating/Cooling Systems and Dwellings" - January 1975

- "Interim Performance Criteria for Solar Heating and Cooling

Systems in Commercial Buildings" - NBSIR 76-1187, November

1976

- "HUD Intermediate Minimum Property Standards Supplement, 1977

Edition, Solar Heating and Domestic Hot Water Systems" -4930.2

- "Interim Performance Criteria for Solar Heating and Cooling

Systems in Residential Buildings" - NBSIR 78-1562, November

1978

- "Performance Criteria for Solar Heating and Cooling Systems

in Residential Buildings" (Draft for Public Comment) - NBSIR

80-2095, Revised January 1981, Federal Register , Vol. 46,

No. 121, pp. 32740-32823, June 24, 1981.

° Experience gained in the Federal Solar Demonstration Program

(Residential/Commercial) through feedback as provided for in

P.L. 93-409

° Findings from solar research activities

- Government laboratories - National Bureau of Standards, Los

Alamos Scientific Laboratory, National Aeronautics and Space

Administration, Argonne National Laboratory

- Sponsored research - Dubin-Bloorae Associates, Planning Research

Corporation Energy Analysis Company, Boeing Aerospace Company,

International Business Machines, University of Wisconsin,

Colorado State University, Mueller Associates, Automation

Industries (Vitro Laboratory Division).

° Critique and commentary from

- Model code groups - Council of American Building Officials,

National Conference of States on Building Codes and Standards,

International Conference of Building Officials, Building Officials and Code Administrators International, Inc., Southern

Building Code Congress International.

vi
- Technical standards organizations - American Society for Testing

and Materials, American Society of Heating, Refrigerating and

Air-Conditioning Engineers, American Society of Mechanical

Engineers, Inc., American National Standards Institute.

- Industry organizations - Solar Energy Industries Association,

Inc., Solar Energy Research and Education Foundation, AirConditioning and Refrigeration Institute, Sheet Metal and AirConditioning Contractors National Association, Inc.

- Professional organizations - American Institute of Architects

- Special studies - Burt-Hill-Kosar-Rittelman Associates, TravisBraun Associates, Robertson Ward, Jr., FAIA, Florida Solar

Energy Center, Polytechnic Institute of New York, Mueller

Associates

- Various organizations and individuals responding to request for

public comments on NBSIR 80-2095, ( Federal Register , Vol. 46,

No. 121, pp. 32740-32823, June 24, 1981.)

vii
Abstxact

This performance criteria, developed for the Eteparbment of Housing

and Urban Developirent , is a baseline document for criteria and

standards for the design, development, technical evaluation, and

procurement of solar heating and cooling systems for residential

buildings in accordance with the requirements of Section 8 of

Public Law 93-409, the "Solar Heating and Cooling DemDnstration

Act of 1974." The document is intended to establish minimum levels

of performance with regard to health and safety and the various aspects

of technical performance. The criteria for health and safety put

primary enphasis on corpliance with existing codes and standards.

The criteria on thermal and mechanical performance, durability/

reliability and operation/servicing present performance requirements

considered to be representative of acceptable levels. By the use of

performance language in the document, it is believed that sufficient

latitude has been provided to allcw the innovation and flexibility that is essential for the stimulation of a viable solar

industry at this time and in the future.

Key Words: building; cooling; heating; hot water; performance criteria;

solar energy; standards.

viii
INTRODUCTION

Background

Public Law 93-409 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, HUD has utilized the services of NBS to develop this document.

Objectives

These criteria have the following objectives:

1. Aid consumer acceptance by the provision of validated consensus performance measures;

2. Assist Industry growth through accepted uniform methods of

technical performance assessment;

3. Assist the administration of Federal Incentives programs.

Including tax credits, by the establishment of standard performance measures

4. Assist regulatory authorities In developing and Interpreting

health and safety code provisions;

5. Aid financial and Insurance organizations by the provision of

standard performance criteria upon which to base risk assessment;

6. Assist public and private building programs through provision of

a technical performance assessment base from which project

construction specifications may be developed; and

7. Guide Industry, professional and educational organizations in

the development of appropriate good practice manuals.

Scope

The performance criteria cover both passive and active solar heating,

cooling, and domestic hot water Installations or combinations thereofi'

in individual buildings or central systems for groups of buildings both

new and existing.

]J Although not specifically mentioned in P.L, 93-409, it is recognized

in this document that not all cooling systems are combined with heating

systems

1
The criteria do not cover swimming pool heaters but they do cover pools

within buildings used to moderate environmental conditions or to store

heat for reuse. They do not cover photovoltaic, wind, biomass, or process

heating or cooling applications. The criteria are related primarily to

technical performance and do not directly address economic considerations,

energy conservation, lighting either natural or artificial, or site

selection.

The criteria given in this document primarily consider aspects of planning

and design that are different from conventional buildings by reason of

the solar energy systems under consideration and are intended to:

1. Establish minimum levels for health and safety that are consistent with those presently established for conventional systems

used in building 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 building applications;

3. Verify that proposed systems and components are capable of

providing their design performance levels;

4. Ascertain that the systems and components are durable, reliable,

readily maintainable, and generally constructed in accordance

with good practice; and

5. Provide appropriate instructions and information for the operation and servicing of the systems and components.

Many of the problems and circumstances discussed in the criteria are unique to solar installations. Several useful references drawn from the

Federal Solar Demonstration Program give insight into such problems,

References [1, 2, 3, 4, 5, 6, 7, 8].*

Reference is also made to the American National Standard Recommended

Requirements to Code Officials for Solar Heating, Cooling, and Hot Water

Systems, Reference [9] . This document identifies health and safety

requirements for solar systems.

The performance criteria are intended to be flexible in order to allow

freedom of design and encourage innovation in keeping with the intent of

P.L. 93-409.

Many of the criteria which explicitly address active solar systems also

have implications with regard to passive systems. The majority of the

* Numbers in brackets [ ] indicate references at the end of this

introductory section.

2
criteria which are directly intended for passive systems are found in

Chapters 1 and 2. Several of the other criteria, especially those dealing with health and safety concerns are applicable to passive systems, as well as active ones. Judgement must be exercised in applying the criteria

to assure that passive system concerns are adequately addressed.

Organization and Format

This document is organized on the basis of performance criteria dealing

with heating, cooling, and hot water systems and their integration into

buildings

Performance statement entries, with the exception of Chapter 1, 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 components 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 considerations that are necessary to meet the requirement. Due to limitations

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

in each criterion in this document. In addition, quantitative statements

have been intentionally omitted in some criteria where these values will

be provided by the designer. The Evaluation sets forth the record of

experience, 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

documentation, or other methods that may be used in evaluating whether or not the system and its components 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

informational purposes and in some instances, provides design guidelines.

Such guidelines are only one suggestion of appropriate methods; in most

instances, there will be other methods equally as effective. Including

a commentary in the presentation ensures a workable process of updating

these performance criteria. The commentary provides the rationale for

selection of performance levels and methods of evaluation. When questions arise as to the basis for a particular criterion, the reader will

have available the rationale behind the criterion. With the present

state-of-the-art, there will be a need for periodic updates to adjust

levels of acceptability for both systems and components.

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

attributes listed below:

3
1. Site and Building performance statements deal with the interactions between the solar energy system and its surrounding environment, the site, and building. 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. Because of their more general nature, the statements in

this chapter are not organized in the Requirement/Criterion/

Evaluation/ Commentary format discussed previously.

2. Thermal performance statements are used to evaluate the ability

of systems and their components, as designed, to operate and

provide their rated output and, in some cases, to evaluate the

determination of that 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.

3. Mechanical performance statements address the mechanical design

and performance of the solar energy systems and their components.

Factors such as the ability of the system to withstand normal

design service conditions, e.g., pressure and temperature, are considered under this category.

4. Safety and Health deals with the mitigation of hazards that

would result in personal injury or property damage. Hazards

such as those due to scalding, lacerating, toxic and/or flammable

materials are also considered under this category.

5. Durability/Reliability relate to the ability of systems and their

components 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 components that allow them to be maintained in good operat-

' ing condition for extended periods of time. Manuals and instructions, routine scheduled maintenance, corrective maintenance,

replacements, and repairs are considered under this category.

Accessibility is an important maintainability consideration.

Appendices A and B reference conditions for and methods of testing and

evaluation that can be used to prove compliance with stated requirements.

As a general rule, concensus standards are to be used when applicable.

The Technical Review Items included in Appendix B can be used as a guide

to system design and technical evaluation. The Abbreviations section

offers the names of Code Groups, Associations, and Government Agencies.

The SI Conversion Units section offers metric conversion factors for all

quantitative units appearing in the text.
The Composite Index locates components, materials, operations, and other

technical topics according to their appearance in the text.

For the purposes of this document, the various systems and components,

both active and passive, treated in this document are abbreviated as follows

(H) Heating system

(C) Cooling system

(HW) Hot water system (domestic HW)

(H/C/HW) is used when a requirement or criterion is applicable to

the individual H, C, HW system or any combination thereof.

1

i

5
References

1 . Proceedings of the Solar Heating and Cooling Demonstration Program

Contractors' Review , December 5-7, 1977, New Orleans, LA, Vol. 2,

CONF 771229, Department of Energy.^/

2 . Proceedings of 3rd Annual Solar Heating and Cooling Research and

Development Branch Contractors' Meeting , September 24-27, 1978,

Washington, DC, Department of Energy.

3 . Conference Proceedings- Solar Heating and Cooling Systems Operational

Results , November 28-December 1, 1978, Colorado Springs, CO, Department of Energy .Jl^

4 . Standard Practice for Installation and Service of Solar Space Heating

Systems for One- and Two-Family Dwellings, ASTM E683-79, 1979, ASTM,

1916 Race Street, Philadelphia, PA 19103.

5. Installation Guidelines for Solar DHW Systems in One- and Two-Family

Dwellings , HUD-PDR-407 , GPO 023-000-00520-4, U.S. Department of Housing and Urban Development, April 1979.^/

6. Welnsteln, S., Architectural Concerns in Solar System Design and

Installation, Solar/0801-79/01, U.S. Department of Energy, March

1979.1/

7. Easterly, J., Engineering Concerns in Solar System Design and Operation , Solar/0811-79/01, U.S. Department of Energy, March 1979._L/

8. National Solar Heating and Cooling Demonstration Program - Project

Experience Handbook , Preliminary Draft, DoE/CS-0045/0 , U.S. Department of Energy, September 1978.J:'

9 . American National Standard Recommended Requirements to Code Officials

for Solar Heating, Cooling and Hot Water Systems , ANSI/CABO 1.0-1981,

Council of American Building Officials, 1981.

1/ Technical Information Center, P.O. Box 62, Oak Ridge, TN 37830.

2./ Superintendent of Documents, U. S. Government Printing Office,

Washington, DC 20402.

A/ National Technical Information Service, 5285 Port Royal Road,

Springfield, VA 22161.

6
TERMINOLOGY*

Absorber: The part of the solar collector that receives the incident

solar radiation and transforms it into thermal energy.

Absotptance: The ratio of the amount of radiation absorbed by a surface

to the amount of radiation incident upon it.

Active solar system: A method of space conditioning or water heating

that utilizes solar radiation primarily by means of mechanical

equipment rather than building elements.

Air chamber: A closed section of pipe or a container filled with air

entrapped at atmospheric pressure that when mounted in a water

supply line absorbs the pressure surges caused by the rapid opening

and closing of valves.

Air mass: The ratio of the mass of atmosphere in the actual earth-sun

path to the mass that would exist if the sun were directly overhead

at sea level.

Aperture: An opening in a building wall, roof, or other collection device

that transmits solar radiation.

Applicable authority: The organization, office, or individual responsible

for approving equipment, an installation, procedures, or performance

levels. An applicable authority may range from a code official to an individual owner.

Auxiliary energy system: 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 necessary energy

back up requirements during periods when the solar H, C or HW systems are inoperable. It may be integrated directly into the solar

energy system or it may be completely separate from it and contain

its own means for delivery of heating, cooling, and/or hot water to

the building.

Backflow: The flow in pipes, ducts, and other chambers opposite to the

intended direction of flow. Backflow may occur under two conditions:

pressure greater than atmospheric and pressure that is subatmospheric

(see "Backsiphonage" )

.

* The definitions given here are for use in this document only.

7
Backflow preventer: A device or means to prevent backflow, especially

in regard to the potential for contamination of potable water supply.

Backsiphonage : A form of backflow due to a negative or subatmospheric

pressure.

Chemical incompatibility: The inability of materials to remain in contact

with each other without chemical interaction, such as electrolytic

action or plasticizer migration.

Closed system: An arrangement in hydronic systems where ambient air is

not allowed to enter the system under normal operating conditions.

Collector array: Group of solar collectors or absorbing surfaces con- nected by pipes or ducts and including any pipes or ducts to the

point where there is only one inlet and one outlet.

Collector array manifold: All pipes or ducts within the collector array

but external to the collector panels.

Collector azimuth angle: The angle between the direction the collectors

face and due south (in the northern hemisphere).

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 time period, under steady

state or quasi-steady state conditions.

Collector orientation: Combination of collector tilt and azimuth angles.

Collector tilt angle: The acute angle between the collector plane and

horizontal.

Cooling degree days: The number of degrees that the daily mean temperature is above 65°F (18.3°C). These are totaled to give cooling

degree days per month or per year.

Cooling (C) system: The complete assembly 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).

Combustible liquid: Combustible liquid shall mean any liquid having a flash point at or above 100°F (37. 8° C) (See "Flammable liquid").

Combustible material: See noncombustible material.

8
Contaminants (hazardous): Materials (solids, liquids or gases) which

when added unintentionally (or intentionally) to the potable water

supply cause it to be unfit for human consumption.

Control system: 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.

Creep: A time-dependent deformation of material resulting from sustained

loads which can be influenced by factors such as temperature and

solar radiation.

Depletable energy: Energy from any source other than solar energy

converted to thermal energy at the building site or from thermal

energy extracted from the air, groundwater, or ground. Depletable

energy sources include coal, natural or manufactured gas, oil, other

petroleum products, wood, and electricity. Electricity produced offsite is considered to be depletable energy, even though the source

of the electricity may be some form of solar energy such as hydropower or wind.

Depletable energy limit: Allowable depletable energy use over one year

for a H/C/HW system based on predicted system performance.

Design hot water load: The rate of energy required to be added by the

mechanical system to the water at design maximum hot water use rate

and temperature, not including energy to offset standby water heater,

recirculation, and distribution losses. Normally, the design hot

water load is determined by a combination of recovery rate and hot

water storage capacity.

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.

Design space cooling load: The instantaneous rate of energy required to

be removed by the mechanical system from the space being cooled to

achieve space cooling under summer design conditions.

9
Design space heating load: The Instantaneous rate of heat required to

be added by the mechanical system to the space being heated to

achieve space heating under winter design conditions.

Design working pressure; The value of the pressure used in design calculations for pressure related operational and construction characteristics. This is the maximum allowable working pressure for which a specific part of a system is designed.

Dielectric fitting: An insulating fitting used to isolate electrochemically dissimilar materials.

Draindown system: Function of an open-loop solar water system in which

all water drains out of the collectors and exposed piping at a pre-set point above the freezing temperature.

Drainback system: A liquid solar collector system in which the collector

fluid drains down to an interior storage tank when the collector is

not operating.

Ease of ignition: The time elapsed between the exposure of a material

to a controlled heat or flame source and the onset of flaming. The ease of ignition may be used in analyzing the relative fire hazard

of the materials.

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 system: Those portions of the H/C/HW systems that

convey energy from one place to another. Heat transfer from the

collector to storage and from storage to the point of use is

accomplished through the energy transport 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

(275 KPa) absolute (2068.6 mm Hg) at 100°F (37.8°C) (NFPA 321) (see

"Combustible liquid").

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 procedures and apparatus as specified in NFPA

321

10

\
Flow condition: The situation that exists when the heat transfer fluid

is moving through the collector array under normal conditions.

Fully conditioned space: The volume within the building envelope in

which a temperature of 70°F (21°C) is capable of being maintained

during the 97-1/2 percent winter outdoor heating design temperature

conditions.

Glazing: A membrane or sheet of transparent or translucent material

(glass or plastic) used for admitting light. Glazing retards heat

losses due to reradiation and convection. Examples: windows,

skylights, greenhouse and collector coverings.

Gross floor area: Floor area of the building measured to the outside of

exterior walls that enclose fully conditioned spaces and to the

center of party walls and walls adjacent to semi-conditioned spaces.

Gross solar contribution: Total solar input of a passive solar energy

system less excess energy discharge (venting) losses due to the

passive solar energy system.

H/C/HW system: The mechanical space heating, space cooling, or hot water

system, or any combination thereof, in which solar energy intercepted

at the building site is converted to usable thermal energy to satisfy

partially or fully the respective energy requirements. This includes

systems having discrete collectors with thermos iphon-driven control

for air- or liquid-type collectors.

Hazardous substances: See "Federal Hazardous Substances Act Regulations,"

Code of Federal Regulations (CFR) , Title 16, Part 1500.3 (b)(4)(i).

The following is an extraction of the definition: "Any substance

or mixture of substances which is toxic, corrosive, an irritant, a strong sensitizer, flammable or combustible, or generates pressure

through decomposition, heat or other means, if such substance or mixture of substances may cause substantial personal injury or substantial illness during or as a proximate result of any customary or reasonably foreseeable handling or use, including reasonably foreseeable ingestion by children. 'Hazardous substances' shall not apply

to substances intended for use as fuels when stored in containers

and used in the heating, cooling, or refrigeration system of a house."

Heating degree days: The number of degrees that the daily mean temperature

is below 65°F (18.3°C). These are totaled to give heating degree

days per month or per year.

Heating (H) system: The complete assembly of systems necessary to convert

solar energy into thermal energy and use this energy in combination

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

Highly toxic: See "Federal Hazardous Substances Act Regulations," Code

of Federal Regulations (CFR), Title 16, Part 1500 .3(b) ( 6) ( i) . The

11
following is an extraction of the definition: "'Highly toxic' means

any substance producing a lethal dose in half (LD50) of white rats,

when ingested as a single dose, of 50 rag or less per kg of body

weight." Part 1500,3(c)( 1 )(i) and (ii) also gives further specific

definitions relative to inhalation and absorption. Human data, when

available, shall take precedence (see also "Toxic").

Hot water energy requirements: Energy required over a given period of

time to heat the supply water to a designated use temperature,

including energy required to offset standby water heater, recirculation and distribution losses, but not including hot water system

operating energy.

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. It may either be integrated directly

into the H, C or combined H and C (H/C) system or be completely

separate from them.

In-service conditions: The conditions to which a solar H/C/HW system

will be exposed during its operational lifetime.

Langley: The meteorologist's unit of solar radiation intensity, equivalent to 1.0 gram calorie per square centimeter, usually used in

terms of langleys per minute. 1 langley per minute = 221.2 Btu per

hour per square foot = 697 watts per square meter.

Liquid heat transfer fluid: The operating or thermal storage liquid

including water or other liquid base and all additives at the

concentration used under operating conditions.

Load: Peak rate of energy demand on a mechanical H/C/HW system. Load

is energy per unit time or power.

Maximum service temperature: The maximum temperature at which a system

is designed to operate either with or without the flow of heat

transfer fluid.

Mechanical system: All equipment and controls required to satisfy space

heating, cooling, or hot water energy requirements. The mechanical

system may contain both solar and auxiliary components, including

pumps, pipes, blowers, ducts, insulation, solar collectors, thermal

storage, heat exchangers, valves, and electrical wiring.

Minimum service temperature: The minimum temperature at which a system

is designed to experience either with or without the flow of heat

transfer fluid.

Net solar contribution: Solar radiation transmitted through a portion

of the building envelope and absorbed within the building during a

12
given daily, monthly, or annual cycle, less the transmission, and

ventilation (excess energy discharge) losses due to the same portion

of the building envelope during the same period. This is equivalent

to net solar gain.

Nocturnal cooling: The cooling of a building or heat storage device by

the radiation of heat to the night sky.

"No-flow" condition: The situation that exists 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 or may not be in the collector but it is

not flowing if present. This condition is sometimes referred to as the "stagnation" condition.

Noncombustible material: Material which does not act to aid combustion

or add appreciable heat to an ambient fire when tested in accordance

with ASTM E136-79, "Standard Test Method for Behavior of Materials

in a Vertical Tube Furnace at 750°C," and pass the tests set forth

therein.

Normal operating condition: Condition of operation during which no applicable parameter (e.g. temperature, pressure or flow rate) is

at or near an extreme or unexpected value.

Open system: An arrangement in hydronic systems where ambient air is

allowed to enter the system under normal operating conditions.

Operating energy: Energy required to operate pumps, compressors, fans,

blowers, valves, controls, movable shutters, or any other equipment,

but not energy intended to directly satisfy a load. Operating

energy, as defined here, includes energy to operate a heat pump

compressor, and defrost energy for heat pumps, when these components

are an integral part of the solar system.

Operative temperature: The average of the dry bulb temperature and the

mean radiant temperature at a given location.

Optimum collector orientation: Collector orientation that results in the

maximum annual solar energy collected and used. The optimum orientation depends on factors such as site location, system type, annual

solar fraction, local weather conditions, load profile, and thermal

storage size.

Outgassing: The emission of gases by materials and components usually

during exposure to elevated temperature or reduced pressure.

Passive solar components: Components of a building that serve to modify

the space conditioning energy requirements by means of reflecting,

absorbing, transmitting, or storing solar energy. These components

13
include fixed and movable apparatus which can be operated either

manually or automatically. Examples of passive solar components

are: shading devices, windows, attached greenhouses, Trombe walls,

and mass placed for storage of solar energy.

Passive solar energy system: A method of space heating or cooling that

utilizes solar radiation primarily by means of building elements

rather than mechanical equipment. In passive systems, the energy

flows are primarily by natural means (radiation, convection, conduction). For the purposes of this document, this definition includes

some systems in which at least one energy flow is by natural means

and at least one is by forced means, otherwise known as hybrid

systems.

Physical incompatibility: The inability of materials in contact with

each other to resist degradation by physical actions such as differential thermal expansion.

Pitting: The process by which localized material loss is caused in

materials by erosion or chemical decomposition.

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 contact with the plastic.

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.

Potential heat: The difference between the heat of combustion of a representative specimen of material and the heat of combustion of

any residue remaining after exposure to a simulated standard fire,

determined by combustion calorimetric techniques.

pphm: Parts per hundred million.

Premature failure: Failure that occurs before the end of the design

life.

Pyranometer: A device used to measure the total solar radiation incident

5 upon a surface per vmit time per unit area. This energy includes

the direct radiation, the diffuse sky radiation, and the solar

radiation reflected from the foreground.

R-value: Resistance to heat flow given in units of ft2»°F*h/Btu

(1 ft2«°F'h/Btu is equivalent to 0.176 m2«°C/W).

Radiation: The process of heat transfer by the transmission of electromagnetic waves between two or more bodies in sight of each other.

14
These radiant waves are converted to heat only after being absorbed

by matter.

Rate of heat release: A measure of the heat production of a material

under a specified set of fire exposure conditions which may be used

in evaluating the relative hazard of the material.

Recovery rate: The rate at which a water heater can replenish its supply

of hot water, traditionally expressed in gallons per hour per 100°F

(37.8°C) temperature rise.

Safety glazing materials: Glazing materials so constructed, treated, or combined with other materials as to minimize the likelihood of

cutting and piercing injuries when these glazing materials are broken.

Service loads: Loads that ar.e expected during the service life of a structure and upon which the design of the structure is based.

Shall: Where "shall" is used with a special provision, that provision

is mandatory if compliance with the criterion is claimed.

Should: Term used to indicate a criterion that is not mandatory but is

desirable as good practice.

Significant (deterioration, loss, etc.): Deterioration that results

either in a decrease in performance greater than that allowed for

in the design, or in the creation of a hazard.

Solar constant: The average Intensity of solar radiation reaching the

earth outside the atmosphere; amounting to 2 langleys or 1.94 calories per square centimeter, per minute equal to 430 Btu/h*ft^ or 1353 watts/m2.

Solar degradation: The process by which exposure to sunlight deteriorates

materials.

Solar energy: Solar radiation or energy from solar radiation intercepted

and converted to thermal energy at the building site.

Solar fraction: The ratio of solar energy applied to the load by the

active solar energy system to the total load. Solar fraction may

be calculated for any time period, for example monthly or annually.

Solar energy applied to the load may include uncontrolled heat

losses from the active solar energy system if these losses contribute

to meeting the load and is reduced by uncontrolled heat losses if

these losses increase the load (cooling systems).

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

15
the sun reaches its maximum altitude for that day. Solar time is

very rarely the same as local standard time in any locality.

Space cooling load: Rate at which heat must be removed from the conditioned space by the mechanical system to maintain indoor temperature

at a constant value. Space cooling load reflects sensible and latent

heat gain due to external and internal sources. However, storage

capacity within the building and contents affects the relationship

between heat gain and space cooling load.

Space cooling system: The mechanical system containing all equipment

and controls required to satisfy the space cooling load.

Space heating load: Rate at which heat must be added to the conditioned

space by the mechanical system to maintain interior temperature at

a constant value.

Space heating system: The mechanical system containing all equipment

and controls required to satisfy the space heating load. The space

heating system may include solar collectors, thermal storage, energy

transport devices, and auxiliary energy equipment. The space heating

and space cooling systems may have some components in common. Fireplaces and wood stoves used for heating are considered to be part of

the space heating system.

Storage system: Equipment in which thermal energy is stored 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.

System: The complete assembly necessary to supply heat, domestic hot

water, or other usable form of solar energy to a structure.

Tap temperature: The temperature at which water is discharged from an outlet at the point of use.

Thermal stratification: Separation into different temperature regions.

Thermal statif ication usually occurs vertically in liquid thermal

storage containers but may also occur horizontally in rock bins.

Thermosiphon: Flow of fluid through a closed loop induced by density

difference in the fluid caused by temperature difference which is

in turn caused by heat transfer into and out of the loop.

Total solar input: Amount of solar radiation transmitted through the

aperture of a passive solar energy system and absorbed within the

building during a specified time period.

Toxic: See "Federal Hazardous Substances Act Regulations," Code of

Federal Regulations (CFR) , Title 16, Part 1500.3(b)(5) and (c)(2).

"'Toxic' shall apply to any substance (other than a radioactive

16
substance) which has the capacity to produce personal injury or Illness to man through ingestion, inhalation, or absorption through

any body surface." An extraction of the more specific definition

in (c)(2) adds the following: "'Toxic' means any substance producing a lethal dose in half (LD50) of white rats when ingested as a single dose, of from 50 mg to 5 g per kg of body weight." Part

1500.3(c)(2)(i) , (ii) and (iii) also give further specific definitions relative to inhalation and absorption (see also "Highly

toxic")

.

Transraittance : The ratio of the radiant flux transmitted through and

emerging from a body to the total flux incident on it.

UV: Ultraviolet radiation, that part of the terrestrial solar energy

between 0.3 and 0.4 micrometers (300-400 nanometers).

Water hammer: Potentially damaging forces, exemplified by pressure surges

and attendant pounding noises and vibration that develop in a pipe

system when a column of liquid flowing through a pipe line is stopped

abruptly.

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 temperaure: The outdoor air temperature will

be higher than the stated value not more than 73 hours per year

(2-1/2 percent 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 percent of the 2,160 hours in December, January and

February)

.

17
CHAPTER 1

SITE AND BUILDING

Page

1.0 Introduction 1-1

1 . 1 Climate and regional considerations 1-1

1.2 Site considerations 1-3

1 . 3 Building considerations 1-4

1.4 Building/solar system interaction 1-5

References 1-6

1-a
CHAPTER 1 SITE AND BUILDING

1.0

Introduction This chapter sets forth considerations of the use of solar

energy as related to broadly encompassing impacts beyond

the scale of the solar energy system itself. The performance criteria for solar energy systems exist within a context of requirements that increase in scope from the

building for which the system is designed, to the site, to

the region and its climate, up to the scale of national

energy goals. At each level, certain requirements have

evolved which will influence solar installations. Policy

decisions concerning energy conservation tax incentives,

grant programs, reduced interest financing, fuel pricing,

or sun rights are examples of issues that may have profound

influence on solar energy applications.

It is critical that solar installations work in harmony with

the overall conditions of climate, site, building characteristics, and use patterns of the occupants. Proper and efficient performance of the site and building will increase

the probability for efficiency of the solar energy system

and in turn the level of performance of components and

materials as well. A comprehensive check, list of factors

used to assess the overall suitability of passive and active

designs proposed for HUD's Cycle 5 Residential Solar Demonstration is given in Appendix B, Technical Review Items.

1.1 Climate and regional considerations. Regional climate and resource conditions may exert a strong influence on designs.

Certain construction materials have strong Indigenous applications and establish constraints within which the designer

or any solar building project must work.

Specific regional climatic considerations Include the following and are subdivided into categories of natural, man

made, and climatic factors.

Natural Factors:

(a) Sun altitude and declination - for consideration of

collector aperture tilt and shading, etc.

(b) Orientation - due south vs. magnetic south - to

determine orientation and building geometry

1-1
(c) Topography - for consideration of building into slopes,

earth berming , and otherwise maximizing southern exposure and minimizing others, References [1, 2]*

(d) Altitude - for the effects of atmospheric density

(e) Vegetation - as it affects shading, reflection and air

movement. References [1, 2]

(f) Ground temperature - as it affects ground water

temperature and earth exchange cooling

(g) Water table height - for considerations of excavation,

burying of storage elements, earth contact housing,

and wetting of insulation

(h) Water quality - its mineral content, pH, etc., when

used for heat transfer fluid or thermal storage

Man Made Factors:

(a) Density and growth of development - in consideration

of solar rights, shading, glare, obtrusive installations. References [2, 3, 4]

(b) Pollution of air - as it affects insolation, corrosion

of exposed parts, stain and dirt deposits on collector

cover plates, or glazing

(c) Building materials and architectural character

consideration of mass and geometry or prevalent building types

(d) Building codes - to the extent that they constrain

solar applications. Reference [4]

Climatic Factors:

Macro-climatic factors have a direct influence on solar

H/C/HW systems. Typical sources of climate data are the

Climatic Atlas, Reference [5] and Comparative Climatic

Data, Reference [6]. Reference [7] describes adaptation

of building form for regional climate characteristics.

Following is a tabulation of typical climate factors:

(a) Temperature (annual average, seasonal, and daily)

(b) Solar radiation (annual, monthly, daily, hourly)

Note: data on a weekly basis would offer many advantages but is usually not tabulated in that form

(c) Wind or air movement (direction, velocity, frequency)

(d) Relative humidity

(e) Rainfall and snow

* Numbers in brackets [ ] indicate references at the end of this chapter.

1-2
Micro-climatic factors are those of specific interest to an individual building, site, and immediate surroundings.

Climatic characteristics become more focused at this scale

and may be tempered or exaggerated by local features,

creating weather characteristics unique to the site. The

characteristics unique to the site may be caused by its

topography, landscaping, and proximity to surrounding buildings, hills, lakes, or open plains. Reference [1]. The

following characteristics should be considered at this

scale:

(a) Shading - time, duration, and season of occurrence are important for heating as well as cooling

(b) Air movement (direction, velocity, frequency)

(c) Atmospheric quality (fog, haze) and direct vs. diffuse

solar radiation

(d) Relative humidity

1.2 Site considerations . Site design and siting criteria for

energy conserving buildings incorporating solar energy systems are similar to good practice guidelines for non-solar

buildings. The difference is in the special affinity for

the sun and the sun's path required for solar energy applications. The performance uncertainties at this time and

marginal energy balances often experienced in the operation

of solar energy systems require greater consideration of

the subtleties of the building/environment relationships.

In passive solar applications, the entire building is likely

to be affected by these relationships and for applications at least the solar energy system will be affected.

Over-design as a means of coping with the performance uncertainties of solar energy installations is expensive and not

likely to be cost effective.

Achieving an optimum orientation for the building and/or

collector apertures is of primary importance. During the

winter months, approximately 90 percent of the sun's energy

occurs between the hours of 9:00 a.m. and 3:00 p.m. It is

important that solar collection surfaces not be significantly shaded during this time. Site planning should also

take into account the direction of prevailing winds.

The judicious use of vegetation and other landscaping

techniques can play a significant role in solar energy

efficiency as well as energy conservation in general. The use of trees and vines to provide summer shading while

still permitting full exposure to solar radiation in the

winter is particularly important in passive applications.

Various ground cover materials can increase reflection or reduce glare as may be appropriate. Trees may be used to

channel cooling breezes and evergreens can be used as

1-3
effective wind breaks to moderate cold winter winds.

Fences, screens, walls, and earth berms are other site

design elements which would be considered to provide sun capturing spaces or as barriers to heat loss. References

[1, 2, 8, 9, 10, 11] describe siting considerations and

Reference [7] describes the extensive influence these have

on passive designs.

Building considerations. A well designed solar energy

system must include a building that is energy conserving

since collector area and sizing of other solar hardware components are proportional to the building load requirements.

There are several aspects that may be considered. One

consideration is the exterior envelope of the building

where energy can be conserved by modifying factors such

as: color, thermal resistance, thermal mass. Reference,

[15], orientation, shading, surface area, and weather

tightness. ASHRAE Standard 90A-1980, Reference [12] 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 90A-1980 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.

Listed in Table B-5 of Appendix B are typical properties

of selected building materials that may be beneficial to

the user selecting building components and materials for

solar application.

A second consideration is the mass of the building which

can exert considerable influence on the building's thermal

behavior. Studies have indicated the beneficial peak leveling and carryover characteristics of properly designed

building mass, Reference [13].

A third consideration is space planning and coordinating

space use with natural temperature variations. The planning of interior spaces and proper temperature zoning is

important for energy conservation and especially important

in passive buildings. Such interior planning has a significant effect on the movement of energy (natural and mechanical) in buildings for both the heating and cooling seasons

and the maintaining of comfort conditions corresponding

with the activity within the spaces. Spaces having minimal

heating and lighting requirements may serve as an effective

buffer zone when placed in the north facing portion of

the building. Spaces having greater heating and lighting

requirements and more frequent use, can benefit from place1-4
ment adjacent to southern exposures. In some passively

designed buildings, the probability of large temperature

swings may also affect zoning and room placement. The

protection of entrances from winter winds by the use of

a double entry or vestibule can be advantageous. Reference

[14] presents a number of projects which illustrate design

response to these needs. The need for grouping of mechanical spaces to take advantage of shorter piping and duct

runs and associated thermal losses is similar to non-solar

buildings but potentially more important in solar applications. Waste heat recovery and storage in the thermal

storage mass of passive solar buildings is often possible.

Which combination of options is chosen and how effective

the selection will be is dependent on design conditions

and design goals.

1.4 Bulldlng/solar system interaction . The adverse effect(s)

that a building or site might have on solar H/C/HW systems

or components and their performance must be considered in

the design. The adverse effect(s) that the solar H/C/HW

systems or components have on the building or site are addressed in Chapters 2 through 6 as appropriate.

Solar components should be located where the potential for

their misuse is minimized. The proximity of system components to sidewalks and playgrounds should be examined to

minimize potential misuse or vandalism.

Building exhausts, plumbing vents, or other air discharge

openings through roofs or exterior walls should not be

located such that their emission will cause the deposition

of grease, lint, condensation, or other deleterious materials

on solar components, especially apertures or collector glazing. Similarly, solar components should not interfere

significantly, either physically or aerodynamically , with

building vents, flues, and exhausts.

Interior items such as rugs, carpets, wall hangings, and

furniture which may cover passive solar components such

as thermal storage, absorbers, or apertures may seriously

reduce the thermal performance of these passive components.

Routine maintenance of the building should not have adverse

effects on the solar components, nor should required maintenance of the solar systems have adverse effects on the

building components. Maintenance of building and site and

roof surfaces are specifically covered in Criteria 6.2.4

and 6.2.5.

1-5
Chapter 1 References

1. Plants, People and Environmental Quality , National Park Service,

U.S. Department of Commerce, Washington, DC and American Society

of Landscape Architects Foundation, 1972.A/

2. Site Planning for Solar Energy Utilization , American Society of

Landscape Architects Foundation, for NBS and HUD, 1975.2./

3. Jaffe, M. and Erley, D., Protecting Solar Access for Residential

Development , for HUD, HUD-PDR 445, GPO 023-000-00523-9.1/

4. A Strategy for Energy Conservation, Proposed Energy Conservation

and Solar Utilization Ordinance for the City of Davis, California,

City of Davis, CA 95616, 1974.

5. Climatic Atlas of the United States , NCAA, National Climate Center,

Federal Building, Ashville, NC 28801, 1977.

6. Comparative Climatic Data , NOAA, National Climate Center, Federal

Building, Ashville, NC 28801, 1978.

7 . Regional Guidelines for Building Passive Energy Conserving Homes , AIA Research Corporation for HUD, HUD-PDR 355, GPO 023-000-00481-0,

1978.1/

8. Mazria, E., The Passive Solar Energy Book , Rodale Press, 33 East

Minor Street, Emmaus , PA 18049, 1979.

9. Wright, D., Natural Solar Architecture , A Passive Primer, Van

Nostrand Reinhold Co., 135 West 50th Street, New York, NY 10020,

1978.

10. Olgyay, V., Design with Climate , Princeton University Press,

Princeton, NJ 08540, 1963.

11. Olgyay, V., Olgyay, A., Solar Control and Shading Devices , Princeton University Press, Princeton, NJ 08540, 1976.

12. Energy Conservation in New Building Design, Standard 90A-1980 , American Society of Heating, Refrigeration and Air-Conditioning

Engineers, 1791 Tullie Circle, NE, Atlanta, GA 30329, 1981.

13. Peavy, B., Powell, F., Burch, D., Dynamic Thermal Performance of an Experimental Masonry Building, BSS 45, National Bureau of Standards,

1973.1/

1-6
14. The First Passive Solar Home Awards , Franklin Research Center,

Philadelphia, PA, for HUD, GPO 023-000-00517-4, 1979.1/

15. Petersen, Stephen R. , Barnes, Kimberly A., and Peavy, Bradley A.,

Determining Cost-Ef f ective Insulation Levels for Masonry and WoodFrame Walls in New Single Family Housing , NBS Building Science Series

134, National Bureau of Standards, Washington, DC 20231, 1981.

]J Superintendent of Documents, U.S. Government Printing Office,

Washington, D.C. 20402.

American Society of Landscape Architects Foundation, 1750 Old Meadow

Road, McLean, VA 22101.

^

National Technical Information Service, 5285 Port Royal Road,

Springfield, VA 22161.

1-7

CHAPTER 2

THERMAL

Page

2.0 Introduction 2-1

2.1 Passive space conditioning 2-2

2.1.1 Net solar contribution 2-3

2.1.2 Thermal storage 2-5

2.1.3 Building overheating 2-7

2.1.4 Mechanical cooling energy 2-9

2.1.5 Thermal environmental conditions 2-9

2.2 Mechanical space conditioning 2-11

2.2.1 Mechanical heating system size 2-11

2.2.2 Auxiliary heating system size 2-13

2.2.3 Cooling system size 2-13

2.2.4 Auxiliary cooling system size 2-14

2.3 Domestic hot water 2-15

2.3.1 Temperature 2-15

2.3.2 Daily water use rate 2-15

2.3.3 Hourly recovery rate 2-16

2.3.4 Auxiliary water heating system 2-16

2.4 Collector array performance 2-17

2.4.1 Collector orientation 2-17

2.4.2 Panel performance in array 2-18

2.4.3 Array manifold energy loss 2-18

2.4.4 Heat loss during non-collection periods 2-19

2.4.5 Energy rejection 2-20

2.4.6 Collector/storage combination 2-21

2.5 Thermal storage performance 2-21

2.5.1 Thermal energy loss 2-21

2.5.2 Thermal stratification 2-22

2.5.3 Addition of auxiliary energy to thermal storage 2-23

2.6 Energy transport performance 2-23

2.6.1 Thermal energy loss 2-23

2.6.2 Operating energy 2-24

2.6.3 Collector loop transfer rate 2-25

2.6.4 Energy transfer to load 2-25

2-a
CHAPTER 2 - (Continued)

THERMAL

Page

2.7 Control performance 2-26

2.7.1 Sensor location 2-26

2.7.2 Collector fluid circulation 2-27

2.7.3 Priority of energy use 2-27

2.7.4 Control valve and damper leakage 2-28

2.7.5 Control set points 2-28

2.8 Component/system interaction 2-29

2.8.1 Collector selection 2-29

2.8.2 Storage selection 2-30

2.8.3 Fluid flow rates 2-31

2.8.4 Auxiliary equipment selection 2-31

2.8.5 Load temperature requirements 2-32

2.9 Effective use of depletable energy 2-33

2.9.1 Depletable energy use 2-33

References 2-37

2-b
CHAPTER 2

THERMAL

2.0

Introduction This chapter sets forth the requirements and criteria that

determine acceptable thermal performance of passive and

active solar energy systems in residential buildings. Some

of the criteria apply only to either active or passive systems, therefore, a means of categorizing systems by type is

required for purposes of thermal analysis. Passive solar

energy systems are considered to be primarily part of the

building structure, whereas active solar energy systems are considered to be part of the mechanical heating, ventilating, and air conditioning (HVAC) equipment. Energy flows

in passive systems are primarily by natural means (radiation, convection, conduction), in contrast to forced flows

(by blower or pump) in active systems. Systems in which

energy flows are accomplished by a combination of natural

and forced means are sometimes referred to as "hybrid"

although for the purpose of this document they are considered passive. Passive solar energy systems are distinguished from other elements of the building in that they

are capable of controlling solar energy by blocking, transmitting, absorbing, reflecting, or storing it to provide

space heating or cooling as desired. Likewise, active

solar energy systems are distinguished from other mechanical

equipment in that they utilize solar radiation as an energy

source. Conventional HVAC equipment used in conjunction

with the active solar energy system is referred to as the

auxiliary energy system and is considered to be part of

the active solar energy system, since the control functions

of each are not normally independent. The classification

of a solar energy system as active or passive should be

done on the basis of whether the system consists primarily

of building elements or primarily of mechanical HVAC equipment. See Reference [1]* for a classification of passive

and hybrid systems. A passive system may include, in addition to natural energy flow, mechanical equipment for con- trol or heat distribution. An active system may include

energy transport by natural convection or solar collectors

incorporated as part of the building envelope although

the system is primarily mechanical in nature.

Requirements 2.1, 2.2, and 2.3 apply to the design of the

solar heating, cooling, and hot water systems with respect

to the ability of the system to provide the applicable

* Numbers in brackets [j indicate references at the end of this chapter.

2-1
functions at peak or design conditions. Each criterion

under these sections represents a "spot check" of the

system capability under selected conditions. The design

conditions are not extremes that the system could actually

experience, but represent normal probabilities of occurrence, for example the ASHRAE 97-1/2 percent winter outdoor

design temperature. Passive solar energy systems (direct

gain, mass walls, attached greenhouses, etc.) are treated

as building components that utilize radiant solar energy to

modify the space conditioning energy requirements. Thus,

the energy required for the mechanical equipment (including

the active solar energy system) results from exposure of

the building, including any passive solar components, to

ambient weather conditions such as temperature and solar

radiation while maintaining required indoor comfort conditions. For solar energy systems that combine two or more

functions, for example, a combined space heating and domestic hot water system with common collectors and storage

components, it must be shown separately under the applicable requirements that each function can be met at the

design conditions.

Requirements 2.4 through 2.8 apply primarily to active solar

energy systems (including auxiliary energy systems). These

sections present criteria which specify that individual

components and subsystems must meet certain minimum levels

of thermal performance as well as interact properly for

efficient overall system performance. Space heating, space

cooling, and domestic hot water system components must

I comply with the requirement of these sections if solar

energy is utilized for these purposes in a residential

building. Thermosiphon HW systems are considered to be

active and are included in these sections.

If both passive and active solar features are included in

the building design, both are to be included in the analysis for determining the calculated depletable energy use.

The end result is the determination of the amount of

depletable energy required to be input to mechanical system

and/or to the passive components to achieve acceptable

system operation.

2.1

Requirement Passive space conditioning . Passive solar heating and

cooling systems, if provided, shall be properly designed

and integrated into the building to reduce the space conditioning energy requirements for the mechanical system.

Passive systems designed for a particular function (heating

or cooling) shall not adversely affect the operation of the

mechanical system or adversely affect the habitability of

the building.

2-2
Commentary If passive solar heating or cooling systems are not provided, this requirement Is not applicable. Requirements for

solar HW systems are described In Requirement 2.3.

Passive solar designs that utilize large south-facing windows to admit winter sun for heating purposes can have a deleterious effect on space cooling loads or habltablllty

,

unless suitable precautions are taken to exclude solar

radiation during the cooling season using such measures as external shading, Internal movable Insulation, or venting.

Net solar contribution . Passive solar heating systems shall

provide a positive net solar contribution to the fully

conditioned space for the month of January.

Evaluation A dally 24 hour energy balance for the passive solar heating system shall be computed for an average day in January.

The option may be taken to demonstrate a net solar contribution for the entire heating season instead of only for

the month of January, to account for unusual circumstances

(i.e., weather pattern, shading, etc.). The gross solar

contribution must exceed the sum of heat losses from the

passive system and excess energy discharges, if any, due

to the system. The energy balance calculation shall Include

either solar radiation clear sky data from ASHRAE, Reference [3], Chapter 57, multiplied by the mean percentage of

possible sunshine. Reference [4], for January 21, or average daily solar radiation for the month as tabulated in

Reference [5] or Appendix A of Reference [6]. The results

of energy balance calculations using the clear day data

multiplied by the mean percentage of possible sunshine has

shown to be reasonably accurate for those parts of the

country having high percentages of sunshine, but can be

seriously in error for those areas having low percentages

of sunshine. The solar radiation data shall be adjusted

for the appropriate tilt and azimuth angles of the solar

aperture. Gross solar contribution may be calculated by

multiplying the total dally solar radiation on the aperture, the transralttance of the glazing, and the absorptance

of the receiving surface as described in ASHRAE design heat

gain calculation. Reflection and shading shall also be

considered. Thermal energy loss through the aperture may

be calculated using the product of surface area of the

passive aperture, the appropriate overall heat transfer

coefficient, and the difference between 70°¥ (21 °C) and

average daily outdoor temperature for the month of January.

Outdoor temperature data are widely available and are also

Included in the above four references. Mass storage wall

components such as Trombe walls or water walls may require more comprehensive analyses than given above If it is

2.1.1

Criterion

2-3
questionable whether they meet the criterion, but the

steady-state calculation should be adequate in most cases provided a rational basis for estimating the storage wall

exterior surface temperature is available. More detailed

calculations may be provided by the designer.

Commentary Computer programs are available for handheld calculators

for analysis purposes, References [7, 8] as well as sophisticated computer programs. References [9, 10, 11]. Reference [12] is a brief but comprehensive survey of passive

solar building design computer programs.

• This criterion is not intended to prevent the use of

• - conventional windows that transmit solar radiation into the

residence but are not a part of the passive solar heating

system and do not give a net solar contribution.

South-facing windows in cold climates have often been found

to be net losers of energy in the winter even though they

transmit considerable quantities of solar energy during

sunny winter days. Various means can be used to increase

the net solar contribution of a passive solar heating system; for example, reflectors to increase incident solar

radiation, multiple glazings to reduce heat loss, movable

insulation to reduce night time thermal energy loss and

appropriately located mass to absorb and store thermal

energy. For direct-gain systems, three layers of glazing

is usually justifiable in climates of more than 5,000

degree-F days (2800 degree-C days). Balcomb, Reference [6],

Chapter E, provides discussion and recommendations for the

number of glazings, with and without night insulation, for

applications in cities with mild, moderate and severe

climates.

The month of January was chosen for evaluation because it

is coldest for most locations in the United States. If

the passive solar heating system provides a net solar con- tribution in January, it will probably do so for the less severe winter heating season months. A one-month calculation was chosen for simplicity and to avoid the ambiguity

of defining the limits of the heating season. This is not

intended to be representative of seasonal thermal performance, but only a check for minimum acceptable performance.

Passive solar heating systems that are net heat losers in

the coldest month place an undue burden on the mechanical

heating system.

Vertical double-glazed windows facing south in Baltimore,

' Maryland meet this criterion without night insulation.

With single glazing, night insulation having an R—value as little as R-1 is needed to meet this criterion. In

2-4
Fairbanks, Alaska, 120 miles (200 km) south of the Arctic

Circle, triple glazed south-facing vertical surfaces give

a net solar contribution in January even with no night

insulation, but assuming some reflection from snow. Two

glazings with R-5 night insulation also qualify with no credit for snow reflection.

Of 266 projects selected for awards for the HUD Passive

Residential Design Competition, Reference [13] and the HUD

Cycle 5 Residential Solar Demonstration Program, Reference

[68], 90 percent have a calculated positive net solar con- tribution in January, Reference [69]

.

Determination of the optimum aperture area may involve a life-cycle cost analysis as described in Chapter H of

Reference [ 6]

.

The size of the aperture may affect the net solar contribution in January if the aperture area is large enough (and

insufficient storage is provided) so that venting of excess

heat is required, since discharged heat reduces net solar

contribution. A given size system that provides a positive

net solar contribution will continue to do so as the aperture area is increased until the size is reached where

venting loss to prevent overheating causes the net solar

contribution to become negative. A passive solar heating

component having a negative net solar contribution cannot

be made to have a positive net solar contribution by

increasing its aperture area. Balcomb, Reference [6],

Chapter D, gives rules of thumb for sizing solar collection

area. The range of values is different for each location.

It is recommended that the larger number not be exceeded

to prevent building overheating on clear winter days.

2.1.2

Criterion Thermal storage . Thermal storage in the building mass or in thermally-coupled thermal storage areas shall be sized

and located to effectively absorb, store, and release thermal energy, reduce space temperature variations, and minimize the space conditioning energy requirements for the

mechanical system.

Evaluation Review drawings , specif ications, and calculations. Calculations shall take into account the amount of the mass, location relative to solar gain areas, forced or natural

convection of air to and from storage, and presence of

insulating materials such as carpets or hangings over massive floors or walls that prevent direct solar radiation.

Commentary The need for storage depends on the size of the aperture

relative to the size of the heated space. In some

2-5
instances, the thermal storage of the building mass alone

may be adequate. Generally 30 to 45 Btu/'F'ft^ (600 to 900

KJ/'C'ra^) based on aperture area is recommended. The lower

end of the range should be used for small aperture areas relative to building size and the upper end to large aperture areas. Storage mass which directly receives sunlight

will store up to four times as much thermal energy as mass which is not in direct sunlight, and storage capacity should

be adjusted accordingly. To prevent overheating of the

conditioned space, it is extremely important that sufficient

thermal storage is provided when the aperture area is large.

Venting of excess heat, instead of redistributing it to

remote storage, reduces the net solar contribution of the

system. (see Criterion 2.1.1).

If locating the storage so that it is exposed to direct

solar radiation is not practical, it may be remotely

located. For large systems this has the advantage of distributing heat to other parts of the building and enabling

a very large storage. The low temperature of heat stored

by this means, however, makes air-flow heat transfer back

to the living space very inefficient and direct thermal

coupling of storage to space is preferred. Remote thermal

mass charged by air may be effective for attached sunspaces

but are not advisable for direct gain systems because of

the moderate temperatures of any available heat. Rock bins

may be located directly under floors for satisfactory

operation. See Criteria 2.5.1-2.5,3 for further discussion

of isolated thermal storage.

Storage mass thickness, exposed area, location relative to

aperture and conditioned space, and thermal characteristics

not only influence heating effectiveness but also have a pronounced effect on space temperature fluctuations. Reference [13] describes these effects and Reference [14] provides procedures for predicting them. For the direct gain

zone in general, massive surfaces should be relatively dark

in color and low density surfaces should be relatively

light. The time delay of thermal conduction should be con- sidered in determining the thickness of passive storage

mass. Thermal properties, including absorptance characteristics, for commonly used storage materials are given in

Table B.5 of Appendix B of this document as well as in

Reference [14],

In direct gain situations and for a fixed quantity of

thermal storage mass, spreading the mass over as large an area as possible will maximize performance and will minimize

the thickness of the mass layer. Mass near the surface is

more effective than mass at a greater depth because it is more directly coupled with the conditioned space. Floor

2-6
slabs directly over dry earth, and with perimeter

insulation only, will likely have a tempering effect on interior temperatures during long, cold, cloudy periods,

although temperatures may drop somewhat.

2.1.3

Criterion Building overheating . Heat gain from passive solar

components shall not cause the instantaneous dry bulb

temperature in occupied spaces to exceed 82 °F (28°C) or 5°F (3°C) above the simultaneously-occurring outdoor dry

bulb temperature, whichever is greater, if mechanical

cooling is not provided. ( If mechanical cooling is

provided, see Criterion 2.1.4.)

Evaluation Review drawings, specifications, and calculations. Review

local weather data and sun angles. Compliance shall be

demons t rated for both the months of July and October.

Commentary The 82°F limit has been established by the American

Ventilation Association as the temperature at which reasonably comfortable conditions can be provided through whole

house ventilation. Reference [15]. With ventilation, the

5°F limit can be maintained. The ASHRAE Thermal Comfort

requirements do not apply in situations where space conditioning is not supplied. The intent of the Criterion is

to make the comfort requirements for passive solar houses

reasonably consistent with conditions found in non-solar,

non-air conditioned houses.

The following three methods might be considered to prevent

building overheating:

1 . Shading

2. Provision of adequate thermal storage

3. Whole-house ventilation

First, it may be shown that appropriate shading devices are utilized to prevent transmission of solar radiation affecting the fully conditioned space. Suitable methods include

fixed or movable shades, movable insulation, and venting of

semi-conditioned spaces such as in attached sunspaces or the space between glazings and mass storage walls. In the case of shading, the solar aperture should be fully shaded

from three hours before until three hours after solar noon

at mid month.

Reference [6], Appendix C, provides data for determining

monthly solar radiation on the collection surface, considering factors such as latitude, solar declination for the

month, overhang, tilt, and azimuth of the collector. Clear

2-7
sky solar radiation values for either the 15th or 21st

(whichever is available) of the month should be used.

Second, it may be shown that thermal energy storage within

the space effectively absorbs and stores heat to limit the

maximum space temperature to the required value. An hourly

simulation for 24 hours should be performed, considering

such factors as solar radiation transmitted, the absorptance of receiving surfaces, placement and capacity of

thermal storage devices, and timing and flow rate of ventilation air. However, there is some concern that excessive

mass in a building may absorb internal heat gains and may

prevent the ability to cool down living spaces quickly

using natural ventilation at nighttime. Fan-forced remote

rock bin storage may be used and may avoid this potential

conflict. Handheld calculator programs such as PEGFIX,

Reference [8] and TEANET, Reference [7] are available and

should assist in carrying out the analysis.

Third , when the normal maximum outdoor temperature is above

75°F (24°C), it may be shown that whole-house ventilation

is provided and adequately sized to maintain indoor temperatures less than 5°F (3°C) above the simultaneouslyoccurring outdoor temperature. A complete discussion of

whole-house ventilation effects is given in Reference [15],

pages 73-104.

Overheating is a potential problem for passive solar

heating systems designed to provide heating during the

winter. Shading of the aperture is an effective way to

prevent overheating. Significant sources of information

for controlling solar heat gain are in References [16, 17

and 18]. Temperatures may rise in attached greenhouses or other serai-conditioned spaces above the outdoor ambient

temperature. Venting of these spaces will help to control

temperatures in adjacent fully conditioned spaces. Vent area equal to 10 percent of the glazed area is generally

suggested, with outlets being slightly larger than inlets.

Fixed shading devices designed to shade at the summer

solstice (about June 22nd) or in July may not be effective

in late summer or early fall due to lower sun angles. The

month of October presents a particularly difficult design

problem to prevent overheating because of the low sun angle

combined with relatively warm weather in many climatic

regions. Various devices such as screens, curtains, shutters, reflective shades, blinds, awnings, vegetation, and

especially adjustable overhangs can be effective in controlling solar radiation. The concern is that these devices

be properly sized and detailed.

2-8
A method for estimating temperature swings In direct gain

spaces is given in Reference [6], Chapter F. Direct gain

spaces are more susceptible to large temperature variations

than indirect-gain types such as Trombe walls or water

walls

.

2.1.4

Criterion Mechanical cooling energy . The net solar contribution from

passive solar components shall not significantly increase

the energy requirement of the mechanical space cooling system relative to typical wall and roof sections during a typical sunny July day, if mechanical cooling is provided.

Evaluation Daily net solar contribution to the fully conditioned space

shall be calculated for the passive solar component and for

a substituted conventional wall/roof section for a typical,

sunny July day. The substitute wall section shall have the same heat transfer coefficient as other exterior walls for

85 percent of its area and shall be considered glazed for

15 percent of its area. The glazed portion shall have a transmissivity of 0.80 and a heat transfer coefficient of

0.6 Btu/h»°F«ft2 (3.4 W/K'm2) and shall be considered to be

fully exposed to direct sunlight throughout the day. Average daily values of outside temperature and solar radiation

may be used in the calculations. Inside temperatures may

be fixed at 78°F (26''C). Calculation of net solar contribution for each case shall be equivalent in detail to the

evaluation procedure of Criterion 2.1.1. Alternatively,

complete shading of the passive solar component for three

hours before and after solar noon shall be sufficient

evidence that this criterion is met.

Commentary The month of July was chosen for simplicity and because it

has the highest dry bulb temperature for many locations in

the United States. The alternative wall section parameters

are based on a typical wall for conventional residences

with a double-glazed window. The net solar contribution

calculation has three components: (1) total solar input,

(2) heat transfer through the solar components (including

inf iltation) , which will be from outside to inside if the

average daily outdoor temperature is above 78°F (26°C),

and (3) ventilation losses to discharge excess heat gain,

for example, venting of a mass wall or sunspace.

2.1.5

Criterion Thermal environmental conditions . For fully conditioned

spaces, passive solar systems shall not cause the thermal

conditioning to exceed the ranges specified by ASHRAE Standard 55-81 [19]. The limits of acceptable comfort conditions that are given in the ASHRAE Standard are summarized

in the following commentary. Should there be conflict

2-9
between this and Criterion 2.1.3, Criterion 2.1.3 shall

prevail.

Evaluation Review drawings, specifications, and calculations.

Compliance shall be demonstrated for the months of January,

July, and October. Corresponding calculations for these

months as required in 2.1.1 and 2.1.3 can be used. Some

conditions may require more detailed analysis such as the

effects of mean radiant temperature.

Commentary The intent of this criterion is to assure reasonable

thermal comfort for the occupants as well as account for

thermal environment variations that are appropriate for

' many passive applications. The operation of many passive

systems are dependent upon temperature gradiants to get

« thermal energy into and out of storage and to transport

energy from one location to another. Moderate temperature

fluctuations, approximately 6 to 8"? (3 to 4°C), outside

the comfort zone may be appropriate during non-use periods

such as night hours (winter).

In addition to air temperature, the thermal comfort in

interior spaces is affected by the temperature of interior

surfaces, air velocity, as well as clothing characteristics

of the occupants. The mean radiant temperature (MRT) is as important as air temperature in affecting heat loss and comfort. When air movement is low, the operative temperature

is approximately the average of air temperature and MRT. A

thorough discussion of these factors and design guidelines

are given in ASHRAE Standard 55-81, Reference [19].

The following comfort zone parameters are summarized from

" ASHRAE Standard 55-81:

° Winter/summer operative temperature ranges: winter 67-

76.4°F (19-22. 7°C); summer 73-79°F (21.9-23.7°C). These

temperatures are acceptable by 80% of sedentary building

occupants and considers typical seasonal clothing.

* The thermal effect of humidity (within the range of 30

to 70 RH) on the comfort of sedentary persons is small.

" Normal acceptable air movement is 30 fpm (.153 mps)

(winter) and 50 fpm (.255 mps) (summer) but it can be

extended in some cases to 160 fpm (.816 mps) to extend

the upper boundary of the comfort zone to 82.5°F (28.5°C)

in summer.

** The rate of cyclic temperature change should not exceed

4°F/h (2°C/h) if the peak to peak variation exceeds 2°F

(1°C).

2-10
° Slow rates of temperature change (approximately l°F/h)

(.5°C/h) during the occupied period are acceptable provided the temperature during this "drift" does not

extend beyond the comfort zone by more than 1°F (.5°C)

for longer than one hour.

° Asymmetric radiation from hot and cold surfaces and from

direct sunlight can cause local discomfort and reduce

the thermal acceptability level of the space. In general, people are more sensitive to asymmetric radiation

caused by a warm ceiling than caused by hot and cold

vertical surfaces.

° To minimize foot discomfort, the surface temperature of

the floor for people wearing appropriate indoor footwear

should be between 65°F (18.3°C) and 84°F (28.8°C).

Although the system may be operated by choice outside the

comfort range, it should be demonstrated that the system is

capable of providing these conditions.

2.2

Requirement Mechanical space conditioning . The mechanical space

heating and space cooling systems, which include the active

solar energy and auxiliary energy systems, shall be capable

of maintaining comfortable indoor conditions during periods

of occupancy and automatically operating to protect the

building and its contents against damage due to temperature

extremes when the building is unattended.

Commentary The mechanical systems must meet the remaining heating and

cooling energy requirements after these requirements have

been reduced by the use of passive solar techniques, if

provided. Provisions should be made to prevent simultaneous

heating and cooling. See Criterion 2.7.3.

2.2.1

Criterion Mechanical heating system size . The mechanical (combined

active solar and auxiliary) heating system shall be capable

of providing 70°F (21 "C) in fully conditioned spaces at

97-1/2 percent winter outdoor design conditions.

Evaluation Review drawings, specifications, and calculations. Design

load calculation shall exclude instantaneous solar gains

and Internal heat release from occupants, lights, and appliances. A building heat loss calculation procedure comparable in detail to the method outlined by ASHRAE, Reference

[20] or [16], Chapters 22, Infiltration and Ventilation;

23, Design Heat Transmission Coefficients; 24, Weather Data

and Design Considerations; and 25, Heating Load, shall be

used. For heat loss calculations, exterior thermal storage

2-11
walls associated with passive solar components shall be

assumed to be at room temperature. The design load may be

reduced by an amount equivalent to the rate of energy

released from thermal storage within the building mass if

shown to be appropriate for the historical frequency of

occurrence of low ambient temperature and solar radiation,

(These frequency distributions have not yet been developed.)

For discussion of typical storage capability and sizing

; ,^ procedures see Reference [21]. At design load conditions,

all movable passive solar components shall be considered to

operate as designed.

Reference [22] provides acceptable methods of design of

conventional space heating systems that are also useful for

solar energy systems.

Commentary Although the residence may not be operated to maintain 70 °F

(21°C) during any or all of the heating season, the mechanical system must be capable of meeting the design load

based on these conditions. Calculation of the amount of

depletable energy used by the system during the heating

season need not necessarily be based on maintaining 70°F

(21°C). This calculation may be based on an interior temperature specified by the applicable authority and should

reflect current trends in energy conservation. This calculation is not required here but is addressed in Requirement

2.9, Effective Use of Depletable Energy.

Comfort conditions combining the effects of dry bulb

temperature, mean radiant temperature, and relative

humidity are presented in ASHRAE Standard 55-81, Reference

[19]. Occupied spaces for sedentary activities in normal

: dress are usually designed for heating to maintain a recom- mended indoor temperature of 70°F (21 °C) dry bulb. References [17, 19]. 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 55-81, Reference [19].

Spaces intended to be used as part of a passive system may

be designed for temperature fluctuations compatible with

their functional use. Housing for the elderly and caretype facilities may use other indoor design temperatures

and design parameters. References [22, 23].

^ Chapter XII of Reference [24] provides a comprehensive

description of considerations in the design of solar space

heating systems. References [25, 26, 27] describe some problems encountered in heating system designs in the

National Solar Demonstration Program.

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2.2.2

Criterion

Evaluation

Commentary

2.2.3

Criterion

Evaluation

Auxiliary heating system size . The auxiliary space heating

system shall be sized and designed to operate automatically

to maintain indoor temperature at or above 55°F (13°C) in

fully conditioned spaces at the 97-1/2 percent outdoor winter design conditions, Reference [16]. Manually-operated

passive solar components (such as movable insulation but

not exhaust vents) shall be considered to be left in the

maximum-heat-loss position.

Review drawings, specifications, and weather data. The

auxiliary system must function independently of the solar

energy portion of the system, when appropriate. Refer to

Criterion 2.2.1 for calculation of space heating load. For

building heat loss calculations see ASHRAE , Reference [20] or [16]. ASHRAE, Reference [22] provides acceptable methods

of design of space heating systems.

The auxiliary space heating system is the part of the

mechanical system that utilizes depletable energy sources,

rather than solar energy, to meet the heating load. The

purpose of this criterion is to maintain habitability and

protection of occupied spaces for periods when there is

insufficient solar energy to operate the system as designed

and for periods when the solar heating system is not operated due to maintenance or repairs. Depending on the building and space heating system design, the auxiliary space

heating system may also be required to meet 70°F (21 °C) comfort conditions in fully conditioned spaces (see Criterion

2.2.1). Spaces which may not be fully conditioned and are susceptible to temperature fluctuations should not contain

elements which would be susceptible to freezing.

Cooling system size . The mechanical (combined active solar

and auxiliary) space cooling system, if provided, shall be

capable of providing temperature and relative humidity

specified by the applicable authority in fully conditioned

spaces at 2-1/2 percent summer outdoor design conditions,

Reference [16].

Review design climatic conditions, design indoor comfort

conditions, and cooling load calculations. A building cooling load calculation procedure comparable in detail to the

method outlined in Reference [16], or Reference [20] shall

be used. The design load may be changed due to the operation of passive solar components such as shading devices

and movable insulation and due to thermal storage within

the building mass if justified by statistical analysis of

weather patterns. For one- or two-family residences, the

design load may be calculated using the simplied procedure

2-13
described in Reference [16] « However, the design

load shall include all sensible and latent heat load from

all solar energy system equipment. Most cooling calculations require consideration of indoor temperature and

humidity and the applicable authority should establish

limits for these factors.

Commentary The space cooling system, if provided, must maintain

comfort conditions when passive solar components for space

heating and/or mechanical components for water heating are operated as designed. Reference [22], provides recommended

design criteria for conventional space cooling systems that are also useful for solar space cooling applications.

Chapter XIII of Reference [24] provides a description of

several methods that directly utilize solar energy for

space cooling. Reference [25] describes some generic system problems encountered with space cooling system designs

from the National Solar Demonstration Program, and Reference [28] provides a summary of measured thermal performance of several of the instrumented space cooling systems.

Cooling equipment utilizing conventional energy, ambient

5/' air, ground sink or stored thermal energy may be used in

conjunction with the solar system in an assist or auxiliary

mode. The use of evaporation, nocturnal radiation, desiccant cooling, or other passive techniques should be designed

to operate in conjunction with devices that 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), References [19, 23].

Minimum and maximum temperatures are also specified in the

' - ASHRAE Standard 55-81, Reference [19]. Indoor design tem5 peratures 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. References [19, 23].

2.2.4

Criterion Auxiliary cooling system size . The auxiliary cooling

system, if provided, shall be capable of providing temperature and relative humidity specified by the applicable

authority in fully conditioned spaces at 2-1/2 percent

summer outdoor design conditions. Reference [16].

2-14
Evaluation Review drawings, specifications, and calculations. Design

cooling load and system design procedure shall be equivalent to that in Criterion 2.2.3 except the interior temperature and/or relative humidity requirements may be less

stringent f or the auxiliary cooling system. For building

cooling load calculations, see ASHRAE, Reference [16] or ASHRAE, Reference [20].

Commentary No auxiliary cooling system is required.

2.3

Requirement Domestic hot water . The combined solar and auxiliary

domestic hot water system shall efficiently utilize solar

energy to reduce the consumption of depletable energy while

providing domestic hot water at required temperatures and

delivery rates.

Commentary Domestic hot water systems may be passive or mechanical

type (including thermosiphon collection loops). Passive

design may be as simple as a dark color water tank exposed

to solar radiation and enclosed by an Insulated box with a transparent cover. Frequently, movable insulation is used

as a nighttime cover to reduce heat losses. Mechanical

systems are designated by type of solar collection fluid

and type of freeze protection, for example, pumped vs. thermosiphon flow, direct vs. indirect heat exchange with

collectors, or water vs. antifreeze systems.

If the solar domestic hot water system is combined with a solar space conditioning system, this requirement applies

to the combined system to the extent sufficient to show

that the domestic hot water function is met.

2.3.1

Criterion

Evaluation

Commentary

Temperature. The hot water system (combined solar and

auxiliary) shall be capable of providing hot water at a tap

temperature up to 140°F (60°C), except in housing for the

elderly and care-type facilities, for which hot water temperatures are specified in Section 615-6.1 of MPS 4910.1,

Reference [29] and MPS 4920.1, Reference [30].

Review drawings, specifications, and calculations.

See Criterion 4.3.4 for health and safety related provisions.

2.3.2

Criterion Dally water use rate . The hot water system shall be

designed to provide daily hot water usage for single family

and multifamily dwellings of up to 20 units based on 20

gal/day (76 L/day) per person for the first two persons and

2-15
15 gal/day (57 L/day) for each additional person with a minimum usage of 40 gal/day (150 L/day). Daily hot water

usage for each dwelling unit in a larger multifamily building shall be based on 40 gal/day (150 L/day) for buildings

having 21 to 200 units and 35 gal/day (130 L/day) for

buildings having over 200 units, Reference [22].

Evaluation Review drawings, specifications, and calculations. This

criterion may be met by storage of a sufficient quantity of

hot water such that the combination of storage volume and

temperature will provide the stated daily usage at the tap

i _ temperature given in Criterion 2.3.1. Heat losses from the

storage container and distribution losses must be subtracted from the stored energy to determine the net quantity of hot water available for use at the tap. Energy in

solar storage containers (heated only by solar energy and

not by auxiliary energy) may not be included in the daily

usage total unless justification is provided based on historical solar radiation data.

Commentary Auxiliary heaters may be provided having a recovery rate

(per hour) equal to the total daily usage rate instead of

storage. Large storage relative to collector area can pre-

. , vent achieving useful temperature as well as causing excess

heat losses. Even a very well insulated solar storage

container of extremely large capacity will seldom get

sufficiently hot, thus requiring auxiliary energy to boost

water temperature to set the temperature.

2.3.3

Criterion Hourly recovery rate . The hot water system shall be capable

of providing hot water at draw and recovery rates as shown

in Tables 6-15.2 and 6-15.3 of HUD Minimum Property Standards, Reference [31] or as given in ASHRAE Systems Handbook, Reference [22] for multifamily as well as care type

facilities.

Evaluation Review drawings, specifications, and calculations.

2.3.4

Criterion Auxiliary water heating system . The auxiliary water heating

system shall be capable of providing 100 percent of the hot

water temperature and recovery rates specified in Criteria

2.3.1 and 2.3.3.

Evaluation Review of drawings, specifications, and calculations.

Commentary Most well-designed solar hot water systems provide over

half of the annual hot water energy requirements with solar

energy. On an hourly basis, however, there are many times

when these systems must operate with no available solar

2-16
energy, such as at night or cloudy days. Therefore, the

auxiliary heating system must be capable of meeting the

hourly loads.

2.4

Requirement

Commentary

2.4.1

Criterion

Evaluation

Commentary

Collector array performance . The solar collector array

shall be capable of absorbing solar radiation and converting it into useful thermal energy for providing the functions of space heating, space cooling, and/or domestic

water heating.

Typical values for the ratio of actual collected solar

energy to theoretical collected energy using collector test

data are given in Reference [32]. Array performance reduction of less than 10 percent relative to individual collector panel test data values can be expected in well-designed

systems.

Collector orientation . The collector array shall be

positioned so that the seasonal/annual incident solar radiation per unit area shall not be significantly less than

the seasonal/annual incident solar radiation on a reference

collector array at optimum collector orientation with no shading, except where special circumstances require non- optimum orientation.

Collector orientation factors are given for converting

radiation on a horizontal surface in Chapter 3 of Reference

[33]. Examine the solar radiation data for the geographic

location, orientation of collector array, shading (external

shading and self-shading by other collectors in the array)

and building shape and orientation.

Retrofit situations may result in deviation from thermally

optimum orientation. Typically, annual/season incident

solar radiation should not be less than 80 percent of the

radiation that would be received at the optimum orientation. In general, collectors should face due south and

have a tilt angle equal to (a) local latitude for water

heating only or for combined space heating and cooling, (b)

local latitude minus 15 degrees for space cooling only, and

(c) local latitude plus 15 degrees for space heating only

or combined space and water heating. High-rise buildings

with small roof areas or unfavorable building orientation

may require special architectural integration and preclude

thermally-optimum orientation, yet these systems may be

technically and economically appropriate. Tilt deviations

of +15° from the above values and deviations of 20° east

and 30° west of true south will not likely decrease performance by more than 10 percent. Local conditions such as

2-17
shading or fog, or the particular advantages of emphasizing

morning or afternoon gain should be considered.

2.4.2

Criterion

Evaluation

Commentary

2.4.3

Criterion

Panel performance in array . An individual collector panel

in the array shall not operate at significantly less efficiency than the test efficiency curve due to differences

between test and actual operating fluid flow rate and fluid

properties

Procedures equivalent in accuracy to ASHRAE Standard 93-77,

Reference [34], shall be used to determine collector test

efficiency curves. Post-stagnation test, as given in Section 10 of the Appendix (modification of test in NBSIR 78-

1305A), Reference [35], is required. Calculation of flow

rate through the lowest flow panel is required. Hydraulic

and thermal calculations shall be made for the condition of

normal total flow rate through the array. Consideration

must be taken for turbulent /laminar flow in the collectors

and manifolds, fluid properties, and array configuration.

Reference [36], page 148, may be used to determine loss in

efficiency due to flow rate and fluid property changes for

a typical liquid collector. Reference [37] gives the

effect of flow rate on a typical air-type collector and

also gives typical collector efficiency curves. Internal

manifolding of collector panels in an array may increase

efficiency relative to single-panel tests by reducing

edge losses.

The middle collectors in parallel arrays tend to have

reduced flow and therefore run hot, resulting in increased

losses. To alleviate this, a high ratio of pressure drop across any panel to the pressure drop across the manifold

is required. The minimum flow through a panel is important

but it is not necessary to have balance of flow to all collectors in the array. Flow should be maintained within the

manufacturer's stated range of flow rates in all collectors

in the array. Too many collectors in series increases the

inlet temperature of the latter collectors and should be

avoided. Any change in inlet temperature will shift the

operating point on the efficiency curve. Experimental

studies. Reference [66], of the influence of flow rate and

fluid type in a broad class of flat plate collectors

resulted in thermal performance variations of up to 10

percent.

Array manifold energy loss . During normal operating

conditions, heat loss, including that due to air leaks

(infiltration or exfiltration) from the collector array

manifolds and piping within the collector array shall not

exceed 15 percent of the solar energy collection rate.

2-18
Evaluation Review drawings and specifications. Examine the Insulation

properties, air leaks In the system, and typical collection

fluid operating temperature.

Commentary Heat loss from Internal manifolds and within Individual

collector panels is taken Into consideration In the panel

performance (Criterion 2.4.2) and Is not Included in this

criterion.

Typical heat loss levels that have been achieved in the

National Solar Demonstration Program are less than 10 percent of the solar energy collection rate for liquid systems

and 15 percent for air systems. Air leakage from ducts can significantly increase thermal energy loss (see Criterion

3.3.4 for specification of allowable air leakage). There

Is evidence that maintaining a slight negative pressure in

the collector array to ensure any leaks result in air infiltration, may be more beneficial than allowing air exflltratlon from the array. Reference [38] provides a simple

analytical technique for analyzing the thermal effects of

collector air leakage. A similar procedure for analyzing

the effect of heat loss from collector supply and return

ducts or pipes on system performance is described in Reference [39]. Chapter 9 of Reference [40] recommends suitable

Insulation type and thickness for collector array manifold

pipes and ducts. Reference [41] describes methods for

determination of economically optimum insulation thickness.

Heat loss during non-collection periods . Heat loss from the

collector array during times other than normal operating

conditions shall not exceed 10 percent of the design monthly

collected solar radiation in the month of January.

Evaulatlon Heat loss due to thermosiphoning , capacitance effects, and

freeze protection shall be evaluated separately.

Review drawings and specifications. Check valves or backdraft dampers must be present to prevent reverse thermosiphoning when the collectors are colder than storage, if

the collectors are located above the storage, remain filled

and the configuration permits thermosiphoning.

Capacitance effects shall be calculated for an average day

In January and compared with the solar energy collected

during that same day. When the collection fluid remains in

the collector during periods of non-operation, daily heat

loss due to capacitance effects may be calculated as the

product of fluid mass in the collector and exterior piping

or ducts, fluid heat capacity, and the difference between

the temperature of the hot fluid at the time of system

2.4.4

Criterion

2-19
shutdown and the temperature to which it cools ("normal

minimum" for the month of January, Reference [4]).

Heat loss due to freeze protection (draindown, fluid

circulation, etc.) shall be calculated for an average day

in January and compared with solar energy collected during

the same 24-hour period. If circulation of liquid from

storage is used as the freeze protection method, heat loss

from collector and exterior piping shall be calculated for

the length of time liquid is circulated. Calculations

shall consider ambient temperature, sky temperature

(approximately 10°F (6°C) below ambient), storage temperature, insulation of pipes, and heat loss factor of collector (FrUl)» The time of freeze control circulation

shall be calculated based on control strategy (Requirement

2.7), length of day, percent possible sunshine, and statistical ambient temperature data. Energy loss due to other

methods and freeze protection such as heat tapes and motorized valves shall be included.

Commentary Draining of all liquid from collector and exterior piping

to the storage tank when energy is not available (collector

drain back system) eliminates heat loss due to thermosiphoning, capacitance, and freeze protection and is recom- mended for many applications. Recirculation requires

proper sensor location and temperature set points for opti-

> mum thermal efficiency. Criteria 2.7.1 and 2,7.5 discuss sensor location and control set points, respectively. The

effect of leaking dampers in air-type systems is discussed

in Reference [42]. Leakage of dampers which serve to

isolate the collector loop from the rest of the system

should be limited to two to five percent. Spring loaded

check valves should be considered for preventing thermosiphoning in liquid systems. See Criteria 3.2.9 and 3.3.3.

The non-collection period addressed in this criterion does

not include shutdown for repairs and maintenance.

2.4.5

Criterion Energy rejection . If energy rejection is provided for in

the design, the collectors shall be capable of rejecting

energy at the required rate.

Evaluation Review drawings, specifications, collector heat loss test

data, and calculations. Collector heat loss rate may be

estimated using the slope of the ASHRAE 93-77, Reference

[34] test efficiency curve. The effect of the collector

loop heat exchanger must be considered.

Commentary The use of the slope of the ASHRAE 93-77 thermal efficiency

curve, FrUl, when multiplied by the collector area and difference between ambient and fluid temperatures, will give

2-20
2.4.6

Criterion

Evaluation

Commentary

a conservative value of heat rejected, and is satisfactory

for design purposes. More accurate (and higher) values of

heat rejected may be calculated using more refined analyses, including the effective temperature of the night sky,

since higher losses would be experienced at night than during the daytime when the ASHRAE 93-77 curve is determined.

Efficient solar collectors are inherently inefficient heat

rejectors, especially designs utilizing selective absorbing

surfaces, double glazing or evacuated tubes. It is difficult to reject at night the amount of heat collected during

a typical sunny day; therefore, special heat rejection

panels may have to be incorporated into the collector array.

Collector/storage combination . Collector/storage combinations shall collect or dissipate energy at the design rate.

Review drawings, specif ications , test data, and calculations.

Collector/storage combinations can be

designed to be placed adjacent to a house

storage materials such as rocks or can be

Trombe walls and similar passive component

under this criterion (see Criterion 2.1.1

systems, it is recommended that test data

accordance with the procedures given in

packaged systems

and filled with

built in place,

s are not covered

) . For packaged

be developed in

Reference [43].

2.5

Requirement Thermal storage performance . The thermal storage subsystem

shall be capable of efficiently accepting thermal energy,

storing it, and releasing it to satisfy partially or fully

the space heating, space cooling, and/or hot water load.

Commentary If thermal storage is not provided, this requirement is not

applicable. Refer to Criterion 2.8.2 for information con- cerning the size of thermal storage and its effect on system performance.

2.5.1

Criterion Thermal energy loss . Thermal energy loss from thermal

storage, including loss due to air leakage (in or out)

shall not exceed 15 percent of the energy input to the

storage subsystem for those months in which the load

exceeds the collected solar energy.

Evaluation Review drawings, calculations, and specifications. Examine

for conductive heat loss through insulation, losses through

storage container structural supports, and losses due to

air leakage.

2-21
Commentary

2.5.2

Criterion

Evaluation

Commentary

For other than domestic hot water storage only and when

such heat loss does not have adverse effect on the cooling

load, thermal energy losses that can he traced directly to

heated spaces and, therefore, reduce the heating load are

not required to be included in the 15 percent limitation.

Specification of allowable air leakage from thermal storage

containers is given in Criterion 3.3.4. Storage containers

for air systems should be sealed in accordance with Criterion 3.3.2. See also Criterion 3.1.3 for coverage on insulation.

Typical measured values in the solar demonstration program

show heat loss as low as five percent of the energy input

to storage, during the heating season. Reference [44],

Section S-615-7.3.4, requires for residences that "the

thermal energy loss from storage containers located outside

the heated dwelling shall not exceed 10 percent of the maximum operating thermal energy capacity over an average 24-

hour winter design day," and Reference [40], Section 9.5,

limits heat loss to two percent of the stored energy over a 12-hour period unless heat loss will supplement the space

heating requirement. Reference [21], page 19, gives a simple calculation procedure for determining the required

insulation to limit heat loss to two percent in 12 hours.

If thermal losses from storage are limited to the levels

specified by this criterion, the adverse effect on the

cooling load during any summertime operation should be

acceptably low.

Thermal stratification . Thermal stratification in the

storage subsystem shall be promoted to reduce the inlet

temperature to collectors and increase the temperature to

loads.

Review drawings and specifications. Examine the geometry

of storage container, location of inlets and outlets, velocity of heat transfer fluid, presence of baffles, and use

of multiple storage containers.

Thermal stratification in the storage container is usually

desirable in order to provide low collector inlet temperatures and to provide high temperatures to load or equipment. Consideration should be given to trade-offs between

stratification and heat losses from a second tank in the case of solar water heaters. F-Chart, Reference [33] assumes fully mixed storage. Improved thermal performance

may be achieved in practice with stratified storage.

2-22
The thermal performance of a well-insulated tank in the

demonstration program was Improved greatly by eliminating

short-circuiting from inlet to outlet by means of baffles.

In single-tank HW systems, the electrical heating element

should be placed at approximately the upper third of the

tank to promote stratification. Short-circuiting of water

flow paths between the inlet and outlet of storage should

be prevented. Reference [45] describes the effect of

stratification by use of mathematical models.

2.5.3

Criterion

Evaluation

Addition of auxiliary energy to thermal storage . Addition

of auxiliary energy to the thermal storage subsystem shall

not significantly reduce the collected solar energy or increase the heat loss from the storage container, except

where special circumstances justify non-optimum design.

Review of drawings and specifications. Examine the system

configuration, control logic, storage configuration, location of inlets and outlets, and stratification.

Commentary The addition of auxiliary heat to thermal storage

containers can severely decrease collection efficiency by

increasing collector inlet temperature.

If the solar and auxiliary subsystems are not separate, the

auxiliary energy may be added to thermal storage if done in

such a way as to preserve thermal stratification in the

storage, for example, in the case of single tank solar hot

water systems.

See Criterion 2.5.2 for discussion of stratification.

2.6

Requirement Energy transport performance . The energy transport system

shall be capable of efficient transfer of thermal energy

among or between the various components and subsystems.

2.6.1

Criterion Thermal energy loss . Under normal operating conditions,

thermal energy loss from the energy transport system shall

not exceed 15 percent of the energy to be transported.

Evaluation Review drawings, specifications, and calculations. An

instantaneous calculation of energy loss shall be performed

considering insulation thickness and conductivity value on pipes and ducts, pipe or duct hangers or other thermal

"shorts," insulation of pumps, blowers, heat exchangers,

location of blower motors (inside or outside of air stream),

and air leaks from ducts and air handling units.

2-23
Commentary

2.6.2

Criterion

Evaluation

Commentary

For other than domestic hot water systems and when such

heat loss does not have adverse effect on the cooling load,

thermal energy losses that can be traced directly to heated

spaces and, therefore, reduce the heating load, are not

required to be included in the 15 percent limitation.

Specification of allowable air leakage from the primary

solar duct system is given in Criterion 3.3.4,

This criterion does not apply to the distribution system

within the conditioned space (see Reference [23], for pipe

and duct insulation guidelines). Typically, heat loss

should be less than 5 percent of the energy transferred for

liquid systems, and 10 percent for air systems under normal

operating conditions. Collector-to-storage losses for systems in the National Solar Demonstration Program are as low

as three percent of the collected solar energy. Reference

[49] discusses the effect of energy transport losses on the

thermal performance of solar energy systems. Chapter 9 of

Reference [40] indicates insulation thickness for pipes and

ducts for residential applications.

There is concern that heat loss from the energy transport

system, especially air leakage, could significantly degrade

the control of energy flow.

If thermal losses from the energy transport system are maintained at the levels specified by this criterion, the

adverse effects on the cooling load during any summertime

operation should be acceptably low.

Operating energy . Under normal operating conditions,

operating power for fluid transport of solar thermal energy

to or from storage shall not exceed 10 percent of the

energy transferred.

Review drawings, specifications, and calculations. Examine

the size of pump or blower relative to flow and pressure

drop in system, viscosity of heat transfer fluid as a function of temperature and fluid type, motor rated capacity,

pump or fan efficiency, electrical energy input to motor

and fluid flow rate, temperature differential, and thermal

capacity of fluid.

All operating energy including that for pumps, fans,

blowers, solenoid valves and controls, should be considered

for solar components. Under normal operating conditions,

operating energy for a given heat transfer loop should not

exceed 5 percent of energy transferred for liquid systems

or 10 percent for air systems. Reference [50] includes

2-24
2.6.3

Criterion

Evaluation

Commentary

values for operating energy in thermal performance analysis

of selected projects monitored in the National Solar Demonstration Program. The use of thermosiphon loops can be

effective in reducing operating energy where feasible.

Collector loop transfer rate . The energy transport system

shall provide adequate transfer rate for the collection of

solar energy during periods of maximum solar radiation.

Review heat exchanger effectiveness under normal and peak,

design conditions, heat transfer fluid flow rate and properties, collector array area, maximum rate of incident

solar radiation, and collector efficiency curve. For thermosiphon or draindown systems, review the piping size and

slope, and the height of storage above collectors.

Reduced collector loop transfer rate will result in high

collector temperature and hence, reduced collection efficiency. If there is a collector loop heat exchanger, the

approach temperature difference should be as low as practical, 5°F-15°F (3°C-8°C) as recommended in Reference [47].

Thermosiphon HW systems for single-family residences should

have at least 3/4 inch nominal diameter pipe and long

radius elbows.

2.6.4

Criterion

Evaluation

Energy transfer to load . The energy transport system shall

be capable of transferring the required solar and auxiliary

thermal energy to the space heating, space cooling and/or

hot water loads at a rate at least equal to the design

load. If a heat exchanger is used between storage or collector array and the load, the heat transfer surface area

and rates of fluid flow shall be adequate for effective

operation of the storage and/or collectors and transfer

energy at a rate to satisfy the design load.

Heat transfer surface area, fluid flow rates, and design

load shall be reviewed. Design loads as determined under

Criterion 2.2.1, 2.2.3, and 2.3.3 shall be used in the

calculations

.

Commentary Liquid-to-air heat exchanger coils in space heating ducts

must be sized large enough to adequately transfer heat at

typical collector or storage outlet temperatures. It is

important that hot water heating coils be large enough to

avoid unnecessary use of auxiliary energy. Information

is generally available from manufacturers on heat exchanger

performance parameters. The temperature ranges will be

somewhat lower for solar applications and should be

reflected in the calculations and documentation.

2-25
During conditions of depleted storage, solar energy will be

wasted or collection efficiency will be decreased if the

storage charging rate is too low. Insufficient heat transfer area is the most likely cause of too low charging rate.

Due to the low temperatures encountered in residential

solar energy systems, much larger heat exchangers are required than for conventional systems. Several design

guides. References [46] and [47], contain useful guidance

on sizing heat exchangers for solar energy applications.

Too low a discharging rate will impair system performance

by requiring excess auxiliary energy to be used and keeping

stored energy longer, which allows greater thermal storage

losses. Reference [48] gives procedures for determining

the storage discharging rate.

2.7

Requirement

Commentary

Control performance . The control system shall be capable

of proper and efficient regulation of all other systems to

fulfill the space heating, space cooling, and/or hot water

system requirements.

Simpler control systems have been found to be just as efficient as complicated ones and are often less prone to

malfunctions. Extensive coverage of control system design

is presented in Reference [51].

2.7.1

Criterion Sensor location . Location of control sensors shall not

significantly increase the use of depletable energy by the

system due to improper location.

Evaluation Review drawings and specifications. Examine the presence

or absence of flow at all times past sensor locations,

. backflow or thermosiphon effects during non-operation, and

precision of sensors.

Commentary Sensor location should not increase depletable energy use

of the system. Normally the temperature differential

between the sensor and the point of desired measurement

should not exceed the precision range of the sensor. The

sensed condition at all times should be considered when

determining sensor placement. In particular, it is the

plate temperature, not the ambient temperature, that indicates the need for recirculation freeze protection. Radiation losses to the night sky can lower collector temperatures below the ambient temperature. If the sensor is

used to deactivate the freeze protection mode, multiple sensors may be required to assure all parts of the

collector loop have received heated water. Thermosiphon

2-26
2,1,2

Criterion

or backflow in an idle loop can cause sensors to give erroneous indications of system operating conditions.

Proper placement, insulation from external conditions, and

the use of check valves or backdraft dampers will reduce sensor susceptibility to the influence of detrimental,

extraneous, or uncontrolled heat flows. Reference [26]

discusses the implications of sensor location on system

performance. A general discussion of freeze protection

strategies and their benefits and drawbacks is given in

Reference [67],

Collector fluid circulation. The circulation of heat

transfer fluid through the collectors shall occur only when

useful heat can be collected except as required for freeze

protection, heat rejection, or dumping of excess energy.

Evaluation Review drawings and specifications. Examine the type of

controller, deadband range, temperature turn on and off

points, and means of prevention of unwanted therraosiphoning

.

Commentary Collector pump or blower cycling can be reduced by proper

deadband in on/off controllers. Studies have shown that

proportional controllers are not substantailly more effective than on/off controllers. References [51, 52]. Heat

rejection from collectors may be used for nocturnal cooling

purposes or for overheat protection (see Criterion 2.4.5).

2.7.3

Criterion Priority of energy use . The controls shall prioritize the use of energy such that solar energy is first applied

toward meeting the load if possible, then auxiliary thermal

energy is used if necessary to supply the balance, unless

such prioritizing increases the depletable energy use of

the system.

Evaluation Review drawings and specifications. Examine the control

logic, system configuration, and operation of space or HW

thermostat

.

Commentary The intent of this criterion is to use solar energy

whenever possible to reduce storage losses and enhance

collection efficiency. It is good practice to keep the

solar and auxiliary subsystems separate with, for example,

the solar coil first in the air stream and the auxiliary

coil second. This criterion is not intended to prevent the

simultaneous use of solar and auxiliary energy. Simultaneous heating and cooling should be prevented. Guidelines

provided in ASHRAE 90A-1980, Reference [23], Section 5.5,

should be followed.

2-27
1,1 ,k

Criterion

Evaluation

Commentary

2.7.5

Criterion

Evaluation

Commentary

Control valve and damper leakage . Leakage past control

valves and dampers shall not significantly increase the

depletable energy use of the system or significantly

degrade system operation.

Review drawings and specifications. Examine the control

logic, operation of control dampers and valves, flow paths,

and temperature of leaking fluids.

As described in Reference [42], it is important that dampers

in the air collection loop close tightly. Leakage past

valves can reject energy to a collection loop or cooling

tower, resulting in system performance degradation. See

Criterion 3.3.3 for specification of allowable damper leakage.

! Large heat losses can occur because of therraosiphoning from

storage to collector at night if valves or dampers in the

collector-storage loop do not close tightly.

Control set points . Controller set points shall maximize

the use of solar energy in effectively meeting the load.

Review drawings and specifications. Examine the control

strategy, set points, fluid flow paths, fluid velocities,

and collector characteristics.

Collection loop set points should be determined considering

operating energy versus energy collected. Under no circumstances should the collection loop operate when operating

energy exceeds solar energy collected.

Set points should address the freeze protection needs of

the system for the local climatic conditions. Sensors that

initiate freeze protection by sensing the ambient temperature shall have sufficiently high set points to prevent

freezing due to collector radiative losses. Set points of

45°F (7.2°C) for recirculation systems and 55°F (12.8°C)

for draindown systems have been used effectively. The set

point for a recirculation system must also be sensitive to

the thermal energy lost (Criterion 2.4.4) and the operating

energy used (Criterion 2.6.2). Efforts should be made to

avoid excessive cycling of the controller which can result

in significant system component degradation over time.

See Criterion 5.2.2. The use of a differential controller

with a time delay to minimize cycling should be considered.

2-28
Typical set points Include a delta-T of 10°F (6°C) between

storage and collector temperature for start up and a deltaT of 3°F (2°C) for shutoff for liquid direct heating and

drain back collection systems. Higher temperature differentials should be used for air collector systems and those

systems with a heat exchanger In the collector loop. References [51, 52] provide useful Information for the determination of set points. Absorption chiller performance In

cooling systems Is sensitive to control set points. Small

temperature variations at the generator (hot water) and

evaporator (chilled water) inlets can have large effects

on the chiller coefficient of performance.

2.8

Requirement Component/system interaction . All components in the H/C/HW

system shall be selected and integrated into the system in

such a manner to reduce the use of depletable energy by the

system.

Interaction of components is extremely Important for

mechanical solar energy systems. In addition to providing

thermally efficient collection, storage, energy transfer,

and control, components must be carefully selected, sized,

and integrated to require minimum depletable energy input

while satisfying system energy requirements.

Collector selection . The solar collector shall be selected

based on efficient operation in the desired operating temperature range of the equipment to which collected solar

energy is delivered.

Post-stagnation, Reference [35], test data. Reference [34] or [53], shall be submitted for the collector used. Temperature requirements of equipment, heat exchanger approach

temperature difference, solar radiation intensity, ambient

temperature, wind, and diffuse/beam solar radiation data

shall be reviewed.

Commentary

2.8.1

Criterion

Evaluation

Commentary High-temperature applications , for example, cooling systems,

may require low-loss collectors. Low temperature applications (space and water heating) can use collectors with a higher loss coefficient depending on ambient temperature

and solar radiation intensity. Heat exchangers with high

approach temperature differences require that the collectors work at a high inlet temperature. See commentary in

Criterion 2.6.3. Degradation of collectors and the effect

on selection is discussed in Chapter 5. Direct/diffuse

radiation data is discussed in Chapter 3 of Reference [36].

2-29
Although cost is not within the scope of these criteria, a number of collector characteristics will affect operation

efficiency and cost effectiveness. These characteristics

might include:

" number and material of cover plate (s)

° heat transfer medium (air, liquid) and flow rate

° freeze protection technique

° absorber coating type

° absorber plate and conduit material, gauge, and

integrating technique

° insulation material effectiveness

Reference [47] gives useful information and discussion on system design.

2.8.2

Criterion Storage selection . The thermal capacity of the thermal

storage system shall not adversely affect overall system

efficiency.

Evaluation Review drawings and specifications. Examine the storage

volume and heat capacity of storage media, collector array

area and efficiency, frequency of periods of no collectable

solar radiation, temperature requirements of equipment supplied by solar energy, number and type (hot or cold) of

units, and load. Justification must be made in design for

abnormally undersized or oversized storage.

Commentary Storage may not be provided, see Requirement 2.5. Storage

size affects collection efficiency, temperature stability

of the system, and cycling of equipment (especially absorption chillers). Too small storage results in waste of

collectable solar energy. Too large storage can result in

unacceptably high losses or too low temperatures to load.

f , The size, or even the presence or absence of storage,

depends on the system design. Storage sizes in the National

Solar Demonstration Program for residential applications

are predominantly between 10 and 20 Btu/°F'ft2 (200-400 x

103 kJ/°C'm2) of collector area, although some systems have

more than 70 Btu/°F'ft2 (1400 x 10^ kJ/°C'm2).

Reference [21], page 10, states that for residential space

and water heating systems, storage capacity should be about

10 to 15 Btu/°F'ft2 (200 to 300 x 10^ kJ/°C*m) of collector

surface.

The 10 to 15 Btu/°F'ft2 (200 to 300 x 10^ kJ/^C'm) range,

though typical, does not apply in cases such as: solar

assisted heat pumps (2-3 times this amount is needed),

2-30
seasonal or annual storage systems, solar powered chiller

systems, systems so small in relation to load that collector output is used immediately.

The use of unlined concrete storage vessels with aqueous

heat transfer fluids is not recommended. Over a period of

time some of the calcium hydroxide from the concrete will

go into solution. As the temperature of the solution

increases, the capacity of the fluid to hold the calcium

hydroxide in solution decreases. In the presence of carbon

dioxide, the calcium hydroxide will convert to calcium car- bonate which tends to deposit on surfaces such as heat

exchangers, piping and pump impellers, and housings. These

calcium deposits can degrade the system performance and

possibly cause physical damage to some of the components.

2.8.3

Criterion Fluid flow rates . Heat transfer fluid flow rates shall be

compatible among the various subsystems with regard to

capacity and heat transfer rates. Heat exchangers and

other devices shall be sized to effectively transfer energy

from one subsystem to another.

Evaluation Review drawings and specifications. Examine the required

flow rate ranges of all components in a loop and system

configuration, parallel or series arrangement of components.

Commentary Overall system efficiency can suffer due to specification

of equipment in the same loop requiring different flow

rates. Equipment sizes and arrangements (in series or parallel) should be chosen considering compatibility of

flows and heat transfer rates.

2.8.4

Criterion Auxiliary equipment selection . Auxiliary energy equipment

shall meet or exceed the minimum efficiency as required in

the applicable energy code, standard, or regulation. Auxiliary energy equipment shall be integrated with the solar

heating/cooling/hot water system to minimize the use of

depletable energy by the system.

Evaluation Review drawings and specifications. Energy Efficiency

Ratings (EER's) of all equipment shall be stated. Justification shall be made for the selection of auxiliary energy

source. Arrangement of auxiliary equipment relative to

load and solar energy equipment will be closely examined.

In particular, source temperature for heat pumps shall be

specified and justified.

Commentary Point-of-use auxiliary heaters, electric baseboard space

heaters and gas or electric water heaters, may use less

2-31
depletable energy than central systems, Point-of-use

heaters eliminate stand-by tank losses and line losses and

offer the possibility of distributed control. Electric

baseboard space heaters allow flexibility in zone heating

and are compatible with programmable thermostats. Pointof-use water heaters can also eliminate the need for hot

water plumbing. Central heating plants, sized to meet the

entire load, may generate much more heat than is necessary

when auxiliary heating is required at only one location or zone.

The thermal storage mass of a passive space heating system

should not also serve as part of the auxiliary space heating system. Supplying auxiliary energy to the thermal

storage reduces the storage capacity and thereby reduces

the overall performance of the passive system. In general,

auxiliary space heaters used with a passive space heating

system should heat only the air within the space. Auxiliary heating of the storage mass may disrupt the designed

thermal cycles of the passive system.

Parallel solar/auxiliary heat pumps may not be efficient

in cold climates. In this arrangement, the heat pump uses outside air as a heat source when the solar portion of the

system cannot supply the load. However, since the heat

pump coefficient of performance and capacity is reduced at

low source temperature, this arrangement is not always

advantageous. In general, solar/auxiliary heat pump

mechanical systems suffer a lack of performance as they

coincidentally depend on the same energy source, the sun.

Two basic methods of augmenting a solar heated absorption

chiller have been used: an independent auxiliary electric

chiller and the use of fossil fuel to fire a boiler to provide the heating energy for the absorption chiller in the

absence of solar heat. One consideration is the peak load on the electric utility at times of peak cooling power

requirements. Such conditions indicate using a fossil fuel

fired boiler. Independent electric chillers provide for

increased reliability in case of absorption chiller failure.

2.8.5

Criterion Load temperature requirements . Component interaction shall

be such that the system is able to meet higher temperature

load requirements before lower temperature loads are satisfied when higher temperature energy is available and a higher temperature load exists.

Evaluation Review drawings, specifications, system configuration, and

control logic.

2-32
Commentary Cooling applications usually require higher temperatures

than water and space heating systems. As an example, the

efficiency of an absorption chiller decreases with decreasing hot water firing temperature, so a combined cooling and

hot water system should supply the hottest solar-heated

water to the chiller and lower-temperature water to the

water heating system.

Effective use of depletable energy . The building including

passive solar components, and the mechanical H/C/HW system,

including active solar and auxiliary energy systems, shall

be designed to minimize the use of depletable energy.

Commentary Requirements 2.1 through 2.8 deal with the thermal

characteristics of the solar energy system design (passive

and active), and component performance. This requirement,

2,9, links the solar energy system performance to the

building system performance with respect to use of depletable energy. All of the system components should be

designed and constructed in a manner consistent with the

practices delineated in Criteria 2.4-2,8 to ensure that

performance determined by Requirement 2,9 is a realistic

estimate of what would be achieved in practice. The

assembled components must be assessed as a total working

system. The building/system combination needs to be evaluated to ensure that building and system are working

together in a manner that will provide reasonable savings

of depletable energy. The determination of depletable

energy used by the total system is of considerable imporrtance to the owner/developer and their 'need to know' for

making economic decisions. The depletable energy use will

also give an indication of the effectiveness of the total

building/ system thermal performance, and this determination

can be used for acceptance in jurisdictions having limits on the use of depletable energy,

Depletable energy use . The annual depletable energy used

in space conditioning and/or the heating of hot water shall

be determined and not exceed the limit established by the

owner, designer, or local jurisdiction, as applicable.

Evaluation The calculation of annual depletable energy use shall be

based on analytical predictions or correlations derived

from simulations using hourly values of solar radiation,

ambient temperature, and system load for at least one day

a month including operating energy requirements and heat

losses, and H/C/HW system and component performance characteristics. Otherwise, it shall be based on experimental

data for similar solar energy systems in similar buildings

in the same climatic area.

2,9

Requirement

2,9,1

Criterion

2-33
The energy-use calculation shall be based on design

conditions provided by the applicable authority. Energy

records of comparable residential buildings may be used to

substantiate calculated energy use, Reference [2].

Depletable energy includes coal, oil, natural and

manufactured gas, other petroleum products, electricity,

and wood. Depletable energy does not include solar energy

converted to heat or electricity at the building site or thermal energy extracted from the air, groundwater, or ground at the site. Electricity produced off-site by

hydropower or wind is considered to be depletable energy.

The end result of the calculation shall be the total annual

energy use for each depletable energy type (oil, electricity, etc.) as delivered to the building site.

Commentary For active systems, collector output should be based on actual fluid flow rate and fluid properties as installed in

the array (see Criterion 2.4.2). The prediction of system

performance shall take into consideration, where information is available , expected normal degradation of components

resulting from environmental deterioration or system wear. Fouling factors of heat exchangers and post-stagnation collector efficiency data are examples of system performance

degradation.

Experimental verification of complete system performance or actual usage data from similar projects may not be available; therefore, analytical simulation methods employing

empirical subsystem or component performance may need to be

used to calculate the performance over the full range of

operating conditions.

All systems that provide the functions of heating and/or

cooling require a thermal load analysis to determine the

total system energy demand. This analysis can vary from

simplified methods such as described in the ASHRAE Systems

Handbook, Reference [22] and based on the modified degreeday method for heating and the equivalent full-load hour

method for cooling, to sophisticated computer programs such

as NBSLD, Reference [54] which perform dynamic simulation

of hourly thermal loads for each building . zone for an entire year. Reference [55] provides a summary of computer

programs available for heating and cooling thermal load

determination. Refinements to the simplified energy calculation procedures. Reference [56] are currently being

developed to include elements deemed essential to the

accuracy of the calculation procedure.

2-34
The choice of a particular method used to calculate

building thermal load depends on the specific application. Residential buildings containing two or less zones and not utilizing passive solar components can usually be

evaluated using the simplified procedures; however, larger,

multiplezoned buildings and buildings having passive solar

corapoonents should utilize the more comprehensive

methods, Reference [57], The annual thermal performance of

all H/C/HW systems can be evaluated using a variety of

methods after the respective energy demands are determined.

Simplified methods, such as the F-Chart method. Reference

[33], varying from handbook calculation procedures to

interactive computer programs. Reference [58] are suitable

for many smaller mechanical solar energy systems. The

F-Chart method is a correlation to liquid and air active

solar systems for space heating and hot water, hot water

only, and space heating only. The F-Chart method is not

yet suitable for use with:

passive components

tracking collectors

space cooling systems

heat pump

multi-zone heating systems

Anticipated advances in the interactive computer version,

F-Chart, are expected to increase the list of system types

that can be modeled. Operating energy for pumps, blowers,

and controls is not calculated by the method and must be

estimated separately.

SOLCOST, Reference [59] is another simplified method of

calculating system thermal performance. In addition to the

systems that can be modeled by the F-Chart method, SOLCOST

is also applicable to heat pump systems, both solarassisted and solar augmented, and for single and double

axis tracking collectors. Like F-Chart, SOLCOST does not

calculate operating energies for pumps, blowers, and

controls. Detailed simulation methods such as TRNSYS,

Reference [11] are warranted for mechanical systems

installed in large complex buildings or for systems not

covered by the simplified procedures. A listing of computer programs for solar system thermal performance is available from the Conservation and Renewable Energy Inquiry and

Referral Service, Reference [60] and a more comprehensive

summary of calculation procedures are described in Reference [61].

Although the thermal performance of buildings containing

passive solar components such as direct-gain buildings can

2-35
usually be calculated using the previously described

building thermal load techniques, thermal network analysis

techniques may be required for buildings having indirectgain features such as Trombe walls. General purpose thermal analyzers such as SINDA, Reference [62] or specialized

programs such as PASOLE, Reference [10] are available for

these types of buildings. Hand calculation procedures such

as the Solar/Load Ratio method, Reference [6], are also

available. Reference [12] is a brief but comprehensive

survey of passive solar building design computer programs.

The choice of a calculation procedure for estimating solar

energy system thermal performance depends on the application.

In recent experiments on solar HW systems at NBS, Reference

[63], the predicted long-term thermal performance using the

F-Chart, SOLCOST and TRNSYS programs were all within 8 percent of the measured results. Similar efforts have been

made to compare space heating system measured performance

with F-Chart predictions using instrumented data from the

National Solar Demonstration Program, References [64, 65].

2-36
Chapter 2 References

1. Holtz, M., Place, W. , Kanunerud, R. , A Classification Scheme for the

Common Passive and Hybrid Heating and Cooling Systems," SERl/TP-63-

218, SERI, Golden, CO, August 1979.2./

2. Energy Performance Standards for New Buildings, Proposed Rule , Office of Conservation and Solar Energy, Department of Energy,

Federal Register, Vol. 44, No. 230, November 28, 1979.

3. Handbook and Product Directory, Applications , ASHRAE, 1982 .J./

4. Climatic Atlas of the U.S. , National Oceanic and Atmospheric

Administration, 1974, Ashevllle, NC 28801.

5. Klein, S, Beckman, W, Duffle, J., Monthly Average Solar Radiation

on Inclined Surfaces for 171 North American Cities , Report No. 44,

University of Wisconsin, 1977.

6. Balcomb, J., et. al.. Passive Solar Design Handbook, Volume Two of

Two Volumes; Passive Solar Design Analysis , DoE/CS-0127 /2 , Los

Alamos Scientific Laboratory, for the Department of Energy, January

1980.A/

7. TEANET: A Numerical Simulation of System Behavior Using Thermal

Network Methods , Total Environmental Action, Inc., Harrisville, NH

03450.

8. Glennie, W. , PEGFIX/PEGFLOAT Passive Solar Design Program , Princeton

Energy Group, 729 Alexander Road, Princeton, NJ 08450.

9. Arumi-Noe, F., DEROB Computer Program , School of Architecture,

University of Texas, Austin, TX 78712, May 1978.

10. McFarland, R., PASOLE; A General Simulation Program for Passive

Solar Energy , Los Alamos Scientific Laboratory Internal Report,

LA-7473-MS, P.O. Box 1663, Los Alamos, NM 87545, October 1978.

11. Klein, S., et. al., TRNSYS - A Transient Simulation Program , Report

38-10, Manual describing TRNSYS-Version 10 computer program. Solar

Energy Laboratory, University of Wisconsin, Madison, WI 53706, June

1979.

12. Solar Passive Building Design Computer Programs; A Brief Survey

With Comments , New England Solar Energy Association, Battleboro,

VT, 1979.

13. The First Passive Solar Home Awards , HUD-PDR-376 , HUD, 1979, GPO

023-000-00517-4, 1979.1^

2-37
14. Mazria, E., The Passive Solar Energy Book , Rodale Press, Emmaus

PA, 1979.

15. Burch, D., Treado, S., "Ventilating Residences and Their Attics for

Energy Conservation - An Experimental Study," Summer Attic and

Whole-House Ventilation , NBS Special Publication 548, National

Bureau of Standards, Washington, DC 20234, July 1979.1/

16. Handbook , Fundamentals , ASHRAE, 1981.1/

17. Olgyay, V., Olgyay, A., Solar Control and Shading Devices , Princeton

University Press, Princeton, NJ 08540, 1976.

18. Ramsey, C. , Sleeper, B. , Architectural Graphic Standards , John

Wiley & Sons, 305 3rd Avenue, New York, NY.

19. Thermal Conditions for Human Occupancy , Standard 55-81, ASHRAE,

1981.1/

20. Cooling and Heating Load Calculations Manual , GRP-158, ASHRAE,

1979.1/

21. Cole, R. , et. al.. Design and Installation Manual for Thermal

Energy Storage , ANL 79-15, Argonne National Laboratory, January

1980.1/

22. Handbook and Product Directory, Systems , ASHRAE, 1980.1/

23. Energy Conservation in New Building Design , Standard 90A-80, ASHRAE,

1980.1/

24. Application of Solar Energy for Heating and Cooling of Buildings , GRP 170, ASHRAE, 1977.l/

25 . National Solar Heating and Cooling Demonstration Program Project

Experience Handbook , Preliminary Draft, DoE/CS-0045/0, Department

of Energy, September 1978.1/

26. Building the Solar Home , HUD-PDR-296-1 , HUD, GPO 023-000-00455-1,

June 1978.1/

27. Easterly, J., Engineering Concerns in Solar System Design and

Operation , Solar 10811-79/01, Department of Energy, March 1979.

28. Bartlett, J., Thermal Performance of Space Cooling Solar Energy

Systems in the National Solar Data Network , Solar/0023-79/40,

Department of Energy, July 1979.^/

29. HUD Minimum Property Standards, Multlfamily Housing, 4910.1, HUD,

1973.1/

2-38
30. HUD Minimum Property Standards, Care-Type Housing , 4920.1, HUD,

1973.

31. HUD Minimum Property Standards, One- and Two-Family Dwellings , 4900.1,

HUD, 1973.2^

32. McCumber, W., Jr., Collector Array Performance Report for Sites of

the National Solar Heating and Cooling Demonstatlon Program , IBM,

July 1979.:^/

33. Beckman, W. , Klein, S., Duffle, J., Solar Heating Design - By the

F-Chart Method , Wlley-Interscience Publication, John Wiley and

Sons, New York, NY, 1977.

34 . Methods of Testing to Determine the Thermal Performance of Solar

Collectors , Standard 93-77, ASHRAE, 1977.1/

35 . Provisional Flat Plate Solar Collector Testing Procedures: First

Revision , NBSIR 78-1305A, National Bureau of Standards, Washington,

DC 20234, June 1978.1/

36. Duffle, J., Beckman, W. , Solar Energy Thermal Processes , Wiley

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

37 . Experimental Verification of a Standard Test Procedure for Solar

Collectors , NBS Building Science Series 117, National Bureau of

Standards, Washington, DC 20234, January 1979.

V

38. Jones, D., Shaw, L., Lof, G., "Air Leakage Effects on Active AirHeating Solar Collector System Performance," Preconf erence Proceedings - Solar Heating and Cooling Systems Operational Results

Conference, Colorado Springs, CO, November 1979.

39. Beckman, W., Duct and Pipe Losses in Solar Energy Systems , Solar

Energy Journal, Vol. 21, Number 6, 1978, p. 531.

40. Heating and Air Conditioning Systems Installation Standards for One -

and Two-Family Dwellings and Multifamily Housing Including Solar , Sheet Metal and Air Conditioning Contractors' National Association,

Inc., P.O. Box 70, Merrlfield, VA 22116, 1981.

41. Jones, G., Llor, N., Optimal Insulation of Pipes and Tanks for Solar

Heating Systems , DoE Publication ALO-5319-2, University of

Pennsylvania, Department of Mechanical Engineering, February 1979 .±./

42. The Effect of Air Damper Leaks on Solar Energy System Performance , National Solar Data Program, Solar/0012-78/29, DoE, 1978.

43. Jones, D., Hill, J., Performance of a Packaged Solar Space Heating

System Used with a Mobile Home , NBSIR 79-1799, National Bureau of

Standards, Washington, DC 20234, 1979.

2-39
44. HUD Intermediate Minimum Property Standards Supplement, 1977

Edition, Solar Heating and Domestic Hot Water Systems , (No. 4930.2).

Department of Housing and Urban Development, Washington, DC, 1977,3./

45. Wu, S., Han, S. , "A Liquid Solar Energy Storage Tank Model-1.

Formulation of a Mathematical Model," Modeling, Simulation, Testing

and Measurements for Solar Energy Systems , J. M. Nash, et. al.,

editor, ASME , presented at the winter annual meeting of the American

Society of Mechanical Engineers, San Francisco, CA, December 10-15,

1978.

46. Montgomery, R., The Solar Decision Book , Dow Corning Corporation,

Midland, MI 48640, 1978.

47. Solar Heating System Design Manual , Revision 1, Bulletin TESE-576,

Bell and Gossett ITT, 8200 N. Austin Avenue, Morton Grove, IL

60053, 1977.

48 . Methods of Testing Thermal Storage Devices Based on Thermal

Performance , Standard 94-77, ASHRAE, 1911 .ll

49. Ward, D. , Solar Heating and Cooling System Efficiency as a Function

of Design and Installation , Solar Energy Applications Laboratory,

Colorado State University, Fort Collins, CO 80521, September 1978.

50. Volume One; Federal Program Presentations and National Solar Data

Program , Proceedings of the U.S. Department of Energy's Regional

Solar Updates, Dearborn, MI; Orlando, FL; Philadelphia, PA; Los

Angeles, CA, July-August 1979.

51. Pejsa, J., et. al.. Cost Effective Control System for Solar Heating

and Cooling Applications , Final Report, SAN-1592-1, DoE, 1978.

52. Swanson, T., Ollendorf, S., "Study on the Application of NASA Energy

Management Techniques for Control of a Terrestrial Solar Water Heating System," AIAA Terrestrial Energy Systems Conference, June 4-6,

1979, Orlando, FL, 1290 Avenue of the Americas, New York, NY 10019.

53. Methods of Testing to Determine the Thermal Performance of Unglazed

Flat-Plate Liquid-Type Solar Collectors , Standard 96-80, ASHRAE,

1980.1/

54. Kusuda, T., NBSLD, the Computer Program for Heating and Cooling

Loads in Buildings , NBS Building Science Series 96. July 1976.±/

55 . Bibliography on Available Computer Programs in the General Area of

Heating, Refrigerating, Air Conditioning and Ventilating , ASHRAE,

1980.1/

2-40
56. Kusuda, T., Saitch, T., Simplified Heating and Cooling Energy

Analysis Calculations for Residential Applications , NBSIR 80-1961,

National Bureau of Standards, Washington, DC 20234, July 1980.

57. Solar Heating and Cooling of Residential Buildings , (Vol. 1, Design

of Systems, Vol, 2, Sizing, Installation and Operation of Systems),

prepared at Solar Energy Applications Laboratory, Colorado State

University (for the Department of Commerce), October 1977 . A/

58. F-Chart Version 3.0 Users Manual , Solar Engineering Laboratory,

University of Wisconsin, Madison, WI 53715, June 1978.

59. SOLCOST, Solar Energy Design Program for Non-Thermal Specialists,

Users Guide , Martin Marietta Aerospace, Denver Division, P.O.

Box 179, Denver, CO 80901, April 1978.

60. Conservation and Renewable Energy Inquiry and Referral Service,

P.O. Box 8900, Silver Spring, MD 20907.

61. Versteegan, P., Cassel, D., "A Survey of Existing Solar System

Simulation Methods," Proceedings of the 1979 International Congress

of the International Solar Energy Society , Atlanta, GA, May 28-

June 1, 1979.^/

62 . SINDA - Systems Improved Numerical Differencing Analyzer , available

from COSMIC, the University of Georgia, Athens, GA 30602.

63. Fanney, A., Liu, S., "Experimental System Reference and Comparison

with Computer Predictions for Six Solar Domestic Hot Water Systems,"

Proceedings of the 1979 International Congress of the International

Solar Energy Society , Atlanta, GA, May 28-June 1, 1979.^/

64. Shenfish, K., Solar Energy System Performance Evaluation - Scattergood

School Recreation Center, West Branch, Iowa - June 1978 through

April 1979 , Department of Energy, Report No. SOLAR/ 2003-79/ 14

.

65. Shenfish, K., Solar Energy System Performance Evaluation - Northview

Elementary School (Howard's Grove) Howard's Grove, Wisconsin - September 1978 through April 1979 , Department of Energy, Report

SOLAR/ 204 1-79/ 14.i./

66. Youngblood, W. , Schultz, W. , Barber, R. , Solar Collector Fluid

Parameter Study , NBS-GCR 79-184, Wyle Laboratories for the National

Bureau of Standards, October 1979.±./

67. Schiller, Steven R., "Freeze Protection," Solar Age , American

Section of the International Solar Energy Society, Vol. 6, Number 8,

August 1981.

2-41
68. Cycle 5 Residential Solar Demonstrations , Request for Grant

Application: H-8800, U.S. Department of Housing and Urban

Development, Washington, DC, 1979.

69. Sabatiuk, P., Cassel, D., McCabe, M. , Scarbrough, C, "Development

of Thermal Performance Criteria for Residential Passive Solar

Buildings," Vol. 51, Proceedings of the American Section of the

International Solar Energy Society, The 5th National Passive Solar

ConferenceAmherst, Massachusetts, 1980.

}J American Society of Heating, Refrigerating and Air Conditioning

Engineers, Inc., 1791 Tullie Circle, NE, Atlanta, GA 30329.

y Technical Information Center, P.O. Box 62, Oak Ridge, TN 37830.

A/ Superintendent of Documents, U.S. Government Printing Office,

Washington, DC 20A02.

A/ National Technical Information Service, 5285 Port Royal Road,

Springfield, VA 22161.

A/ AS/ISES, P.O. Box 1416, Killeen, TX 76541.

2-42
CHAPTER 3

MECHANICAL

Page

3.0 Introduction 3-1

3.1 System design conditions 3-1

3.1.1 Solar collectors 3-1

3.1.2 System balancing 3-2

3.1.3 Insulation 3-3

3.1.4 Structural deflection 3-4

3.2 Liquid systems 3-4

3.2.1 Piping design 3-5

3.2.2 Leak testing 3-6

3.2.3 Liquid quality 3-7

3.2.4 Thermal expansion of fluids 3-7

3.2.5 Draining and filling 3-8

3.2.6 Entrapped air 3-8

3.2.7 Vacuum relief 3-8

3.2.8 Thermal expansion of materials 3-9

3.2.9 Valves 3-9

3.2.10 Pumps 3-10

3.3 Air systems 3-11

3.3.1 Duct design 3-11

3.3.2 Sealing of air systems 3-12

3.3.3 Damper leakage 3-14

3.3.4 Air leak testing 3-15

3.3.5 Air quality 3-17

3.4 Building solar (passive) components 3-17

3.4.1 Energy transport and distribution 3-18

3.4.2 Movable insulation 3-19

3.5 Control system 3-19

3.5.1 Inhabited space temperature control 3-20

3.5.2 Domestic hot water temperature 3-20

3.5.3 System temperature and pressure limit control 3-20

3.5.4 Temperature sensor Installation 3-21

3.5.5 Auxiliary system control 3-22

3.5.6 Tracking collector controls 3-22

3.5.7 Control wiring 3-22

3-a
CHAPTER 3 - (Continued)

MECHANICAL

Page

3.6 Freeze protection 3-23

3.6.1 Antifreeze concentration 3-23

3.6.2 Draindown, drainback systems 3-23

3.6.3 Power operated protection 3-25

3.6.4 Freeze tolerant designs 3-26

References 3-27

3-b
CHAPTER 3

MECHANICAL

3.0

Introduction This chapter presents performance criteria for the

mechanical aspects of solar energy systems. The mechanical

requirements are directly related to active systems. For

passive systems, many of the design features can be considered structural, as well as mechanical. Where appropriate,

these criteria have been included. For simplicity, both

are considered in this chapter. Criteria that pertain to

passive systems are incorporated into sections throughout

the chapter under applicable topics (for example, sealing

of air systems) and are not limited to Requirement 3.4.

3.1

Requirement System design conditions . The H/C/HW system and components

shall be capable of being operated over the flow rate, pressure and temperature ranges, and under structural conditions

anticipated in actual service without significant impairment

and shall conform to applicable local and nationally

recognized codes and standards.

It is desirable that the design consist of components that are covered by recognized standards, where available, and are specified by the manufacturer to be suitable for the

pressure, temperature, and flow application. Available codes

and standards are listed by ASHRAE, Reference [1]*. Underwriters' Laboratories currently has under development a set

of standards for solar collectors that may be applicable.

Heat transfer through the system may use a number of

different transfer approaches such as gravity (or thermosiphon) circulation, combined forced and gravity circulation, or forced circulation. Systems or applications that

do not lend themselves to engineering analysis may require

prototype tests or documented performance under in-use

conditions. A standard practice for installation and ser- vice of solar heating systems (H) , Reference [2] and

installation guidelines for solar hot water systems (HW),

Reference [3] have been prepared.

Solar collectors . The solar collectors shall be designed

to accommodate the specified pressure drops and to resist

* Numbers in brackets [] indicate references at the end of this chapter.

Commentary

3.1.1

Criteria

3-1
Evaluation

Commentary

3.1.2

Criterion

Evaluation

Commentary

stagnation and thermal stress conditions. Criteria

Involving thermal performance are covered In Requirement

2.4.

Review drawings, specifications, manufacturer's literature,

test data, and design calculations. Provisional tests

described In test methods 7.2 (no-flow 30-day degradation)

and 7.6 (thermal cycling) of NBSIR 78-1305A, Reference [4] are one means of assessing the effects of several of these

conditions on collectors. ASHRAE 93-77, Reference [5]

provides coverage of collector pressure drop.

Collectors must often withstand considerable thermal

cycling and weathering conditions. Thermal performance

may be reduced by the degradation of glazings, seals, and

absorber materials.

System balancing. The energy transport system shall be

designed with provisions for balancing of all specified

design flows and shall be balanced after Installation to ensure that specified flow rates are achieved.

Flow rates shall be adjusted to meet the requirements of

Criteria 2.4.2, 2.5.3, -2.5.4, 2.6.3, 2.6.4, and 2.8.3. Two

methods for balancing are Procedural Standards for Testing,

Adjusting, and Balancing of Environmental Systems, NEBB,

Reference [6] and National Standards for Field Measurement

and Instrumentation, Total System Balance, AABC, Reference

[7] . These methods are cited as examples of currently used

air balancing test methods. Review of drawings, specifications, historical performance, previous test data, and

design calculations or testing can provide the basis for

judging compliance

Flow rates can vary widely or even short circuit areas within collector arrays, storage assemblies, and energy

transport systems resulting In reduced performance.

Typically, liquid flow Is about 0.02 gal/mln'ft^ (0.014

L/s*m2) of collector. Reverse return piping configurations

are self-balancing within certain limits. Balancing devices

must be provided on each parallel leg of a direct return

system. For air collectors, a flow rate of 2 ft-^/mln*

ft^ (0.01 m^/s'm.^) of collector Is typical. Balancing

dampers placed In ducts having excessive air flow rates Is a common means of balancing air systems.

3-2
Flow rates and velocities for thermosiphon systems will vary

dynamically and will not necessarily fall within stated

ranges.

3.1.3

Criterion Insulation . Insulation of collectors, piping, ducts,

thermal storage containers and heat exchangers shall be of

a type satisfactory for its intended purpose and installed

in accordance with recognized standards and practices.

Evaluation Review drawings and specifications. Insulation design and

installat ion shall be in accordance with ASHRAE, Reference

[8], and NFPA 90B, Reference [24], as applicable. Factory

manufactured insulated ducts shall satisfy the requirements

of UL 181, Reference [9]. Fibrous glass ducts shall satisfy

SMACNA requirements. Reference [10].

Commentary Protection of exterior pipe and duct and storage container

insulation is of great importance in preventing thermal

losses. Joints in waterproof coverings may allow moisture

intrusion into the insulation resulting in decreased Rvalue. Requirements for resistance to weathering and ultraviolet exposure are contained in Criteria 5.1.1 and 5.1.2,

for thermal stability in 5.2.1, and for fire resistance in

4.4.3 and 4.4.4.

Insulation should be protected against compressive loads

from pipe and duct supports and storage tanks. Some

insulating materials such as cellular glass foam have high

compressive strength and may be suitable for insulating

both around and under earth supported storage containers.

Most insulation materials do not have adequate compressive

strength and may require additional supporting devices,

when used beneath storage containers or other heavy components. Care should be taken that thermal shorts through

supports and fittings are minimized. Insulation on underground and unsheltered above ground components must be

well waterproofed. Provisions for sub-surface drainage

are highly recommended. Construction in high water-table

areas may be impractical. Concrete or other storage mass

on grade should have perimeter insulation either vertically

along the foundation wall or horizontally under the storage

mass, from the perimeter inward for a distance of 1 to 2

ft (.3-. 6 m) . Such insulation may be placed outside the

foundation wall to increase the volume of the insulated

thermal mass, but only if well protected from physical

damage and weathering, and be impervious to moisture

absorption. ASHRAE, Reference [8], and Reference [11]

contain guidance.

3-3
3.1.4

Criterion Structural deflection . Under the effect of deflections

caused by the loads defined in Criterion 4.6.1, 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 Review documentation of data for design, tests, and

installations. Evaluate and/or test components and elements

where deemed essential. Determine 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.

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

functioning of the system under service loading conditions

without breakdown or permanent impairment beyond levels

comparable to conventional heating and cooling systems.

Loads lower than required ultimate loads should not cause

large, irrecoverable deformations. The deflection of con- ventional elements supporting the system elements should

not exceed the limits of conventional engineering standards

for the appropriate materials and for nonconventional elements the deflection should not exceed the limitations

specified in Section 13.2.4 of Reference [13].

Reference [14] gives a range of limits on deflection

depending on circumstances that may be used for guidance

in assessing compatibility. Safety concerns such as broken

glazing and hazardous fluid leaks that may be caused by

excessive deflections are covered in Criteria 4.6.1, and

4.3.3.

3.2

Requirement Liquid systems . The subsystems and components of liquid

systems shall be designed for flow rates, temperatures,

pressures, mechanical stresses, material properties, and

heat transfer liquid characteristics to provide proper and

efficient performance.

Commentary In liquid systems, maximum pressure and temperature are primarily a function of fluid properties and relief valve

settings, along with the properties of the materials that

comprise system components. Fluid compatibility is an important consideration and is covered in Requirement 5.3.

3-4
See 6.2 and 6.3 for requirements for system maintenance,

servicing, and monitoring. Illustrations of recommended

design practices are contained in References [1, 2, 3, 12].

3.2.1

Criterion Piping design . Pipe sizing shall be in accordance with

accepted design practice or recognized methods and velocities shall not exceed the values listed in Tables 5.3 and

5.4. Anchorage shall be provided where necessary. Support

shall be provided to prevent piping from deflecting beyond

acceptable limits and to maintain a slope for positive

drainage

.

Evaluation Review drawings, specifications, and design calculations

for compliance with applicable local and national codes

and standards.

Commentary Since the size and energy requirements of pumps are a function of the system flow resistance, pressure drops

should be kept as low as practical. Fittings such as bends,

tees, globe valves, reducers, or other obstructions to flow

should be minimized or simplified by careful arrangement of

piping runs. For long runs, smooth turns with soft temper

pipe or large radius elbows should be considered. Accepted

practices for plumbing design are discussed in standard

plumbing guides. References [15, 16]. Velocities are given

in Tables 5.3 and 5.4 for the materials listed to prevent

erosive wear.

A thermosiphon water heating system is an example where pipe

sizing is essential as hot water circulation results from

the change in density of the fluid with temperature. Movement of a heat transfer fluid by natural convection is

achieved by relatively low pressure differentials and low

pressure drops are essential. Design considerations and

equipment performance data are available in References [17,

18, 19, 20].

Adequate anchorage and support are necessary in order to

prevent damage to the piping, insulation, or building sur- faces from sagging, vibration, and thermal cycling. Support

and anchorage systems are illustrated in Reference [21].

Maximum intervals for supports for horizontal runs should

be eight foot (2.4 m) for drawn copper tubes, six foot

(1.8 m) for annealed copper tube, twelve foot (3.7 m) for

threaded pipe, one to two foot (.3-. 6 m) for rigid plastic

pipe, and six foot (1.8 m) for aluminium tubing.

3-5
See also Chapter 5, especially 5.1, 5.2, and 5.3 for

additional concerns including non-metallic piping and

coupling hoses.

3.2.2

Criterion Leak testing . The portions of installed H/C/HW systems

that contain pressurized liquid heat transfer fluids shall

not leak, when exposed to designated pressures.

Evaluation Review specifications and testing. The portions of the

H/C/HW systems that contain pressurized liquid heat transfer

fluids and are not directly connected to the potable water

supply shall be leak tested at pressures not less than

1-1/2 times their design working pressure for a minimum of

15 minutes, when filled with a recommended testing fluid.

Those portions of the system designed to operate at atmospheric pressure shall be filled with a recommended testing

fluid and tested for a minimum of 30 minutes. Those portions of installed H/C/HW systems that are directly con- nected to the potable water supply system shall be tested

in accordance with applicable local and nationally recognized codes and standards. Pipes and tanks shall be leak

tested before enclosing, backfilling , or insulating. The

test pressure shall be applied for the period of time necessary to inspect for leakage. The temperature of the liquid

shall be within 5°F (3°C) of the initial ambient conditions.

Provisional tests for evaluating the leakage and pressure

resistance of solar collectors are described in test method

7.12 of NBSIR 78-1305A, Reference [4].

Commentary In most applications, the leak testing should be done with

the specified heat transfer fluid. Glycol mixtures and

-

: oils have lower surface tensions than water and can leak

through normally watertight connections. In addition, use

of water in systems later filled with oils or other immiscible liquids could lead to fluid deterioration or corrosion

due to residual water. If the fluid temperature is significantly lower than that of the ambient conditions, sweat-

,:} ing may 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

Provisions should be made at the highest point or points

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

during the filling operation. See also Criterion 3.2.6.

In applying the pressure, caution should be exercised so that excess pressure is not applied to the system. Protection of certain components such as expansion tank(s), air

vent(s) and pressure gauge (s) and capping of pressure

3-6
relief devices should be considered to avoid damage of

these components during pressure testing.

3.2.3

Criterion

Evaluation

Commentary

Liquid quality . The systems shall have strainers, filters,

or other means to collect particulate matter that could

impair the flow of the heat transfer fluid and result

either in a reduction of system efficiency or deterioration

of system components beyond acceptable limits.

Review drawings and specifications.

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. A

strainer with a brass or stainless steel screen should be

Installed ahead of the pump to remove foreign matter that

might damage the pump, clog collector or heat exchanger

passages, or cause galvanic corrosion in the system. The

change in pH of some heat transfer fluids due to their

decomposition at elevated temperatues is of great concern.

See Criteria 5.2.1, 5.3.1, and 6.2.1.

To aid in preventing sludge, the system piping should be

thoroughly cleaned and flushed prior to the introduction of

the heat transfer fluid. Problems can develop when liquids

such as "hard" water are used. See also Criteria 6.1.5 and

6.2.1

.

3.2.4

Criterion

Evaluation

Commentary

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.

Review drawings, specifications, and design calcuatlons.

Expansion tanks shall be sized in accordance with ASHRAE

Handbook/Systems, Reference [16].

Water expands about 4 percent in volume when heated from

40°F to 200°F (4°C to 93°C). Other heat transfer fluids

will have different coefficients of volumetric expansion.

Means should be provided in the system design to contain

this additional fluid volume without exceeding the relief

pressure of the system resulting in venting of fluid.

3-7
3.2.5

Criterion

Provisions for expansion of fluids should be located in all

loops in which thermal energy may be added to or removed

from the fluid and that may be isolated by valves.

Draining and filling . Fill and drain devices shall be

provided for the flushing, filling and periodic recharging

of the system, and to facilitate maintenance and repair of

liquid systems. In systems employing toxic or combustible

fluids, such devices shall be in compliance with Criteria

4.2.2 and 4.2.4.

Evaluation Review drawings

instructions.

specificationsand maintenance

Commentary In systems using toxic or combustible liquids, it may be

desirable to design fill and drain devices so that only

skilled maintenance personnel can service the system.

See Criteria 6.2.1 and 3.2.3 for further discussion

maintaining the quality of heat transfer liquids.

of

3.2.6

Criterion

Evaluation

Commentary

3.2.7

Criterion

Water wall units, barrels, columns, and other collector/

storage assemblies may require draining and filling provisions for the individual liquid containers.

Entrapped air . When liquid heat transfer fluids are used,

the system shall provide suitable means for air or gas

removal from the piping and liquid containment system.

Review drawings and specifications.

Entrapped air in piping and collectors can impede the flow

of liquids through piping, reduce heat transfer effectiveness, and otherwise reduce overall system efficiency. The

freezing of exterior uninsulated air vents has been known

to occur and create trapped air conditions in solar piping

systems. Air vents are typically installed in the high

points of the system and above the air eliminator. Automatic float vents must be mounted vertically and the cap

must not be tightened.

Vacuum relief . Closed storage tanks, expansion tanks, and

piping located at elevations above the system served shall

be protected against collapsing when subjected to vacuum. Such components shall be designed to withstand negative

pressures or have vacuum relief protection.

3-8
Evaluation Review drawings and specifications.

Commentary Possible collapse of tanks and piping from being subjected

to negative pressure Is an Important design consideration,

Reference [22]. If vacuum relief valves are used, It la

Important to protect them from freezing. See also Criterion 3.6.2. (These valves are also used In drain down

systems to permit drainage by admitting air at atmospheric

pressure.)

3.2.8

Criterion Thermal expansion of materials . The system components

and assemblies shall be designed to allow for the thermal

expansion and contraction and the flexing of plumbing and

fittings that will occur over the service temperature

range

.

Evaluation Review drawings, specifications, and calculations.

Commentary Piping, solar collectors, 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 and anchorages, structural elements, pumps, and solar collectors If means are

not Incorporated In the system design to allow for the

thermal movement. These problems are especially severe In

long pipe runs and pipes with connecting lines. Movement

due to thermal changes can also result In Inadvertent

dissimilar metals contact with other components or building

elements, leading to possible corrosion problems. See

also Criterion 3.2.1.

Expansion coefficients for commonly used materials are given In Tables B.2 and B.5 of Appendix B.

3.2.9

Criterion Valves. Valves shall be specified and located to provide

proper and efficient system performance and be In accordance

with applicable local and nationally recognized codes and

standards. Valves shall be specified and set to avoid

system or components damage.

Evaluation Review drawings and specifications for proper design

application and code compliance.

Commentary Improper application or Installation, malfunction, and

failure of valves has caused significant problems In solar

energy demonstration projects.

3-9
Valves may be either manual or motor operated. Motor

operated valves that control the draindown cycle of a draindown type solar energy system are covered in 3.6.2. Motor

operated valve installations should be designed for failsafe operation in the event of power failure. Solenoid

valves may also present problems due to incomplete closure.

Globe valves should not be used as isolation (shut-off)

valves because of the restriction they introduce. Gate or ball valves are preferable for shut-off. Square head cocks,

ball or globe valves are commonly used as balancing valves.

Gate valves are unsuited for balancing. Temperature and

pressure relief valves and vented backflow preventers should

be set to avoid system damage and should not be located in

such a way that they can discharge near personnel, electrical components, and other vulnerable items. See also Criterion 4.3.1. Because of the low flows generated in

thermosiphoning , check valves used to prevent such thermosiphoning should be mounted carefully to ensure closure.

The use of control valves with visual position indicating

devices is encouraged.

Pumps . Pumps shall be specified to provide proper and

efficient performance. Selection and installation shall

be in accordance with the requirements of the Hydraulic

Institute, Reference [23] and local and nationally recognized codes and standards where applicable.

Review drawings, manufacturer's literature, and

specifications for compliance with Hydraulic Institute

Standards.

Pump selection in accordance with the heat transfer fluid

is important with respect to viscosity, specific heat, and

specific gravity. Sizing of pumps should consider additional static head during filling operations. The energy

consumption of pumps must be considered in satisfying

Criterion 2.6.2 which establishes the limit for operating

energy.

Bronze or stainless steel pumps should be used in open

systems to prevent corrosion. Cast iron pumps should be

used with glycol/water heat transfer fluids in closed systems. It is important that the fluid corrosion inhibitors

be maintained. Galvanized pumps should not be used with

glycol solutions. As a general rule, dissimilar metals

should be avoided where possible. Specific coverage of

materials/heat transfer fluid degradation is given in

Criterion 5.3.1.

3-10
3.3

Requirement

Commentary

In draindown systems, the pump must be a certain distance

below the minimum water level in the receptor tank, to retain

prime and provide adequate positive suction head. Running

air-bound for more than ten seconds may damage the pump.

Air systems . The subsystems and components of air systems

shall be designed for capacity, temperatures, mechanical

stresses, materials properties, and flow rates to provide

proper and efficient performance.

For active systems, see 6.2 and 6.3 for requirements for

system maintenance, servicing, and monitoring. Illustrations of recommended design practices are contained in

References [1, 2, 3]. For passive systems, particularly

those with separate air distribution systems (such

as envelope designs), care should be taken to meet the

intent of this requirement.

3.3.1

Criterion Duct design . The sizing and specification of ducts, duct

joints, dampers, air movers, and other air handling components shall be in accordance with recognized standards.

Installation shall comply with National Fire Protection

Association (NFPA) Standards 90B, Reference [24], 31,

Reference [47], and 54, Reference [48]. Velocities shall

not exceed 900 ft/min (4.6 m/s).

Evaluation Review plans and specifications. Design of all heating

and cooling duct systems shall be in accordance with recommendations as applicable in ASHRAE Fundamentals, Reference

[8], the Air Conditioning Contractors of America (ACCA)

,

Reference [25] and/or the Sheet Metal and Air Conditioning

Contractors National Association (SMACNA), Reference [19].

See Criterion 4.4.3.

Commentary Ducts should be designed for the shortest practical run

and elbows should be kept to a minimum. Constrictions

should be avoided whenever possible. The use of turning vanes should be considered at duct bends to reduce pressure

losses. Recommended air velocities for main trunk ducts,

air collector manifold ducts, and air collector riser ducts

fall in the range of 700-900 ft/min (3.6-4.6 m/s). References [19, 26]. The gauge pressure of the air in the collectors should be slightly negative and as close to atmospheric as possible to minimize leakage. This usually

requires the collectors to be on the suction side of the

air mover.

Air flow through ducts , filters , heat exchangers, collectors,

and other flow restrictions will establish the total pres3-11

1
sure loss, which should be kept to a minimum in order to

reduce blower operating cost. Blowers sized near the center

of their performance curves and the use of variable speed

or belt-driven fans will allow for "tuning" flexibility in

air flow; however, sizing should also consider efficiency

of operation. Standards for design, sizing, construction,

and installation of ducts used with solar energy systems

are covered in Reference [19].

3.3.2

Criterion Sealing of air systems . The following sealing requirements

shall be used for the various components of air systems.

Restrictions on the percentage of air leakage for various

components are given in Criterion 3.3.4. Requirements for

sealing according to high pressure duct standards does not

imply that these components will function at high pressures.

(a) Primary solar duct system (PSDS) (duct system between

the collectors and thermal storage and the ducts making connection to the space distribution system; this

does not include the manifold-to-collector connection) : The PSDS shall be sealed in accordance with

Seal Class A of SMACNA High Pressure Duct Construction

Standards, Reference [27] or otherwise constructed in

such a manner to provide equivalent air tightness.

Fibrous glass ducts shall be sealed in accordance with

SMACNA Fibrous Glass Duct Construction Standards, Reference [26] and any applicable conditions of listing

for Class 1, UL 181 ducts. Reference [9].

(b) Space distribution duct system (SDDS): The SDDS shall

be sealed in accordance with Seal Class B, C, or D of

SMACNA Low Pressure Duct Construction Standards, Reference [28] for the appropriate pressures where losses

may be considered non-detrimental. This occurs where

losses are to heated space and the components are not

used to transport heat during the cooling season. In cases where leakage is detrimental or to unheated

spaces, the SDDS shall be sealed in accordance with

Seal Class A. In either case, construction that will

provide equivalent airtightness shall be allowed in

lieu of the sealing requirement.

(c) Thermal storage: Thermal storage shall be constructed

of or lined with low permeability materials and sealed

or otherwise fabricated to limit air leakage. This is

not intended to apply to storage which is directly

coupled to heated spaces as commonly done in passive

applications. Sealing shall include joints in thermal

storage, duct, and access openings.

3-12
(d) Collector arrays and other components: Collector

arrays and other manufactured components such as air

handling units, heat exchangers, and filters shall be

assembled and sealed in accordance with manufacturers'

instructions. Sealing shall include all joints between

manufactured components and ducts. Equivalent airtightness shall be provided for site-built collector

arrays.

(e) Passive air transport assemblies exposed to the

outdoors or semi-conditioned spaces shall be tightly

constructed in accordance with energy conservation

guidelines to control air infiltration and leakage,

References [29, 30, 31, 32, 33].

Evaluation Review drawings and specifications. Airtightness of

equivalent construction shall be demonstrated by documentation of satisfactory long-term performance under in-use

conditions or testing in accordance with Criterion 3.3.4.

Commentary These requirements are beyond standard practice for small

scale conventional HVAC installations. However, the prevalence of air leakage in many demonstration projects and

evidence of detrimental effect on thermal performance

dictate these sealing levels for all air solar systems.

The principals described in the SMACNA Standards, References [10, 27, 28] should be utilized in deciding upon

techniques and materials to be used in providing equivalent

air tightness.

(a) PSDS: Sealing to Class A levels should limit PSDS

leakage to one percent of system operating air flow.

All metal ducts should be examined to gain an indication of airtightness. Application of such ducts in a solar system may require extensive sealing of seams

and joints. Flexible canvas connections will probably

have too much leakage to be satisfactory in the PSDS.

Checking for leakage and sealing leaks are best accomplished during the process of field assembly before

the installation is covered by other construction.

Sealing as required above includes connections to all

ancilliary units such as storage and blowers, but does

not include manifold-to-collector connections.

(b) SDDS: Sealing of SDDS to the recommended levels

should limit air leakage to 5 percent of system operating air flow for Class B, C, or D sealing and to one percent for Class A.

(c) Thermal Storage: Thermal storage using metal as the

airtight barrier may be sealed in accordance with Seal

3-13
Class A and should achieve air leakage rates of one percent or less of system operating air flow. Thermal

storage using plastic may be appropriate for similar

treatment. Construction involving wood, masonry, or other porous materials may call for other methods, but

techniques which would make the container airtight

while simultaneously being able to withstand all ser- vice temperatures would seem appropriate. The objective of such sealing should be to limit leakage to one

to five percent of system operating air flow.

Concrete should be considered potentially porous and

may require lining and sealing to bring air leakage

within acceptable limits. Problems associated with

shrinking, warping, and cracking should be considered

when detailing storage containers made of wood.

(d) Collector arrays and other components: In designing

collectors, air handling units, heat exchangers, etc.,

for solar applications, designers should pay particular attention to details of construction and field

installations that will minimize air leakage. Airtightness of manufactured as well as site-built units

may be addressed through numerous techniques including

basic product configuration and materials selection as well as factory installed gaskets, felts, mastics, etc.

Careful attention to the collector-to-manifold connection detail will result in decreased leakage. Reference [34] discusses the effect of air leakage on system performance.

(e) Passive air transport assemblies: Since air pressures

in passive systems are essentially those generated by

natural buoyancy, good construction practices used for

the control of infiltration should provide acceptable

airtightness . Attention to the quality of construction for leakage control is very important. The sur- face areas involved in passive air transporting

assemblies are sometimes very large and contain many

sources for air leakage.

Damper leakage . Volume control dampers and back draft

dampers in the PSDS shall comply with SMACNA Solar Installation Standards, Reference [19] and shall have resilient

blade edges, such as felt, or shall be otherwise con- structed to ensure tight cutoff of the air stream.

Review drawings and specifications to determine that

correct damper type is specified.

3-14
Commentary Damper leakage has a major effect on the performance of the

system. Analysis of some operating systems has shown a 40

percent system performance loss due to leaky dampers, Ref- erence [35]. Leaking back draft dampers have allowed cold

night air to circulate over domestic HW coils and cause freezing. Leakage should be limited to two to five percent

on critical dampers, particularly those which serve to isolate the collector loop from the rest of the system. Carefully designed, constructed, and installed dampers should

be capable of meeting this level of performance. Details

of damper design are as important in ensuring tigVit cutoff over an extended service life as the materials used. Adequate sealing can be achieved using felt, vinyl, foamed

plastic, and other materials. Specifically designed "low

leakage" dampers may be required. Many seal materials are especially prone to deterioration after a period of use. Access ports should be provided for inspection and periodic

maintenance

.

See Criterion 6.2.2 for access requirements. Lightweight

back-draft dampers used in passive applications, i.e.,

Trombe walls, are discussed in Criterion 3.4.1.

3.3.4

Criterion Air leak testing . Specification for installations with

more than 1500 ft^ (139 m^) of total active collector gross area shall contain provisions for testing in accordance

with Chapter 10 of SMACNA High Pressure Duct Construction

Standards, Reference [27]. A minimum of 25 percent of each

of the following portions of the system for each category

(unheated or non-detrimental loss) shall be arbitrarily

selected and tested. Leaks shall be corrected to restrict

leakage to the percentages of total system design air flow

rate, as indicated below. If losses from ducts and storage

are into the heated space and these portions of the system

are not used during the cooling season, the losses

shall be considered non-detrimental.

Non-detrimental

Unheated spaces losses

Primary Solar Duct System 2% 2%

Space Distribution Duct 2% 10%

System*

Thermal Storage** 2-10% 10%

Collector Array 15% N/A

* Systems exempt from this requirement are defined in Criterion 3.3.2b.

** Varies according to material of construction. See Criterion 3.3.2c

(Commentary)

.

3-15
.f- Evaluation For active systems, leak testing shall be performed in

accordance with SMACNA High Pressure Duct Construction

Systems, Reference [27] as applicable.

These threshold leakage limits are based on the achievable

levels noted in Criterion 3.3.2 for each portion of the

system. There are no criteria yet established for air

leakage in passive systems. See Commentary below for subjective evaluation of passive system leakage using visual

inspection and the more quantitative techniques of pressurized and the trace gas testing for determining building/

system performance.

Commentary Higher leakage rates for the PSDS in non-detrimental loss

situations are not allowed because control of energy flows

in the solar system is of critical importance. Uncontrolled

leakage, even to heated spaces, may result in inefficient

utilization of thermal storage and thus, higher auxiliary

energy use.

In order to perform leakage tests, it may be necessary to

make provisions for blanking dampers at various locations

in the system.

" In small installations, not governed by this requirement,

it may be desirable to conduct simple leak tests by operating the system (with outlets appropriately covered over)

and feeling or listening for points of leakage or introducing smoke from a smoke bomb or other chemical source and

making a visual inspection.

Correct duct design can significantly impact air leakage

I (see Criterion 3.3.2). References [34, 36] discuss cer-

' ' tain aspects of air leakage in air systems.

For passive systems, a method of checking for gross leakage

is to conduct a careful visual inspection of the building

' ' exterior at night with strong light sources inside the

! building. Leakage paths will be revealed by the presence

\ of visible openings. Another technique that may be useful

. for determining building tightness is the fan pressurization or depressurization procedure, Reference [37]. Tracer

gas decay and air bag techniques might also be useful.

Section 301.4 of Reference [30] gives quantitative information for air leakage rates for some building components and

includes a standard test method for air leakage.

Differences between the above values for loss rates and

those in the commentary of 3.3.2 reflect the difference

between what is achievable (1%, 5%) and what may be

considered a reasonable minimum (2%, 10%).

3-16

\

\
3.3.5

Criterion Air quality . Adeqtjate means shall be provided to prevent

the accumulation of dust, dirt, water, or gases that could

result either in a reduction of system efficiency, deterioration of system components, or discomfort of building

occupants.

Evaluation Review 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. Health requirements for air quality are given in Criterion 4.1.4.

ASTM C33-81, "Standard Specification for Concrete

Aggregate," [49] gives some guidelines that are helpful for

quality control of gravel.

To facilitate rock bed washing to 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 . Drains should not be the normal

water trap type because the water will probably be evaporated by the heat from storage, thereby destroying the trap

and allowing sewer gases to enter rock bed storage. Better

arrangements might simply employ a removable plug or valve

in the bottom corner of the rock bed.

In air collectors, performance reduction due to internal

dirt accumulation from the system may be a significant

problem. In collectors where air flow is in contact with

glazing, 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 (Trombe walls, air thermos ip ho ns , etc.) where

dirt deposits may occur on absorber or glazed surfaces.

Because of the low air velocities involved with passive

systems, filtration may be impractical and access for

cleaning should be considered.

3.4

Requirement Building solar (passive) components . Proper and reliable

techniques and devices shall be provided to collect, store,

distribute, control, and prevent the loss of passively

collected solar energy.

3-17
Commentary

3.4.1

Criterion

Evaluation

Commentary

References [38, 39, 40] provide a full discussion of

the technical aspects of passive solar design.

Energy transport and distribution . Mechanical devices,

when used in conjunction with passive solar components for

energy transport and distribution, shall provide proper and

reliable performance.

Review drawings and specifications.

Inadequate or inefficient energy distribution systems have

been reported as one of the most common design faults in

passive projects in the Federal solar heating and cooling

demonstration program.

Passive systems rely primarily upon natural means of energy

flow. However, some designs work more effectively when

supplemented by devices that enhance and/or control such

energy movement. Location, sizing, and details of devices

should be of concern when designing means of distributing

thermal energy to achieve desired temperature levels and

for exhausting excessive heat.

Thermocirculation control vents should avoid undue

restriction to air flows and provide airtight closure

against backdraft. Lightweight (1 to 1.5 mil), (.0254 mm to

.0381 mm) plastic film one-way dampers have demonstrated

adequate performance in Trombe wall applications. The vent

opening with which they operate must also be well con- structed to assure a tight fit. A backing of wire mesh or other means may be required in larger vent openings or when

strong drafts are anticipated to prevent suction of the

film into the openings. Typically the size of these vents

are approximately one percent of the Trombe wall area (this

percentage being for the lower vents with upper vents of

equal size). Reference [38] provides a full discussion of

the effects of vent size on thermal performance.

A number of areas of potential mechanical inadequacy should

be noted

(a) Lightweight backdraft dampers may be fragile and of

limited reliability. Such components should be

accessible for inspection and repair.

(b) Overheat vents may be located in remote positions and

be operated only on a periodic basis. Such vents

should be accessible for inspection and cleaning to assure effective opening and closure.

3-18
(c) Thermally activated operators such as freon cylinders

and liquid pistons should be selected for reliable

service and installed in a manner which will allow

periodic inspections.

(d) Installations of heat pipes and thermic diode

assemblies should be done with a recognition of the

need for future inspection and possible removal for

testing or recharging.

3.4.2

Criterion Movable insulation . Manual or automatic movable insulation

shall be designed and installed for proper perimeter sealing

and reliable manipulation, operation, and storage.

Evaluation Review drawings and specifications, especially for details

of fit and closure of insulation at the perimeter of glazed

openings.

Commentary There are three general categories of movable insulation

applications; manual, thermally driven, and motor driven.

Some applications combine movable insulation with shading

and/or reflection devices. To be effective, surface mounted

insulation must make a tight and well-sealed cover for the

aperture to prevent drafts behind the insulation panel which

will render it ineffective. Night insulation is likely to

improve performance more than double glazing if a tight seal

is achieved. The higher the R-value of the insulation, the

tighter the air seals it should have. Unless the edges are adequately sealed, an R-f actor greater than five is questionable, Reference [39]. Some of the techniques used to

provide effective seals include channels or slots in jambs

and sills, magnets, weights, and friction fit.

Of particular concern is the potential for binding, racking,

and inadequate closure of large area coverage devices.

Also, there have been problems with blowers and suction

equipment in some applications utilizing pelletized or granular movable insulation materials. Condensation

between tight fitting insulation and glazing has been a problem. See Criterion 4.4.3 for fire hazards of

insulation.

For further discussion including guidelines and assessment

methods, see References [37, 39].

3.5

Requirement Control system . The control system shall be designed to

operate the solar and auxiliary H/C/HW system in a proper

and efficient manner.

3-19
Commentary

3.5.1

Criterion

Evaluation

Commentary

3.5.2

Criterion

Evaluation

Commentary

3.5.3

Criterion

Evaluation

See Criteria 2.7.1 through 2.7.5. Control systems have

been found to be a major source of operational difficulties

in Federal demonstration programs as described in the

National Solar Data Network, Reference [41]. Reference [42]

also gives guidelines for control systems and components.

Inhabited space temperature control . Each space

conditioning system shall be capable of providing occupied

space temperature regulation by at least one adjustable

control capable of adjustment within a minimum range from

55°F to 75°F (13°C to 23°C) where used to control heating

only and 70°F to 85°F (20°C to 30°C) where used to control

cooling only and 55°F to 85°F (13°C to 30°C) where used to

control both heating and cooling.

Review drawings and specifications.

Controls may be automatic or manual. This is intended to

include manual adjustment of devices such as wood stoves

used as auxiliary or back-up. Localized controls for

building heating and cooling are discussed in Reference

[1]. See also Section 2.2.2 for requirements for auxiliary

heating systems size.

Domestic hot water temperature . The temperature control

for the combined solar and auxiliary energy source shall be

capable of adjustment over the range of temperatures

acceptable for the intended use.

Review drawings and specifications. Review mechanical

design for compliance with Criterion 4.3.4.

Small residential domestic HW tanks are typically equipped

with a thermostat capable of controlling heating in the

temperature range of 120°F to 160°F (49°C to 66°C) . Temperature control devices used with solar energy systems

must be compatible with safety requirements and may require

the capability to cool the discharged water as does a tempering valve. Controls and valves should fail-safe to a position that would prevent scalding of a hot water user

(see Criterion 4.3.4).

System temperature and pressure limit control . Controls

shall maintain the H/C/HW system within the temperature and

pressure operating limits of the equipment specified in the

design. See also 2.3.1 and 4.3.4.

Review drawings and specifications.

3-20
Commentary Control provisions may be required for the dumping of heat

when temperatures approach unacceptable levels. Should the

temperature or pressure exceed specified limits, deterioration of components may occur and/or system function may be

impaired due to such factors as boiling, vapor locks, cavitation, degradation of insulation and seals, and unacceptable expansion of fluids or materials. Bleeding in of cold

water to replace hot water in storage is one means of

achieving this control. For safety in use provisions, see Requirement 4.3.

In systems that 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

non-insolation periods.

Thermal shock and cycling stresses can be severe over the

life of many system components. Mechanical components and

system control functions should be designed to optionally

minimize the effects of such stresses. Some collector types

such as evacuated glass tubular collectors may be especially

sensitive to these stresses, and appropriate means of protection should be provided. Provisions for thermal shock

resistance of components and materials are given in

Criterion 5.2.3.

3.5.4

Criterion Temperature sensor installation . Temperature control

sensors shall be specified to be installed in a manner as

to provide proper system control. See Criterion 2.7.1.

Evaluation Review 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 and improper physical placement of

the sensors. Degraded performance, incorrect indication of

system performance, or system failure by freeze-up can result from such erroneous readings. Problems have occurred

with sensor installations for storage containers as well as collector components.

The sensor should be in direct contact with the measured

object or substance. Heat transfer pastes may be used to

increase contact areas. Sensors for sensing fluid temperatures should be immersed directly in fluids or in direct

contact with the containment device. Insulation of sensors from extraneous heat flows can increase the accuracy of the

readings obtained from them.

3-21
Location of sensors based on their influence on system

thermal performance is specified in Criterion 2.7.1. Reference [43] gives guidance in the correct installation of sensors and probes.

3.5.5

Criterion

Evaluation

Commentary

Auxiliary system control . Provisions shall be made in the

control system to allow separate operation of the auxiliary

system.

Review drawings, specifications, and control system.

Installations with integrated solar and auxiliary control

systems have caused the auxiliary heating system to become

inoperative when the control failed on the solar side.

Such failure leaves the building without any heat.

Separate control provisions are also desirable with

integrated solar cooling control systems but failure of

such controls will not result in a level of hazard comparable to failure of the heating system. In most systems, it

is desirable that controls be designed so that the solar

components and auxiliary components will operate both

jointly and independently.

3.5.6

Criterion

Evaluation

Commentary

Tracking collector controls . Control devices and drive

mechanisms of tracking collectors shall be capable of

maintaining the focus of collectors on the daily path (or

reflection) of the sun within design limits. For tracking

collectors that cannot tolerate stagnation, control devices

shall be capable of moving the collectors off-focus during

no-flow periods or other protective measures shall be

provided

Control devices shall be specified to automatically stow

the collectors if the wind velocity exceeds the specified

limits; otherwise, the collectors shall be designed to

withstand maximum design wind speeds at that location.

Review past performance data, drawings, and specifications.

Malfunction of sensors and associated circuitry, elongation

and slippage of cables, shearing of gears, and binding of

rotational elements have resulted in improper tracking and

reduced performance of the collector array.

3.5.7

Criterion Control wiring . Control wiring designed for exterior use

shall be suitable for weather exposure or protected from

3-22
weathering. Control wiring shall be selected and installation specified to prevent damage and breakage of wiring.

Evaluation

Commentary

3.6

Requirement

Commentary

3.6.1

Criterion

Evaluation

Commentary

3.6.2

Criterion

Review drawings and specifications.

Control wiring should be in general compliance with Section

725 of the National Electric Code, Reference [44]. All

wires and cables should be supported along runs and electric cable should be securely anchored to junction boxes.

Some control devices may require shielded control wires to

prevent electromagnetic interference. Wire runs should be

soldered (using rosin flux) or properly crimped to obtain

the most accurate signal transmission. Some devices may

require protection from soldering temperatures.

Freeze protection . System components shall be protected

from or tolerant of damage by freezing of heat transfer

liquids at the lowest ambient temperatures that will be

encountered in actual use.

Various methods of freeze protection are available

including the use of f reeze-inhibited fluids such as glycol solutions and oils, warm water circulation, and

draindown. Antifreeze solutions and oils are incompatible

with many standard seal materials. Studies of freeze

associated problems are detailed in Reference [45].

Antifreeze concentration . Systems using antifreeze

solutions shall have an adequate concentration of antifreeze to prevent freezing at the coldest ambient temperatures expected to occur in the geographic location for

which they are installed.

Review specifications and weather data.

At the approach of cool weather, the antifreeze content

should be checked for proper concentration. System leaks

and improper solution make-up may result in inadequate

concentrations. For this reason, the use of automatic

water-only make-up techniques are not recommended . See

Criteria 6.1.5 and 6.2.1 and Requirements 4.1 and 4.2.

Reference [45] provides detailed recommendations for antifreeze systems.

Draindown, drainback systems . Systems using automatic

draindown for freeze protection shall provide for complete

and timely drainage of components exposed to freezing

3-23
conditions by the proper combination of sensing and control

mechanisms, valves, vents, pipe slopes, flow and pressure

control

Evaluation Review drawings and specifications.

Commentary References [20, 45] provide detailed recommendations for

draindown systems. Draindown systems require control provisions to provide venting for draining and refill (see

Criterion 3.2.7) and may require special provisions to prevent corrosion of system components during these operations. For this reason, pumps for open systems using water

as the heat transfer liquid should be either bronze or stainless steel. Pumps in closed systems may be cast iron.

See Criterion 3.2.10.

Automatic air vents, vacuum relief valves, and draindown

valves should be insulated to protect them from freezing.

The rate of draindown should be such that ice blockages do

not form in the process of draindown. It is important that

draindown systems be designed and installed so that all

! lines are pitched to drain a minimum of 1/4 inch per foot

(21 mm/meter) since roof deflection can counter this by as much as 1/10 inch per foot (8 mm/meter). It is also important that lines are adequately supported and joints are

, leaktight. In air-assisted draindown systems, moistureladen warm air may be drawn from storage into exterior

components. If this is not prevented, the moist air can freeze a control valve or create blockage in the exposed

collector loop resulting in severe freeze problems.

Fail-safe freeze protection methods are desirable since, in

the event of power failure, freeze protection methods

involving pumps, heaters, and valves that require electric

power will be inoperative.

Draindown systems are frequently designed to drain at an outdoor temperature of about 38°F (3°C) and to refill at

. about 42 °F (6°C). 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.

This problem can be avoided by initiating draindown based

on the collector absorber plate temperature. The temperature sensor initiating draindown should be located on the

component having the smallest thermal time constant. Collector panel time constants are available from the ASHRAE

test, Reference [5]. However, the water pipe time constant

would have to be calculated based on its heat capacity and

insulation R-value.

3-24
The hardness or mineral content of the water used in drain

down systems should be evaluated for the potential bulld-up

of scaling products In piping, valves, or collector

passages. See Criterion 3.2.3.

The collector loop holding tank or the expansion tank

should be properly located with respect to the system

pumps and should be placed in a warm space. Water level

indication should be marked on the storage tank, clearly

distinguishing between the appropriate water level during

normal operation and level at drainback to allow adequate

capacity for drainage. The control valves should be properly located, be air and water tight, and fail safe in a manner that assures system drainage.

3.6.3

Criterion Power operated protection . Systems using the circulation

of warm water or other methods that use electrical power

for freeze protection shall have provisions for back-up

protection of the system in the event of power failure.

The method and degree of automation of back-up protection

shall be related to the probability of concurrence of

power failure with freezing conditions and the presence of

operating personnel.

Evaluation Review drawings and specifications.

Commentary Continuous circulation of heat transfer fluid should not be

used for freeze protection due to the excessive energy loss

this causes. Pulse or intermittent warm water circulation

or heat tapes may be justified in very mild climates where

freezing temperatures are infrequent.

Back-up protection methods should be selected for the level

of potential risk that is projected. If, for example,

records indicate freezing will occur once every 20 years,

the probability of this happening concurrently with a power failure and with no one present to manually drain the

system is probably acceptably low and reliance on simple

drain methods without backup would be justified. For small

HW systems, manual methods might be considered acceptable

for somewhat more frequent freezing recurrence intervals.

Judgement must be exercised as experience has shown the

simultaneous occurrence of freezing conditions and power

outage, or exceedingly high power demand to be reasonably

high. Larger systems would probably warrant consideration

of more automated back-up provisions such as automatic

draindown or possibly even stand-by electrical generation.

Back-up stand-by power is probably most feasible where it

is being considered for other back-up reasons as well.

3-25
Reference [46] contains a detailed discussion of freeze

protection for warm climates.

3.6.4

Criterion Freeze tolerant designs . Components that will experience

freezing conditions (based upon 20 year extreme weather

data) and are not provided with specific freeze protection

techniques shall be capable of withstanding freezing

conditions and perform reliably after exposure to such

conditions.

Evaluation Review drawings and specifications. Freeze tolerance of

collectors shall be tested in accordance with test method

7.6 of NBSIR 78-1305A, Reference [4].

Commentary Stresses in collector assemblies caused by differential

. thermal expansion and contraction and by freezing of heat

transfer fluids, if any, can cause permanent damage: dis-

• .,, tortions, dislocations, and bursting of collector components. Care is necessary to ensure that all components

exposed to freezing conditions, not just collectors, be

freeze tolerant. Also, differential controllers should not

on, allow pumps to start when ice in the upper part of the

collector warms and melts while the lower part is still

blocked with ice. Water wall units, drums, etc., normally

thought to be protected may be exposed to freezing conditions during extreme conditions, i.e., when the building is

shutdown in the winter. Under ordinary operating conditions, these water walls would be protected by auxiliary

back up.

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.

3-26
Chapter 3 References

1. Handbook and Product Directory Equipment , ASHRAE, 1979.1./

2. Standard Practice for Installation and Service of Solar Space

Heating Systems for One and Two Family Dwellings , ANSI/ASTM E683-79

(1979).A/

3. Installation Guidelines for Solar DHW Systems In One- and Two-Family

Dwellings , HUD-PDR-407. U.S. Department of Housing and Urban

Development, GPO 023-000-00520-4, April 1979.1/

4. Provisional Flat Plate Solar Collector Testing Procedures , First

Revision, NBSIR 78-1305A, National Bureau of Standards, Washington,

DC, June 1978, PB 272 500.A/

5 . Methods of Testing to Determine the Thermal Performance of Solar

Collectors , Standard 93-77, ASHRAE, 1977.l/

6. Procedural Standards for Testing, Adjusting and Balancing of

Environmental Systems , National Environmental Balancing Bureau, 8224

Old Courthouse Road, Vienna, VA 22180, 1981.

7. National Standards for Field Measurement and Instrumentation, Total

System Balance , Associated Air Balance Council, 1000 Vermont Avenue,

N.W., Washington, DC 20005, 1974,

8. Handbook , Fundamentals , ASHRAE, 1981.1./

9. Standard for Factory Made Air Duct Materials and Air Duct

Connectors

,

UL 181, Underwriters' Laboratories, 333 Pflngston Road,

Northbrook, IL 60062, 1974.

10. Fibrous Glass Duct Construction Standards, Fifth Edition, SMACNA,

1979.1/

11. Williams, K. (ed.), Burt, Hill and Associates, Planning and Building

the Minimum Energy Dwelling , Craftsman Book Company, 542 Stevens

Avenue, Solana Beach, CA, 1977.

12. Avery, J. and Krall, J., Corrosion Prevention and Fluid Maintenance

in Active Solar Systems; The State-of-the-Art , Los Alamos Scientific

Laboratory, LA-UR 81-3339.M/

13 . Performance Criteria Resource Document for Innovative Construction , NBSIR 77-1316, National Bureau of Standards, Washington, DC,

November 1977.A/

3-27
14. Building Code Requirements for Reinforced Concrete , ACT 318-77,

American Concrete Institute, P.O. Box 19150, Redford Station,

Detroit, MI 43219, 1977.

15. National Standard Plumbing Code , as recommended by the National

Association of Plurablng-Heatlng-Coollng Contractors, Appendix B,

1971.1/

16. Handbook and Product Directory, Systems , 1980.1./

17. 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, FL..2./

18. Applications of Solar Energy for Heating and Cooling of Buildings , 1977, GRP 170, ASHRAE.1/

19. Heating and Air- Conditioning Systems Installation Standards for Oneand Two-Family Dwellings and Multi-Family Housing Including Solar , SMACNA, 1981.1/

20. Solar Heating Systems Design Manual, Revision 1 , TESE-576 ITT, Bell

& Gossett, 8200 N. Austin Avenue, Morton Grove, IL 60053, 1977.

21. Active Solar Energy Design Practice Manual , Solar/0802-79/01,

Mueller Associates, Inc., The Ehrenkrantz Group, for DoE, October

1979.1/

22. Wlndenburg, D., "Vessels Under External Pressure," Mechanical

Engineering , pp. 601-607, January 1937..2./

23. Hydraulic Institute Standards for Centrifugal, Rotary and

Reciprocating Pumps , 13th Edition, 1975, The Hydraulic Institute,

1230 Keith Building, Cleveland, OH 44155.

24. Warm Air Heating and Air Conditioning , NFPA No. 90B, 1980.12./

25. The Standards and Manuals of the Air Conditioning Contractors of

America (ACCA), 1228 17th Street, N.W., Washington, DC 20036.

26. Fundamentals of Solar Heating, (Correspondence Course) , HCP/M4038-01

SMACNA for DoE, January 1978 .A/

27. High Pressure Duct Construction Standards , Third Edition, 1975,

SMACNA.l/

28. Low Pressure Duct Construction Standards , Fifth Edition, 1976,

SMACNA. ' i

29. Thermal Performance Guidelines for One- and Two-Family Dwellings , NAHB Research Foundation, Inc., P.O. Box 1627, Rockville, MD 20850.

3-28
30. BOCA Basic Energy Conservation Code - 1977 , Building Officials and

Code Administrators International, Inc., 1313 East 60th Street,

Chicago, XL 60637.

31. Energy Conservation in New Building Design , Standard 90A-1980,

ashraeTIT

32. Watson, D., (ed). Energy Conservation Through Building Design , McGraw-Hill, New York, NY , 1979.

33. Insulation Manual - Homes, Apartments , Second Edition, NAHB Research

Foundation, Inc., P.O. Box 1627, Rockvllle, MD 20850, 1979.

34. Overton, R. , Cassel, D., McCabe, M. , "Evaluation of Proposed

Modification to F-Chart to Include Collector Array Air Leakage,"

Proceedings of the ASME 1980 Winter Annual Meeting, Chicago, IL,

November 16-21 , 1980.O./

35. The Effects of Air Damper Leaks on Solar Energy Systems Performance , DoE Report Solar/0012-78/29, Department of Energy, 1978.^/

36. Close, D. and Yusoff, M. , "The Effects of Air Leaks on Solar Air

Collector Behavior," Solar Energy , Vol. 20, No. 6, ISES, 1978.1/

37. Tamura, G., "Measurement of Air Leakage Characteristics of House

Enclosures," ASHRAE Transactions , Vol. 81, Part 1, pp. 202-211,

1975.1/

38. Balcomb, J., et. al., Passive Solar Design Analysis , Vol. Two,

DOE/CS-0127/2, Dlst. Cat. UC-59.A/

39. The First Passive Solar Home Awards , HUD-PDR-376, U.S. Department

of Housing and Urban Development, GPO 023-000-00517-4, April 1979.1/

40. Mazria, E., The Passive Solar Energy Book , Rodale Press, Emmaus,

PA, 1979.

41. Britnell, 0., Thermal Performance Analysis of Space Heating Systems

in the National Solar Data Network , IBM, DoE Solar/ 0025-78/42

,

1979.1/

42. Pejsa, J., et. al., Cost Effective Control Systems for Solar

Heating and Cooling Applications , Final Report, SAN- 1 592-1 , DoE,

1978.1/

43. Waite, E. , et. al.. Reliability and Maintainability Evaluation of

Solar Control Systems , ANL/ SDP- 114-79-5 , Argonne National Laboratory .A/

44. National Electric Code , NFPA No. 70, National Fire Protection

Association, 470 Atlantic Avenue, Boston, MA 02210, 1978.

3-29
45. Chopra, P. and Wolosewicz, R. , Reliability and Maintainability

Evaluation of Freezing Solar Systems , ANL/SDP-TM-78-3 , Argonne

National Laboratory,

46. Massena, P., Rool, D. , Starr, S., and Walker, R. , Solar Water and

Pool Heating Installation and Operation , Florida Solar Energy Center

300 State Road 401, Cape Canaveral, FL 32920, 1978.

47. Oil Burning Equipment , NFPA No. 31, 1974 (Also ANSI Z951).i£»li/

48. Gas Appliances and Gas Piping Installation , NFPA No. 54, 1974.

(Al.cin ANSI 7.?1.?? and ANSI 7.83.1, 1 97? ') . -L*^* H/

49. Standard Specification for Concrete Aggregates , ASTM C33-81.A/

A/ American Society of Heating, Refrigerating and Air Conditioning

Engineers, Inc., 1791 Tullie Circle, N.E. Atlanta, GA. 30329.

2_/ American Society for Testing and Materials, 1916 Race Street,

Philadelphia, PA 19103.

Superintendent of Documents, U.S. Government Printing Office,

Washington, DC 20402.

hJ National Technical Information Service, 5285 Port Royal Road,

Springfield, VA 22161.

A/ National Association of Plumblng-Heatlng-Coollng Contractors,

1016 20th Street, N.W., Washington, DC 20036.

6./ AS/ISES, P.O. Box 1416, Kllleen, TX 76541.

JJ Sheet Metal and Air Conditioning Contractors National Association,

Inc., P.O. Box 70, Merrlfleld, VA 22116.

8./ Technical Information Center, P.O. Box 62, Oak Ridge, TN 37830.

^/ The American Society of Mechanical Engineers, Inc., 345 East 47th

Street, New York, NY 10017.

National Fire Protection Association, Battery March Park, Quincy, MA

02 269.

il/ American National Standards Institute, Inc., 1430 Broadway, New York,

NY 10018.

i?./ Los Alamos Scientific Laboratory, P.O. Box 1663, Los Alamos, NM 87545

3-30
CHAPTER 4

SAFETY AND HEALTH

Page

4.1 Contamination hazards 4-1

4.1.1 Protection of potable water 4-1

4.1.2 Separation of circulation loops 4-1

4.1.3 Backflow prevention 4-2

4.1.4 Contamination of air 4-3

4.1.5 Growth of fungi 4-3

4.2 Control of hazardous substances 4-4

4.2.1 Toxic fluids 4-4

4.2.2 Identification of hazardous fluids 4-5

4.2.3 Detection of hazardous fluids 4-5

4.2.4 Disposal of hazardous fluids 4-6

4.3 Protection from physical hazards 4-6

4.3.1 Pressure and/or temperature relief devices 4-6

4.3.2 System failure prevention 4-7

4.3.3 Glazing materials 4-7

4.3.4 Scalding 4-9

4.3.5 Surface temperature 4-10

4.3.6 Water storage hazards 4-10

4.3.7 Snow and ice 4-10

4.3.8 Lightning 4-11

4.4 Fire safety 4-11

4.4.1 Liquid flash point 4-12

4.4.2 Combustible liquids 4-13

4.4.3 Flame spread classification of insulation 4-14

4.4.4 Areas of application of insulation 4-14

4.4.5 Fire resistance requirements 4-15

4.4.6 Roof covering fire performance 4-16

4.4.7 Self-ignition of combustibles 4-16

4.5 Installation arrangement 4-17

4.5.1 Identification and location of controls 4-17

4.5.2 Emergency egress and access 4-18

4.5.3 Electrical wiring 4-18

4-a
CHAPTER 4 - (Continued)

SAFETY AND HEALTH

Page

4.6 Structural safety 4-19

4.6.1 Structural resistance of H/C/HW systems 4-20

References 4-24

4-b
CHAPTER 4

SAFETY AND HEALTH

4.1

Requirement Contamination hazards . No material, form of construction,

fixture, appurtenance, or item of equipment shall be employed

that will support the growtli of microorganisms 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

.

4.1.1

Criterion Protection of potable water . Potable water shall not come

in contact with materials that 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, Reference [1].*

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.

4.1.2

Criterion

Evaluation

Commentary

Separation of circulation loops . Potable water systems

shall be separated from circulation loops of systems utilizing non-potable heat transfer or thermal storage fluids by

a minimum of two physically separated walls or interfaces

between the potable water supply and the non-potable liquid

or shall be protected in such a manner that equivalent

safety is provided. Alternative protection shall be provided in a manner acceptable to the applicable authority-

(ies) having jurisdiction.

Review drawings and specifications. Alternate levels of

protection shall be directly related to the toxicity potential of the heat transfer fluid used. For example, a suggested guideline for levels of protection is currently

being examined by ASME.JL/

It is very difficult for the system designer to assess the

safety of the heat transfer fluids that are currently on the market. It is also very difficult for the designer to

* Numbers in brackets [] indicate reference at end of this chapter.

4-1
determine the safeguards that must be taken to ensure safe

system operation. Data are available in the literature

that rank various heat transfer liquids on the basis of

their relative toxicity,^/ These data do not indicate the

cut-off points at which various degrees of protection must

be taken; however, consensus standards (in development )A/

may consider these relationships for solar applications.

This problem is compounded by factors such as: (1) the use

of additives to modify fluid properties; (2) the possible

formation of harmful decomposition products, e.g., by thermal degradation; (3) dilution of the heat transfer fluid in

the potable water stream, should failure occur, will help

to reduce the level of toxicity hazard; (4) the fact that

liquids are generally available in varying grades of chemical purity; (5). the possibility that the system will be

refilled in the future with a hazardous liquid; and (6) the

possibility that the circulation in a closed loop system

for prolonged periods of time will even result in the con- tamination of potable liquids, e.g. by metal ion buildup.

Thus, one must consider the attributes of the actual fluid

as used in the system.

4.1.3

Criterion Backflow prevention . Backflow of non-potable fluids into

the potable water systems shall be prevented in a manner

approved by the applicable authority.

Evaluation Review drawings and specif iciations

systems

Inspect assembled

Commentary Pollution of the potable water supply can occur by way of

backflow caused by back pressure and/or backs iphonage

within an inadvertent cross connection between the potable

supply and non-potable fluid in the system.

Piping arrangements, backflow prevention and/or air gaps

are commonly used to prevent contamination of potable water

systems, A check valve is not a substitute for an approved

backflow preventor and should not be used in its place.

J./ A preliminary draft standard prepared by the ASME Solar Energy Standards Committee in June 1980, contains guidelines for liquid-to-liquid

heat exchangers which relate the toxicity of the fluid to the extent

of protection provided.

]J Toxicity ratings of commercial substances from two widely acknowledged

sources, Gosselin, Reference [2] and Durham, Reference [3] are available. These have been summarized and tabulated in a convenient manner

for many materials commonly used in solar systems in Reference [4] .

4-2
Reference [5] provides discussion as well as evaluation of some of the many backflow prevention devices available.

4.1.4

Criterion

Evaluation

Commentary

Contamination of air . Materials which come in contact with

air shall not affect the odor or biological quality of the

air in an occupied space in an undesirable manner.

Review drawings and specifications.

Special consideration should be given to the presence of

fungus, mold, or mildew in air handling systems since such

microorganisms are often allergenic. Filtering of air

streams to reduce dust which may carry such microorganisms

is desirable. 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 Criterion 3.3.5.

4.1.5

Criterion

Evaluation

There is growing concern over the possible occurrence of

harmful air pollutants in tightly sealed buildings. Reference [46] . Release of radioactive radon gas in particular

has been associated with some masonry and concrete products

such as those that may be used in large quantities in passive solar components or in rock storage bins, References

[6, 7, 8]. Release of formaldehyde gas from the resins

used in urea formaldehyde foam insulation, adhesives, and

binders could present a problem when associated with air

carrying components such as storage units or collectors.

Protection from contamination of the air supplied to occupied spaces may be accomplished by the use of suitable,

non-corrosive heat exchangers. The use of heat exchangers

will penalize the thermal performance of the system to some degree

.

Growth of fungi . Components and materials used in the

H/C/HW systems that come in contact with air being supplied

to a conditioned space 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 10 of UL 181, Reference

[9] or Appendix D, Section E, of the MPS 4900.1 and 4910.1,

References [10, 11]. Review environmental and design

operation conditions.

4-3
Commentary 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

underground or exterior containers 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, therefore, other

methods may be preferable.

The formation of condensation is a related problem that is

also a concern. Condensation may occur on materials when

used for cooling storage in air systems as well as on aperture glazing and between glazing and movable insulation.

4.2

Requirement Control of hazardous substances . The use of hazardous substances within the solar energy system shall be controlled

in such a manner to prevent any unreasonable risk or danger

to the occupants, building, or surrounding area.

Commentary See the Terminology section for the definition of "hazardous substances" and the indicated reference providing guide-

- lines to regulations regarding such substances.

4.2.1

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

the Federal Hazardous Substances Act, Reference [12] and the

requirements of the applicable authority. (See definition

of "toxic" in Terminology section.)

Evaluation Review specifications.

Commentary Toxic fluids are those having the capacity to produce

personal injury or illness to man through ingestion, inhalation or absorption through any body surface, Reference

[12]. A compilation of the toxicity characteristics of

materials used in solar systems has been prepared, Reference [4]. 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. Characteristics

of the complete fluid mixture must be considered in determining toxicity. For example, the addition of inhibitors

and/or buffers to antif reeze/water mixtures or to water may

affect toxicity characteristics.

4-4
4.2.2

Criterion

Evaluation

Commentary

Identification of hazardous fluids . Systems using heat

transfer fluids or thermal storage fluids that are designated as toxic or flammable by the supplier or the applicable authority shall be identifiable, and drains and other

designated fluid discharge or fill points in the solar system should be labeled with: a warning identifying and summa- rizing the hazardous properties of the fluid, instructions

concerning the safe handling of the fluid, safe means of

disposal, and emergency first aid procedures.

Review drawings, specifications, and labeling (size, color,

etc.) for compliance with the Federal Hazardous Substances

Act, Reference [12].

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.

4.2.3

Criterion

Evaluation

Commentary

Detection of hazardous fluids . 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 if heat transfer

fluids or thermal storage fluids that require special

handling are used. 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 drawings and specifications. Test detection and

warning system(s), i.e., visibility of a dye or operation

of warning device.

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.

4-5
4.2.4

Criterion

Evaluation

Commentary

4.3

Requirement

4.3.1

Criterion

Evaluation

Disposal of hazardous fluids . Systems utilizing toxic,

corrosive, combustible, or explosive heat transfer fluids

or thermal storage fluid shall provide for the catchment

and/or harmless removal and disposal of these fluids from

drains, recharge points, vents, or points of probable leakage (i.e., leakage from components that would not normally

be expected to last the life of the system) as approved by

applicable authority.

Review drawings and specifications and local disposal

regulations.

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 disposal 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 the specialized treatment facilities may be the only

acceptable disposal method. Under such conditions, adequately sized and protected catch basins must be provided.

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.

Protection from physical hazards . The H/C/HW systems shall

not create a hazard to people greater than those found in

conventional buildings.

Pressure and/or temperature relief devices . Pressure and/

or temperature relief devices shall be provided in each

portion of the system where excessive pressure and temperatures can develop and shall be set to open at not more than

the maximum pressure and temperature for which the system

is designed.

Review drawings and specifications and/or determine that

methods, devices, and materials to be used are approved by

a recognized testing and evaluation agency as being suitable for the proposed use.

4-6
Commentary Care should be taken in the design and layout of the fluid

transport system to prevent conditions in which locally

excessive pressures or temperatures are developed as a result of flow restrictions or air locks. Large pressure

or temperature changes due to flow of vapors or boiling

fluids should be considered in the selection and location

of relief devices. Relief devices must be protected from

freezing as conditions can occur when relief is needed and

the relief valves are inoperable because they are frozen.

General requirements for use and installation of pressure

relief devices are given in Reference [45].

4.3.2

Criterion

Evaluation

Commentary

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.

Review drawings, specifications, and design calculations.

Excessive pressure and temperatures that can build up

within or on collectors under "no-flow" conditions are an important consideration. Consideration should be given to

the thermal shock which could occur when cool heat transfer

fluids are introduced into collectors which have been

exposed to solar radiation under "no-flow" conditions. Due

to the possibility of large hydrostatic head 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 designed

for maximum temperatures less than the maximum no-flow temperature (see Appendix A, Section 1) it is essential that some means of protection such as energy dumping be provided.

System protection for failure at low temperature conditions

is covered in Requirement 3.6, Freeze Protection.

4.3.3

Criterion Glazing materials . Glazed solar components with slopes less

than 45° from the horizontal and which are lower than 8

feet (2.4 m) above a walking surface for unrestricted

traffic adjacent to the component shall be safety glazed

or otherwise protected against impact of persons falling

against the glazing. Application of glazing materials in

solar components that otherwise might present a risk of

injury to persons because of falling or blowing of broken

pieces or shards shall consist of safety glazing or be

protected against breakage or restrained from falling.

4-7
Evaluation Review plans and specifications for glazing locations and

characteristics. Review compliance certification documents

or test in accordance with procedures specified in "Federal

Mandatory Standard for Architectural Glazing Materials",

Reference [13] and "Performance Specification and Method of

Test for Safety Glazing Materials Use in Buildings" , Reference [ 14 ] .

Commentary This criterion and references cited in the Evaluation 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 might fall or which is overhead and

susceptable to breakage.

An additional concern is for glazing materials presenting a risk of injury to persons because of broken, sharp pieces

or sheets that could fall from their mounting or be picked

up and driven by wind.

Glazing considered by this criterion include those used as covers for flat plate solar collectors, as tubes in solar

collectors, as solar reflectors, as roof or wall panels in

passive installations, and as storage containers which are routinely accessible.

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 con- ventional design when used for solar applications.

For tubular type collectors, safety glazing may be inappropriate and should be considered on the basis of their particular design. In such cases other means of protection

such as screening, etc., may be required where installations

fall under this criteria.

Where large expanses of glazing are used, as in passive

installations, the Federal safety standard for architectural

glazing materials. Reference [13] 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 frequent hail storms, falling limbs or other

projectiles with regard to installation of skylights,

4-8
clerestory 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. 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 hazards by excessive shattering of glazed

elements

.

Film-type glazing materials for the outermost cover plates,

if unsupported, may be unacceptable if they undergo large

deflection under load, e.g., a flexible type glazing could

deflect to the extent that a person's hand could touch the

hot absorber surface, resulting in personal injury. See

Criterion 4.3.5.

4.3.4

Criterion Scalding . Domestic hot water systems shall limit the

temperature of the hot water for personal use at the tap

to 140° + 5°F (60°C + 3°C) except where other limits are established by applicable authority. See Criterion 2.3.1.

Evaluation Review drawings and specifications.

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

tempering or mixing valves or by the use of controls such

as a high temperature cutoff on the solar energy storage

device (which may result in wasteful energy loss). If

other than the mixing valves or high temperature cutoff are

used, it should be demonstrated that the required safe temperature limit will not be exceeded. This should be done

by calculation of the temperatures in the system as a function of time throughout three successive clear sunny days

in mid-July with the ambient temperature assumed at design

conditions. The calculations should include the effect of

water draw rate, tank heat losses, and typical collector

efficiency values.

The major concern is not only for dangerously high temperatures but also for the sudden rise to such temperature. It

is generally suggested that mixing or tempering valves are

the most cost effective means for providing for protection

from scalding. See also Section 615-6.2 of the MPS, Reference [10] for controls and safety devices for all tankless

indirect water heater installations and for installations

in housing for the elderly.

4-9
The 4-5°F (+3°C) margin is given to allow a reasonable

margin of error for the design temperature capability that

must be provided (see Criterion 2.3.1) and the temperature

limitations of this section.

4.3.5

Criterion

Evaluation

Commentary

Surface temperature . Components of the H/C/HW systems that are accessible, located in areas normally subjected to

public traffic and which are operated at elevated temperatures shall either be insulated to maintain the exposed

surface temperatures at or below 140°F (60°C) at all times

during their operation or be suitably isolated. Any other

exposed areas that are operated at hazardous temperatures

shall be insulated or identified with appropriate warnings.

Review drawings and specifications.

The maximum allowable temperature commonly accepted for use

in domestic hot water installations without special protection is 140°F (60°C). In addition to the physical safety

aspect, hot surfaces should be insulated to conserve energy

or to prevent unwanted heat exchange with the space.

4.3.6

Criterion

Evaluation

Commentary

Water storage hazards . Water storage containers larger

than 200 gal. (755 L or .755 m-^) and located in or immediately adjacent to occupied spaces shall be adequately

protected from damage and structurally restrained in such

a manner to prevent rupture or collapse into the occupied

spaces

Review drawings and specifications.

Large volumes of stored water are a potential hazard

whether heated or not. The flood of water that may result

from ruptured tanks as well as the mass of the water-filled

containers are of concern. These containers, individually

or collectively, may fail due to impact, faulty fabrication

or possibly corrosion. The safety hazard is greatly

increased if the water is heated. See Criterion 4.6.1 for

structural design considerations.

4.3.7

Criterion Snow and ice . Provision shall be made over entrances and

locations of pedestrian and vehicular ways to restrain or deflect accumulated snow and ice masses which may slide off

elevated solar system components.

Evaluation Review drawings and specifications.

4-10
Commentary 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. This criterion is not intended to apply to areas where snow and

freezing conditions do not normally occur.

4.3.8

Criterion Lightning. As applicable, lightning protection shall be

provided in accordance with the NFPA No. 78 Lightning Protection Code, Reference [15].

Evaluation Review of calculations, drawings, and specifications.

Commentary Damage to control components and the potential of fire are major concerns for lightning protection.

If solar system piping is used as grounding for lightning

protection, there must be a continuous electrical path to

ground. Care must be taken that this does not short circuit dielectric isolation and thus result in corrosion

problems if dissimilar metals are used in the system.

4.4

Requirement

Evaluation

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

systems and their components shall provide a level of fire

safety consistent with applicable codes and standards.

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, Reference [16]

NFPA 90A, Reference [17] and 90B, Reference [18]

NFPA 211, Reference [19]

NFPA 54, Reference [20]

NFPA 30, Reference [21]

NFPA 31, Reference [22]

NFPA 256, Reference [23]

The National Electrical Code, Reference [24]

ASTM E84, Reference [25]

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.

4-11
and smoke generation will be considered in assessing the

potential fire hazards.

- Commentary It is the intent of the criteria of this requirement to

(1) assure that the use of materials, equipment, and fluids

will present no greater fire hazard 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. Special

consideration should also be given to the use of combustible glazing materials, particularly when those materials

are used in large quantities and/or exposed to the building

interior either directly or through air passages.

4.4.1

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

transfer fluid shall equal or exceed the higher temperature

determined from A and B below:

t" a. A temperature of 50°F (28°C) above the design maximum

flow temperature of the fluid in the solar system;

b. The design maximum no-flow temperature of the fluid.

Exception: When the collector manifold assembly is

located outside of the building and exposed to the

weather and provided that the relief valves located

adjacent to the collector or collector manifold do not

discharge directly or indirectly into the building,

and such discharge is directed away from flames and

ignition sources, only A above applies.

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 determined in NFPA No. 321, "Basic Classification of Flammable and Combustible Liquids," Reference

[27]. Flammable liquids shall not be used, and 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. Generally, this temperature will occur in the

4-12
collector when it is receiving its maximum level of solar

radiation at maximum ambient temperature.

Evaluation Review 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 to limit 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 by measuring the fluid

temperature under stagnation conditions. The no-flow, 30

day test is presented in Section 10 of Appendix A. 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.

Commentary 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. Reference [27].

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 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 study of solar heat transfer fluid

flash points and flash point criteria is presented in

Reference [28] .

4.4.2

Criterion Combustible liquids . The storage, piping, and handling of

combustible liquids shall be in accordance with the Flammable and Combustible Liquids Code NFPA No. 30, Reference

[21].

Evaluation Review specifications or code compliance.

Commentary This criterion applies to those liquids which have met

Criterion 4.4.1 for flash point. See also Criteria 4.2.2,

4.2.3, and 4.2.4.

4-13
4.4.3

Criterion 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 or air passage

ways shall meet the requirements of either NFPA 90A, Reference[17] or 90B, Reference [18], whichever is applicable.

Evaluation The ASTM E84 , Reference [25] 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 materials shall be measured.

Commentary

4.4.4

Criterion

No single test is sufficient to provide a full estimate of

performance of a product in a fire. Plastic foams and

loose fill insulation are difficult to evaluate by 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 of insulation . Materials used for

thermal insulation shall be in accordance with Criterion

4.4.3 and may be applied to the following areas: walls,

roofs, ceilings, floors, pipes, ducts, vessels, and equipment exposed to the external environment.

Exposed plastic foam (untreated or f ire-retardant treated)

Kraf t-asphaltic vapor barrier on mineral and organic fiber

insulations, and non-f ire-retardant treated loose fill

insulation shall not be permitted in habitable areas unless

fully protected from the interior of the building by a

* 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 supercedes these requirements

for cellulose insulation where applicable. Modifications to this

standard are under consideration by CPSC.

4-14

1
thermal barrier having a finish rating of not less than 15

minutes as determined by NFPA 251, Reference [29]. 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 f or that purpose.

Evaluation Review drawings and specifications.

Commentary Although a degree of material combustibility is allowed,

the intent is to allow thermal insulating materials which

are not more combustible (or flammable) than existing con- struction and insulation materials, and to preclude any

increased fire hazard due to the retention of heat from

energy dissipating objects. Electric fixtures and circuit

wires which are surrounded by substantial thermal insulation may be subject to overheating especially for circuits

loaded at or beyond their rated capacity. In areas where

occupants are likely to be engaged in normal activities, or in spaces in contact with the air stream, 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 smouldering

and its inaccessibility for f iref ighting.

4.4.5

Criterion

Evaluation

Fire resistance requirements. The presence of solar

components and their installation (penetration, etc.) shall

not reduce the fire resistance of building elements (walls

partitions, roofs, floors, etc.) required by the applicable

authority.

Review drawings and specifications. Testing to show compliance in accordance with NFPA 251, Reference [29] and applicable standards.

Commentary Solar components may form the load bearing elements of

walls, roofs, etc. In addition, the presence of solar com- ponents (collectors, storage, etc.) and the passage of system components through fire-rated assemblies may adversely

affect the fire endurance rating of the assembly in terms

of fire penetration or premature collapse of structural ele4-15
merits. Large expanses of combustible glazing or other com- ponents used in wall and roof elements may significantly

reduce the fire resistance of these components.

4.4.6

Criterion

Evaluation

Roof covering fire performance . The presence of roof

mounted solar collectors or other components shall not

reduce the required fire rating of the roof covering materials below that required by the applicable authority.

Review drawings and specifications. Testing when necessary

to show compliance shall be in accordance with NFPA 256,

Reference [23 J with the collectors mounted as intended to use.

Commentary Special consideration should also be given to the use of

combustible glazing materials, particularly when those

materials are used in large quantities and/or exposed to the

building interior either directly or through air passages.

The type of testing that should be performed to evaluate

the influence of solar collectors on the fire resistance of

roof assemblies is described in test method 7.13 of NBSIR

78-1305A, Reference [26]. Testing using these procedures

has shown that when collectors are mounted parallel to the

roof, with a space greater than 1 1/2 inches between the

collector and the roof, the fire resistance of the roof

covering is generally reduced. Reference [44].

4.4.7

Criterion Self-ignition of combustibles . Combustible solids used in

solar equipment and adjacent combustible solids shall not

be exposed to elevated temperatures which may cause

ignition.

Clearance between combustible solids and system components

having elevated temperatures shall be maintained in accordance with the following:

4-16
Installation Clearances

Maximum Surface

Temperature (°F)

less than 200

200 to 250

250 to 500 over 500

Required Clearance

( inches)

0

1

6

not allowed*

Evaluation Review calculations, drawings, and specifications. Test to

show compliance where necessary.

Commentary Exposure of wood and/or other fibrous materials as well as other combustible materials over an extended period of time

may result in the material reaching and surpassing its

self-ignition temperature, Reference [49]. 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 on the order of 392°F

(200°C). However, studies have indicated that wood may

ignite when exposed to a temperature of 212°F (100°C) for

prolonged periods of time. The ignition temperatures of

plastics may be above or below those of wood or fibrous

materials. Clearances for HVAC equipment, ducting and piping are discussed in NFPA No. 89M, Reference [16] and 90B,

Reference [18]. Where applicable, clearances specified by

a nationally recognized testing laboratory may be used.

4.5

Requirement

Commentary

Installation arrangement . The location of solar components

shall not increase the accident/hazards potential to a greater extent than would be expected for a conventional

non-solar building.

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.

4.5.1

Criterion Identification and location of controls . Main shutoff

valves and switches should be conspicuously marked and

Combustible solids shall not be exposed to temperatures above 500°F

unless the components are so listed and the clearances to combustible

materials as specified in the component listing and marking shall be

maintained for such elevated temperatures.

4-17
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 250.24

of NFPA 70, Reference [24] for electrical panels.

Review drawings and specifications.

In large buildings, accessibility would normally be limited

to qualified personnel; however, in small buildings, accessibility for the tenants should be provided.

In addition, controls which should only be adjusted by

skilled personnel should not be located in areas subjected

to normal occupant access.

Emergency egress and access . The design and installation

of the H/C/HW systems shall not impair the emergency movement of occupants of the building or emergency personnel to an extent greater than that allowed by NFPA 101 , Reference

[30] and applicable codes and standards.

Review drawings and specifications. Evaluate alternative

means for provision of equal safety protection.

If operable windows or exterior doors, required by many

codes for sleeping areas, are eliminated for increased

thermal control, such rooms and adjacent corridors should

have listed smoke detectors which are interconnected and a door opening directly into a corridor that has access to

two remote exits in opposite directions.

The location of solar equipment on a roof could reduce the

usability of that roof for firefighting or egress. Solar

system components located outside the building but near a means of egress could block the means of egress if a fire occurs.

Electrical wiring . Electric wiring shall be installed in

accordance to the requirements of the National Electrical

Code, Reference [24] or the applicable authority. Particular attention must be given to the routing of wire and

placement of electrical equipment in or near spaces which

have higher than normal temperatures as a result of the

operation of solar components.

Review of specifications and building drawings. The

National Electrical Code, Reference [24], Chapter 3, states

the requirements for temperature limits and derating factors for wiring exposed to elevated temperatures.

4-18
Commentary Experience from the Solar Demonstration program has shown

that spaces adjacent to solar collectors can become heated

to higher than normal temperatures. The installation of

residential branch circuit wiring in spaces that will

experience elevated temperatures requires that special

types of wire be used or the type generally used in residential applications having a thermal limit of 140°F (60°C)

be derated. Recent studies. References [47, 48] have shown

that the 140°F (60°C) limit can be reached when residential

branch circuits are located in attic spaces and normal loading is assumed. Thus special precautions should be used

when locating electrical equipment and wiring either in or near collectors, or other components which might cause the

wire to exceed its rated temperature limit.

4.6

Requirement Structural safety . The H/C/HW system shall provide a level

of structural safety consistent with applicable codes and

standards

.

Commentary This requirement deals 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; collapse of the

thermal storage vessel or its supporting structure; the

blowing off or fracture of a glass cover plate due to wind

or thermal stresses.

Note that this applies 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, and

concrete, that will be exposed to service conditions that are normally considered in such documents are examples of

conventional elements. Newer 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.

4-19
Structural resistance of H/C/HW systems * The elements and

connections of the H/C/HW systems shall safely support all

loads expected during the design life of the system without

failure.

The structural resistance of conventional elements shall

be determined in accordance with generally accepted engineering practices for the appropriate material, References

[31, 32, 33, 34].

When common building materials cannot be judged by conventional criteria because they are exposed to unusual service

conditions such as high temperatures, or where new materials

are used structurally, the guide performance criteria in

section 13.2.4 of Reference [35] should be used to determine

structural resistance.

The design load shall include the following loads and shall

be taken from and combined in accordance with ANSI Standard

A58.1, Reference [36] and as noted:

1. Dead loads. Include the weight of heat transfer fluid

contained in the component except when using dead load

to resist uplift or overturning.

2. Live loads. Include all static and dynamic loads

caused by the operation of the solar energy system and

all appropriate maintenance loads. Surfaces that must

support maintenance personnel shall resist a single

concentrated load of 250 lbs (113 kg) distributed over

a 4 square inch (2580 mm^) area at the most critical

locations. Also include vehicular loads as stipulated

by AASHTO, Reference [37] on elements at or below grade

subjected to traffic.

3. Soil and water pressures on buried elements.

4. Wind loads. Account for any unusual shape or exposure

factors in accordance with accepted engineering practice. Reference [38] includes information on wind

loads on solar collectors.

5. Snow and ice loads. Include any unusual loads due to

drifting or slide-off. Solar components shall resist

the appropriate surcharges, as defined in Reference

[36]. Reference [39] provides information on ice loads

on slender elements.

6. Earthquake loads. For components and connections which

cannot be evaluated within the scope of the referenced

4-20
provisions, the value of "Cp" (horizontal force factor)

shall be taken as 1.0. Reference [38J includes information on earthquake loads.

7. Constraint loads. Those loads caused by temperature

changes, shrinkage, moisture changes, normal functioning of the system, time-dependent 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. Ihe load from ponding of water on large horizontal

surfaces shall be considered.

Evaluation Review drawings, specifications, calculations, and testing.

Commentary It is expected that most aspects of structural design for

solar installations will fall within the domain of conventional engineering practice and that existing codes and

standards may be applied to such. The intent of this criterion is that conventional elements and systems continue

to be designed in accordance with applicable building code

documents. The performance criteria in Section 13.2.4 of

Reference [35] are specified for use in those situations

in which accepted engineering standards are not applicable.

Considerable care is required in determining the structural

resistance in such situations. For structural testing of

flat plate collectors, a test method has been proposed in

Reference [26] for the following tests: positive live

loads, negative and combination wind loads, and longitudinal

loads.

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:

(1) The design dead load of mass storage materials (water

tubes, drum walls, etc.) may in some instances need

to be considered on other portions of the structure

4-21
(floors, partitions, etc.)* These loads can be quite

important, particularly in retrofit application.

(2) The design live loads 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 should be

required, because the roof will need to be repaired

from time to time and must support the workman making

the repairs.

(3) Wind load pressure coefficients for flat plate collectors are presented in Reference [40] and a tabulation

of extreme wind speeds is contained in Reference [41].

Wind loads due to the presence of solar systems may be

more severe than those normally acting on buildings

and require special attention especially in retrofitting an existing building.

(4) Rows of solar collectors protruding from a roof are similar to a snow fence and may significantly increase

the amount of snow retained on the roof, requiring

special attention especially in retrofitting an existing building. Reference [38] provides design guidelines.

(5) The value of "Cp" for seismic design supplied for elements that are not specified by the referenced provisions is consistent with conservative values for

elements appended to structures.

(6) The possibility of stresses being imposed by thermal

expansion or contraction, wind movement, seismic loads,

vibratory loads, or foundation settlement need to be

considered. Thermal expansion and contraction effects

should be evaluated for the extreme operating temperature range; note particularly, pipe thrusts at anchors

and elbows. Solar components vary in their ability to

withstand the effects 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.

4-22
Time dependent changes within materials or the system

should include consideration of materials degradation.

Of particular concern may be deterioration of plastics

and organic materials, corrosion and electrolytic

action between dissimilar metals such as between a collector and its support. Materials degradation is

further discussed in Chapter 5.

In some circumstances, such as collectors framed in

wood or attic collectors, wood and other fibrous 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, References [42, 43]. 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.

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.

4-23
Chapter 4 References

1. National Interim Primary Drinking Water Regulations , 1977,

Environmental Protection Agency, Office of Water Supply, Stock

Number 055-000-00157-0.1/

2. Gosselin, Hodge, Smith and Gleason, Clinical Toxicology of Commercial

Products , 4th Edition, Williams and Wilkins Co., 428 E. Preston St.,

Baltimore, MD 21202, 1975.

3. Durham, W., "Toxicology" in Dangerous Properties of Industrial

Materials , Sax, N., ed. Van Nostrand Reinhold Co., 135 W. 50th St.,

New York, NY 10020, 1975.

4. Searcy, J., ed. Hazardous Properties and Environmental Effects of

Materials Used in Solar Heating and Cooling (SHAC) Technologies;

Interim Handbook , SAND 78-0842, Sandia Laboratories, Albuquerque,

NM, June 1978.2^

5. Sherlin, G., Beausoliel, R. , Evaluation of Backflow Prevention

Devices; A State-of-the-Art Report , NBSIR 76-1070, National Bureau

of Standards, Washington, DC 20234, 1976.1/

6. Kusuda, T., Hunt, C, McNall , P., "Radioactivity (Radon and Daughter

Products) as a Potential Factor in Building Ventilation", ASHRAE

Journal , July 1979 .A/

7. Johnson, J. and Olson, H. , "Measurement of 222Rn Bulld-Up in Solar

Heated Buildings and Calculation of Radiation Doses", DoE Publication COO-4546-2, Solar Energy Applications Laboratory, Colorado

State University, October 1978.

8. Draft Environmental Impact Statements , DoE Publication EIS-0050-D,

July 1979.

9 . Standard for Factory Made Air Duct Materials and Air Duct Connectors , UL 181, Underwriters Laboratories, 333 Pfingsten Road, Northbrook,

IL 60062, 1974.

10. HUD Minimum Property Standards, One- and Two-Family Dwellings , No.

4900.1, U.S. Department of Housing and Urban Development, Washington,

DC, 1973, revised 1976.1/

11. HUD Minimum Property Standards, Multifamily Housing , No. 4910.1,

U.S. Department of Housing and Urban Development,- Washington, DC,

1973, revised 1976.1/

12. Federal Hazardous Substances Act , Code of Federal Regulations (CFR)

Title 16, Part 1500.1/

4-24
13. Federal Mandatory Standard for Architectural Glazing Materials , 16

CFR 1201, Federal Register, January 6, 1911 .l^

14. Performance Specification and Method of Test for Safety Glazing

Material Use In Buildings, American National Standards Institute,

ANSI Z97.1-1975.A/

15. Lightning Protection Code , NFPA No. 78, 1977.A/

16. Clearances, Heat Producing Appliances , NFPA No. 89M, 1976.^/

17. Air-Condltlonlng and Venting Systems , NFPA No. 90A, 1981 .A/

18. Warm Air Heating and Air Conditioning , NFPA No. 90B, 1980 .A/

19. Chimneys, Fireplaces and Vents , NFPA No. 211, 1977.^/

20. Gas Appliances and Gag Piping Installation , NFPA No. 54, 1974 (also

ANSI Z83.1 , 1972).l/^o./

21. Flammable and Combustible Liquid Code , NFPA No. 30, 1977.A/

22. Oil Burning Equipment , NFPA No. 31, 1974 (also ANSI Z95.1).A/

23. Fire Tests of Roof Coverings , NFPA No. 256, 1976 (also ASTM E108,

197 5i./ and UL 790).^/

24. National Electric Code , NFPA No. 70, 1978 (also ANSI CI, 1978).A/

25. Surface Burning Characteristics of Building Materials, Test for , ASTM E84-77, 1977.i.^

26. Provisional Flat Plate Solar Collector Testing Procedures , First

Revision NBSIR 78-1305A, National Bureau of Standards, Washington,

DC, June 1978.1/

27. Basic Classification of Flammable and Combustible Liquids, NFPA No.

321, 1976.y

28. Lee, B. T. and Walton, W. D., Fire Experiments and Flash Point

Criteria for Solar Heat Transfer Liquids , NBSIR 79-1931, National

Bureau of Standards, Washington, DC 20234, November, 1979.1/

29. Standard Methods of Fire Tests of Building Const:ruction and Materials , NFPA No. 251, 1972 (also ASTM El 19 and UL 263). ~

30. Life Safety Code , NPPA No. 101, 1976.1/

31. Building Code Requirements for Reinforced Concrete , ACI 318-77,

American Concrete Institute, P.O. Box 19150, Redford Station,

Detroit, MI 43219, 1977.

4-25
32. Manual of Steel Construction , American Institute of Steel

Construction, 1973.

33. Specifications for Aluminum Structures , The Aluminum Association,

1976.

34 . National Design Specifications for Stress-Grade Lumber , National

Forest Products Association, 1979.

35 . Performance Criteria Resource Document for Innovative Construction , NBSIR 77-1316, National Bureau of Standards, Washington, DC,

November 1977.1/

36 . Building Code Requirements for Minimum Design Loads in Buildings

and Other Structures , ANSI A58.1, American National Standards

Institute, proposed 1980 revision.!./ U

2)1. Standard Specification for Highway Bridges , American Association of

State Highway and Transportation Officials (AASHTO) , 444 No. Capital

Street, N.W. , Washington, DC 20001, 1973.

38. Wind, Earthquake, Snow and Hail Loads on Solar Collectors , NBSIR

81-2199, National Bureau of Standards, Washington, DC, February

1981.1/

39. "Design of Steel Transmission Pole Structures," ASCE Journal of the

Structural Division, December 1974.

40. lieleman, H. , Sparks, P., Aklns , R. , "Wind Loads on Flat Plate Solar

Collectors", Department of Engineering Science and Mechanics,

Virginia Polytechnic Institute, presented at National ASCE Conference,

Atlanta, GA, October 22-26, 1979.

41. Simiu, E., Changery, M. , Fllliben, J., Extreme Wind Speeds at 129

Stations in the Contiguous United States , BSS 118, National Bureau

of Standards, Washington, DC 20234, 1979.1/

42. Wood Handbook , 1974, p. 4-32, 4-40, Forest Product Laboratory, P.O.

Box 5130, North Walnut Street, Madison, WI 53705.

43. MacLean, J., Rate of Disintegration of Wood Under Different Heating

Conditions , American Wood Preservers Association, 1625 Eye Street,

N.W., Washington, DC 20036, 1951.

44. Walton, William D. and Waksman, David, Fire Testing of Roof-Mounted

Solar Collectors by ASTM E108 , NBSIR 81-2344, National Bureau of

Standards, Washington, DC 20234, 1981.1/

4-26
45. ASME Boiler and Pressure Vessel Code , ANSI/ASME BPV-VIII-1, 1980,

Division 1, Pressure Vessels.

46. Indoor Pollutants , National Research Council, National Academy

Press, 1981.

47. Beausoliel, R.W. , Meese, W.J. and Galowin, L.S., Exploratory Study

of Temperatures Produced by Self-Heating of Residential Branch

Circuit Wiring When Surrounded by Thermal Insulation , NBSIR 78-1477,

National Bureau of Standards, Washington, DC 20234, 1978.1/

48. Faison, T.K., Field Measurement of Branch Circuit Wire Temperatures , NBSIR 81-2347, National Bureau of Standards, Washington, DC 20234,

1981.i/

49. Walton, William D. , Solar Collector Fire Incident Investigation , NBSIR 81-2326, National Bureau of Standards, Washington, DC 20234,

1981.1/

}J Superintendent of Documents, U.S. Government Printing Office,

Washington, DC 20402.

2J American Society for Testing and Materials, 1916 Race Street,

Philadelphia, PA 19103.

1/ National Technical Information Service, 5285 Port Royal Road,

Springfield, VA 22161.

A./ American Society of Heating, Refrigerating and Air Conditioning

Engineers, Inc., 1791 Tullie Circle, N.E. Atlanta, GA 30329.

1/ American National Standards Institute, Inc., 1430 Broadway, New York,

NY 10018.

A/ National Fire Protection Association, Battery March Park, Quincy, MA

02269.

U Note that the reference is to the proposed new edition, not to the

current (1972) edition.

A/ The American Society of Mechanical Engineers, Inc., 345 East 47th

Street, New York, NY 10017.

1! Council of American Building Officials, 5201 Leesburg Pike, Suite 507,

Falls Church, Virginia 22041.

4-27

CHAPTER 5

DURABILITY/RELIABILITY

Page

5.0 Introduction 5-1

5.1 Effect of external environment 5-2

5.1.1 Solar degradation 5-2

5.1.2 Moisture penetration/degradation 5-3

5.1.3 Pollutant degradation 5-5

5.2 Effect of temperature 5-6

5.2.1 Thermal degradation 5-6

5.2.2 Thermal cycling degradation 5-8

5.2.3 Thermal shock degradation 5-9

5.3 Effect of chemical compatibility of components 5-10

5.3.1 Materials/transfer fluid degradation 5-10

5.3.2 Dissimilar metals degradation 5-12

5.3.3 Compatibility of adjacent organic materials 5-13

5.4 Effect of wear 5-14

5.4.1 Degradation by wear 5-14

Table 5.1. a Guide for Durability/Reliability Evaluation of

Collector Subsystems, Components and Materials 5-15

Table 5.1.b Guide for Durability/Reliability Evaluation of

Energy Transport Subsystems, Components and

Materials 5-16

Table 5.1.C Guide for Durability/Reliability Evaluation of

Storage Subsystems, Components and Materials 5-17

Table 5.1.d Guide for Durability/Reliability Evaluation of

Control Subsystems, Components and Materials 5-18

Table 5. 2. a Property Assessment of Materials — Collector

Components 5-19

Table 5.2.b Property Assessment of Materials — Energy Transport

Components 5-20

Table 5.2,c Property Assessment of Materials — Storage

Components 5-21

Table 5,3 Open System Parameters: Generally Acceptable and

Unacceptable Use Conditions for Metals in Direct

Contact with Heat Transfer Fluids 5-22

Table 5.4 Closed System Parameters: Generally Acceptable and

Unacceptable Use Conditions for Metals in Direct

Contact with Heat Transfer Liquids 5-24

5-a
CHAPTER 5

DURABILITY/RELIABILITY (Cont.)

Page

References 5-26

5-b
CHAPTER 5

DURABILITY/ RE LIABILITY

5.0

Introduction The performance requirements and criteria in this chapter

deal with the ability of components and materials to maintain satisfactory long-term performance under in-service

and extreme conditions. Factors such as the effect of

external environment, temperature, chemical compatibility

and wear or fatigue are addressed.

The intent in developing the requirements of Chapter 5 on durability/reliability is to assure that the components and

materials designed to work as a system in the application

of solar energy have a reasonable level of reliability.

Much of the evaluative testing needed to assess performance

should already have been carried out as part of the materials manufacturer's product development process, thus much

of the requested information should be relatively easy to

supply. There may be cases where a proposed design or application creates a unique condition of exposure, and

additional testing will be needed to demonstrate compliance

with the intent of the criteria. When testing of components or assembly of components is necessary, the performance of the assembly should indicate whether or not more detailed materials evaluation may be required. For

instance, water leakage into a component would indicate

that either the material must be resistant to moisture

damage or the component must be redesigned to prevent

water penetration. If the material is to resist degradation from moisture, evidence must be made available to

show that the proposed materials possess the required characteristics to resist exposure to moisture.

As an aid to the user, a guide has been prepared which

lists requirements and criteria for various components and

materials, and the corresponding need for evaluative testing and analysis. A general guide for the consideration

of each requirement and criterion for the various components and materials is contained in Tables 5.1a, 5.1b, 5.1c

and 5. Id. The subsystems covered by these tables include

the collector, the energy transport, the storage and the

control subsystems and their components. These tables

delineate the types of environmental conditions to which

solar components and their materials could be exposed in

actual service.

Tables 5.2a, 5.2b and 5.2c on collector, energy transport

and storage components, respectively, are provided as an

5-1
aid to identifying the need for assessing properties of

materials. These tables do not relate directly to

specific criteria, but guide the evaluator in determining

which materials properties are critical for various subsystem components. The designated critical properties,

when evaluation is required, should be measured before and

after exposure to the environmental conditions or aging

procedures presented in Chapter 5. Table B.l (see Appendix

B) presents standard practices which are available for

determining physical properties of materials.

Appendix A provides test methods for evaluating components

and materials to determine if satisfactory performance is

achieved. The test methods listed in Appendix A are to be

used when standard practices, such as ASTM standards, are not available. If standard practices are available, and

satisfactorily address the issues of conditioning exposure

and measurement of performance, such standards are preferred over the test method presented in Appendix A.

Appendix B contains several tables intended to assist

evaluators and designers with durability/reliability issues

when materials are considered for solar application. In

addition to Table B.l, which lists available ASTM standards

useful in materials property measurement, tables of materials properties and characteristics are presented. Tables

B.2, B.3, B.4 and B.5, which were derived from literature

sources, provide the evaluator/designers with baseline

information on properties of: cover plates, absorptive

coatings, heat transfer liquids, and selected building

materials.

5.1

Requirement Effect of external environment . The H/C/HW systems and

their various components shall not be affected by external

environmental factors to an extent that will significantly

impair their function during their design lives.

5.1.1

Criterion Solar degradation . Solar 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 lives.

When components or materials are exposed to ultraviolet

radiation, there shall be no signs of excessive deterioration of optical, physical, or mechanical properties, or any

other changes that would significantly affect the performance of the components in the system.

5-2
Evaluation Compliance may be documented with data on satisfactory

long-term performance under In-servlce conditions or engineering analysis. Where adequate information is

unavailable , evaluation shall, where applicable, be carried

out using the following standard practices which include

solar degradation provisions: for cover plate materials,

ASTM E765-80, "Standard Practice for Evaluation of Cover

Materials f or Flat Plate Solar Collectors", Reference

[1]; and ASTM E782-81, "Standard Practice for Exposure of

Cover Materials for Solar Collectors to Natural Weathering

Under Conditions Simulating Operational Mode", Reference

[2]. For absorptive coatings ASTM E744-80, "Standard Practice for Evaluating Solar Absorptive Materials for Thermal

Applications", Reference [3], and/or as appropriate ASTM

E781-81, "Standard Practice for Evaluating Absorptive Solar

Receiver Materials When Exposed to Conditions Simulating

Stagnation in Solar Collectors with Cover Plates", Reference [4], If the test methodology described in these standards is not appropriate for the component or material in

question or for the environmental conditions expected in

service, the methodology outlined in Section 3 of Appendix

A or other methods, shall be used to demonstrate that the

intent of the criterion is met.

Commentary Organic materials may be particularly susceptible to

degradation resulting from prolonged exposure to solar

radiation. Ultimate failure of these materials is frequently caused by physical impact, wind flutter, etc.

Components of particular concern include cover plates,

coatings, sealants, gaskets, absorber surfaces, collector

heat traps, exposed coupling hoses, coatings or coverings

of exposed insulation, devices for controlling entrance of

sunlight (shutters, shades, drapes, blinds, etc.), reflectors, and collector casing assemblies. Combinations of

materials (i.e., dissimilar metals) may give rise to cor- rosion problems that are not obvious from testing

individual materials.

5.1.2

Criterion Moisture penetration/degradation . Solar components or materials shall not be adversely affected by exposure to

moisture in service to an extent that will significantly

Impair their function during their design lives.

Evaluation When components, materials, or combinations thereof are exposed to moisture, there shall be no signs of excessive

material degradation or reduction in insulation effectiveness that would significantly affect the performance of

the components or the system.

* Numbers in brackets [] indicate references at the end of this chapter.

5-3
Compliance with the above criterion may be documented with

data on satisfactory long-term performance under in-use

conditions or engineering analysis. If evaluative testing

is required, the complete collector assembly shall be

assessed for water leakage according to tests in Section 10

of Appendix A; or Section 7.5 of NBSIR 78-1305A, Reference

[5] for thermal shock/water spray penetration and rain

penetration. Consideration of water vapor stability of

materials can be determined by the method described in ASTM

D2247-68 (1973), "Standard Method for Testing Coated Metal

Specimens at 100 Percent Relative Humidity", Reference [6] or ASTM E744-80, "Standard Practice for Evaluating Solar

Absorptive Materials for Thermal Applications", Reference

[3]. The effect of moisture upon the weathering of cover

plate materials can be evaluated using ASTM E765-80,

"Standard Practice for Evaluation of Cover Materials for

Flat Plate Solar Collectors", Reference [1]. ASTM E765-80

describes both natural and artificial weathering accompanied by water spray cycles. For determining the effect

of moisture and water upon thermal insulation used in

solar collectors, ASTM E861-82, "Standard Practice for

Evaluating Thermal Insulation Materials for Use in Solar

Collectors", Reference [7] can be used. Where other tests

are available, that meet the intent of evaluating resistance to moisture penetration/ degradation, such tests may

be used.

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

rainfall, melting snow and ice, condensation or vapor. The

intent of this criterion is to ensure adequate performance

of components or materials that are exposed to moisture

from the external environment or exposed to condensation in

the collector interior. 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. Guidance

for the waterproofing of exposed insulation both above and

below ground is given in the HUD MPS Section 607-2, Reference [8], and also the ASHRAE Handbook of Fundamentals

Chapter 17, Reference [9]. Salts extracted by moisture

from some types of insulation or from organic components

may cause corrosion of other system components in close

proximity. Chlorides or sulfates that may be leached are a particular concern in regard to metallic corrosion. This

criterion is not intended to address the effect that water

in heat transfer fluid can have on system components which

contact the fluid.

5-4
Efflorescence on the absorber surface of masonry walls such

as greenhouse and Trorabe walls can cause the deterioration

of the absorber coating. Efflorescence Is commonly caused

by high mineral content in water used for the production of

masonry units or the mixing of mortar and is activated by

the presence of moisture in the wall.

5.1.3

Criterion Pollutant degradation . Solar components and materials that

are exposed to regionally prevalent air pollutants such as photochemical oxidents (ozone), sulphur dioxide, nitrogen

oxides, or salt spray shall not be adversely affected to

the extent that will significantly impair their function

during their design lives.

Evaluation Compliance may be documented with data on satisfactory

long-term performance under in-use conditions or engineering analysis. Several standard specifications have

been developed for solar energy system components that

address the problem of pollutant degradation. The procedures cited in the specifications which address pollutant

degradation shall be used as appropriate. Specifications

related to rubber seals and hoses are: ASTM D3667-78,

"Standard Specifications for Rubber Seals Used in Flat

Plate Solar Collectors", Reference [10]; ASTM D3771-79

"Standard Specification for Rubber Seals Used in Concentrating Solar Collectors", Reference [11]; ASTM D3832-79,

"Standard Specification for Rubber Seals Contacting Liquid

in Solar Energy Systems", Reference [12]; ASTM D3903-80,

"Standard Specification for Rubber Seals Used in Air-Heat

Transport of Solar Energy Systems", Reference [13]; and

ASTM D3952-80, "Standard Specification for Rubber Hose Used

in Solar Energy Systems", Reference [14]. For other components or materials where adequate information regarding

resistance to degradation from pollutants is unavailable,

testing using either the methodology outlined in Section 4

of Appendix A or other methods which can be shown to meet

the intent of the criterion shall be used.

The maximum pollutant levels in the geographic areas where

the system will be installed shall be used to determine the

pollutant levels required for testing. The pollutant

levels shall be obtained from the most recent edition of

"Air Quality Data - Annual Statistics Including Summaries

with References to Standards", Reference [15]. If components are to be used in areas where they are exposed to

very low pollutant concentrations, then the degradation

test(s) for pollutants need not be conducted.

When components or materials are tested in accordance with

the procedure outlined in Section 4 of Appendix A, there

5-5
shall be no signs of excessive deterioration of optical,

physical, or mechanical properties, or any other changes

that would significantly affect the performance of the

components of the system.

Commentary The effects of solar radiation in combination with air

pollutants may also be an important consideration in the

dry as well as wet conditions. Factors of concern include

surface erosion and consequent transmission loss of cover

plate, deterioration of coupling hoses, exposed seals, and

corrosion of metallic elements.

A potential problem with collectors in industrial

atmospheres is that pollutants can go into solution in

moisture and cause permanent etching of the cover plates

and absorber surfaces and other metallic components over a period of time. Such etching can permanently reduce optical properties and may cause deterioration of mechanical

properties. When this possible condition exists, design

consideration must be given to avoid the problem.

5.2

Requirement Effect of temperature . Solar components or materials and

building elements with which they interact shall be capable

of performing their intended function for their design

lives when exposed to temperatures that can develop in the

system.*

5.2.1

Criterion

Evaluation

Thermal degradation . When exposed to maximum service

temperatures, solar components or materials shall not

degrade to the extent that will significantly impair their

function during their design lives.

Compliance may be documented with data on satisfactory

long-term performance under in-use conditions or engineering analysis. Evaluation may occur at the collector, com- ponent and/or material level. There are several recently

developed standard practices and standard specifications

which address thermal degradation problems. When assessing

the assembled collector for resistance to thermal degradation, ASTM E823-81 "Standard Practice for Nonoperational

Exposure and Inspection of a Solar Collector", Reference

[16], Section 5 of Appendix A, or Section 10 of Appendix A,

as appropriate, shall be used. Test methods for thermal

degradation of cover plates are addressed in ASTM E765-80,

"Standard Practice for Evaluation of Cover Materials for

Maximum and minimum service temperatures are defined in Section 1 of

Appendix A.

5-6
Flat Plate Solar Collectors", Reference [1], and ASTM

E782-81, "Standard Practice for Exposure of Cover Materials

for Solar Collectors to Natural Weathering Under Conditions

Simulating Operational Mode", Reference [2]. Absorptive

coatings shall be evaluated using ASTM E744-80, "Standard

Practice for Evaluating Solar Absorptive Materials for

Thermal Applications", Reference [3] and ASTM E781-81,

"Standard Practice for Evaluating Absorptive Solar Receiver

Materials when Exposed to Conditions Simulating Stagnation

in Solar Collectors with Cover Plates", Reference [4]. For

sealants and gaskets the following ASTM specifications

address the problem of thermal degradation and shall be

used as appropriate: ASTM D3667-78, "Standard Specification for Rubber Seals Used in Flat Plate Solar Collectors",

Reference [10]; ASTM D3771-79, "Standard Specification for

Rubber Seals Used in Concentrating Solar Collectors", Ref- erence [11]; ASTM D3903-80 "Standard Specification for

Rubber Seals Used in Air-Heat Transport of Solar Energy Systems", Reference [13]; and ASTM 3952-80, "Standard Specification for Rubber Hose used in Solar Energy Systems", Ref- erence [14], Thermal degradation is also covered in the

recently developed insulation standard ASTM E861-82, "Standard Practice for Evaluating Thermal Insulation Materials

Used in Solar Collectors", Reference [7] and ASTM E862-82;

"Standard Practice for Screening Polymeric Containment

Materials f or the Effects of Heat and Heat—Transfer Fluids

in Solar Heating and Cooling Systems", Reference [19].

When information is not available on performance regarding

outgassing of materials , the thermal stability of components

or materials and the long-terra performance of heat-transfer

fluid under in use conditions, testing using either the

methdology outlined in Section 5 of Appendix A or other

methods which can be shown to meet the intent of the criterion shall be used. When components or materials are tested

in accordance with the procedures outlined in Section 5 of

Appendix A, there shall be no signs of excessive deterioration of optical, physical, or mechanical properties or any

other changes that would significantly affect the performance of the components or the system.

Commentary Organic components in the system may be particularly

susceptible to thermal degradation under prolonged exposure.

Organic collector components of particular Concern include

glazing, absorbers, absorptive coatings, heat traps, insulation, sealants, gaskets, and collector casing assemblies.

Storage containers, piping, ducts, storage liners, and coatings composed of organic materials may also be affected.

Organic materials may change shape or dimensions and may

lose strength or become more brittle.

5-7
Outgassing of condensible volatiles from components inside

the collector could lead to deposits on the underside of

the collector glazing reducing glazing transraissivity or other changes in the optical properties of collector

components. Materials that have been observed to outgas in

operational systems are gaskets and sealants, absorptive

coatings, and insulation.

Of major concern is the breakdown of some heat transfer

fluids at elevated temperatures resulting in corrosive byproducts and formations which create scale and sludge

within the system.

If not considered in the design, viscosity changes in heat

transfer fluids may lead to pumping problems, such as excessive pumping power requirements or overheating due to

heat transfer fluid thickening,

5.2.2

Criterion Thermal cycling degradation . The H/C/HW systems, their

various components, and building elements with which they

interact shall be capable of withstanding the stresses

induced by thermal cycling for their respective design

lives

Evaluation Compliance may be documented with data on satisfactory

long-term performance under in-use conditions or engineering analysis. Evaluation may occur at the collector,

component, and/or material level.

When adequate information is unavailable to assess the

effects of thermal cycling upon absorber materials, ASTM

E744-80, "Standard Practice for Evaluating Solar Absorptive

Materials for Thermal Applications", Reference [3] may be

used.

For other materials and components which require assessment

of the effects of thermal cycling, testing procedures

outlined in Section 6 of Appendix A or other methods which

meet the intent of the criterion shall be used.

After components or materials have been exposed to thermal

cycling between their maximum and minimum service temperatures, there shall be no signs of excessive deterioration

of optical, physical, chemical or mechanical properties or any other changes that would significantly affect the

performance of the components or the system.

Commentary This criterion is intended to identify potential problems

that may occur as a result of differential thermal movement. Physical restraints (including support conditions)

5-8
that will be imposed on the system in actual use shall be

considered when testing is required. Permanent dlraens"'.onal changes caused by expansion or contraction can result from thermal cycling.

If thermal expansion or contraction 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, solder

joints, coupling hoses, sensors, the bond of tubing or coatings to absorber plates, and warping or shrinkage of cover plate or absorber.

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 Thermal shock degradation . Solar components and materials

shall be capable of withstanding the stresses induced by

thermal shock for their respective design lives.

Evaluation Compliance may be documented with data on satisfactory

long-term performance under in-use conditions, by engineering analysis, or by review of plans and specifications.

When adequate information regarding thermal shock resistance of collectors is unavailable. Section 7.4 (cold

fill) of NBSIR 78-1305A, Reference [5] shall be used.

Other tests which can be shown to meet the intent of this

criterion may also be used.

After the thermal shock test, there shall be no signs of

excessive deterioration of physical or mechanical properties or any other changes that would significantly affect

the performance of components, collectors, or materials.

Commentary The intent of the criterion is to determine the ability of

the solar collector to withstand thermal shock caused by

heavy rains falling on heated collectors and also to ensure

the reliability of solar collectors to withstand thermal

shock induced through filling the hot collector with relatively cool heat transfer fluid during daytime start-up.

It has been reported that cover plates have failed due to

the thermal differential created in the glass by the rapid

sliding off of snow cover, exposing cold collectors to the

heat of solar radiation.

5-9
For collectors not capable of withstanding cold fill under

stagnation conditions, if the collector is protected with

means of preventing circulation of cold fluid in the hot

collector, this provision may be waived.

5.3

Requirement Effect of chemical compatibility of components . Materials

used in the solar energy system, its various components and

the building elements with which they interact shall have

sufficient chemical compatibility to prevent corrosion,

deterioration, or wear that would significantly shorten

their intended service lives under in-use conditions.

5.3.1

Criterion Materials/transfer fluid degradation . Materials designed

to be used in contact with heat transfer fluids or the

fluid itself shall not be deteriorated or otherwise

adversely affected by such contact to the extent that

their function will be significantly impaired under in-use

conditions during their design life.

Evaluation Compliance may be documented with data or satisfactory

long-term performance under in-use conditions, engineering

analysis, or testing.

Where adequate information is unavailable regarding the

performance of containment materials in contact with heat

transfer fluids, evaluative testing will be required. For

rubber materials several ASTM standard specifications are available, ASTM D3832-79, "Standard Specification for Rubber Seals Contacting Liquids in Solar Energy Systems",

Reference [12] and ASTM D3952-80, "Standard Specification

for Rubber Hose Used in Solar Energy Systems", Reference

[14] can be used as applicable.

For metallic containment materials, ASTM E712-80, "Standard

Practice for Laboratory Screening of Metallic Containment

Materials for Use with Liquids in Solar Heating and Cooling

Systems", Reference [17] and ASTM E745-80, "Standard Practices for Simulated Service Testing for Corrosion of Metallic Containment Materials for Use with Heat-Transfer Fluids

in Solar Heating and Cooling Systems", Reference [18] as appropriate shall be used.

For the evaluation of polymeric containment materials in

contact with heat transfer fluids, ASTM E862-82, "Standard

Practice for Screening Polymeric Containment Materials for

the Effects of Heat and Heat-Transfer Fluids in Solar

Heating and Cooling Systems", Reference [19] shall be used.

For the evaluation of containment materials not addressed

by the above specifications and standard practices, testing

5-10
shall be conducted using the methodology outlined in

Section 7 of Appendix A or other methods which can be shovm

to meet the intent of the criterion.

Commentary This criterion is intended to address the compatibility of

the heat transfer fluid and the materials and components in

the energy transport system, i.e., collectors, piping,

tanks, connectors, pumps, valves, heat exchangers , and their

related seals and gaskets. Metals and plastics are used in

these applications. The heat transfer fluid may be water,

aqueous-organic liquid solutions, or organic fluids. All

may contain various additives. Metals may be susceptible

to corrosion In systems with aqueous or organic heat transfer fluids. See also discussion of problems created by the

thermal degradation of heat transfer liquids in 5.2.1. Some

plastic materials are sensitive to exposure to either aqueous or organic fluids. Corrosion of metals by heat transfer fluids could be a serious problem in solar energy systems. SAE Standard J447a (1964), Reference [20] provides

guidance in preventing corrosion. Experience indicates that

tight closed-loop systems help to minimize metallic corrosion by reducing the oxygen content of the transfer fluid.

Any use of inhibitors in heat transfer fluids should be

keyed to the characteristics of all elements of the solar

energy system which come in contact with the fluid including collectors, piping, connectors, tanks, pumps, valves,

heat exchangers, and their related seals and gaskets.

Inhibitors used with non-toxic heat transfer fluids should

be selected to comply with the fluid safety requirements

of Requirement 4,1. Further discussion is included in

Reference [21],

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 level is outside the allowable range, the transfer fluid or at least the buffers must

be renewed. Buffer or transfer fluid renewal 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.

When heat transfer fluids are used as absorbers, a bleaching of the fluid may significantly reduce system performance. See also Criterion 5,1,1.

5-11
Tables 5.3 and 5.4 are intended to provide general

guidelines for the selection of metals or alloys for use in

solar collectors. Various alloys of the same base metal

may show significant variation in resistance to corrosion.

Small concentration changes in a number of chemical

elements may significantly change the corrosion behavior of

a material at a specific temperature. A complete description of this behavior is not possible in this document.

Generally unacceptable use conditions as stated should be

avoided unless it has been demonstrated that the metal or alloy perform suitably in the anticipated use condition.

Adequate performance is anticipated for normal operation in

generally acceptable use conditions if these general guidelines are followed.

Since plastics are generally nonconductors, galvanic and

electrochemical corrosion encountered with metals are nonexistent in plastic components. However, the physical and

mechanical properties of some plastics can be affected significantly by heat transfer fluids. These effects are usually more pronounced at the elevated temperatures which

accompany the heat transfer fluid in an operating solar

system. Incompatibility can cause plastics to swell,

delaminate, soften, crack, become brittle, lose strength,

etc. The specific response is dependent upon the combination of polymer and heat transfer fluid. The Uni-Bell

Plastic Pipe Association has developed a Handbook of PVC

Pipe Design and Construction, Reference [22] which provides

tables of the resistance of PVC pipe and elastomeric seals

to reaction with or attack by the chemical agents. The

information in it should be used as a guide only. Due to

the complexity of some organic chemical reactions, additional long-term testing should be performed to determine

performance of plastic components with fluids at elevated

temperatures

Dissimilar metals degradation . Non-isolated dissimilar

metals shall not be degraded to the extent that their function will be significantly impaired under in-use conditions

during their design lives.

Compliance may be documented with data on satisfactory

long-term performance under in-use conditions or engineering analysis. Where adequate information is unavailable,

testing using either the methodology outlined in Section 8

of Appendix A or other methods which can be shown to meet

the intent of the criterion shall be used. Dissimilar

metals 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.

5-12
Commentary The use of corrosion Inhibitors and dielectric fittings

that electrically isolate dissimilar metals is desirable.

When using an electrically conductive heat transfer fluid,

dielectric isolation of dissimilar metal connections should occur whenever there is a galvanic couple. The use of

dielectric fittings may conflict with electrical grounding

or lightning protection requirements. The presence of pinholes in protective coatings can drastically accelerate

corrosive action.

Attention should be paid to all elements of a solar

energy system when considering compatibility of dissimilar

metals. This should include energy transport system,

structural support and connections, and fabricated parts.

Compatibility of adjacent organic materials . Organic

solids in contact with other organic solids or inorganic

materials shall not be degraded to the extent that their

function will be significantly impaired during their design

lives

.

Evaluation Compliance may be documented with data on satisfactory

long-term performance under in-use conditions on engineering analysis. For corapatability of collector components

and thermal insulation used in the collector, ASTM E86I-82,

"Standard Practice for Evaluating Thermal Insulation

Materials for Use in Solar Collectors", Reference [7] shall

be used, as applicable, to demonstrate satisfactory performance, if testing is required. If adequate Information is

unavailable for other materials or components, testing is

required. If adequate information is unavailable for other

materials or components, testing using either the methodology outlined in Section 9 of Appendix A or other methods

which can be shown to meet the intent of the criterion

shall be used.

Commentary Incompatibility can occur between organic materials and

between organic materials and inorganic materials such as metals or phase change salts. Some sealants and gaskets

are incompatible with plastic glazing materials. Plasticizer migration can result in discoloration, softening, and

other types of deterioration.

Inorganic phase change salts have been stored in plastic

containers. Leakage in the containers can result from

deterioration of the material caused by either mechanical

(e.g., thermal expansion) or chemical incompatibility of

the salt and plastic.

5.3.3

Criterion

5-13
This criterion is not intended to address the compatibility

of organic transfer fluids with adjacent materials covered

in Criterion 5.3.1.

5.4

Requirement

5.4.1

Criterion

Evaluation

Effect of wear . Components that involve moving parts

shall, with normal maintenance, be capable of performing

their intended function without excessive wear or deterioration for their design lives.

Degradation by wear . Dampers, check valves, pressure

control devices, collector tracking

mechanisms and assemblies,

operating under

fatigue that

regulators, pumps,

mechanisms, insulation movement

and similar components shall be capable of

in-use conditions without exhibiting wear or would significantly impair their ability to

intended function over their design lives.

perform their

Compliance may be documented with data on 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 Inclusion of the heat transfer fluid during tests of

components with moving parts may be necessary to meet the

intent of this criterion. Many of the components described

in this criterion involve the use of conventional components in unusual applications. A record of satisfactory

performance in conventional applications may not be sufficient to adequately predict performance in solar applica-

> tions and careful evaluation is desirable. Components con- taining moving parts whose use rarely occurs, except for

safety reasons such as pressure relief devices, vacuum

breakers, etc., are of particular concern.

5-14
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5-21
Table 5.3 - Open System Parameters: Generally Acceptable and Unacceptable Use Conditions for Metals in Direct Contact with Heat Transfer Fluids

Generally Unacceptable Use Conditions Generally Acceptable Use Conditions^./

Aluminum

3.

When in direct contact with untreated,

uninhibited tap water with pH <5 or >9.

When in direct contact with aqueous

liquid containing halide ions or less electro positive metals ions, such as copper or iron.

When specific data regarding the behavior of a particular alloy are not available, the velocity of aqueous

liquid shall not exceed 4 ft/s

(1.22 m/s).

When in direct contact with a liquid

which is in contact with corrosive

fluxes.

When in direct contact with distilled

or deionized water which contains

appropriate inhibitors and does not contact copper or iron.

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.

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

contain 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

liquid having a velocity greater than 4 ft/s (1.22 m/s).!/

4. When in direct contact with a liquid

which is in contact with corrosive

fluxes.

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 in direct contact with distilled,

deionized or low chloride, low sulfate,

and low sulfide tap water.

When in direct contact with stable anhydrous organic liquids.

When operating under conditions

conducive to water line corrosion.

Steel

1. When in direct contact with untreated

tap, distilled, or deionized water with

ph <8 or >12.

When in direct contact with distilled,

deionized, or low salt content water

which contains appropriate corrosion

inhibitors, with pH >8 and <12.

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 shall 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.

5-22
Table 5.3 - (Continued)

Generally Unacceptable Use Conditions Generally Acceptable Use Conditional/

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/s (1.83 m/s).i/

4. When operating under conditions

conducive to water line corrosion.

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).

Stainless Steel

1. When the grade of stainless steel 1. selected is not corrosion resistant

in the anticipated heat transfer liquid.

2. When in direct contact with a liquid 2. which is in contact with corrosive

fluxes.

When the grade of stainless steel

selected is resistant to pitting,

crevice corrosion, intergranular attack

and stress corrosion cracking in the

anticipated use conditions.

When in direct contact with stable

anhydrous organic liquids.

Galvanized Steel

1. When in direct cont act with aqueous

liquid containing copper ions.

2. When in direct contact with aqueous

liquid with pH <8 or >12.

3. When in direct contact with aqueous

liquid with a temperature >131°F (SS'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 2XXX series) exhibit generally the same behavior

as copper when exposed to the same conditions. However, the brass selected should

resist dezincif ication in the operating conditions anticipated. At zinc contents of

15 percent and greater, these alloys become increasingly susceptible to stress corrosion. Selection of brass with a zinc content below 15 percent 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.

y 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 shall not promote corrosion.

U The flow rates at which erosion/corrosion becomes significant will vary with the

conditions of operation. Accordingly, the value listed is approximate.

5-23
Table 5.4 - Closed System Parameters: Generally Acceptable and Unacceptable Use Conditions for Metals in Direct Contact with Heat Transfer Liquids

Generally Unacceptable Use Conditions Generally Acceptable Use Conditionai.^

Aluminum

When in direct contact with untreated,

uninhibited tap water with pH <5 or >9.

When in direct contact with uninhibited

aqueous liquid containing copper, iron, or halide ions.

When in direct contact with distilled

or deionized water which contains

appropriate corrosion inhibitors.

When in direct contact with stable

anhydrous organic liquids.

3. When specified data regarding the behavior of a particular alloy are not available, the velocity of aqueous liquid

shall not exceed 4 ft/s (1.22 m/s).

1. When in direct contact with an aqueous

liquid having a velocity greater than

4 ft/s (1.22 m/s).l/

Copper

1. When in direct contact with untreated

tap, distilled, or deionized water.

When in contact with a chemical that can form copper complexes such as ammonium

compounds

When in direct contact with stable

anhydrous organic liquids.

3. When indirect contact with aqueous

liquids which do not form complexes

with copper.

Steel

1. When in direct contact with untreated

tap, distilled, or deionized water with

pH <8 or >12.

2. When in direct contact with liquid

having a velocity greater than

6 ft/s (1.83 m/s).l/

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.

Stainless Steel

2.

When the grade of stainless steel

selected is not corrosion resistant

in the anticipated heat transfer

liquid.

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.

}J 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 shall 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.

5-24
Table 5.4 - (Continued)

Generally Unacceptable Use Conditions Generally Acceptable Use Condi t lonsi/

Galvanized Steel

1. When in direct contact with water of

pH <8 or >12.

1. When In contact with water of pH >8

but <12.

2. When in direct contact with an aqueous

liquid with a temperature >131°F (SS'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 dezincif ication in the operating conditions anticipated. At zinc contents of

15 percent and greater, these alloys become increasingly susceptible to stress corrosion. Selection of brass with a zinc content below 15 percent 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 shall not promote corrosion.

5-25
Chapter 5 References

1. Standard Practice for Evaluation of Cover Materials for Flat Plate

Solar Collectors , ASTM E765-80.J-/

2. Standard Practice for Exposure of Cover Materials for Solar

Collectors to Natural Weathering Under Conditions Simulating Operational Mode , ASTM E782-81.1^

~

3. Standard Practice for Evaluating Solar Absorptive Materials for

Thermal Applications , ASTM E744--80.1/

4. Standard Practice for Evaluating Absorptive Solar Receiver Materials

When Exposed to Conditions Simulating Stagnation In Solar Collectors

with Cover Plates , ASTM E781-81,l/

5. Provisional Flat Plate Solar Collector Testing Procedures , First

Revision, NBSIR 78-1305A, National Bureau of Standards, Washington,

D.C., June 1978, PB 283-721.1/

6. Standard Method for Testing Coated Metal Specimens at 100 Percent

Relative Humidity , ASTM D2247-68 (1973).l/

7. Standard Practice for Evaluating Thermal Insulation Material for

Use In Solar Collectors , ASTM E861-82._L/

8. HUD Minimum Property Standards, One-and Two-Family Dwellings , No.

4900.1, U.S. Department of Housing and Urban Development,

Washington D.C., 1973.1/

9. ASHRAE Handbook of Fundamentals - 1981.A/

10. Standard Specification for Rubber Seals Used In Flat Plate Solar

Collectors , ASTM 03667-78.1/

11. Standard Specification for Rubber Seals Used In Concentrating Solar

Collectors , ASTM D3771-79.1/

12. Standard Specification for Rubber Seals Contacting Liquid In Solar

Energy Systems , ASTM 03832-79.1/

13. Standard Specification for Rubber Seals Used In Air-Heat Transport

of Solar Energy Systems , ASTM 03903-80 .J./

14. Standard Specification for Rubber Hose Used In Solar Energy Systems , ASTM 03952-80.1/

15. "Air Quality Data - Annual Statistics Including Summaries with

Reference Standards," EPA-450-2-78-040.1/

5-26
Standard Practice for Nonoperatlonal Exposure and Inspection of a Solar Collector , ASTM E823-81.-L^ ~~

Standard Practice for Laboratory Screening of Metallic Containment

Materials for Use with Liquids In Solar Heating and Cooling Systems,

ASTM E7 12-80.1^

18. Standard Practices for Simulated Service Testing for Corrosion of

Metallic Containment Materials for Use with Heat-Transfer Fluids

In Solar Heating and Cooling Systems , ASTM E745-80._L/

19. Standard Practice for Screening Polymeric Containment Materials for

the Effects of Heat and Heat-Transfer Fluids In Solar Heating and

Cooling Systems , ASTM E862-82.1/

Prevention of Corrosion of Metals , Society of Automotive Engineers,

Standard J447a, 1964

State-of-the-Art Study of Heat Exchangers Used with Solar Assisted

Domestic Hot Water Systems , F. E. Metz and M. J. Orloskl, NBSIR

78-1542, June 1978, PB287-410.1/

22. Handbook of PVC Pipe Design and Constructlon.Z/

J_/ American Society for Testing and Materials, 1916 Race Street,

Philadelphia, PA 19103.

2./ National Technical Information Service, 5285 Port Royal Road,

Springfield, VA 22161.

3./ Superintendent of Documents, U.S. Government Printing Office,

Washington, DC 20402.

A./ American Society of Heating, Refrigerating and Air Conditioning

Engineers, Inc., 1791 Tullle Circle, N.E., Atlanta, OA 30329.

If U.S. Environmental Protection Agency, Office of Air Quality Planning

and Standards, Monitoring and Data Analysis Division, Research Triangle

Park, NC 27711.

A/ Society of Automotive Engineers, Inc., Two Pennsylvania Plaza, New

York, NY 10001.

Z./ Uni-Bell Plastic Pipe Association, 2655 Villa Creek Drive, Suite 164,

Dallas, TX 75234.

5-27
CHAPTER 6

OPERAnON AND SERVICING

Page

6.0 Introduction 6-1

6.1 Manuals and instructions 6-1

6.1.1 Installation instructions 6-1

6.1.2 Operation and maintenance instructions 6-2

6.1.3 Maintenance plan 6-2

6.1.4 Maintenance hazards 6-3

6.1.5 Flushing of liquid system 6-3

6.1.6 Protection 6-3

6.1.7 Normal operation by occupant 6-4

6.2 Maintenance and servicing 6-4

6.2.1 Heat transfer liquid quality 6-4

6.2.2 Access for system maintenance 6-5

6.2.3 Servicing of H/C/HW systems 6-6

6.2.4 Maintainability of building and site 6-6

6.2.5 Maintainability of roof surfaces 6-6

6.3 System monitoring 6-8

6.3.1 Checkout 6-8

6.3.2 Minimum operating information 6-8

6.3.3 Access for system monitoring 6-9

References 6-10

6-a
CHAPTER 6

OPERATION AND SERVICING

The installation, operation, and servicing phases are most

critical to the performance of solar energy systems. There

has been consistent evidence that faulty actions during

these phases are a primary cause of poor performance,

accelerated deterioration, and system damage. The difficulties of mandating performance criteria for installation,

operation, and maintenance is acknowledged; however, it is

essential that owners and installers be provided with

appropriate instructions for their systems and that good

practice methods are followed.

This chapter complements and extends certain provisions in

Chapter 3 such as: system balancing, 3.1.2; liquid quality,

3.2.3; draining and filling, 3.2.5; and freeze protection

in general, 3.6. An initial checkout must verify that the

system is installed correctly and that it functions properly

in all modes of operation including proper flow rates. It

is important that adequate information and access be provided for monitoring of the system to assure a high level

of performance and to anticipate problems.

Manuals and instructions . A manual shall be provided con- taining instructions for the installation, operation, and

maintenance of the H/C/HW systems and/or components. The

extent of detail of the manuals shall be consistent with

the need for descriptive information to properly operate

and maintain the system.

Commentary Uiis manual may consist in whole or in part of a series of

instruction sheets provided by the various system or component manufacturers. It may be a single manual, or installation instructions may be separate from operation and

maintenance. Complex installations should be provided with

comprehensive manuals. A packaged hot water system con- versely may require only a simple manual. The simplest

passive system may warrant no more than an attached

informative label or tag.

Installation instructions . Instructions shall be provided

which describe the installation and removal (when required)

of each solar energy system component in step-by-step

fashion with appropriate detail.

6-1

6.0

Introduction

6.1

Requirement

6.1.1

Criterion
These Instructions shall describe the interconnection

requirements of the various systems and components and their

interface requirements with the building and site.

The instructions shall be available at the installation

site or from normally accessible sources.

Evaluation Review installation instructions.

Commentary It is not the intent of this criterion to require the provision of complete, detailed system installation specifications. For active systems, such specifications would

normally be project specific and part of the procurement

process. Construction drawings and specifications may be

required for passive and other site built systems.

Reference [1]* provides guidelines for installing, operating, and servicing solar HW systems. Reference [2] provides

standard practice for installation and service of solar

space heating systems (H) for one-and two-family dwellings.

6.1.2

Criterion

Evaluation

Commentary

Operation and maintenance Instructions . Operation instructions shall be provided which describe operation in all

modes, including start-up and shutdown under normal and

emergency conditions. Description of important temperature,

flow, and pressure information for checkpoints throughout

the system shall be given. The maintenance manual shall

provide a system schematic diagram and describe required

periodic maintenance and detailed information for selected

repair procedures such as removal and replacement of cover

plates

Review maintenance and operating instructions.

For most active systems, flow diagrams and wiring diagrams

should be included. In any system where performance

requirements are dependent upon specific maintenance procedures, these should be tabulated. The manual should specify

acceptable methods of cleaning glazed surfaces.

6.1.3

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.

Evaluation Review of maintenance plan.

* Numbers in brackets [] indicate references at the end of this chapter.

6-2

i
Commentary This criterion is applicable to both active and passive

systems in new as well as existing buildings. The plan

should include all the necessary ordinary maintenance,

preventive maintenance and minor repair work, and projections for equipment replacement and maintenance of heat

transfer fluid quality as appropriate. Periodic changing

or cleaning of strainers and filters is one example of

ordinary maintenance. Cleaning, repairing, or replacing

of cover plate materials should also be included.

6.1.4

Criterion Maintenance hazards . The manual shall provide prominently

displayed warning against hazards that could arise in the

maintenance of the system and shall fully describe the

precautions that should be taken to avoid these hazards.

Evaluation Review the maintenance Instructions.

Commentary Some systems contain toxic and/or combustible materials

that could result in ill effects to maintenance personnel

or result in fires, explosions, or toxic fumes when repairs

Involving soldering or welding are undertaken. See

Criterion 4.2.4 for handling and disposal of toxic fluids.

Hot pipes or valves and discharge points should be

identified.

6.1.5

Criterion Flushing of liquid system . The manual shall provide

instructions for initial flushing as required and periodic

flushing (cleaning), if required, of the liquid passages.

Evaluation Review drawings, specifications, and operation manual.

Commentary Metal filings, flux, solder, silt, and other contaminants

should be flushed out of the system prior to operation.

Water should not be used to flush systems that use hydrocarbon or silicone heat transfer fluids. Systems using oil

as the heat transfer fluid should be flushed with a cleaner

which is soluble with the solder flux used and then

thoroughly dried before filling with the oil.

Flux within the system may be caught in creyices. At this

point, with elevated temperature, any moisture would rapidly

oxidize the adjacent metal. See also Criterion 3.2.2.

6.1.6

Criterion Protection. The instructions shall provide information

for protection of the system during installation and maintenance .

6-3
Evaluation

Commentary

6.1.7

Criterion

Evaluation

Commentary

6.2

Requirement

6.2.1

Criterion

Evaluation

Commentary

Review installation and maintenance instructions.

Collectors, controls, and other components may require

special protective measures during installation and shutdown for maintenance such as covering of collectors to

prevent breakage of glazings and to prevent stagnation.

Caution should be exercised in the selection and use of

temporary coverings to avoid permanent damage of glazing

such as etching and staining, and adhesive materials which

may become difficult to remove.

Normal operation by occupant . Instructions shall be written

to inform the occupant of the minimum actions required for

the normal operation of the solar energy system including

the probable heat gains or losses dependent on occupant

actions

Review operation instructions.

Required occupant activity such as operating movable insulation, shades, or controls may be critical, especially for some passive installations. Required manual operations

should be minimized and the occupant should be advised of

the consequences of energy gained or lost and potential system or building damage (e.g. water freezing) for actions

taken on a daily and seasonal basis including times of

building vacancy.

Maintenance and servicing . The H/C/HW systems shall be

designed, constructed, and installed to provide sufficient

access and appurtenances for general maintenance and

convenient servicing.

Heat transfer liquid quality . Provisions shall be made to

maintain the quality of the heat transfer liquid at a level

that does not significantly impair its heat transfer function, reduce its compatibility with adjacent materials, or reduce freeze protection.

Review specifications and monitoring of the heat transfer

liquid for pH, buffering level , viscosity , and concentration.

Experience from demonstration programs indicates the importance of heat transfer liquids and their quality in preventing freeze-ups and corrosion, and for general system

performance. 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

6-4
Association Industry Standards S-100-75 and S-200-73 should

be provided, Reference [3]. The chemical composition of

the heat transfer liquid should be maintained (perhaps by

periodic replenishment of additives) 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. 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

should be available. See Criteria 3.2.3 and 3.2.5 for maintenance related devices and Reference [4] for the influence

of heat transfer fluid properties on thermal performance.

Heat transfer liquids should be tested and replaced at

Intervals suggested by the manufacturer. Some sources recommend checking water/glycol mixtures twice a year.

See also Criterion 6.1.3. Water in unprotected steel drums

or other metal containers in water storage walls should be

deionized or distilled and buffered to reduce corrosion

(pH>8 or <12 for steel).

6.2.2

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 an adjoining major component or building element.

Evaluation Review drawings and specifications.

Commentary Accessibility as a function of component life is an important consideration. Individual collectors in an array

should be replaceable or repairable without disturbing non- adjacent collectors in the array or other access provisions

should be made. Cover plates and roof glazing, especially

those susceptable to degradation by environmental exposure

and hazards such as damage by falling hail, limbs, etc.,

should be readily accessible for repair or replacement without special skills or tools and with readily available materials. Provisions for recoating of Trombe walls and

cleaning of glazing and space between glazing and wall

should be considered. Access to collector glazings which

require periodic recoating may be necessary.

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. Isolation

valves may be necessary for the repair or replacement of

system components. Dampers require access for maintenance,

6-5
monitoring, adjusting, and balancing. Information on access provisions is provided in Reference [5].

6.2.3

Criterion

Evaluation

Commentary

6.2.4

Criterion

Evaluation

Commentary

6.2.5

Criterion

Evaluation

Commentary

Servicing of H/C/HW systems . The H/C/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.

Review drawings, specifications, and service instruction

manuals.

Ihe complexity and design of certain components may require

their removal and replacement to accomplish repair of the

system. Routine servicing of many systems may not require

special personnel and equipment.

Maintainability of building and site . The H/C/HW system

shall not impair accessibility for or add significantly to

the practical maintainability of the building or site.

Review maintenance plans, site plans, and building and solar

system drawings.

Building materials adjacent to solar equipment should not

be exposed to elevated temperatures that result in adverse

physical, chemical, mechanical, or thermal changes causing

additional maintenance problems or such materials should

be selected to withstand these effects.

Maintainability of roof surfaces . The installation of

collectors and other solar energy components on the building roof should not reduce the ability of the roof covering

to restrict the entrance of moisture and water, nor reduce

its resistance to weather and deterioration.

Review drawings and specifications.

Damage to the roof covering or the roof assembly can occur during installation of the solar energy system or during

servicing. Measures to protect the roof from damage and

the entry of water during installation and servicing should

be taken. Reference [6]

The presence of solar equipment on roofs may lead to

numerous potential problems:

6-6
a. Reroofing in future years may be complicated by collectors mounted close to the surface, by supports, and by

pipe and wiring penetrations.

b. Numerous penetrations of roof coverings mean greater

maintenance problems and potential leakage. It is

important that collector supports be flashed properly.

c. Some heat transfer fluids will attack certain roofing

materials, and leakage from the solar system may present problems of roof degradation and deterioration.

d. The growth of fungi (mold and mildew) is possible when

collectors are applied to a roof surface. If the collectors are in contact with the roof covering or held

away from the covering to allow for drainage , the

shaded area can support the growth of a fungus leading

to roofing deterioration. Special design considerations

should be included to avoid this problem.

e. Hot collector surfaces and other heated components

closely adjacent to the roof surface can cause softening of the roofing materials leading to damage and

deterioration,

f. The presence of solar equipment, its position relative

to the roof and the various supports and penetrations,

may increase the collection of debris such as branches

and leaves, and thus require additional maintenance.

g. The installation of solar collectors and components

should not affect the capacity of the roof to drain

water completely.

h. The ice and melt water that may occur in the winter due

to the presence of solar equipment requires attention

to the adequacy of roof moisture barriers. Improper

installation and roof details may promote the accumulation of large quantities of ice, or may cause damage

to the roof by the weight or expansive action of ice.

i. The foot traffic generated by solar system maintenance

personnel may cause deterioration of the roof system.

Roof inspections should be performed at regular intervals

and repairs made to the roofing system as soon as they are needed

.

For existing roofing systems, its condition should be

determined prior to the installation of the solar system.

6-7
6.3

Requirement

Solar system components should only be installed on roofs

which are assessed to be in good condition and are expected

to provide satisfactory performance for their design lives.

System monitoring . Provision shall be made for system

monitoring in accordance with the specifications of the

operation and maintenance manual.

6.3.1

Criterion

Evaluation

Commentary

6.3.2

Criterion

Evaluation

Commentary

Checkout . On completion of installation, the system operation shall be checked for adequate performance of all

components as well as the system as a whole.

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 Requirement 6.1.

Monitoring means may involve sensors and indicators or may

be as simple as inspection.

Controls should be checked in operation to determine that

components 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. Poor

design and improper installation of components is a major

cause of system malfunction. A large proportion of mechanical failures become 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 faulty

design and/or installation.

It is important to check distribution systems to assure

that all spaces intended to receive heating and cooling in

the design receive it in the actual installation. This is

particularly important with passive systems.

Minimum operating information . Provisions shall be made to

indicate to the user when the collector loop and/or the

auxiliary energy system is operating.

Review drawings, specif ications , and operation instructions.

A minimum level of information is essential to the user to assure that the solar system is functioning as intended.

6-8
Monitoring means may involve sensors and indicators or may

be as simple as observation and awareness of appropriate

radiant temperatures and air movement.

6.3.3

Criterion Access for system monitoring . Appropriate access shall be

provided for checking essential system parameters.

Evaluation Review drawings and specifications for the placement of

fittings and indicators of essential system parameters.

Commentary Adequately located test fittings and indicators will permit

system monitoring and expedite the maintenance and repair

of equipment. Access for sensors and other techniques for

monitoring parameters such as temperature, pressure, and

critical voltages are of concern in this provision.

6-9
Chapter 6 References

1 . Installation Guidelines for Solar DHW Systems In One-and Two-Family

Dwellings , HUD-PDR-407 , U.S. Department of Housing and Urban

Development, GPO 023-000-00520-4, April 1979.1/

2 . Standard Practice for Installation and Service of Solar Space Heating

Systems for One-and Two-Family Dwellings , ASTM/ANSI E683-79, American

Society for Testing and Materials, 1916 Race Street, Philadelphia,

PA 19103, 1979.

3 . Industry Standard for Household, Commercial and Portable Exchanger

Water Softeners , S-100-75 and Recommended Industry Standards for

Household and Commercial Water Filters , S-200-73, Water Quality

Association, 447 East Butterfield Road, Lombard, IL 60148, 1974.

4. Chang, C, Singh, H., Chopra, P., Influence of Solar-Fluid Properties

on Thermal Performance Based on Nominal and Measured Values , ANL/SDPTM-79-6, S0LAR/0904-79/70.A/

5. Uniform Mechanical Code , International Conference of Building

Officials, 5360 South Workman Mill Road, Whittier, CA 90601, 1973.

6. Mathey, Robert G. and Rossiter, Walter J. Jr., Guidelines for the

Installation of Solar Components on Low-Sloped Roofs , NBS Technical

Note 1134, National Bureau of Standards, Washington, DC 20234, 1980.1./

U Superintendent of Documents, Government Printing Office, Washington,

DC 20402.

1/ Technical Information Center, P.O. Box 62, Oak Ridge, TN 37830.

6-10
APPENDIX A

Page

INTRODUCTION A-c

Section 1 Temperature Conditions A-1

2 Evaluation Methods A-7

3 Test Methodology; Criterion 5.1.1 Solar Degradation . . . A-7

Aging Procedure 1 (Simulated Laboratory Exposure) A-7

Aging Procedure 2 (Outdoor Exposure Using Concentrated

Natural Radiation) A-8

Aging Procedure 3 (Natural Weathering) A-8

Property Assessment A-9

Commentary A-9

A Test Methodology: Criterion 5.1.3 Pollutant

Degradation A-10

Aging Procedure 1 (Resistance to Ozone) A-10

Aging Procedure 2 (Resistance to Salt Spray) A-10

Aging Procedure 3 (Resistance to SO2 and NO^) A-10

Property Assessment A-10

Commentary A-10

5 Test Methodology: Criterion 5.2.1 Thermal Degradation . A-10

Aging Procedure 1 (Resistance of Fluids to Maximum

Service Temperature) A-11

Aging Procedure 2 (Resistance of Components and

Materials to Maximum Service Temperature) A-12

Aging Procedure 3 (Resistance of Fluids to Minimum

Service Temperature) A-12

Property Assessment A-12

Commentary A-12

6 Test Methodology: Criterion 5.2.2 Thermal Cycling

Degradation A-12

Aging Procedure 1 (Resistance of Components and

Materials to Thermal Cycling) A-12

Property Assessment A-13

Commentary A-13

A-a
APPENDIX A (Continued)

Page

Section 7 Test Methodology; Criterion 5.3.1 Materials/Transfer

Fluid Degradation A-13

Aging Procedure 1 (Resistance of Metallic Containment

Materials to Non-Aqueous Liquids) A-13

Aging Procedure 2 (Resistance of Plastic Containment

Materials to Liquids) A-14

Property Assessment A-14

Commentary A-14

8 Test Methodology: Criterion 5.3.2 Dissimilar Metals

i ; Degradation A-14

. Aging Procedure 1 (Resistance of Metallic Containment

Materials to Liquids) A-15

Aging Procedure 2 (Resistance to SO2 and NO^) A-15

. Property Assessment A-15

Commentary A-15

9 Test Methodology; Criterion 5.3.3 Compatibility of

Adjacent Organic Materials A-15

Aging Procedure 1 (Resistance of Dissimilar Organic

Materials Exposed to Maximum Service Temperature) A-15

Property Assessment A-15

10 No-Flow 30-Day Degradation A-15

REFERENCES A-21

A-b

II
INTRODUCTION

Appendix A references conditions for and methods of testing and evaluation of system components and materials. These conditions and methods

can be used to prove compliance with stated requirements.

The testing and evaluation methods contained in this Appendix primarily

concern corrosion and thermal degradation, and can be used to satisfy

many of the durability/reliability requirements stated in Chapter 5.

Specific criteria from Chapter 5 are listed with the test methodologies

which can be used to prove their compliance.

Conditions for and methods of testing and evaluation found in Appendix A

are cross-referenced in Chapter 5 as well as throughout the text of this

document where their use is potentially appropriate.

A-c

Section 1 Temperature Conditions . Many of the criteria j^iven in

Chapter 5 and this Appendix 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) the

collector is not exposed to solar radiation, (2) the heat

transfer fluid is not flowing through the system, and

(3) the ambient 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 system 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). This

temperature may be determined by limiting the 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 A.l through

A. 4.

Figures A.l through A. 4 are intended to provide assistance

in establishing the maximum no-flow temperature of critical

components for four "typical" flat plate collector designs.

Glazing and absorber plate temperatures are plotted as a function of ambient temperature for exposure to a solar

radiation flux of 340 Btu/ft2.h (1070 W/m2). Data are shown for single and double covers and absorber surfaces

A-1
of flat plate collectors assuming two types of cover glass

materials (a typical window glass material and a more

transparent glass material with a low iron oxide content)

and two types of absorbers (spectrally flat and selective

black absorber coatings). The calculations were performed

with a transient thermal analysis computer program using

finite difference techniques [1].* The calculations were

based on the following assumptions:

(1) a glass cover plate thickness of 1/8 in. (0.32 cm);

(2) air space thickness of 3/8 in. (0.95 cm) between the

two glazings and between the absorber surface and the inner

glazing; (3) zero edge and back losses; (4) incident solar

radiation is normal to the collector; and (5) the following

properties of the glass glazing:

Conventional Low Iron Oxide

Glass Glass

Absorptance 0.06 0.02

Extinction 0.07 per in. 0.20 per in.

Coefficient (2.76x10-2 per mm) (7.87x10-^ per mm)

Index of 1.52 1.52

Refraction

Thermal 0.589 BTU/ft.h-°F 0.589 BTU/ft.h'°F

Conductivity (1.019 W/m'°C) (1.019 W/m-°C)

Transmittance 0.86 0.90

Emittance 0.86 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 a particular collector

design whenever possible.

Numbers in brackets [] indicate reference at end of this chapter.

A-2
900

SOLAR RADIATION IW/m^)

950 1000 1050 1100

500

400

300

200

100

COLLECTOR NO-FLOW TEMPERATURES

2 glass cover - flat black

id =15% a = 0.96 ^ - 15° e - 0.89

Vw = 7 mph

ambient temp. = 60°, 80°, 100°F

• measured points

ABSORBER

- 250

INNER COVER

OUTER COVER

100°F (38°C)

80°F(27°C)

°F (16°C)

100°F (38°C

80°F(27°C)

60°F (16°C)-

100°F (38°C)

80°F(27°C

60°F(16°C

200

oo

150

100

50

280 290 300 310 320 330 340 350

SOLAR RADIATION (Btu/hr ft^

Figure A. 1. No-flow temperatures at various locations in a collector

with a flat black absorber and two glass cover plates

A-3
900

SOLAR RADIATION (W/m^)

950 1000 1050 1100

500 T

ABSORBER

400

100°F (38°C)

80°F (27°C)

60°F (16°C)

300

COLLECTOR NO-FLOW TEMPERATURES

2 etched glass - selective

• measured Id = 15% ol = 0.94

points (9= 15° e = 0.25

Vw = 7 mph

ambient temp. = 60°, 80°, 100°F

INNER COVER 100°F |38°C)

80°F (27°C)

60°F (16°C)

200

OUTER COVER

100

100°F (38°C)

80°F (27°C)

60°F (16°C) -

280 290 300 310 320 330 340

SOLAR RADIATION [Btu/hr ft^j

350

Figure A. 2. No-flow temperatures at various locations in a collector

with a selective absorber and two glass cover plates
900

SOLAR RADIATION (W/m^j

950 1000 1050 1100

500

400

300

200

100

COLLECTOR NO-FLOW TEMPERATURES

1 glass cover - flat black

Id = 15%

^=15°

Vw = 7 mph

oi = 0.96

e = 0.89

ambient temp. - 60°, 80°, 100°F

ABSORBER

COVER

250

100°F (38°C)

80°F (27°CJ

60°F (16°C)

100°F (38°C)

80°F (27°CJ

60°F (16°C) -

280 290 300 310 320 330 340

SOLAR RADIATION (Btu/hr ft^j

350

200

oo

150

100

50

Figure A. 3. No-flow temperatures at various locations in a collector

with flat black absorber and one glass cover plate

A-5
900

SOLAR RADIATION (W/m^

950 1000 1050 1100

500

400

300

200

100

COLLECTOR NO-FLOW TEMPERATURES

1 glass cover - selective

Id =15% a = 0.94

0 = 15° e = 0.25

Vw = 7 mph

ambient temp. = 60^ 80^ 100T

ABSORBER

COVER

100°F (38°C)

80°F (27°C)

60°F (16°C)

100°F (38°C)

80°F (27°C)

60°F (16°C)-

250

200

150

100

50

280 290 300 310 320 330 340

SOLAR RADIATION |Btu/hr ft^|

350

igure A. 4. No-flow temperatures at various locations in a collector

with a selective absorber and one glass cover plate
Section 2 Evaluation Methods . The evaluations given In Chapter 5 and

Sections 3 through 9 of this Appendix are Intended to provide a means of measuring the deterioration of materials

which would occur during use. Deterioration of materials

Is a measure of their durability. Deterioration is a result

of exposure of the material to an environment which causes changes In Its properties. To screen materials and to assess durability, properties must be measured before and

after exposure to an environmental aging procedure. Assessment of properties should include: visual Inspection of

surfaces plus measurement of appropriate optical, physical,

mechanical or chemical properties. Important properties

will depend upon the application and the type of material.

Tables 5.2a, 5,2b, and 5.2c identify the properties which

must be measured before and after aging for various materials and components. Methods to perform typical property

tests are listed in Table B.l of Appendix B. Other test

methods may also be used. If necessary, to document performance. Recommended aging procedures and property assessment

methods are included In Sections 3 through 9.

Section 3 Test Methodology; Criterion 5.1.1 Solar Degradation . Components or materials shall be tested using at least one aging procedure and appropriate property assessment methods

(Table 5.2a of Chapter 5).

Aging

Procedure 1 (Simulated Laboratory Exposure)

Acceptable exposure procedures include ASTM G26-77,

Operating Light Exposure Apparatus (Xenon-Arc Type ) With

and Without Water for Exposure of Non-Metallic Metals, [2] or ASTM D2565-79, Operating Xenon Arc-Type (Water Cooled)

Light and Water Exposure Apparatus for Exposure of Plastics

[3].

Expose components or materials to simulated solar radiation.

With the Type A or AH apparatus, the exposure periods shall

be 1400 hours. With the Type B or BH apparatus, the exposure periods shall be 1900 hours. The exterior surfaces of

components which are exposed to rainfall in service shall

be subjected to a water spray. The exposure cycle should

be 90 minutes of light only, followed by 30 minutes of

light with water spray. For components not exposed to

moisture under normal operating conditions, the water spray

shall not be Included in the procedure.

A-7
Aging

Procedure 2 (Outdoor Exposure Using Concentrated Natural Radiation)

Using ASTM E838-81, Standard Practice for Performing

Accelerated Outdoor Weathering Using Concentrated Natural

Sunlight, Reference [4] expose components or materials to

concentrated natural solar radiation until they have

received a total incident radiant exposure of 5 .4 x lO^

Btu/ft^ (6.0 GJ/m2). Exterior surfaces exposed to moisture

in service shall be subjected to water spray for a period

of 8 minutes during each 60 minutes of sunlight exposure.

The water spray should be at a rate of 1.75 x 10~^ gal/min.

ft"^ (1.18 X 10"^ L/s.m^) +20 percent. For components not

exposed to rainfall under normal operating conditions, the

water spray shall not be included in the procedure.

Test specimen mounting and temperature control shall be in

accordance with the procedures described in ASTM E838-81,

Reference [ 4]

Aging

Procedure 3 (Natural Weathering)

Expose components and materials to 12 months of solar

radiation outdoors by the most appropriate aging procedure

listed below. The average daily flux of the solar radiation, as obtained by averaging the daily fluxes over the 12

month period of outdoor exposure, shall be at least 1200

Btu/ft2 (14.8 Mj/m2).

Cover Materials

(Flat Plate

Collectors)

ASTM E782-81 Standard Practice for

Exposure of Cover Material for Solar Collectors

to Natural Weathering

Under Conditions Simulating Operational Mode

Absorber

Coatings

ASTM E781-81 Standard Practice for

Evaluating Absorptive

Solar Receiver Materials

When Exposed to Conditions Simulating Stagnation in So'lar Collectors

with Cover Plate(s)

Exterior Paints

(Not Absorber

Coatings)

ASTM D1006-73 Standard' Recommended

Practice for Conducting

Exterior Exposure Tests

of Paints on Wood

A-8
Exterior Paints ASTM D1014-66

(Not Absorber (Reapproved 1973)

Coatings)

Standard Method of

Conducting Exterior

Exposure Tests of Paints

on Steel

Adhesive

Joints

ASTM D1828-70

(Rapproved 1976)

Standard Recommended

Practice for Atmospheric

Exposure of Adhesive

Bonded Joints and

Structures

Plastics ASTM D1435-75

(Reapproved 1979)

Non-Metallic ASTM G7-77a

Materials

Standard Recommended

Practice for Outdoor

Weathering of Plastics

Standard Practice for

Atmospheric Environmental

Exposure Testing of NonMetallic Materials

Pipeline ASTM Gll-79 Standard Test Method for

Effects of Outdoor

Weathering on Pipeline

Coatings

Any material ASTM G24-73

(Rapproved 1980)

Standard Recommended

Practice for Conducting

Natural Light Exposures

Under Glass

Property

Assessment Properties listed in Tables 5.2a, 5.2b, and 5,2c shall be

measured to determine the effect of aging procedures on visual appearance and important optical, physical, or mechanical properties of the components or materials.

Other properties may be used for assessment as appropriate.

Properties must be measured for 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 exposure period for the aging procedure is considered to provide approximately the same total energy below 400 nm as would be received in 12 months of actual solar exposure in

in Phoenix, Arizona.

A-9
Section 4 Test Methodology: Criterion 5»1.3 Pollutant Degradation

Aging

Procedure 1

Aging

Procedure 2

Aging

Procedure 3

Property

Assessment

Commentary

Section 5

(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 of 73.4 + 3.6°F (23 + 2°C). An ozone test chamber

is described in ASTM Dll49-78a, "Rubber Deterioration - Surface Ozone Cracking in a Chamber (Flat Specimens)",

Reference [5]. Specimens should be stressed to simulate

service conditions.

(Resistance to Salt Spray)

Coupon specimens of components shall be exposed for 21 days

in accordance with ASTM Method Bl 17-73 (1979), Salt Spray

(Fog), Reference [6].

(Resistance to SO2 and NO^)

Coupon specimens of components shall be supported vertically in a closed chamber having openings for gas inlet and

outlet and maintained at a temperature of 73.4 + 3.6°F (23

+ 2°C) for a period of 21 days. An amount of (SO2 or NO^)

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.

Properties listed in Tables 5.2a, 5,2b, and 5.2c shall be

measured to determine the effect of the aging procedures on important optical, physical, mechanical, or chemical properties. In addition, the surfaces of the test specimens

shall be visually examined for signs of deterioration such

as cracking, blistering, or dimensional changes using a microscope with an eyepiece micrometer at 20X magnification.

Other properties may be used for assessment, as appropriate.

Properties must be measured for both aged and unaged

specimens to establish a basis for comparison.

These tests are intended to determine the resistance of

components to airborne pollutants.

Test Methodology; Criterion 5.2.1 Thermal Degradation . Heat transfer fluids shall be tested using aging procedures

1 and 3. Other components and materials shall be tested

using aging procedure 2. Property assessment methods

A-IO
listed in Tables 5.2a, 5.2b, and 5.2c shall be performed

before and after aging. Supplemental aging procedures are listed below and may be added where applicable. Section 1 of this Appendix may be useful in determining the maximum

service temperature.

Sealants ASTM C792-75

(Reapproved 1980)

Rubber ASTM D454-81

Plastic ANSI/ASTM D794-68

(Reapproved 1977)

Plastic ANSI/ASTM D1042-51

(Reapproved 1978)

Plastic ANSI/ASTM D1204-78

Plastic ANSI/ASTM D1299-55

(Reapproved 1979)

Plastic ANSI/ASTM D1203-67

(Reapproved 1974)

Standard Method of Test for

Effects of Heat Aging on Weight Loss, Cracking and

Chalking of Elastomeric

Sealants

Standard Test Method for

Rubber Deterioration by

Heat and Air Pressure

Standard Recommended

Practice for Determining

Permanent Effect of Heat

on Plastics

Standard Test Method for

Linear Dimensional Changes

of Plastics Under Accelerated Service Conditions

Standard Test Method for

Linear Dimensional Changes

of Nonrigid Thermoplastic

Sheeting or Film at Elevated Temperatures

Standard Test Method for

Shrinkage of Molded and

Laminated Thermosetting

Plastics at Elevated

Temperatures

Standard Test Method for

Loss of Plasticizer from

Plastics (Activated Carbon

Methods

)

Aging

Procedure 1 (Resistance of Fluids to Maximum Service Temperature)

Expose the heat transfer fluids to their maximum service

temperature for a period of 21 days. In some cases, this

may require the use of an autoclave. 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.

A-11
Aging

Procedure 2

Aging

Procedure 3

Property

Assessment

Commentary

Section 6

Aging

Procedure 1

Aeration shall be provided in fluids to be used in "open"

systems. Fluid aeration need not be included for

"closed" system usage. The test must be repeated

separately for all metal materials that are present in the

system.

(Resistance of Components and Materials to Maximum Service

Temperature)

Components or coupon test 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.

(Resistance of Fluids to Minimum Service Temperature)

Expose the heat transfer fluids to their minimum service

temperature for a period of 24 hours and remove and

immediately examine for freezing.

Properties listed in Tables 5.2a, 5.2b, and 5.2c shall be

measured to determine the effect of the aging procedures

on visual appearance and important optical, physical,

chemical, and mechanical properties of the components or materials. At the completion of aging procedure 1, the

fluids shall be visually inspected for signs of undesired

changes such as excessive precipitation or boiling. Other

properties may be used for assessment as appropriate. Properties must be measured for both aged and unaged specimens

to establish a basis for comparison.

The tests are intended to permit estimations to be made of

the effect of heat in degrading collector components and

in reducing the system efficiency. Aging procedure 3 is

intended to evaluate freezing of transfer fluids at the

minimum service temperature. (See Criterion 3.6.1.)

Test Methodology; Criterion 5.2.2 Thermal Cycling

Degradation . Materials and components shall be subjected

to the aging procedure and appropriate property assessment

methods (Tables 5.2a, 5.2b, and 5.2c).

(Resistance of Components and Materials to Thermal Cycling)

Complete components or material test specimens shall be

subjected to thermal cycling between the maximum service

temperature and minimum service temperature for a total of

A-12
30 cycles. Each cycle shall consist of: 7.5 hours at the

maximum service temperature; 0.5 hours at room temperature;

15.5 hours at the minimum service temperature; and 0.5

hours at room temperature.

Property

Assessment

Commentary

Section 7

Properties listed in Tables 5.2a, 5.2b, and 5.2c shall be

measured to determine the effect of thermal cycling on visual appearance and on important physical, mechanical,

and chemical properties of the components or materials.

Other properties may be used for assessment as appropriate.

Properties must be measured for aged and unaged specimens

to establish a basis for comparison.

These tests are intended to permit estimations to be made

of the effect of thermal cycling in degrading collector

components and materials.

Test Methodology; Criterion 5.3.1 Materials/Transfer Fluid

Degradation . Metallic containment materials used with non- aqueous liquids shall be tested using aging procedure 1 and

plastic containment materials shall be tested using aging

procedure 2. After aging, appropriate property assessment

methods (Tables 5.2a, 5.2b, and 5.2c) shall be performed.

Aging

Procedure 1 (Resistance of Metallic Containment Materials to Nonaqueous Liquids)

The apparatus for this test consists of heating tape with

appropriate power and control systems, and a variable flow

pump with a reservoir for the heat transfer fluid.

The primary sample typically consists of a 36 in. (914 mm)

length of tubing bent around an 8 in. (203 mm) diameter

mandril so that each leg of the U-bend is of approximately

equal length. Other specimen designs are permitted if they

more closely approximate conditions of application. Care

should be taken in making the U-bend so that fluid flow

through the tube is not significantly restricted. The tubing sample is mounted with an inclination of the plane of

the U-bend at about 45 degrees to horizontal during

testing. Secondary samples of similar or dissimilar metal

tubing may be introduced in the loop. The test shall be

carried out for a minimum period of 30 days. During the

test, the temperature shall be maintained at the maximum

service temperature.

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

A-13
used in the actual system. Testing shall be followed by

visual Inspection, With appropriate modification. Standard

TM-01-71, "Autoclave Corrosion Testing of Metal in High

Temperature Water", Reference [7] of the National Association of Corrosion Engineers for materials used in pressurized systems of ASTM D1384-80, "Corrosion Test for Engine

Coolants in Glassware", Reference [8] for materials

used in systems at atmospheric pressure, may be used in

the evaluation of metal coupons.

Aging

Procedure 2 (Resistance of Plastic Containment Materials to Liquids)

Plastic containment materials shall be tested for 7 days at

maximum service temperature in accordance with ASTM D543-67

(1978), Reference [9] or ASTM D1239-55( 1971 ), Reference [10].

The heat transfer fluid specified by the solar system manufacturer should be used. For organic based heat transfer

fluids commonly used in aqueous solutions, the test reagents

k': should include the concentrated heat transfer fluid and

dilute solutions at concentrations similar to actual use.

Property

Assessment 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.

Properties listed in Tables 5.2a, 5.2b, and 5.2c shall be

measured to determine the effect of the aging procedures

on visual appearance and on important chemical, physical,

or mechanical properties. Other properties may be used for

assessment as appropriate. Properties must be measured for

both aged and unaged specimens to establish a basis of

comparison.

Commentary These tests are intended to permit estimations to be made

of the effect of chemical imcompatibility of the heat

transfer fluids and materials in the energy transport system. Data derived from these aging procedures and property

assessment methods may be used as guidelines. Assurance of

chemical compatibility of critical components may require

additional long-term testing under conditions (temperature,

pressure, and flow rates) simulating actual use*

Section 8 Test Methodology; Criterion 5.3.2 Dissimilar Metals

Degradation . Adjoining dissimilar metals u^ed in contact

with the transfer fluid should be tested using aging procedure 1. Adjoining dissimilar metals not used in contact

with the transfer fluid should be tested using aging procedure 2. After aging, appropriate property assessment

methods (Tables 5.2a, 5.2b, and 5.2c) shall be performed.

A-14
Aging

Procedure 1

Aging

Procedure 2

Property

Assessment

Commentary

Section 9

Aging

Procedure 1

Property

Assessment

Section 10

(Resistance of Metallic Containment Materials to Liquids)

Test specimens consisting of dissimilar metals in direct

contact with one another shall be subject to the test as described in aging procedure 1 of Section 7.

(Resistance to SO2 and NO^)

Test specimens consisting of dissimilar materials in direct

contact with one another shall be subject to the test as described in aging procedure 3 of Section 4.

Properties listed in Tables 5.2a, 5.2b, and 5.2c shall be

measured to determine the effect of the aging procedures on visual appearance and on important chemical, physical, or mechanical properties. Other properties may be used as appropriate. Properties must be measured for both aged and

unaged specimens to establish a basis for comparison.

These tests are intended to permit estimations to be made

of the effect of corrosion on non-isolated dissimilar

metals

.

Test Methodology; Criterion 5.3.3 Compatibility of

Adjacent Organic Materials

(Compatibility of Adjacent Organic Materials)

Test specimens consisting of the dissimilar organic

materials in direct contact with one another shall be

exposed to the maximum service temperature for a period of

120 hours.

Properties listed in Tables 5.2a, 5.2b, and 5.2c shall be

measured to determine the effect of the aging procedure on visual appearance and on important chemical, physical, or mechanical properties. Other properties may be used as appropriate. Properties must be measured for both aged and

unaged specimens to establish a basis of comparison.

No-Flow 30-Day Degradation

Testing Procedure

Evaluation of changes in collector materials or performance

due to environmental conditioning shall be determined in

A-15
accordance with the test procedure described in ASHRAE

' Standard 93, Reference [11], either before and after or only after exposing the collector panel assembly to the

/ Exposure Test described below. Both the before and after

collector thermal performance tests (ASHRAE Standard 93)

shall be performed utilizing the same test facility under

similar climatic conditions.

Exposure Test:

A. Test specimen shall consist of a complete air or liquid

collector panel assembly.

B. Pre-exposure -preparation ;

• 1. Air collector duct opening shall be sealed to

prevent cooling by convective air flow and the

entry of dirt or precipitation. The collector

shall be vented to prevent build-up of pressure.

2 . Liquid collectors intended for use in all systems

(with or without draindown) shall be completely

filled with distilled waterA/ following which the

inlet shall be sealed and the outlet provided with

a pressure relief valve set to a value between 0

percent and +10 percent over the manufacturer's

recommended maximum operating pressure.

3 . Liquid collectors limited to use in systems that

draindown when not operating shall be completely

filled with distilled waterii/ following which the

fluid shall be allowed to gravity drain for 15

minutes with the collector mounted at a 45° tilt

angle. The collector inlet shall then be protected

to prevent entry of dirt or precipitation. The

collector shall also be vented to prevent buildup

of pressure.

A./ Manufacturer's/designer's recommended fluid shall be used in those

instances when they specifically prohibit the use of distilled water.

A-16
C. Exposure Conditions:

!• Exposure conditions shall consist of 30 days of

cumulative exposure to a minimum dally Incident

solar radiation flux of 1500 Btu/ft2-day (17,000

kj/m^'day) as measured in the plane of the collector aperture .A^

2. The exposure conditions shall include at least one consecutive 4-hour period or two 2-1/2 hour periods

with a minimum instantaneous flux of 300 Btu/ft^'h

(946 W/m^). The exposure test is only concluded

after the requirements in the table following

paragraph D.3. have been met.

a. Collector orientation changes to maximize the

solar radiation or supplementary reflectors may

be necessary to obtain the 300 Btu/ft^'h (946

W/m^) insolation level at certain locations.

However, the maximum peak flux shall not exceed

370 Btu/ft2»h (1165 W/m^) under normal sun-sky

or simulator exposure conditions.

b. A reflector may be used if it has sufficient

width and height to uniformly Irradiate the

collector aperture during the 300 Btu/ft2«h

exposure period. Solar irradlance measurements

shall be performed in the plane of the collector to verify that the irradlance does not vary

by more than 10 percent over the collector

aperture and that the minimum Instantaneous

flux requirement is met.

2/ For collectors governed by paragraph B.2., the filled collector shall

be exposed to at least one day with a minimum daily Incident solar

radiation of 1500 Btu/ft^'day. If freezing conditions are anticipated, the collector may be drained after exposure to this day. The

pressure relief valve and inlet seal shall be removed when the collector is drained of all fluid. The collector inlet shall then be protected to prevent entry of dirt or precipitation and shall be vented

to prevent pressure buildup. The collector shall be exposed for a total of thirty cumulative 1500 Btu/ft^-days (either filled or unfilled) as described above. The filled exposure day(s) may occur

at any time during the 30-day exposure if so desired.

A-17
c. A transparent enclosure may be used to raise

the ambient temperature around the collector.

The enclosure material shall have a total solar

transmittance of at least 0.85 and a spectral

transraittance of at least 0.80 in the wavelength band from 0.3 to O.A ym. If used, the

pyranometer shall be mounted within the enclosure and within the plane of the collector for

measurement of the solar irradiance.

Thermal Shock/Water Spray Penetration ; This test is

intended to induce the thermal stresses that would

occur when rain impinges on a heated collector to

determine the penetration of rain into the collector

and the effect of such penetration or moisure condensation, if any, on collector performance.

1. Period of test ; The test shall be performed three

times during the 30-day exposure period; once during the first 10 days of the exposure period as defined in paragraph C.l. and once each during the

second and third 10 days of the exposure period.

2. Pre-test exposure ; The spray test shall be con- ducted after at least one hour of radiant exposure

with a minimum solar irradiance of 270 Btu/ft^*h

(850 W/m^) measured in the plane of the collector.

3. Apparatus ; The test apparatus consists of three or more spray heads in a water supply rack. The water

pressure for all tests is maintained at a minimum

of 5 psi (34.47 kPa) at each spray head and is

equivalent to simulating a rain of about 12 inches

per hour or a water flow rate of 50 gallons per

hour per nozzle. The supply water temperature

shall not exceed 86°F (30°C). A complete description of the apparatus and procedure is presented in NBSIR 78-1305A, Reference [12].

A- 18
Specific Test Requirements and Options

Test

Requirement

Solar

Radiation (min.)

Ambient

Temperature Time Other

30-days at 1500 Btu/ft2-day - 24-h period Liquid collectors

shall be exposed

filled for at least one of these

days

.

4-hour period

or

300 Btu/ft^-h

or

80°F or minimum

of 70°F if the

solar irradiance

is greater than

300 Btu/ft2'h

(see NBSIR 78-

1305A for

options)

.

Continuous

Irradiance for

either 4 hours

or two 2-1/2

hour periods.

Exposure to occur after

collector has

boiled dry or been drained.

Reflector and/or

enclosure may be

used to reach

required irraditwo 2-1/2 hour ance or temperature.

periods

300 Btu/ft2-h

with 1 h minimum

of 225 Btu/ft2«h

preceding each

2-1/2 h period

Water spray One h minimum

of 270 Btu/ft2-h

to preceed each

application

Above freezing Each application

for 15 minutes

continous

period.

Supply water

temperature of

86°F or less

E . Data Requirements

1. The exposure conditions Including hourly irradiation, ambient temperature, wind velocity, and daily

precipitation shall be recorded to enable determination of the average daily values. Irradiance and

the ambient temperature values shall be recorded

every 30 minutes during the 4-hour 300 Btu/ft^'h

(946 W/m2) minimum flux exposure period.

2. A regularly scheduled weekly visual inspection

shall be made and a record of changes in the physical construction or appearance of the collector

maintained.

3. The results of the pre-test and post-test thermal

performance shall be plotted on the same graph for

comparison purposes. A written description of

observed changes in the physical or optical

A-19
appearance of the collector shall be reported and

substantiated with photographs where appropriate.

4. For collectors receiving only a post-test thermal

performance measurement, the collector shall be

completely disassembled and inspected for any evidence of functional impairment or material deterioration which could result in an abnormally short

collector life when operated under normal service

conditions. Evidence of material degradation will

require documented experimental test data indicating the ability of the material to withstand and

continue to function under the conditions

commensurate with the application and design

lifetime.

Commentary The purpose of this test is to identify, in a relatively

short time, potential problems with collector materials or construction resulting from prolonged exposure to natural

environments.

Recognizing that elevated temperature is one of the most

damaging environments, solar irradiance and ambient temperature levels have been selected which represent typical

summer conditions in most U.S. climatic regions. These

conditions will produce the temperatures that the various

materials used in solar collectors (cover plates, absorptive coatings, sealants, etc.) will experience in use. Until adequate laboratory test procedures are adapted to ensure the ability to select reliable materials and

designs, an assembly level test is considered to be necessary for evaluating collector reliability.

A 4-hour or two 2-1/2 hour exposure periods with a minimum

flux of 300 Btu/ft2«h (946 W/m^) is specified in the test

method. During this exposure period, it is intended that

the collector be exposed to the normal peak profile that

it would see on a fixed mount facing south.

The test procedure does not include provisions for

evaluating tracking concentrating collectors or collectors

designed for use with external reflectors to enhance solar

radiation. Modifications to the exposure apparatus may be

necessary to accommodate these collectors.

A-20
REFERENCES

1. Ramsey, J. W., Borzonl, J. T. and, Holland T. H., Development of

Flat Plate Solar Collectors for the Heating and Cooling of Buildings,

NASA CR-134804, June 1975.i./

2. Standard Recommended Practice for Operating Light-Exposure Apparatus

(Xenon Arc Type) With and Without Water for Exposure of Nonmetallic

Materials , ANSI/ASTM G26-77.£/^/

3. Operating Xenon-Arc Type (Water Cooled) Light- and Water- Exposure

Apparatus for Exposure of Plastics , ANSl/ASTM D2565-79 .1^^/

4. Standard Practice for Performing Accelerated Outdoor Weathering Using

Concentrated Natural Sunlight , ASTM E838-81.^/

5. Standard Test Method for Rubber Deterioration - Surface Ozone

Cracking In a Chamber (Flat Specimens) , ANSl/ASTM D1149-78a.A/^/

6. Standard Method of Salt Spray (Fog) Testing , ASTM B117-73 (1979).2./

7. Autoclave Corrosion Testing of Metal in High Temperature Water , NACE TM-01-71.2/

8. Standard Method for Corrosion Test for Engine Coolants in Glassware , ANSI/ASTM D1384-80.i./^/

9 . Standard Test Method for Resistance of Plastics to Chemical Reagents , ANSI/ASTM D543-67 (1978).£/5/

10. Standard Test Method for Resistance of Plastic Films to Extraction

by Chemicals , ANSl/ASTM D1239-55 (1971).i./^/

11. Methods of Testing to Determine the Thermal Performance of Solar

Collectors , Standard 93-77, ASHRAE 1977.^/

12. Provisional Flat Plate Solar Collectors Testing Procedures , First

Revision, NBSIR 78-1305A, National Bureau of Standards, Washington,

DC, June 1978, PB 283-721.1/

A-21
1./ National Technical Information Service, 5285 Port Royal Road,

Springfield, VA 22161.

2_/ American Society for Testing and Materials, 1916 Race Street,

Philadelphia, PA 19103.

2./ National Association of Corrosion Engineers, Box 1499, Houston, TX

77001.

^/ American Society of Heating, Refrigerating and Air Conditioning

Engineers, Inc., 1791 Tullie Circle, N.E., Atlanta, OA 30329.

J./ American National Standards Institute, Inc., 1430 Broadway, New York,

NY 10018.

A-22
APPENDIX B

Page

INTRODUCTION B-b

MATERIALS TABLES B-1

Table B.l List of Test Properties, Test Method Designations

and Titles B-1

Table B.2 Properties of Typical Cover Plate Materials B-4

Table B.3 Characteristics of Absorptive Coatings B-5

Table B.4 Examples of Typical Heat Transfer Liquid

Properties B-6

Table B.5 Typical Properties of Selected Building Materials

for Solar Application B-7

TECHNICAL REVIEW ITEMS B-8

REFERENCES B-1

5

ABBREVIATIONS B-1

6

SI CONVERSION UNITS B-17

B-a
INTRODUCTION

Appendix B contains tables which have been compiled to provide the user

with resources related to properties of materials used in solar application. Standards are listed in Table B.l which could be of assistance in

making physical property determination of materials. Typical physical

properties and characteristics of materials have been tabulated to provide baseline values of a selected number of materials. These tables provide guidelines for selection and use of components and materials and may

be useful in proving compliance with stated requirements.

The Technical Review Items identify major areas of concern with regard

to system design and technical evaluation, and could be used as a guide

for those purposes. The names of all code groups, associations, and

government agencies which appear in the text are listed in Abbreviations.

Conversion factors for all quantitative units used in the text can be

found in the section on SI Conversion Units.

B-b
Table B.l List of Test Properties, Test Method Designations and Titles

Test Method

Property Designation Number Title

Chalking

Checking

Cracking

Blistering

Solar Transmittance

Solar Reflectance

Emittance

Hardness

Hardness

VISUAL OBSERVATION

ASTM D659-80

ASTM D660-44

(Reapproved 1976)

ASTM D661-44

(Reapproved 1975)

ASTM D714-56

(Reapproved 1974)

OPTICAL PROPERTIES

ASTM E424-71

ANSI Z138. 7-1973

ASTM E424-71

ANSI Z138. 7-1973

ASTM E408-71

(Reapproved 1980)

ASTM E434-71

(Reapproved 1980)

PHYSICAL PROPERTIES

ANSI/ASTM D785-65

(Reapproved 1976)

ANSI/ASTM D2583-75

Standard Method of Evaluating Degree

of Chalking of Exterior Paints

Standard Method of Evaluating Degree

of Checking of Exterior Paints

Standard Method of Evaluating Degree

of Cracking of Exterior Paints

Standard Method of Evaluating Degree

of Blistering Paints

Standard Test Method for Solar

Transmittance and Reflectance

(Terrestrial) of Sheet Materials

Standard Test Method for Solar

Transmittance and Reflectance

(Terrestrial) of Sheet Materials

Standard Test Method for Total Normal

Emittance on Surfaces Using InspectionMeter Techniques

Standard Test Method for Calorimetric

Determination of Hemispherical Emittance and the Ratio of Solar Absorptance to Hemispherical Emittance

Using Solar Simulation

Standard Test Method for Rockwell

Hardness of Plastics and Electrical

Insulating Materials

Standard Test Method for Indentation

Hardness of Rigid Plastics by Means

of a Barcol Impressor

B-1
Table B.l (Continued)

Property

Test Method

Designation Number Title

Dimensional Stability ANSI/ASTM D2122-76

Tensile Strength

Tensile Strength

Tensile Strength

Tensile Strength

Tensile Strength

Loading or Compression

Strength

MECHANICAL PROPERTIES

ANSI/ASTM D638-80

ANSI/ASTM D882-80a

ASTM C297-61

(Reapproved 1980)

ANSI/ASTM D897-78

ANSI/ASTM D412-80

ANSI/ASTM D695-80

Loading or Compression ANSI/ASTM D2412-77

Flexure Strength

Flexure Strength

Flexure Strength

Fatigue

ANSI/ASTM CI 58-80

ASTM C393-62

(Reapproved 1980)

ANSI/ASTM D790-80

ANSI/ASTM D671-71

(Reapproved 1978)

Standard Method of Determining

Dimensions of Thermoplastic Pipe

and Fittings

Standard Test Method for Tensile

Properties of Plastics

Standard Test Method for Tensile

Properties of Thin Plastic

Sheeting

Standard Method of Tension Test of

Flat Sandwich Constructions In

Flatwise Plane

Standard Test Method for Tensile

Properties of Adhesive Bonds

Standard Test Method for Rubber

Properties In Tension

Standard Test Method for Compressive

Properties of Rigid Plastics

Standard Test Method for External

Loading Properties of Plastic Pipe

by Parallel-Plate Loading

Standard Method for Flexure Testing

of Glass (Determination of Modulus

of Rupture)

Standard Method of Flexure Test of

Flat Sandwich Constructions

Standard Test Method for Flexure

Properties of Plastics and Electrical

Insulating Materials

Standard Test Method for Flexural

Fatigue of Plastics by Constant

Amplitude of Force

B-2
Table B.l (Continued)

Property

Test Method

Designation Numbe

r

Title

Burst or Rupture ANSI/ASTM D1598-76 Standard Test Method for Tlme-toFallure of Plastic Pipe Under

Constant Internal Pressure

Burst or Rupture

Burst or Rupture

ANSI/ASTM Dl 599-74

(Reapproved 1980)

ANSI/ASTM D2143-69

(Reapproved 1976)

Standard Test Method for ShortTime Rupture Strength of Plastic

Pipe, Tubing and Fittings

Standard Test Method for Cyclic

Pressure Strength of Reinforced

Thermosetting Plastic Pipe

B-3
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B-4
Table B.3 Characteristics of Absorptive CoatlngaJ.'

Property

Material

Absorptancel^

a Emlttance

e

01e Breakdown Temperature

•P (*C)

Cooaents

Anodic Aluminum

.94-. 96 .3-.

8

1.2-3 May be Influenced by moisture Black Chrome .87-. 93 .1 ~9

Alkyd Enamel .9 .9 1 Durability United at high temperatures

Black Acrylic

Paint

.92-. 97 .84-. 90 ~1

Black Inorganic

Paint

.89-. 96 .86-. 93 ~1

Black Silicone

Paint

.86-. 94 • .83-. 89 ~1 Silicone binder

PbS/Slllcone

Paint

.94 .4 2.5 662 (350) Has a high emlttance

for thicknesses >10pa

Flat Black

Paint

.95-. 98 .89-. 97 ~1

Ceramic Enamel .9 .5 1.8 Stable at high

temperatures

Black Zinc .9 .1 9

Copper Oxide over Aluminum.93 .11 8.5 392 (200)

Black Copper

over Copper

.85-. 90 .08-. 12 7-11 842 (450) Patlnates with moisture

Black Chrome

over Nickel

.92-. 94 .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

Nl-Zln-S over Nickel.96 .97 14 536 (280)

Black Iron over Steel.90 .10 9 U These values 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. Sectlon-ISES Meeting, Ft. Collins, Colorado, August 19-23, 1974

D. P. Grimmer, S. W. Moore, "Practical Aspects of Solar Heating: A Review of Materials Used in Solar Heating Applications", LA-UR-75-1952, paper presented at SAMPE Meeting, October 14-16, 1975, Hilton Inn, Albuquerque, MN.

R. B. Toenjes, "Integrated Solar Energy Collector Final Summary Report", LA-6143-MS, Los Alaaoa 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. Klrkpatrlck, "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.

Dependent on thickness and vehicle to binder ratio. B-5
C M

o o>

O ON o <r

CO O

o o

r-t O

u o

a o ^ a o

o »< ^ o

rH O

2 ^ w

o o

r-j O

a» ON o o

o <a a A

O.'.' go 01

U-l W 4J [It, O

(0 K

•H m ^1 ~i

B-6
.e B.5 Typical Propertle* of Selected Building KaCerlal* for Solar Application*

Property

Material

Abaorptance Ealttance

MASONRY

Specific Heat Aablent Btu/(lb)CP)

Denaicy lb/ft'

Thermal Conductivity

Btu in/h-ft2-*F

(W/(.2-K)l

Ezpanaloo

Co«f f Iclent ln/ln/'FMl0~*

(c»/c«/*CiilO-*|

Brick***

(Glazed, white to creaa) 0.26 to 0.35 0.92 0.22

1921] 130 (2080)

1.3 to 3.8 [0.19 to 0.55]

S to 9

Sof tmod

WATgR

Clear

Black (1/2 percent carbon suspenalon)

0.60

1.00

0.06 to 0.7 22 to 46 (2510 to 2930) [350 to 740)

1.00 [4.19] 62.4 [1.00)

1.00 [4.19] 62.4 [1.00]

0.7 to 1.1 (0.10 to 0.16)

4.1

4.1

3.6 to 8.5

(6.5 to 15.3)

fO 77 to 1 301 Brick***

(Coamon, light red to red) 0.52 to 0.68 0.93 0.22

[921

)

120

(19201 Saaa Saaa

Brick***

(Halted purple to blue)

0.77 to 0.89 0.22

(921) 130

[2080] Concrete, atone aggregate

(Saooth, light)

0.60 to 0.65 0.88 0.20

(834) 120 to [1920 to 140

2440] 0.9 to 12.0

[0.13 to 1.73] 5.5

(9.9) Concrete, atone aggregate

(Rough, light) 0.60 to 0.85 0.94 0.20

(834) 120 to (1920 to 140 2240) Saae

Concrete, atone aggregate (PigMntal, dark)

0.85 to 0.91 0.97 0.20

[834] 120 to [1920 to 140

2240) Saaa Saaa

Stone (Light color)

0.35 to 0.54 0.36 0.21 to 0.25

[880 to 1050) 117 to (1870 to 187 3000]

11 to 20

I X . CO £ . oO

1

3.6 to 22 lOaJ CO J7*DJ Stone

(Dark color) 0.50 to 0.73 0.90 0.21 to 0.25

(880 to 1050]

117 to (1870 to187 3000] Saae

uxay rxoor ixxe (Light color) 0.20 to 0. 50 0.19

(8001

12 to 20

[1.73 to 2.88) Clay Floor Tile

(Dark color) 0.50 to 0.80 0.19

[800] METALS

Aluainua (Polished) 0.10 to 0.40 0.03 0.21 [880] 171 (27401 1404 [202.51 13.9 (25.0) Alualnua (Dull) 0.40 to 0.65 0.09 0.21 [8801 171 (27401 1404 [202.5] 13.9 (25.0) Copper (Bright) 0.18 to 0.40 0.07 0.09 (3801 556 (8910) 2688 (387.71 9.2 (16.6) Copper (Tarnished) 0.40 to 0.64 0.20 0.09 [3801 556 [89101 2688 (387.71 9.2 (16.6)

Iron (Oxidized) 0.80 to 0.92 0.94 0.12 (5001 (212*F)

450 (7210

J

384 [ 55.4] 6.7 (12.11

Steel 0.12 (5001 489 [7830] 314 [ 45.31 9.6 (17.31 WOOD

Hardwood 0.90 0.06 (25101 23 to 70

[370 to 1120] 0.8 to 1.8(0.12 to 2.6] 1.1 to S.3

(2.0 to 9.61

Varlea (Water expanda

about 4X in voluae

froa 40 to 200*F)

* These values were taken froa different sources, as referenced below, and are aeant to serve as a guide only.

i/ "Handbook of Air Conditioning, Heating and Ventilating', Clifford Strock and Richard L. Roral , Industrial Praas, Inc., New York, NY, Second Edition, 1965.

1/ 'Handbook of Fundaaentals" , Aaerican Society of Heating, Refrigerating and Air Conditioning Engineera, 1791 Tullla Circle, Atlanta GA 30329, ASHRAE 1977.

2/ "Building Construction Handbook", Chapter 2, McGraw-Hill Book Coapany, Third Edition.

"Journal of Reaearch of the National Bureau of Standards", Voluae 6, page 1003.

1/ "Concrete Manual", Bureau of Reclaaation, U.S. Departaent of Interior

** May vary with the water containaent device.

**• For additional inforaatton on the properties of brick, see Technical Notes on Brick Construction , 43 D Sept/Oct 1980. "Brick Paasive Solar Heating Systems - Material Properties - Part N". Brick Institute of Aaerica, McLean, Virginia.
TECHNICAL REVIEW ITEMS

The following list of factors is included here as an aid to system deslg

and evaluation. It identifies areas of major consideration which could

be beneficial as a design guide or in the technical review of a system.

This list was used in the technical review of proposals in HUD's Cycle 5

Residential Solar Demonstrations, Used as a review form, each of the

review items (see Review Items, below) was evaluated satisfactory, margl

nal, or unsatisfactory and tracks the more detailed application form

required of each of the grant applicants. An analysis and evaluation of

these factors were used to determine if the proposed projects could be

expected to perform reliably.

General Information

Type of Project: Category 1 (Multi-family)

Category 2 (Single family)

Building Size: gross sq, ft. Net heated sq. ft.

Project Location Latitude

Nearest City

Type of Solar Energy System (check all applicable items)

Active Passive If Passive Indicated

Space Heating ( ) ( ) Sun tempered ( ) Space Cooling ( ) ( ) Direct Gain ( ) Domestic Hot water ( ) ( ) Indirect Gain ( ) Isolated Gain ( ) Type of Backup System

Most efficient system type

Most cost efficient fuel type

Is system over or under sized

Heating Conditions

Total Heating Degree Days DD/YR

Design Temperature "F inside °F outside

Winter UA Total

Annual Heating Loads (before solar) 10^ BTU/YR BTU/DD/SF

Annual Heating Contributions: Net Passive 10^ BTU/YR

Net Active 10^ BTU/YR

Net Auxiliary Fuel Requirements 10^ BTU/YR BTU/YR/ SF

BTU/DD/SF

Cooling Conditions

Design Temperature °F inside °F outside

Annual Cooling Loads (before passive) 10^ BTU/YR

Annual Cooling Contributions: Net Passive 10^ BTU/YR

Net Active 10^ BTU/YR

Net Auxiliary Fuel Requirements 10^ BTU/YR BTU/YR/SF

B-8
DHW Conditions

Total No. of People Gallons per person per day ____ GPP/D

Cold Water Inlet Temperature °F Distribution Temperature °F

Annual DHW Loads (before solar) 10^ BTU/YR

Annual DHW Contributions: Net Passive 10^ BTU/YR

Net Active 10^ BTU/YR

Net Auxiliary Fuel Requirements 10^ BTU/YR

Review Items

A. ENERGY CONSERVATION

1. Are the design temperatures, relative humidity, thermostat

settings, etc., compatible with energy conservation?

2 . Protection from outside temperature variation

a. Compact building form - minimum surface exposure

b. Use of earth-berming or underground structures

c. Use of utility spaces as buffers between living spaces and

outside

d. Is the building envelope well insulated?

Walls

Ceilings and roof

Windows, storm windows

Doors, vestibules

Perimeter insulation of floor slab - basement insulation

Glass area (double panes or insulated glass)

e. Use of movable insulation

f. Use of time lag effects

3. Protection from infiltration and wind

a. Use of site and vegetation as wind breaks

(trees, slope, earth-berming, etc.)

b. Use of building orientation and form for protection from

the wind (small exposure of building to wind; proper placement of windows and doors. Use of utility spaces as buffers)

c. Proper caulking and weathers tripping to minimize infiltration

d. Cut down winter wind, but allow summer ventilation

4. Protection from summer overheating

a. Proper siting and orientation to minimize exposure to summer

sun. Small east and west glass areas

b. Natural shading devices (vegetation, earth berms)

c. Use of overhangs, recessed windows and doors

d. Use of natural and induced ventilation

e. Summer shading, but solar access in winter

B-9
5. Proper humidity level

a. Avoiding excessive humidity in summer

b. Avoiding excessive dryness

c. Proper use of vapor barriers

6. Use of natural light for lighting

7 . Are the load calculations and results given clearly and correctl:

a. Cooling

b. Heating

c. Domestic hot water

d. Time lag

e. Optional

8. Are the relevant climatic data given for the site (or another

similar site) ?

9. Are the appliances and equipment energy efficient?

10 . Is the backup system energy efficient? Is it properly sized?

B. PASSIVE SOLAR HEATING

1 . Proper site and orientation for passive solar heating

a. South facing exposure

b. No winter shading

2. Clear description of system and passive solar methods used (sun

tempering, direct gain, indirect gain, isolated gain. Elements

such as Trombe wall, Sunspace, etc.)

3 . Glazing

a. Adequate south facing glazing area

. b. Has heat loss through glazing been minimized?

(e.g. double glazing, shutters, movable insulation)

4 . Direct gain systems

a. Will the interior surfaces absorb sunlight sufficiently wel]

^ b. Have glare problems been minimized?

5. Passive storage

a. Clear description of kinds of storage used - location,

dimensions and storage capacity of each

b. Sufficient storage capacity (thermal mass)

B-IO
c. Is the massive wall, floor, etc., sufficiently exposed to

direct sunlight through the day in winter?

d. Massive walls and floors: Is the thickness too little, too

much or just right?

e. Is the insulation located properly?

f. Water walls: Have leakage problems been addressed?

6 . Heat distribution

a. If system depends on natural convection and radiation, are these adequate? (Are the air flow distances small? Will

the air flow along the desired paths?)

b. If blowers are used, will the operating energy used be small?

c. Thermos iphoning device: Is collecting surface at a lower

height than the storage by a proper amount?

7 . Passive system controls

a. Are the controls properly designed, simple and reliable?

b. Degree of occupant participation required

8. Protection from overheating

Proper use of storage sizing, venting, shading devices

9. Will the system be easy to install and maintain? (e.g. glazing

easily accessible for cleaning, accessible for maintenance, no inaccessible pipes)

10 . Backup for passive system

1 1 . Other considerations

a. Use of proper building materials, sealants, etc.

b. Weather proofing and moisture proofing

c. Problems from expansion and contraction

d. Freeze protection

e. Safety features - freedom from fire hazards

f. Structural integrity

12. Are the passive solar heating calculations and results given

clearly and correctly?

PASSIVE COOLING

1, Clear description of passive cooling methods being used (natural

ventilation, induced ventilation, night sky radiation, evaporative

cooling, desiccant cooling or dehumidification, use of earth for

cooling)

B-U
2. Are the proposed cooling methods appropriate to the climatic

region? (e.g. evaporative cooling In hot, arid climates,

deslccant cooling in hot humid climates)

3 . Have humidity and condensation problems been addressed ? (e.g.

in rock beds used for cooling)

4. Have sufficient details of the calculations been provided ?

PASSIVE SOLAR DOMESTIC HOT WATER

ACTIVE SOLAR HEATING, DHW, AND COOLING SYSTEMS

1. Collectors (Sections S-515-2 ,S-615-2 of Reference [1])

a. Collector manufacturer

b. Collector model number

[Test data (refer to stagnation checklist)]

c. Transfer medium

Type Water

Air

Other

If Other:

Specific Heat Btu/lb°F

Depsity Ib/cu.ft.

d. Design total flow rate ^gpm or cfm

e. Design flow rate per net

Sq. ft. of collector (guidelines) gpm or cfm

Note: Does flow rate include allowances for heat transfer

fluid specific heat and density?

f . Total area (guidelines) gross SF net (aperture) ^SF g. Collector type (flat plate, concentrating, etc.)

h. Tilt (Section S-615-2.1.2 of Reference [1])

1. Orientation (0° = True South)

j . Type of freeze protection

k. Maximum percent shading

1. Provisions for stagnation

m. Number of covers

n. Cover plate material

o. Absorber plate material

p. Liquid passage material

q. Absorber coating material

r. Overall construction

s. Ease of replacement (Section S-615-1.1.10 of Reference [1])

t. Access for maintenance, repairs

u. Mounting (flashing, wind, vandalism/accidents)

v. Snow hang up; blockage of breather vents

w. Provisions for f ill/draln/venting

X, Flow balance (reverse return, balance valves, etc.)

B-12
2. Storage (Sections S-515-7, and S-601-12 of Reference [1])

a. Storage type - rock , water , other

b. Specific heat - rock , water , other _^Btu/lb°F

c. Density - rock , water , other Ib/f t^

d. Total storage volume - gal. or cu.ft.

e. Volume per net sq. ft. collectors (guidelines) - gal. or cu. ft.

f. Construction

g. Insulation

h. Pressure/vacuum protection

i. Corrosion protection

j . Connection locations

k. Provisions for f ill/draln/vent

1. Access, location

3 . Back-up system (Section S-615-11 of Reference [1])

a. Fuel type

b. Type of heating distribution system

c. Design temperature of heating supply air or water for peak

load

4. Heat Exchangers (Section S-615-12 of Reference [1])

a. Load loop exchanger sizing

b. Collector loop exchanger sizing

5 . Systems

a. Flow diagram

b. Controls and control diagram

c. Pump fan sizing. Note: Does pump/pipe sizing include

allowance for heat transfer fluid viscosity?

d. Piping/ductwork sizing, materials

e. Dampers, proper type, location

f. Expansion/contraction provisions (Sections S-615-10.3 and

S-615-10.9 of Reference [1])

(1) Piping

(2) System fluids

g. Drain down provisions (Section S-615-10.9 of Reference [1])

h. Potable/non-potable separation (Section S-615-10.1.1 of

Reference [1])

i. Backflow prevention (Section S-615-10.1.3 of Reference [1])

j. Scald protection for DHW (mixing valve, etc.) (Section

S-615-10.1.3 of Reference [1])

k. Valving (Section S-615-10.7 of Reference [1])

1. Solar system operating energy use

m. Simplicity

B-13
6. Solar Cooling System (If Any)

a. Type of solar cooling system

b. Cooling capacity, in relation to cooling load

c. Temperature of solar heat delivered to absorption chiller

d. C.O.P, of cooling system

e. Operating energy usage

OVERALL SYSTEM

1 . Has adequate use been made of energy conservation to

reduce the loads?

2. Are the total loads (in BTU/DD/SF or BTU/YR/SF)

acceptable ?

3. Is there a sufficient contribution of solar heat to the living

space?

4. Are the different parts of the system (passive solar, active

solar, back up system, and the building) well integrated ?

5 . Is the operating energy use kept relatively small ?

6. Simplicity of overall system?

7. Conformity with the HUD Minimum Property Standards, local codes,

etc.

B-14
REFERENCES

1. 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 .ii/

}J U.S. Government Printing Office, Public Documents Department,

Washington, DC 20402.

B-15
ABBREVIATIONS (Code Groups, Associations and Gov't. Agencies)

AABC Associated Air Balance Council

AASHTO American Association of State Highway and Transportation Officials

ACCA Air-Conditioning Contractors of America

AIA American Institute of Architects

AIAA American Industrial Arts Association

ANL Argonne National Laboratory

ANSI American National Standards Institute, Inc.

ARI Air-Conditioning and Refrigeration Institute

ASHRAE American Society of Heating, Refrigerating and Alr-Conditioning

Engineers, Inc.

ASME American Society of Mechanical Engineers, Inc.

ASPO American Society of Planning Officials

ASSE American Society of Sanitary Engineers

ASTM American Society for Testing and Materials

AWWA American Water Works Association

BOCA Building Officials and Code Administrators International, Inc.

CABO Council of American Building Officials

CDA Copper Development Association

CPSC Consumer Product Safety Commission

DoE U.S. Department of Energy

EPA U.S. Environmental Protection Agency

FHA Federal Housing Administration

FSEC Florida Solar Energy Center

HUD U.S. Department of Housing and Urban Development

lAPMO International Association of Plumbing and Mechanical Officials

ICBO International Conference of Building Officials

ISES International Solar Energy Society

LASL Los Alamos Scientific Laboratory

NACE National Association of Corrosion Engineers

NAHB National Association of Home Builders

NASA National Aeronautics and Space Administration

NBS National Bureau of Standards

NCSBCS National Conference of States on Building Codes and Standards

NEBB National Environmental Balancing Bureau

NFPA National Fire Protection Association

NOAA National Oceanographic and Atmospheric Agency

NWTI National Wood Tank Institute (ceased operations, standards

available)

ORNL Oak Ridge National Laboratory

SAE Society of Automotive Engineers, Inc.

SAMPE Society for the Advancement of Material and Process Engineering

SBCC Southern Building Code Congress International

SEIA Solar Energy Industries Association, Inc.

SERI Solar Energy Research Institute

SEREF Solar Energy Research and Education Foundation

SMACNA Sheet Metal and Air-Conditioning Contractors* National

Association, Inc.

UL Underwriters Laboratories, Inc.

B-16
SI CONVERSION UNITS

Length

1 in = 0.0254 meter (exactly)

1 ft = 0.3048 meter (exactly)

Area

1 ln2 = 6.45 X 10"^ meter2

1 ft2 = 0.09290 meter2

Volume

1 in3 = 1.639 x 10"^ meter^

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

Mass

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

1 pound-mass (avoirdupois) = 0.4536 kilogram

Pressure or Stress (Force/Area)

1 inch of mercury (60"^) = 3.377 x 10^ pascal

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

Energy

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

1 Btu (International Table) = 1.055 x 10^ joule

1 Kilowatt-hour = 3.600 x 10^ joule = 3.412 x 10^ Btu

Power

1 watt = 1 X 10^ erg/second

1 Btu/h = 0.2929 watt

Temperature

t'C = 5/9 (t°F - 32)

Heat

1 Btu*in/h'ft2»°F = 1.442 x 10"! W/m'K (thermal conductivity)

1 Btu/lb*°F = 4.194 X 10^ J/kg*K (specific heat)

1 langley = 4.184 x 10^ J/m2 = 1 cal/cm2 = 3.69 Btu/ft2

B-17

CXIMPOSITE INDEX

ATMOSPHERES

Industrial 5.1.3

AUTO-IGNITION (Also self-ignition)

Wood and/or other fibrous

materials 4.4.7

AUXILIARY ENERGY

Equipment selection 2.8.4

For space heating 2.2.2

HW load 2.8.2

Performance 2.8

Priority 2.7.3

AUXILIARY SYSTEMS

Controls 3.5.5

Cooling (sizing) 2.2.4

Domestic hot water 2.3, 2.3.4

Heat pump 2.8.4

BACKFLOW

Idle loop 2.7.1

Prevention 4.1.3

BACKS IPHONAGE

Prevention 4.1.3

BLOWERS

Energy loss 2.6.1

Insulation 2.6.1, 3.4.2, 4.4.4

Location 2.6.1

Operating energy 2.0, 2.6.2, 2.9.1

Sealing, leakage 3.3.2

BUILDING

Design (See "Building Design")

Exhausts 1.4

Maintainability, site 6.2.4

Mass 1.3

Orientation 1.2

BUILDING (Continued)

Overheating 2.1.3

Solar system interaction 1.4

Space 1.3

BUILDING DESIGN

Building considerations 1.3

Building/solar system interaction

1.4, 2.8

Climate factors 1.1

Integration of passive solar 2.1

Natural factors 1.1

Orientation 1.2

Site Consideration 1.2

Special function requirements

2.2.3

CALCULATION, SOLAR CONTRIBUTION

Heat loss 2.2.1, 2 .4 .4 Monthly 2.1.1, 2.1.3

CHEMICAL COMPATIBILITY

Adjacent organic materials 5.3.3

Components 5.3

Dissimilar metals 5.3.2

Galvanic and electrochemical/

corrosion 5.3.1

Materials/ transfer fluid 5.3.1

CLOSED SYSTEMS

Prevention of corrosion 3.2.10

COLLECTORS, ACTIVE

Flow 2.4.2

Orientation 2.4.1

Performance 2.4.2

Selection 2.8.1

Shading 2.4.1, 1.2

Stagnation test, post 2.4.2

Tilt angle 2.4.1

Usability of roof for firefighting or egress 4.5.2

I-l
COLLECTORS ,i >

''

Air leakage 2.4.3, 3.3.2, 3.3.4

Architectural integration 2.4.1

Array performance 2.4.2

Chemical compatibility of

components 5.3.1

Cleaning glazing 3.3.5 ' Degradation by wear 5.4.1

Effect of roof deterioration

6.2.5

Energy transfer rate 2.6.1

Flow balance 2.4.2

Fluid circulation 2.7.2

Freeze protection 2.4.4

Heat loss during non-collection

periods 2.4.4

Insulation 3.1.3

Lightning protection 4.3.8

Orientation (tilt and azimuth

angles) 2.1.1, 2.4.1

Panel performance in array 2.4.2

Pressure drop 3.1.1

Protection during installation and

shutdown 6.1.6

Protection from snow and ice

buildup 4.3.7

Rain penetration 5.1.2

Storage combination 2.4.6

Structural safety 4.6

Thermal cycling degradation 5.2.2

Thermal degradation 5.2.1

COLLECTORS, PASSIVE •

Trombe walls 2.1.1

Water walls 2.1.1

Windows 2.1.1

COMBUSTIBLE MATERIALS

Adjacent to high temperature

components 4.4.7

Flame spread 4.4.3

Warning to maintenance personnel

6.1.4

COMFORT CONDITIONS

Occupied space 2.1.3, 2.1.5,

2.2.1

COMPONENT/ SYSTEM

Interaction 2.8

Sealing 3.3.2

Thermal expansion 3.2.8

COMPUTER PROGRAMS

Building design 2.1.1

F-Chart 2.5.2, 2.9.1

Handheld calculators 2.1.1,

2.1.3, 2.9.1

NBSLD 2.9.1

PASOLE 2.9.1

SINDA 2.9.1

SOLCOST 2.9.1

Thermal loads 2.9.1

TRNSYS 2.9.1

CONDENSATION

Adverse effects (building or

site) 1.4

Performance of components or materials 5.1.2

COLLECTOR/ STORAGE COMBINATION CONDITIONED SPACE

2.4.6

Overheating 2.1.3

COMBUSTIBLE LIQUID Passive contribution 2.1.4

Shading 2.1.3

Drain and filling 3.2.5 Thermal condition 2.1.5

Handling 4.4.2

Liquid flash point 4.4.1

1-2
CONTAINERS, STORAGE

Safety hazards 4.2

CONTAMINATION

Air 4.1.4, 4.1.5

Backflow preventor 4.1.3

Dyes 4.1.1

Growth of fungi 4.1.5, 4.1

Hazards 4.1

Heat exchanger 4.1

National Interim Primary Drinking

Water Regulation 4.1.1

Potable water 4.1.1

CONTROLS

Auxiliary energy 2.7.3, 3.5.5

Domestic hot water 3.5.2

Effects of wear 5.4, 5.4.1

Emergency requirements 4.5.1

Fail safe 3.5.2

Incorrectly wired 6.3.1

Inhabited space 3.5.1

Installation 3.5.4, 3.5.7

Operating energy 2.6.2, 2.9.1

Passive solar components 2.1.3

Performance 2.7, 3.5

Priority of energy use 2.7.3

Protection during installation

and shutdown for maintenance

6.1.6, 3.5.3, 6.1.7

Sensor location 3.5.4

System checkout 6.3.1

Temperature and pressure limit

3.5.3

Tracking 3.5.6

CONVECTION

Forced or natural 2.1.2, 2.0

Piping (size) 3.2.1

Thermal storage 2.1.2

CORROSION

Air pollution 1.1, 5.1.3

CORROSION (Continued)

Chemical compatibility 5.3,

5.3.1

Dissimilar metals 5.3.2

Extracted salts 5.1.2

Galvanic 3.2.3, 3.2.8, 4.3.8,

4.6.1

Material compatibility with

heat transfer fluid 5.3.1

Treatment of transfer fluid

3.2.3, 6.2.1, 4.1.2

COVER PLATES

Exposed to pollutants 5.1.3,

1.1

Film type 4.3.3

Injuries due to accidental

contact 4.3.3

Operation and maintenance

instructions 6.1.2

Physical impact 5.1.1

Solar degradation 5.1.1

Thermal cycling degradation

5.2.2

Thermal shock degradation 5.2.3

COUPLING HOSES

Thermal cycling degradation 5.2.2

DAMPERS

Access for maintenance 6.2.2

Backdraft 2.4.4, 3.3.3, 3.4.1

Balancing 3.1.2

Effects of wear 5.4.1

Leakage 2.4.4, 2.7.4, 3.3.3

Operating conditions 3.3.3

Sealing 3.3.3

Sizing 3.3.1

Thermo siphoning 2.7.4

DEFLECTION

Caused by loads 3.1.4, 4.3.3

Cover plates 4.3.3

Draindown systems 3.6.2

Ponding 4.6.1

1-3
DEGRADATION

Dissimilar metals 5.3.2

Moisture 5.1.2

Pollutant 5.1.3

Solar 5.1.1

Thermal 5.2.1

Thermal cycling 5.2.2

Thermal shock 5.2.3

Wear 5.4.1

DEPLETABLE ENERGY

Auxiliary equipment selection 2.8.4

Depletable energy use 2.9.1

DESIGN LIFE

Effect of temperature 5.2

Thermal degradation 5.2.1

DIAGRAMS

Flow and wiring 6.1.2

DOMESTIC HOT WATER (DHW)

Auxiliary system 2.3.4

Daily water use rate 2.3.2

Energy use 2.9.1

Fail safe 3.5.2

Limits controls 3.5.3

Passive or mechanical 2.3

Recovery rate (hourly) 2.3.3

Scalding 4.3.4

Storage 2.3.2

Tap temperature 2.3.1, 4.3.4

Temperature control 3.5.2

DRAINBACK 3.6.2

DRAINDOWN

System 3.6.2

DUCTS

Air leakage 2.4.3, 2.6.1, 3.3.4,

3.3.2

DUCTS (Continued)

Design 3.3.1

Fibrous glass 3.1.3

Flow rates 3.1.2

Heat loss 2.4.4, 2.6.1

Insulation 2.6.1, 3.1.3, 4.4.4

Sealing 3.3.2

Thermal degradation 5.2.1

ECONOMICS OF SOLAR

Life-cycle cost analysis 2.1.1

EFFICIENCY CURVE

Solar panel 2.4.2

EFFLORESCENCE

Absorber surfaces, trombe walls

5.1.2

EMERGENCY REQUIREMENTS

Egress and access 4.5.2

Identification and location of

controls 4.5.1

ENERGY

Blowers 2.0, 2.6.1, 2.9.1

Depletable energy used 2.0,

2.2.1, 2.2.2, 2.9.1

Dumping 4.3.2, 2.4.5

Efficiency rating (EER) 2.8.4

Loss due to damper leakage 2.4.4

Loss from thermal storage 2.5.1

Loss from transport system 2.6,

2.6.1

Operating 2.6.2

Rejection 2.4.5

Requirements for mechanical space

cooling system 2.1.4

Total requirement (heating) 2.2.1

Transfer rate .2.6.4

ENERGY TRANSPORT

Air leakage 2.6.1

1-4
ENERGY TRANSPORT (Continued)

Combustible liquids 4.4.2

Flash point 4.4.1

Liquid quality 6.2.1

System balancing 3.1.2

ENVIRONMENT

External factors affecting

solar systems 1.1, 1.2, 5.1

EXCESS HEAT

Venting 2.1.1, 2.1.2, 2.1.3, 2.4.5,

4.3.2

FAIL-SAFE CONTROLS

Pressure and temperature relief

devices 4.3.1

System failure prevention 4.3.2

F-Chart 2.9.1

FIRE SAFETY

Auto-ignition (self -ignition)

4.4.7

Combustible liquids 4.4.2

Design and installation of H/C/HW

systems 4.4

Insulation 4.4.3, 4.4.4

Liquid flash point 4.4.1

FLAME SPREAD

Insulation 4.4.3

FLAMMABLE AND COMBUSTIBLE LIQUIDS

CODE 4.4.2

FLASH POINT

Determination 4.4.1

Heat transfer fluids 4.4.1

FLOW RATE

Balancing 3.1.2

FLOW RATE (Continued)

Checkout 6.3.1

Collector loop 2.6.3

Heat transfer fluid 2.8.3

Liquid velocities 3.1.2, 3.2.1

Loss in efficiency 2.4.2

Operating energy 2.6.2

System design 3.1

Variations 2.4.2, 2.8.3, 3.1.2

Ventilation air 2.1 .3

FLUIDS, HEAT TRANSFER

Circulation 2.7.2

Compatibility 3.2, 5.3.1

Fire safety 4.4

Quality 3.2.3

Thermal expansion 3.2.4

FLUSHING OF LIQUID SYSTEM 6.1.5

FREEZE PROTECTION

Back-up, power failure 3.6.2,

3.6.3

Control setpoints 2.7.5

Domestic hot water 2.3

Draindown 2.4.4, 2.6.3, 3.6.2

Heat loss 2.4.4

Maintaining chemical composition

3.6, 3.6.1, 6.2.1

Tolerant design 3.6.4

FUNGI

Growth 4.1.5

Rock storage containers 4.1.5

Roof surface (mold and mildew)

6.2.5

GASKETS

Chemical compatibility of

components 5.3.1, 5.3.3

Factory installed 3.3.2

Outgassing 5.2.1

Solar degradation 5.1.1

1-5
GLAZING

Acceptable methods of cleaning

6.1.2

Compatability of adjacent

materials 5.3.3

Condensation 3.4.2, 5.2.1

Deflection 4.3.3

Dirt deposits 1.1, 1.4, 3.3.5

Multiple 2.1.1

Reduce risk and injuries from

accidental contact 3.1.4,

4.3.3

Safety (See "Safety of Dwelling

and Site")

Single 2.1.1

Temporary coverings 6.1.6

Thermal degradation 3.1.1, 5.2.1

Transmissivity 2.1.1, 2.1.4, 5.2.1

HAIL

Glazing materials 4.3.3

HEAT EXCHANGER

Blockage 3.2.3

Chemical compatibility of

components 5.3.1

Effectiveness 2.6.3, 2.6.4

Insulation 2.6.1, 3.1.3

Pressure loss 3.3.1, 3.3.2

Safety and health 4.1.2, 4.1.4

Separation of circulation loops 4.1.2

Sizing 2.6.3, 2.6.4, 2.8.3

System balance 3.1.2

HEAT LOSSES

Collector-to-storage 2.6.1

Due to freeze protection 2.4.4

Due to thermal capacities 2.4.4

During non-collection periods 2.4.4,

2.3

During normal operating conditions

2.4.3

From passive system 2.1.1

From thermal storage 2.5.1, 2.5.2

Thermos iphoning , reverse 2.4.4,

2.7.4

HEAT PUMPS

Coefficient of performance 2.8,4

HEAT TRANSFER FLUID

Degradation 5.3.1

Quality 6.2.1

Velocity 2.8.3

Viscosity changes 5.2.1, 2.6.2

HEATING SYSTEM

Auxiliary heating system sizing

2.2.2

Building heat loss calculation

2.2.1

Design load calculation 2.2.1

Effect of passive (January) 2.1.1

HOSES

Compatibility with transfer

fluids 5.3.1

Exposed to pollutants 5.1.3

HYBRID SYSTEM (See "Passive

Solar")

INSTALLATION INSTRUCTIONS

Availability and suitability

6.1.1

Protection of system during

installation 6.1.6

INSULATION

Degradation and wear 5.4.1

Design and installation 3.1.3,

4.4.4

Exposed plastic foam 4.4.4

Exposure to sunlight 5.1.1

Fire hazard 4.4.4, 4.4

Flame spread classification 4.4.3

Formaldehyde gas 4.1.4

Heat loss 2.5, 2.6, 3.1.3

Moisture degradation, 5.1.2

Movable 2.1.1, 2.2.2, 2.3, 3.4.2,

4.4.4, 6.1.7

Optimum thickness 2.4.3, 2.5.1, 2.6.1

1-6
INSULATION (Continued)

Protection of exposed pipe and duct

3.1.3, 4.4.4, 3.2.1

System components 3.1.3

Thermal degradation 5.2.1

Thermal storage 2.5.1

INTERIOR ITEMS

Effects on thermal storage 1.4

LABELING

Identification of toxic fluids

4.2.2

LEAKS

Air leaks 2.4.3, 3.3.2, 3.3.4

Concentration (heat transfer fluid)

3.6.1

Control valve 2.7.4

Dampers 2.4.4, 2.7.4

Ducts and air handling units 2.6.1,

3.3.2

Protection of potable water 4.1.1,

4.1.2, 4.1.3

Structural deflection 3.1.4

Testing 3.2.2, 3.3.2, 3.3.4

Thermal storage 2.5.1

LIQUID SYSTEMS

Entrapped air 3.2.6

Flushing 3.2.5, 6.1.5

Performance 3.2

MAINTAINABILITY

Building and site 6.2.4

Roof surfaces 6.2.5

MAINTENANCE

Access 6.2.2

Hazards 6.1.4

Operation and maintenance

instruction 6.1.2

Plan (active and passive systems)

6.1.3

MAINTENANCE (Continued)

Protection of system 6.1.6

Servicing 6.2

MAINTENANCE INSTRUCTIONS

System schematic diagram 6.1.2

MAKE UP WATER

Excessive corrosion 6.2.1

MANIFOLD

Duct design 3.3

Flow rates 2.4.2

Heat loss 2.4.3

Insulation 2.4.3

Relief valves 4.3.1

Sealing 3.3.2

MANUAL AND INSTRUCTIONS

Installation operations and

maintenance 6.1, 6.1.1,

6.1.2, 6.1.3

Occupant participation 6.1.7

MECHANICAL EQUIPMENT

Heating and cooling 2.2

Operated automatically 2.2

MECHANICAL SYSTEM

Design load (heating) 2.2.1

MOISTURE DEGRADATION

Collectors 5.1.2

Efflorescence 5.1.2

MONITORING

Access for system 6.3.3

1-7
NO-FLOW PASSIVE SOLAR

Aging procedure 5.2.1

Excessive pressure and

temperature A. 3.1, A. 3.

Provisional tests 3.1.1

Temperature of fluid 4.4.1

Thermal cycling loads 5.2.2

30-day test , Appendix A Section

10

Tracking collector, off-focus

3.5.6

NOCTURNAL

Night sky 2.4.5

Radiation 2.2.3, 2.4.4

OCCUPANT .

Manual of instruction 6.1.7

Required activity 6.1.7

OPERATING ENERGY

Blowers, pumps, and valves 2.0,

2.6.2, 2.9.1

Normal conditions 2.6.2

OPERATION INSTRUCTIONS

Minimum operating information

6.3.2

Start up and shutdown 6.1.2

OUTGASSING

Thermal degradation 5.2.1

ORIENTATION, OPTIMUM 1.2

PASSIVE COOLING TECHNIQUES

Desiccate cooling 2.2.3

Evaporation 2.2.3

Nocturnal radiation 2.2.3

Classification 2.0

Components 3.4

Contribution to conditioned space

2.1.1, 2.1.4

Movable insulation 3.4.2

Net solar contribution 2.1.1,

2.1.4

Optimum aperture area 2.1.1

Overheating 2.1.3

Panels - protection from

accidential contact 4.3.3

Reduce space condition

energy requirement 2.1

Seasonal contribution 2.1.1

Shading 2.1.4

PENETRATIONS

Buildings 1.4

Fire resistance 4.4.5

Roof 6.2.5

PERFORMANCE

Collector panel 2.4.2

Efficiency curves 2.4.2

Stagnation, post 2.4.2

System checkout 6.3.1

PHASE CHANGE MATERIALS

Thermal cycling 5.2.2

PIPING ASSEMBLY

Chemical compatibility of

components 5.3

Design 3.2.1

Safety and health 4.1.1,

4.1.3

Sizing 3.2.1

Thermal cycling degradation

5.2.2

1-8
PLASTICS

Effect of heat transfer fluids

5.3.1

Structural safety 4.6.1

POLLUTANT DEGRADATION

Effects of design life 5.1.3

Levels 5.1.3

Permanent etching of components

5.1.3

POTABLE WATER

Growth of microoganisms 4.1, 4.1.5

Leak testing 3.2.2

Protection 4.1.1, 4.1.2, 4.1.3

Quality 4.1.1

Separation of circulation loops

4.1.2

PRESSURE

Negative, storage tanks 3.2.7

Relief (See Relief devices)

PUMPS

Chemical compatability of

component s 5.3.1

Effects of wear 5.4.1

Insulation 2.6.1

Performance 3.2.10

Size 2.6.2, 3.2.1

Viscosity changes 3.2.10

RADIATION

Clear sky solar 2.1.3

Collector selection 2.8.1

Conversion to thermal energy 2.4,

2.4.1

Depletable energy 2.9.1

Exclusion during non-heating

season 2.1

Incident 2.4.1

January contribution 2.1.1

Net solar contribution 2.1.1

Nocturnal 2.2.3

RADIATION (Continued)

No flow conditions 4.3.2,

Appendix A, Section 10

Reflectors 2.1.1

Seasonal/annual 2.1.1

Shading devices 2.1.3

Site considerations 1.2

Solar degradation 5.1.1, 5.1.3

Thermal storage exposure 2.1.2,

2.8.2

REFLECTORS

To increase incident solar

radiation 2.1.1

RELIEF DEVICES

Pressure and temperature 4.3.1

Protection from freezing 4.3.1

REMOVAL INSTRUCTIONS 6.1.1

ROCK

Asbestos 4.1.4

Bins 2.1.2

Cleanliness 4.1.4

Size 2.5

Washing 3.3.5

ROOF

Damage due to leaking heat

transfer fluid 4.2.4

Maintainability of surfaces

6.2.5

Resistance to deterioration

due to solar energy

components 6.2.5

SAFETY PROVISIONS

Emergency egress and access 4.5.2

Fire safety 4.4

Lightning 4.3.8

Liquid flash point 4.4.1

Structural 4.6, 4.6.1

1-9
SAFETY OF DWELLING AND SITE

Glazing materials 4.3.3

Scalding 4.3.4

Snow and ice 4.3.7

Surface temperature 4.3.5

Water storage hazards 4.3.6

SEALS

Chemical compatibility of

components 5.3.1, 5.3.3

Exposed to pollutants 5.1.3

Thermal degradation 5.2.1

SELF- IGNITION

Wood and/or other fibrous

materials 4.4.7

SENSORS

Location 2.7.1, 3.5.4

Thermal cycling degradation 5.2.2

SETPOINTS

Collection loop 2.7.5

SHADING

Devices to reduce cooling load on passive 2.1, 2.1.3

During winter months 1.2

Fixed 2.1.3

SITE

Design 1.2

Influence of prevailing winds 1.2

Maintainability of building 6.2.4

Siting criteria 1.2

SNOW AND ICE

Buildup on collectors 4.3.7

SOLAR ARRAYS

Accident prevention - reflected

rays 4.5

SOLAR ARRAYS (Continued)

Lightning protection 4.3.8

Usability of roof for firefighting as egress 4.5.2

SOLAR CONTRIBUTION

January 2.1.1

July 2.1.3

October 2.1.3

SOLAR SYSTEM/ BUILDING

INTERACTION 1.4, 2.8

SPACE COOLING SYSTEM

Maintain comfort conditions

2.2.3

SPACE HEATING SYSTEM

Auxiliary design 2.2.1, 2.2.2

Building unattended 2.2

Measured performance (F-Chart)

2.9.1

Operation and maintenance 6.1.2

SPACE, INTERIOR

Planning and coordinating 1.3

SPACE, OCCUPIED

Design conditions 2.1.3, 2.1.5

STORAGE CONTAINERS

Air leakage 2.5.1

Chemical compatibility of

components 5.3.1, 5.3.3

Corrosion 4.3.6

Drainage provisions 3.3.5

Energy loss 2.5.1, 2.3.2

Exposed to solar radiation

2.1.2

Glazing 4.3.3

Hazards 4.3

Insulation 3.1.3

Sizing 2.3.4, 2.8.2

I-IO
STORAGE CONTAINERS (Continued)

Thermal degradation 5.2.1

Thermal stratification 2.5.2

Vacuum relief 3.2.7

STORAGE SYSTEM

Thermal capacity 2.8.2

STAGNATION

Maximum no flow temperature 4.4.1

Post 2.8.1, 2.4.2

Protection (installation and

maintenance) 6.1.6

Resistance to 3.1.1

Tracking collector, off focus

3.5.6

STRATIFICATION, THERMAL

Mathematical models 2.5.2

Storage 2.5.2

STRUCTURAL

Deflection compatibility 4.6.1,

3.1.4, 4.3.3

Safety 4.6, 4.6.1

STRUCTURAL DESIGN LOADS (LOADS,

STRUCTURAL)

Constraint 4.6.1

Cyclic 4.6.1

Dead 4.6.1

Deflections, specified loads 4.6.1

Earthquake 4.6.1

Hail 4.3.3

Live 4.6.1

Snow and ice 4,6.1

Wind 4.6.1

SUNSHINE PERCENTAGE 2.1.1

TEMPERATURE

Building materials due solar

equipment 6.2.4

TEMPERATURE (Continued)

Comfort 2.1.3, 2.1.5, 2.2.1

Effect 5.2

Hot water at tap 2.3.1, 4.3.4

Load requirements 2.8.5

Overheating (passive) 2.1.3

THERMAL DESIGN LOADS (LOADS,

THERMAL)

Hot water 2.3

Loads requirement 2.8.5 (See

"Temperature"

)

Space cooling 2.2.3

Space heating 2.2.1, 2.2.2

THERMAL PROPERTIES

Storage materials 2.1.2

THERMAL STORAGE

Access for cleaning or replacement 6.2.2

Addition of auxiliary energy

2.5.3

Air leakage 2.5.1, 3.3.2

Collector/storage combination

2.4.6

Effect of interior items 1.4

Energy loss 2.5.1

Hot water load 2.3.4, 2.5

In building mass 2.1.3

Insulation 2.5.1

Location 2.1.2

Performance 2.5

Potential for fungus growth

4.1.5

Sealing 3.3.2

Size 2.8.2

Size of aperture 2.1.2

Sizing and location 2.1.2,

2.8.2

Space cooling 2.5

Space heating 2.5

Stratification 2.5.2

Thermally-coupled area 2.1.2

Thickness of the mass layer 2.1.2

Trombe walls 2.4.6

Use of building mass 2.1.1, 2.1.2

I-ll
THERMOS IPHON

Collection loop 2.3, 2.6.3, 2.7.2

Domestic hot water system 2.3, 2.4.4,

2.6.3, 3.2.1

Non-collection period losses

2.4.4, 2.7.1, 2.7.2

Prevention 2.7.2

TOXIC FLUIDS

Detection of 4.2.3

Disposal of 4.2.4

Draining and filling 3.2.5

Identification of 4.2.2

Rating of commercial substances

4.1.2

The Federal Hazardous Substances

Act 4.2.1

Toxicological properties 4.2.1

Warning for maintenance

personnel 6.1.4

TRANSFER FLUIDS, HEAT

Compatibility 3.2, 5.3, 5.3.3

Flash point 4.4.1

Fluid flow rates 2.8.3

Plastics 5.3.1

Treatment of 3.2.3, 6.2, 6.2.1

TRANSMISSIVITY

Glazing 2.1.4, 5.1, 5.2, 5.3

TRANSMITTANCE

Glazing 2.1.1, 2.1.4, 5.1, 5.2, 5.3

TRANSPORT ENERGY

TRANSPORT SYSTEM (Continued)

Energy transfer 2.6.3, 2.6.4

Leakage 3.2.2, 3.3.2

Operating energy 2.6.2

Performance 2.6

Testing 3.2.2, 3.3.2

TROMBE WALLS

Efflorescence on absorber surfaces

5.1.2

Provision for recoating 6.2,2

Thermal storage 2.1.1

ULTAVIOLET EXPOSURE

Deterioration 5.1.1

Deterioration of organic materials

5.1.1

VANDALISM

Minimize 1.4

VALVES

Chemical compatibility of

components 5.3.1

Effects of wear 5.4.1

Isolation, system maintenance

6.2.2

Operating conditions 3.2.9

Relief devices 4.3.1

Shutoff, conspicuously marked

4.5.1

Specification and location 3.2.9

VENTILATION

Whole-house 2.1.3

Collector loop rate 2.6.3

Load transfer rate 2.6.4 VENTING

Losses 2.6.1

Passive 3.4.1 Draindown systems 3.6.2

Performance 2.6 Mass wall 2.1.2

Piping, during filling operation

TRANSPORT SYSTEM 3.2.2

Reduces the net solar contribution

Balancing 3.1.2 2.1.1, 2.1.2, 2.1.3

Energy loss 2.6.1 Thermal expansion of fluids 3.2.4

1-12
VISCOSITY

Heat transfer fluids 2.6.2

Pump selection 3.2.10

WALLS, THERMAL STORAGE

Trombe walls 2.1.1

Water walls 2.1.1

WASTE HEAT RECOVERY AND STORAGE

IN THE THERMAL MASS OF PASSIVE

SOLAR BUILDINGS 1.3

WATERPROOFING

Exposed Insulation 5.1.2

WEAR

Degradation 5.4.1

WINDOWS

Impact on space cooling loads

2.1, 2.1.1

Solar radiation 2.1.1

WINDS, WINTER

Protection 1.3

1-13
NBS-114A (REV. 2>ec) U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

PUBLICATION OR

REPORT NO.

NBS BSS 147

2. Performing Organ. Report No 3. Publication Date

September 1982

4. TITLE AND SUBTITLE

Performance Criteria for Solar Heating and Cooling Systems In Residential Buildings

5. AUTHOR(S)

Center for Building Technology

6. PERFORMING ORGANIZATION (If joint or other than NBS. see /n struct/on sj NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No. IAA-H-54-81

8. Type of Report & Period Covered

Final

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City, State, ZIP)

U.S. Department of Housing and Urban Development

Office of Policy Development and Research

Building Technology Division

Washington, DC 20410

10. SUPPLEMENTARY NOTES

Library of Congress Catalog Card Number: 82-600581

Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most si gnificant information. If document Includes a significant

bibliography or literature survey, mention it here)

TUnis performanoe 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 solar heating and cooling systems for residential

buildings in accordance with the requirements of Section 8 of

Public Law 93-409, the "Solar Heating and Cooling Denionstration

Act of 1974." The document is intended to establish iTunimum levels

of perfonrence with regard to health and safety and the various aspects

of technical performance. The criteria for health and safety put

primary emphasis on ccrrpliance with existing codes and standards.

The criteria on thermal and mechanical performance, durability/

reliability and operation/servicing present performance requirements

considered to be representative of acceptable levels. By the use of

performance language in the document, it is believed that sufficient

latitude has been provided to allc^^r the innovation and flexibility that is essential for the stimulation of a viable solar

industry at this time and in the future.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

building; cooling; heating; hot water; performance criteria; solar energy; standards.

13. AVAILABILITY

[X] Unlimited

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14. NO. OF

PRINTED PAGES

236

15. Price

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GOVERNMENT PRINTING OFFICE

... DC 6043-P80 1982-3 60-997/2233
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