NATL INST. OF STAND & TECH

AlllDS T7M377

REFERENCE Publications

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*'"tEAxy o« * NBS TECHNICAL NOTE 1187

U.S. DEPARTMENT OF COMMERCE/National Bureau of Standards

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no.ll37-

Performance Criteria for Solar [Heating and

Cooling Systems in Commercial Buildings
NATIONAL BUREAU OF STANDARDS

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the Institute for Computer Sciences and Technology.

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'Headquarters and Laboratories at Gaithersburg, MD, unless otherwise noted; mailing address Washington, DC 20234. 'Some divisions within the center are located at Boulder, CO 80303.
NATIONAL BUREAa OF Z . '.HDAROS Performance Criteria for Solar Heating and

Cooling Systems in Commercial Buildings n^l

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Center for Building Technology , (JSli

National Engineering Laboratory

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National Bureau of Standards

Waslilngton, DC 20234 ^^4-

Prepared for:

Active Heating and Cooling Division

Office of Solar Heat Technologies

U.S. Department of Energy

Washington, D C 20585

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

NATIONAL BUREAU OF STANDARDS. Ernest Ambler. Director

issued April 1 984
National Bureau of Standards Technical Note 11 87

Natl. Bur. Stand. (U.S.), Tech. Note 1 187. 229 pages (Apr. 1984)

CODEN: NBTNAE

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1984

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

This document establishes baseline criteria for the design, development,

technical evaluation and procurement of solar heating and cooling systems for

commercial buildings. These performance criteria were developed in accordance

with Public Law 93-409 the "Solar Heating and Cooling Demonstration Act of

1975." The document is intended as a resource for use in establishing minimum

acceptance levels of performance for solar heating and cooling systems. Criteria which deal with public health and safety are in compliance with general

building 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 for conventional space conditioning equipment. By the use of performance language in the

document, it is believed that sufficient latitude has been provided to allow

innovation and flexibility that is essential for the stimulation of a viable

solar industry.

Key words: building; cooling; heating; hot water; performance criteria; solar

energy; standards

iii
TABLE OF CONTENTS

Page

Abstract «. Ill

Foreword v

Acknowledgment vlll

Introduction 1

Terminology 8

1. Site and Building 1-1

2. Thermal 2-1

3. Mechanical 3-1

4Safety and Health A-1

5

Durability/Reliability 5-1

6. Operation and Servicing 6-1

Appendix A...... A-a

Durability/Reliability test and evaluation methods A-1

Appendix B B-a

Materials Tables B-1

Abbreviations B-8

S I Conversion Units B-9

Composite Index I-l

iv
FOREWORD

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

a 5-year program for research, demonstration, and development for solar heating

and cooling systems in residential and commercial buildings. As part of the

demonstration 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 for residential buildings

within 120 days of enactment and to use the criteria in the selection of solar

energy systems and demonstration projects. The Interim Performance Criteria

were published on January 1, 1975. The Act further directed that the services

of NBS be used to develop and publish "definitive performance criteria" as soon as feasible with information gained from the demonstration program.

The initial Interim Performance Criteria for Commercial Solar Heating and

Combined Heating/ Cooling Systems and Facilities were published by the National

Space and Aeronautics Administration (NASA) for the Energy Research and

Development Administration (ERDA). The interim commercial criteria were made

available in February 1975 with similar technical content and format developed

for the residential criteria.

In November 1976 the interim commercial criteria were updated after the

technical responsibility was transferred from NASA to NBS. The revision was issued as NBS IR 76-1187, "Interim Performance Criteria for Solar Heating and

Cooling Systems in Commercial Buildings," and was used in evaluation of project

proposals submitted under the Commercial Solar Demonstration Program and the

Federal Solar Buildings Program. Because of advances in the state-of-the-art

of solar technology, the Department of Energy (DOE) sponsored the preparation

of this revision of the November 1976 document.

The document is intended to serve as a technical reference and resource for

the solar industry, the building industry. Federal, State and local agencies,

designers and building owners concerned with assessing the design and performance of solar energy systems in commercial buildings.

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 relative to conventional space conditioning equipment. By the use of performance language in

the document, it is believed that sufficient latitude has been provided to

allow the 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:
9 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.

- "Performance Criteria for Solar Heating and Cooling Systems in

Residential Buildings," Building Science Series 147, National Bureau

of Standards, September 1982.

9 Experience gained in the Federal Solar Demonstration Program

(Residential/Commercial) through feedback as provided for in P.L. 93-409

9 Findings from solar research activities

- Government laboratories - National Bureau of Standards, Los Alamos

National Laboratory, National Aeronautics and Space Administration,

Argonne National Laboratory.

- Sponsored research - Dubin-Bloome 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)

- Special studies - Burt-Hill-Kosar-Rittelman Associates, Travis-Braun

Associates, Robertson Ward, Jr., FAIA, Florida Solar Energy Center,

Polytechnic Institute of New York, Mueller Associates, TPI, Inc.

- Technical standards organizations - American Society for Testing and

Materials, American Society of Heating, Refrigerating and AirConditioning Engineers, American Society of Mechanical Engineers , Inc.

,

American National Standards Institute.

- Industry organizations - Solar Energy Industries Association, Inc.,

Solar Energy Research and Education Foundation, Air Conditioning

vi
and Refrigeration Institute, Sheet Metal and Mr Conditioning

Contractors National Association, Inc.

- Professional organizations - American Institute of Architects

vil
ACKNOWLEDGMENTS

This document was prepared by the Center for Building Technology staff of the

National Bureau of Standards. Members and former members who participated in

the preparation of this document, as well as previous performance criteria

documents prepared for the Energy Research and Development Administration and

Department of Housing and Urban Development (see Foreword) include:

Robert Beausoliel Lawrence W. Masters

Thomas H. Boone Michael F. McCabe

Paul W. Brown F. Eugene Metz

Elizabeth J. Clark Kent A. Reed

Richard Crenshaw Belinda C. Reeder

Robert D. Dikkers Leopold F. Skoda

Thomas K. Faison Elmer R. Streed

James R. Harris David Waksman

John K. Holton W. Douglas Walton ( Center for Fire

Research)

Acknowledgment is also made of the helpful comments and suggestions received

from Carl W. Conner, Department of Energy, William Freeborne and David Moore,

Department of Housing and Urban Development, and the many organizations mentioned in the Foreword.

The buildings drawn on the cover are representative of commercial buildings

that were built with support from the Department of Energy. They demonstrate

applications of passive and active solar heating and cooling systems. Shown are an intercultural center in Washington, D.C. ; a visitors information center

in Troy, NY; a showroom in Denver, Colorado; a gymnasium in Alexandria, VA; and an elementary school in Baltimore, MD.

viii
INTRODUCTION

Background

Public Law 93-409 provided for "demonstration within a three-year period of the

practical use of solar heating technology, and .... the development

within a five-year period of the practical use of combined heating and cooling

technology." Under the provisions of the Act, the Department of Energy had

reponsibility for implementation of the commercial building solar demonstration

program. As part of that program, the National Bureau of Standards was utilized to develop this document. This document follows earlier work by the

National Bureau of Standards and the National Aeronautics and Space Administration in developing "interim" performance criteria for the National Solar

Demonstration Program, References [1, 2].*

A companion document for residential application which was sponsored by the

Department of Housing and Urban Development has been referenced in the Federal

Register , Reference [3] and is available through the Government Printing Office

as a National Bureau of Standards publication. Building Science Series 147,

"Perfoirmance Criteria for Solar Heating and Cooling Systems in Residential

Buildings," Reference [4].

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 solar programs 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

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

section.

1
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 thereof_' in individual

buildings or central systems for groups of buildings both new and existing.

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

of components and systems and do not directly address economic considerations

and energy conservation.

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

[5, 6, 7, 8, 9, 10, 11, 12].

Reference is also made to the American National Standard Recommended

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

Systems , Reference [13]. This document identifies health and safety requirements for solar systems.

U 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.
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 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-theart, 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:
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 HeaJ th 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 operating 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, consensus standards are to be used when applicable. 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 (service HW)

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

Individual H, C, HW system or any combination thereof.
References

1. "Interim Performance Criteria for Commercial Solar Heating and Combined

Heating/Cooling Systems and Facilities," NASA, Marshall Space Flight

Center, Document No. 98M10001, February 1975.

2. "Interim Performance Criteria for Solar Heating and Cooling Systems in

Commercial Buildings", NBSIR 76-1187, National Bureau of Standards,

U.S. Department of Commerce, Washington, D.C. 20234, November 1976 ._^'

3. Federal Register , Vol. 46, No. 121, pp. 32740-32823, June 24, 1981.

4. "Performance Criteria for Solar Heating and Cooling Systems in Residential

Buildings," Building Science Series 147, National Bureau of Standards,

U.S. Department of Commerce, Washington, D.C. 20234, September 1982.£/

5. Proceedings of the Solar Heating and Cooling Demonstration Program

Contractors' Review , Vol. 2, CONF 771229, Department of Energy,

New Orleans, LA, December 5-7, 1977 .£/

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

Development Branch Contractors' Meeting , U.S. Department of Energy,

Washington, D.C, September 24-27, 1978 .J^^^

7. Conference Proceedings-Solar Heating and Cooling Systems Operational

Results , U.S. Department of Energy, Colorado Springs, CO, November 28-

December 1, 1978.2^

8

Standard Practice for Installation and Service of Solar Space Heating

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

Society for Testing and Materials, 1916 Race Street, Philadelphia, PA

19103, 1979.

9. "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._^'

10. Weinstein, S., Architectural Concerns in Solar System Design and

Installation , Solar/0801-79/01, U.S. Department of Energy, March 1979 .J_/

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

12. "National Solar Heating and Cooling Demonstration Program - Project

Experience Handbook," Preliminary Draft, DoE/CS-0045/0 , U.S. Department of

Energy, September 1978. ^z
13. 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.

}J Technical Information Center, P.O. Box 62, Oak Ridge, TN 37830.

±1 Superintendent of Documents, U. S. Government Printing Office, Washington,

D.C. 20402.

U National Technical Information Service, 5285 Port Royal Road, Springfield,

VA 22161.
TERMINOLOGY*

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

radiation and transforms it into thermal energy,

Absorptance: 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 com- pletely separate from it and contain its own means for delivery of

heating, cooling, and/or hot water to the building.

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

intended direction of flow.

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.

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

8
Closed system: An arrangement In hydronlc systems where ambient air Is not

allowed to enter the system under normal operating conditions.

Collector array: Group of solar collectors or absorbing surfaces connected 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**? (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.

Contaminants (hazardous): Materials 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.

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: An open-loop water system in which all water drains out of

the collectors and exposed piping at a pre-set point above the freezing

temperature.

10
Drainback system: A liquid solar collector system in which the collector

fluid drains down to an interior storage tank when design conditions

require such action (either automatic or manual).

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 lOO^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.

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.

11
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 thermosiphon-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 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 mg 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.

12
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 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.

13
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 hydronlc 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

radiant temperature at a given location.

mean

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.

Outgasslng: 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 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.

Plastlclzer migration: The movement of plastlcizers used in plastic materials.

These plastlcizers may concentrate in a narrow boundary area or migrate to

another material in contact with the plastic.

14
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 upon

a surface per unit 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 f t^'^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. 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 are 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.

15
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/m^.

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 satisfying 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 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 con- stant 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.

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 employ either

heat or cold storage in all or part of the storage subsystem.

System: The complete assembly necessary to supply heat, service hot water, or other usable form of solar energy to a structure.

16
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 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").

Transmittance: 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
1.0

Introduction

1.1

CHAPTER 1

SITE AND BUILDING

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.

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

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

earth berming, and otherwise maximizing southern exposure

and minimizing others. References [1,2]*

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

1-1
(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/KW

systems. Typical sources of climate data are the Climatic

Atlas, Reference [5] and Comparative Climatic Data, Reference

[6]. Reference [7] although specifically directed to residential application may be useful in small commercial designs and

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)

1-2
(d) Relative humidity

(e) Rainfall and snow

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. Overdesign 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

1-3
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 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.

1.3 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

1-4
benefit from placement adjacent to southern exposures. Bi 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. Recent publications give the designer and potential owner information on

the integration of passive solar concepts and practices for

commercial application, References [16,17,18,19,20,21].

1.4 Building/ 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 com- ponents, especially apertures or collector glazing. Similarly,

solar components should not interfere significantly, either

physically or aerodjmamically, 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 and American Society of Landscape Architects

Foundation, Washington, DC, 1972.J_'

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

Architects Foundation, for National Bureau of Standards, U.S. Department

of Commerce and the U.S. Department of Housing and Urban Development,

Washington, D.C. , 1975.^/

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

Development," HUD-PDR 445, GPO 023-000-00523-9, for the U.S. Department

of Housing and Urban Development, Washington, D.C.J_'

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 , NCAA, National Climate Center, Federal Building,

Ashville, Ng 28801, 1978.

7. "Regional Guidelines for Building Passive Energy Conserving Homes," AIA

HUD-PDR 355, GPO 023-000-00481-0, AIA Research Corporation for U.S.

Department of Housing and Urban Development, Washington, D.C, 1978^'.

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, U.S.

Department of Commerce, Washington, D.C, 1973.-^'

1-6
14. "The First Passive Solar Home Awards," GPO 023-000-00517-4, Franklin

Research Center, Philadelphia, PA, for the U.S. Department of Housing and

Urban Development, Washington, D.C., 1979^'

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

"Determining Cost-Ef fective Insulation Levels for Masonry and Wood-Frame

Walls in New Single Family Housing," NBS Building Science Series 134,

National Bureau of Standards, U.S. Department of Commerce, Washington, DC

1981.

16. Project Summaries , Passive Solar Commerical Buildings Program, Chicago

Workshop, U.S. Department of Energy, Washington, D.C., December 1981.

17. Miller, Michael J., "Lessons Learned from Passive Solar Design," Building

Design & Construction , February 1983.

18. "Passive Design for Commercial Buildings," Passive Solar Trends In

Technology , T-2 Commercial, Passive Solar Industries Council, c/o Potomac

Energy Group, 125 S. Royal St., Alexandria, Virginia 22314.

19. Adams, M. Ross, "Passive Strategies for Commercial Buildings," Solar

Age, April 1982.

20. Passive Solar Commercial Building Program , Case Studies, DOE/CE-0042,

U.S. Department of Energy, Washington, D.C., May 1983.

21. Greer, Nora Richter, "Previews of Some Coming Attractions," AIA Journal , January 1981.

]_' Superintendent of Documents, U.S. Government Printing Office, Washington, DC

20402.

21 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 Design conditions 2-2

2.1.1 Space comfort/Interior design conditions 2-3

2.1.2 Habltablllty 2-5

2.1.3 Hot water design conditions 2-5

2 .

2

Building energy requirements 2-6

2.2.1 Space heating energy 2-7

2.2.2 Space cooling energy 2-9

2.2.3 Lighting energy 2-10

2.2.4 Service water heating energy 2-11

2.3 System design capacity 2-12

2.3.1 Heating system design capacity 2-13

2.3.2 Cooling system design capacity 2-14

2.3.3 Lighting system design capacity 2-15

2.3.4 Water heating system design capacity 2-16

2.4 Collector array 2-17

2.4.1 Collector orientation 2-17

2.4.2 Individual collector performance 2-18

2.4.3 Manifold thermal loss 2-20

2.4.4 Thermal loss during noncollection periods 2-21

2.4.5 Thermal energy dissipation 2-23

2.5 Thermal storage 2-23

2.5.1 Thermal energy loss 2-24

2.5.2 Thermal stratification 2-25

2.5.3 Auxiliary energy to thermal storage 2-26

2.6 Energy transport 2-26

2.6.1 Thermal energy loss 2-27

2.6.2 Operating power 2-28

2.6.3 Collector loop energy transfer 2-29

2.6.4 Energy transfer to load 2-30

2.6.5 Thermal energy rejection 2-30

2-a
CHAPTER 2

THERMAL

Contents (continued)

Page

2.7 Controls 2-31

2.7.1 Sensor location 2-31

2.7.2 Collector circulation set points 2-31

2.7.3 Leakage past valves and dampers 2-32

2.7.4 Priority of energy use 2-33

2.8 Component/ system intergration 2-33

2.8.1 Collector selection 2-33

2.8.2 Storage size 2-34

2.8.3 Fluid flow rates 2-36

2.8.4 Auxiliary equipment selection 2-36

2.9 System performance 2-37

2.9.1 Depletable energy use 2-37

References 2-41

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 commercial buildings. In those

instances where both active or passive systems apply to the

criteria, the general term "solar energy system" will be used.

The definitional distinction between active and passive

systems, however, can be useful where only one type is affected

by the criteria. Passive solar energy systems are usually

elements of the building envelope and mass which are designed

to have a beneficial effect in reducing the depletable energy

requirements of the building. These passive systems employ

primarily natural means for accomplishing energy flows such as radiation, natural convection or conduction. Active systems, on

the other hand, can be thought of as external equipment procured

for the purpose of meeting the energy requirements of the

building. Most systems have the ability to supply energy on demand (controllers) through the use of forced convection

energy flows. Because of the interrelationship between the

conventional HVAC system and the active solar system, the con- ventional system is considered a part of the solar system acting as backup. A more detailed discussion of the classification of active and passive systems is available in Reference

[1].*

Chapter 2 is divided into nine requirements. The first three

requirements; 2.1, 2.2, and 2.3, apply to the design of the

solar system with respect to its ability to provide comfort

at ASHRAE design conditions while not adversely affecting the

energy consumption of the building. Specifically, Requirement

2.1 treats the definition of design conditions and preservation

of the habitability of the building when considering the integration of a solar system. Requirement 2.2 states that the

solar system shall reduce conventional energy consumption for

the intended end-use without significantly increasing the other

end-use energy consumptions. When comparisons of different

fuel consumption are required, the energy value is that at the

building envelope and does not reflect fuel costs or quality.

It is assumed that design analyses will account for such factors. Requirement 2.3 specifies the sizing of the solar system

with respect to design conditions and peak demand. Peak demand

is included in the requirement because of the importance of

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

2-1
building energy demands at the community level. Public law

mandates that utilities maintain sufficient generating capacity

to meet the maximum requirement. This results in considerable

excess capacity during average conditions. If the use of solar

in a considerable number of buildings within a community

increased the peak demand, it may result in further power plant

construction and a reduction in overall utility efficiency.

Requirements 2. A through 2.7 present specific criteria related

to the selection and design of specific components within the

overall solar energy system. These requirements are primarily

aimed at active solar systems. Because of the similarity

between thermosyphon system components and active service hot

water components, criteria from these requirements can usually

be applied directly to the design of a thermosyphon system.

Requirement 2.8 deals with those problems related to the

integration of components into an efficient solar energy

system. Again, the material is primarily directed toward active

rather than passive systems.

Requirement 2.9 is concerned with the overall effect of the

solar energy system on the use of depletable energy sources. Integration of all factors is considered in this requirement

including active and passive solar system contributions,

effects on all end uses, and effect on equipment efficiencies.

The criteria of this chapter are not intended to supplant

general practice design procedures but rather to avoid unintentional deleterious effects on the overall thermal performance

of the building and its equipment through the use of solar

energy.

2.1

Requirement Design conditions . The solar energy space conditioning and/or

service hot water systems in combination with conventional

mechanical systems, shall be capable of maintaining conditions

which are suitable for normal usage of the building. The use

of such systems shall not adversely affect the habitability of

the building. These systems, in combination with conventional

mechanical systems, shall be capable of automatically operating to protect the system components, the building and its

contents against damage due to temperature extremes when the

building is unattended.

Commentary If passive solar techniques are utilized, the mechanical system

for active solar must provide the means by which the space

temperature, humidity, and ventilation requirements are met

after the space has been tempered by the passive solar techniques. The resulting restructuring or modification of a building's energy loads due to the inclusion of passive solar

techniques should be realized and quantified. The design

2-2
process for modification of the buildings energy load through

incorporation of passive features requires analysis of climatic conditions and an understanding of how building energy

loads respond to exterior conditions. The extent to which

building energy load is changed as the result of passive solar

design must be known before the conventional mechanical and/or

active solar system is designed. For passive solar buildings

with no active solar space conditioning system, this requirement must be met entirely by the conventional system. This

requirement addresses the ability of the mechanical system to

meet peak design conditions, and not the amount of depletable

energy used, which is covered under Requirement 2.9, System

performance . The mechanical system must be adequately sized,

to meet the design condition, but not oversized, to avoid the

excessive use of depletable energy.

2.1.1

Criterion Space comfort/interior design conditions . Minimum and maximum

allowable dry-bulb air temperature shall be specified in the

design for each interior space, and shall be suitable for its

intended use. Other design parameters such as relative humidity, air movement, and temperature of interior surfaces may be

specified for certain categories of spaces if required by the

applicable authority.

Evaluation The ASHRAE Handbook, Applications Volume, Reference [2] shall

* be used to determine the suitability of the specified interior

design conditions for each conditioned space. ASHRAE Standard

55-81 shall be used to determine the suitability of specified

thermal conditions for occupied spaces. Reference [3]. Broad

categories of building types and representative interior design

conditions are given below:

Category I Buildings (examples) ; Recreation facilities, hotels,

motels, shopping centers, schools, assembly places (theaters,

churches, convention centers), restaurants, transportation

centers, and guard office spaces. Category I spaces shall be

designed to satisfy the environmental conditions established

in ASHRAE Standard 55-81. Human occupancy is the primary

consideration in these spaces.

Category II Buildings (examples) ; Hospitals, laboratories

(clean rooms), computer facilities, museums, and libraries.

Category II spaces require tight control and generally the

specific control limits are not to satisfy human comfort needs,

but provide more stringent control. Because the limits are generally in response to individual space uses, the specific — limits shall be supplied by the applicable authority who must

establish the design limits for individual space use conditions.

2-3
Category III Buildings (examples) ; Warehouses , and

greenhouses. Category III spaces may not require as tight control as required by the other two categories. Because

of the wide range of space condition requirements that may be

applicable to solar energy assisted space conditioning systems,

the control limits for Category III space conditioning shall be

specified by the applicable authority.

Although the three broad building categories are given as a guide, the specific use of each identifiable space and its

space conditioning requirements shall be listed separately.

Commentary The operation of many passive solar energy systems is dependent

upon temperature gradients to get thermal energy into and out

of storage and to transport energy from one location to

another. The transfer of heat from a solid to an airstream can

be a difficult process. The movement of air at speeds greater

than natural convection in order to convect heat from a mass

surface requires the use of parasitic fan energy. Tolerances

for dimensions and airflows can be very small and must be

analyzed accordingly. Moderate temperature fluctuations,

approximately 6 to 8 degrees F, outside the comfort zone may

be appropriate during non-use periods such as night hours.

Consideration must be given to the specific use and occupancy

schedule of each identifiable space to ensure the appropriateness of the passive strategy to provide suitable comfort con- ditions when needed. An example of an inappropriate choice

would be the use of a Trombe wall in a commercial building that

needs heat only during the day. Mass walls typically have a slow morning warm-up and store heat for use at night, when in

this case it is not really needed.

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 effective temperature is approximately the average

of the air temperature and the MRT. The effective use of mass

in a building can have a moderating effect on the MRT and,

thereby, the interior comfort conditions. A thorough discussion of these factors and design guidelines appropriate for

Category I buildings are given in Reference [3].

When passive techniques are employed for cooling purposes,

comfort is frequently maintained by providing sufficient air

movement to compensate for dry bulb temperatures which exceed

the boundaries of the normal comfort zone. These considerations should be accounted for when using the ASHRAE Standard

55-81.

2-4
For Category II and III buildings. Reference [2] provides very

thorough coverage of specific applications.

2.1.2

Criterion

Evaluation

Habitability. Solar systems used for heating, cooling,

lighting, or combinations of these energy requirements shall

not adversely affect the habitability or productivity of the

occupants of the building.

For thermal evaluation, refer to Section 2.1.1 Space comfort/

interior design conditions for applicable guidelines in determining the suitability of the specified interior design

conditions for each conditioned space.

For lighting evaluation, the lES Lighting Handbook, References

[4] and [37, gives acceptable lighting levels and calculation

procedures for both electric lighting and daylighting systems.

All assumptions upon which analysis is based must be explicitly

stated.

Commentary Refer to Section 2.1.1 Space comfort/ interior design conditions

for appropriate commentary regarding comfort conditions and

habitability.

The inclusion of passive solar in commercial buildings may

influence the behavior, and, therefore, productivity of its

' occupants. This effect can be either beneficial or deleterious.

A well-designed passive system can create a more pleasant working environment for occupants, whereas a poorly designed and/or

operated passive system may diminish worker effectiveness.

The DoE Passive Commercial Buildings Program is conducting a survey of the occupants of the various buildings in the program. Although the majority of the occupants (and users of the

building) have reported an increase in satisfaction with the

working environment (compared to conventional alternatives),

excessive temperature swings, lighting glare and accoustical

problems have been reported in some cases.

Additionally, active solar systems, which are usually isolated

from the occupied spaces , seldom produce these types of

benefits or problems. Also, the problems associated with

passive solar systems in commercial buildings are often a result of diminished tolerance and system control by occupants

as compared to their residential building counterparts.

2.1.3

Criterion Hot water design conditions . Hot water temperature and hourly

recovery rate shall be specified in the design and shall be

suitable for the building category, function, and specific

application.

2-5
Evaluation The temperature and recovery rate shall be compared to values

given in ASHRAE Systems Handbook, Chapter 37, Service Hot

Water, Reference [6] , for the appropriate building category and

specific use. Combinations of hot water storage and recovery

rate may be specified as provided by ASHRAE.

Commentary See Criterion

safety.

4.3.4 for provisions related to health and

2.2

Requirement Building energy requirements . Solar energy system design

shall show evidence of reducing the need for depletable energy

sources for each energy end-use to which the system is applied,

without significantly increasing depletable energy requirements

for end-uses which are not served by the solar energy system.

Commentary Solar energy systems are typically used in combination with

conventional mechanical/lighting systems to provide

satisfactory space conditioning (heating and cooling), visual

conditions (lighting), and service hot water systems. The

solar components may be used to address one of these energy

end-uses, or to address any combination of these end-uses.

In most residential solar designs (especially passive designs),

the solar elements address a single energy requirement

(usually heating) and augment a conventional auxiliary mechanical system of relatively simple control. However, due to

thermal and cost-performance limitations, commercial scale

solar designs typically include solar elements that address

multiple aspects of the energy requirement (lighting, cooling,

heating) and, therefore, must be integrated with the

applicable mechanical/electrical systems and controlled

accordingly.

Traditionally, architects and engineers have focused more on

the net heating, cooling, and lighting loads which are met by

the mechanical and lighting equipment rather than on the

energy input to the equipment to meet these loads. Consequently, decisions are made which have a substantial effect on reducing the net load , but may be of relatively little importance in terms of energy consumption or energy cost . Designers

need to understand the choice which must sometimes be made

between saving units of energy (such as BTU's or kwh's) and

saving the cost of that energy (dollars).

The largely intuitive approach which many designers have

developed to address residential energy problems with passive

strategies is of little use in the design of most commercial

(nonresidential) buildings — in fact, it may be quite misleading. Many experienced designers have erred by assuming that

heating oriented passive strategies were appropriate for

2-6
buildings with low surface/volume ratios, substantial internal

heat generated by people and lights, and "business day" occupancy patterns. This mistaken assumption leads to overly

complex strategies, which deliver heat to the building at the

wrong time of day, and which may actually increase building

operating costs compared to a nonsolar alternative.

Analysis of a reference building can often assist the designer

in determining appropriate passive strategies for commercial

buildings. In this analysis, energy loads and their costs in

a conventional, nonsolar building of identical size, use,

patterns of use, and site as the building to be designed, are generally determined. The result of this analysis is the

identification of typical energy loads and loading schedules

for heating, cooling, lighting, and hot water purposes in a building of the use type under consideration. Such information

gives the designer a framework of energy use to which an effective passive solar strategy can then be addressed.

Although the criteria in this section are separated according

to individual energy end uses, it should be recognized that the

typical commercial building application will make use of solar

energy to serve combinations of these end-uses.

2.2.1

Criterion Space heating energy . Solar energy space heating systems shall

• reduce the total depletable energy requirement for heating when

compared to a reference building of similar size and use, established by an owner, designer or other applicable authority,

without significantly increasing other energy requirements.

Evaluation Review drawings, specifications, and design calculations.

Analysis tools available range from hand calculation

techniques, References [7] and [8] to computer analysis programs for hand-held calculators References [9, 10, 11] and

mainframe computers References [12, 13, 14, 15, 16, 17, 18,

73]. Reference [19] is a brief survey of passive solar

building design computer programs.

Calculations shall take into account the size of the mass,

thermal conductivity, absorptance, 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.

Movable insulation may be considered to operate as designed,

whether it is manually or automatically operated. Interior

space temperature may vary according to occupancy schedules

2-7
or nighttime setback, and should be accurately reflected in the

calculation.

Active space heating systems are usually composed of components

which are isolated from the habitable spaces in the building

and which interface with the conventional mechanical equipment

with automatic controls.

In passive systems, care should be taken to design the solar

elements, including thermal storage and controls, to deliver

heat to the occupied spaces at the appropriate time. In com- mercial buildings with high occupancy levels and artificial

lighting/equipment use, the internal heat may cause a cooling

load on a typical winter day.

Additional thermal mass for thermal storage is not necessarily

required for all passive solar heating systems, but the need

for additional mass depends on the size of the aperture relative to the size of the heated space. Storage is not needed

if solar gains can be utilized directly without causing the

interior design temperature to exceed the specified range.

Thermal mass not only affects heating effectiveness, but can also have a pronounced effect on space temperature fluctuations by storing excess thermal energy (either from solar

gains or internal gains) until needed or exhausted.

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 conditioned space

very inefficient and direct thermal coupling of storage space

is preferred. Remote thermal mass charged by air may be effective for attached sun spaces but are not advisable for direct

gain systems because of the moderate temperatures of any

available heat.

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 considered in determining the thickness of passive storage

mass. Thermal properties for commonly used storage materials

are given in Table B,5 of the Appendix to this document as well

as in Reference [20],

In direct gain designs that have a fixed quantity of thermal

storage mass, distributing the mass over as large an area as possible will maximize performance and will minimize the thickness of the mass layer. Mass within 4 in, of the surface is

2-8
more effective than mass at a greater depth because it is more

directly coupled with the conditioned space. Floor 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.

2.2.2

Criterion Space cooling energy . Solar energy space cooling systems shall

reduce the total depletable energy requirement for cooling when

compared to a reference building of similar size and use,

established by the owner, designer or other applicable

authority, without significantly increasing other energy

requirements.

Evaluation Review drawings, specifications, and design calculations.

Analysis tools available range from hand-calculation techniques.

References [7] and [8] to computer analysis programs for handheld calculators. References [9, 10, 11] and mainframe com- puters. References [12, 13, 14, 15, 16, 17, 18, 73]. Reference

[19] is a brief survey of passive solar building design

computer programs.

Commentary Active and/or passive space cooling systems are usually

designed to serve more than one building requirement, except in some buildings which are used only seasonally. Refer to

Criteria 2.2.1 and 2.2.3 for additional considerations.

Passive cooling systems in commercial buildings are usually

defined to include : natural or fan assisted ventilation

(including economizer cycles); shading and other cooling load

reduction techniques; evaporative effects; dehumidification;

radiant cooling effects; and possibly earth contact. Many of

these techniques rely on factors other than the control of dry

bulb temperature alone to produce space comfort (see Criterion

2.1.1 and related Commentary).

The opportunity to utilize thermal mass associated with a passive system for cooling is often overlooked due to

preoccupation with passive solar heating in building design.

When properly designed, thermal mass for heat storage has the

potential to provide both heating and cooling in certain

climates.

The designer should take precautions to avoid conditions under

which the solar components increase the space cooling loads.

Active solar collectors, which are a part of the building envelope or connected closely to the building, may transmit heat to

to the conditioned interior spaces during the cooling season,

particularly if allowed to stagnate. Uncontrolled fluid flow

2-9
through a heat exchange coil in the space conditioning

ductwork may increase cooling energy requirements.

In passive heating systems, components such as direct gain

glazing, mass walls (particularly those without seasonal

exterior venting) , and attached sunspaces or atriums may substantially increase cooling energy requirements, unless appropriate preventative measures are taken. Fixed or movable shading devices, deciduous vegetation, and movable insulation with

reflective exterior surfaces are some of the control measures

frequently used.

The building storage mass can act as a heat sink and

substantially decrease cooling energy requirements. Cooling

can result from daytime shading and utilizing nighttime ventilation techniques, either natural or mechanically induced.

This strategy is most effective in climates with relatively

low nighttime humidity levels and large day/night temperature

swings during the cooling season.

2.2.3

Criterion Lighting energy. Passive solar systems which are designed

primarily for daylighting shall reduce the total depletable

energy requirement for artificial lighting when compared to a reference building of similar size and use, established by an owner, designer, or other applicable authority, without significantly increasing other energy requirements.

Evaluation Review drawings, specifications, and design calculations.

Analysis tools available range from hand calculation techniques

to analysis programs for handheld calculators and mainframe

computers. References [11, 18, 73].

For analysis purposes, the daylighting aperture shall be

replaced by an opaque material having the same thermal properties as a typical wall or roof section used on the rest of the

building. It must be demonstrated that the building with the

daylighting system will use less energy than the building that

relies entirely on electric lighting. Compliance need be demonstrated only for the months of January and July, If the criterion is not met for those two months, an annual energy calculation will be necessary. Depletable energy shall be calculated as delivered to the building site. Electric lighting

energy savings due to the daylighting system shall be calculated relative to the energy required for standard lighting

levels as required by local building codes. Automatic electric

light dimming devices or manually operated devices may be

assumed to operate as designed. Chapter 9 of the lES Lighting

Handbook Reference Volume, Reference [4] gives acceptable

lighting and daylighting systems. All assumptions upon which

the analysis is based must be explicitly stated.

2-10
Conunentary In commercial buildings, lighting is often the largest energy

requirement, and, due to the characteristics of the current

energy pricing structure, frequently the largest single element

in energy cost for a building. Many commercial building designs

which use passive techniques are designed to reduce artificial

lighting by the use of daylighting. Usually these designs are also intended to reduce the energy required for space heating

and space cooling.

Studies of daylighting systems have included comparisons of

combined lighting and space conditioning energy requirements

with and without electric lighting control devices, Reference

[21]. Simply turning down the lighting level in perimeter areas will save electric lighting energy equal to many times any

increase in space conditioning energy requirements. Studies

have shown that an economic payback period of several years was achieved for the cost of the automatic control devices.

Simulation of a double-domed acrylic skylight in three

locations — Boston, Pittsburgh, and San Diego — resulted in

net annual energy savings for each location, both with and

without building mechanical space cooling. Reference [22].

Experimental studies at the National Bureau of Standards,

Reference [23], have indicated that the use of daylighting can reduce the combined space conditioning and light energy

requirements when proper window management is used,

A general discussion of daylighting system design is given

in Reference [2A]. Lighting of perimeter zones with windows,

intermediate zones with lenses and reflectors, and deep zones with tracking reflectors, concentrators, and light conduits,

are discussed. The lES Lighting Handbook, Reference Volume,

Reference [4], includes a chapter on daylighting, and the

corresponding Applications Volume, Reference [5] , includes a chapter on energy management of lighting systems.

2. 2.

A

Criteria Service water heating energy. The combined solar and auxiliary

service hot water system shall be capable of providing service

hot water at the required temperature and delivery rate. The

system shall reduce the requirement for conventional energy.

Evaluation The temperature and recovery rate shall be compared to

values given in ASHRAE Systems Handbook, Chapter 37, Service

Hot Water, Reference [6] , for the appropriate building category

and specific use. Combinations of hot water storage and

recovery rate may be specified as provided by ASHRAE.

Commentary Service hot water systems may be of the passive or active type.

Thermosiphon collection loop systems are considered to be of

2-11
the active type, because of the existence of mechanical components such as solar collectors, pipes, and heat exchangers.

Active systems are often categorized by type of solar collection loop. For example, there are pumped or thermosiphon

systems, and direct or indirect systems, depending on whether

the potable water circulates through the collectors. Indirect

systems usually employ an antifreeze solution as a collection

fluid and one or more heat exchangers in the collection loop.

On the load side, recirculation systems continuously circulate

hot water to the use points so that hot water is available at

all times at each use point. If the solar service 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 service hot water function is met.

2.3

Requirement System design capacity . The solar energy systems, in combination

with conventional HVAC and lighting systems utilizing conventional energy sources, shall be capable of maintaining space

comfort conditions, lighting conditions, and service hot water

at the levels required for the normal intended use of the

building. The inclusion of solar energy systems shall not

increase the demand rate (the instantaneous requirement for

energy) of conventional energy sources above that caused by

similar buildings not using solar energy.

Commentary Electrical demand, or the instantaneous requirement for

electricity which a building places on a utility, is a factor

which must be considered in any design, but particularly in

solar commercial buildings. It is important to the owner to

know the magnitude of both consumption (kilowatt hours per

month) and peak demand (maximum rate of usage in kilowatts).

Frequently, demand charges are the major portion of an electrical service bill.

Passive systems installed in commercial buildings can have a more significant effect on electrical peak demand than other

types of solar buildings because of the direct integration of

the solar elements and the type of energy requirements which

solar can displace. For example, daylighting is frequently

used as a passive technique in commercial buildings, displacing

some of the electrical demand for lighting. Daylight also has

a higher luminous efficacy than most artificial lights (greater

lumens per watt) resulting in a diminished cooling load. If

the building is operated properly, the use of daylighting will

reduce electrical demand by (1) lessening the requirement for

electricity for artificial lighting and (2) reducing the cooling load which must be met by the mechanical system. If,

however, the artificial lights are not dimmed or switched off

when sufficient daylight is available, the electrical demand

will probably increase since the mechanical system must meet

2-12
the combined cooling load imposed by the

and the solar gain through the glazing.

artificial lighting

2.3.1

Criterion

Evaluation

Commentary

Heating system design capacity . The solar energy heating

system, including the auxiliary, shall have the capacity of

maintaining, in conditioned spaces, the minimum interior design

temperature specified under Criterion 2.1.1 at the 97-1/2

percent winter outdoor design conditions.

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, References [25] or [20],

Chapter 21, Infiltration and Ventilation, Chapter 22, Design

Heat Transmission Coefficients, Chapter 23, Weather Data and

Design Considerations, and Chapter 24, Heating Load, shall be

used. For heat loss calculations, exterior thermal storage

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 must be documented by the designer.) For discussion of typical storage capability and sizing procedures see Reference [26]. At design load conditions, all movable passive

solar components shall be considered to operate as designed.

Reference [26] provides acceptable methods of design of

conventional space heating systems that are also useful

for solar energy systems.

The intent of this criterion is to insure that the heating

system is sized properly to meet winter design conditions.

It is not intended that control of interior conditions to

meet the specified interior design conditions be accomplished

at all times.

The system performance on the basis of annual depletable energy

use is covered under Requirement 2.9, System performance .

The relationship between the size of the solar energy heating

system and the auxiliary heating system is not covered here.

No minimum solar contribution to the heating load is required.

Solar contribution is covered indirectly under Requirement

2.9, but the issue of the size of the solar system relative

to the load is an economic one, and, therefore, outside the

scope of the Performance Criteria. The only concern here is

that the combined solar and auxiliary heating system can meet

design conditions.

2-13
Chapter XII of Reference [27] provides a comprehensive

description of considerations in the design of solar space

heating systems. References [28] and [29] describe some problems encountered in heating system design in the National

Solar Demonstration Program.

2.3.2

Criterion Cooling system design capacity . The solar energy cooling

system, including the auxiliary, shall be capable of limiting

the temperature and relative humidity in conditioned spaces to

the maximum specified under Criterion 2.1.1 at design cooling

conditions.

Evaluation Design cooling conditions shall include the 2-1/2 percent

summer outdoor design conditions, (Chapter 23 of Reference

[20]), maximum solar heat gain, maximum design occupancy,

internal heat generation, heat gain due to passive solar heating

systems, and all sensible and latent load due to active solar

energy equipment. A building cooling load calculation procedure comparable in detail to the method outlined in Reference

[20], Chapters 21, 22, 23, and 25 or Reference [25] shall be

used. The design load may be modified due to the operation of

passive components such as shading devices or movable insulation and due to thermal storage within the building mass if

justified by statistical analysis of weather patterns. For

small single-zone buildings, the design load may be calculated

using the simplified procedure described in Reference [20],

Chapter 25.

Commentary The space cooling system must maintain comfort conditions

when passive solar components for space heating and/or mechanical components for water heating are operated as designed.

Reference [6] , Section I, provides recommended design criteria

for conventional space cooling systems that are also useful for

solar space cooling applications. Chapter XIII of Reference

[27] provides a description of several methods that directly

utilize solar energy for space cooling. Reference [28] describes

some generic system problems encountered with space cooling

system designs from the National Solar Demonstration Program

and References [30] and [31] provide a summary of measured

thermal performance of several of the instrumented space

cooling systems. References [32] and [33] describe applications

of cooling systems for commercial buildings.

Air conditioning equipment utilizing conventional energy,

ambient air, ground sink, or stored thermal energy may be used

in conjunction with the solar system in an assist or axixiliary

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

2-14
distribute the converted thermal energy In a controllable

manner

.

2.3.3

Criterion Lighting system design capacity . The combined natural and

artificial lighting systems shall be capable of providing the

required lighting conditions for performance of the tasks for

which the building is designed.

Evaluation Design lighting conditions shall be selected based on the

illuminance selection procedure (Appendix A of Reference [4])

developed by the lES. Using this quantity of light, the

lighting system can be designed using the average luminance

(or zonal cavity) calculation procedure (Chapter 9 of Reference

[4]). Actual coefficient of utilization tables for proposed

equipment used in this calculation procedure should be generated by an independent testing laboratory to ensure accurate

and uniform data.

The artificial lighting system can be reduced to evening use requirement levels if daylighting will provide the supplemental lighting required during daylight hours. Daylighting

levels should be determined for the worst case condition (i.e.,

8 a.m. in December) and the occupants must realize the reduced

lighting levels will occur during evening hours or worst-case

"^ conditions.

Task lighting systems shall be sized to provide the quantity of

light described above; however, calculations should be done

using the point calculation methods (Chapter 9 of Reference

[4]). This lighting system should include both task lights

and a general lighting system which provides a minimum task to

surround luminance ratio 3:1.

Commentary Historically, lighting systems have been designed using

rules-of-thumb and intuition which are based on constant

worst-case conditions. This design procedure has caused many

spaces to be overlit and/or underlit. The average luminance

calculation procedure has been selected because it relates

room conditions, light level, and actual fixture efficiency to

arrive at the proper quantity of fixtures and/or lamps

required. (The actual fixture efficiency is very important

with today's new higher efficiency fixtures.) The lighting

system should be sized for a maintained level of light (i.e.,

including maintenance factors). Designers and owners should

realize the benefits of improved maintenance procedures. Group

lamp replacement, annual fixture cleaning, and higher quality

equipment can reduce the required number of fixtures and,

therefore, reduce depletable energy consumption.

2-15
This procedure does not account for the quality of the lighting

system which can have a large effect on energy consumption.

Lighting quality can be described by Equivalent Sphere Illumination (ESI) and/or Visual Comfort Probability (VCP). A system

(which includes both equipment and layout) with a higher ESI

and VCP may actually require less footcandles to give the same user comfort and efficiency. This higher quality system may

reduce depletable energy consumption while maintaining

habitability of the space.

Many analysis tools are available to determine daylighting

levels in a space; however, the most accurate and most

informative still remains the three dimensional, built to scale

model. New weather data are being made available to determine

the worst-case condition described above.

No matter how efficient the final lighting system is,

additional energy can be saved through the use of manual and

automatic controls. Separately switched lights can allow

unneeded lights to be kept off. Photocell controls can dim or switch-off lights when daylighting is adequate. Motion detector switches can be useful in seldom used spaces such as conference rooms and private offices. Energy management systems

can be used to turn off lights during unoccupied hours, or adjust the levels for cleaning and maintenance operations.

Care should be taken in selecting the appropriate control for

each lighting system.

Energy saving lamps and ballasts are another way to reduce

energy consumption. New high efficiency lamps can give the same quantity of lumens for less watts; however, designers

should be aware of possible problems such as color rendition,

lamp life, and compatibility with ballasts and switching/ dimming

controls.

2.3.4

Criterion Water heating system design capacity . The combined solar and

auxiliary water heating system shall be capable of providing

the design hot water temperature and recovery rate specified

under Criterion 2.1.3.

Evaluation Documentation shall be provided to show that the temperature

and recovery rate (or combined recovery rate and storage capacity) of the auxiliary water heating system are capable of

meeting the design load. Average cold water supply temperature

for the month having the lowest water temperature shall be

stated and used for calculation of design load. If the

auxiliary water heating system is not sized to meet the design

load alone, it must be shown that the combined solar and

auxiliary water heating system can meet the design load at all

times. In this case, the solar heat collection and storage

2-16
system must be able to maintain a sufficient quantity of water

at an elevated temperature (relative to that of the cold water

supply)at times of design hot water usage so that the auxiliary

system can meet the reduced load.

Commentary In most systems the auxiliary system is sized to meet 100

percent of the design load. There may be applications, however,

for which it is more efficient to allow a reduced-size auxiliary system. Storage of a large volume of solar-heated water

and an elevated temperature during cloudy periods can result in

high heat losses (see Criterion 2,5.1, Thermal energy loss and

Criterion 2.8,2, Storage size).

Chapter 37 of the ASHRAE Systems Handbook, Reference [6]

provides design guidance for design of water heating systems

for a variety of applications.

2.4*

Requirement Collector array . The solar collector array shall be capable of

of absorbing solar radiation and converting it to useful

thermal energy for providing the functions of space heating,

space cooling, and/or service water heating under expected

operating conditions.

Commentary The collector array normally consists of several individual

collector units connected by a manifold and positioned to

receive maximum or near maximum solar radiation. The total

collector array must be properly designed to assure effective

energy transfer to the other parts of the active solar energy

system, the storage or point of use.

2.4.1

Criterion Collector orientation . The collector array shall be positioned

to provide the maximum usable collected solar energy on an annual or seasonal basis depending upon the type of system. If

special circumstances require a different orientation, the

resulting reduced performance shall be determined and stated

in the design documentation.

Evaluation Solar radiation for the geographic location, orientation of the

collector array type (stationary or tracking), shading

(external shading and self-shading by other collectors in the

* Note ; Requirements 2.4 through 2.8 address active solar energy system

components and their integration, assuming conventional active system design.

Innovative or nonconventional active system components and subsystems do not

have to meet specific criteria under these requirements if they are not

applicable. However, it must be shown that innovative active components or subsystems do meet the intent of these requirements.

2-17
array) , and building shape and orientation shall be considered

in determining the optirautn collector orientation. The system

type (space heating and/or cooling and/or water heating) and

daily profile of energy use shall also be examined. Collector

orientation factors are given for converting radiation on a horizontal surface in Chapter 3 of Reference [34].

Commentary Situations in which collectors are placed on existing buildings

may result in deviation from thermally optimum orientation.

Typically, annual or seasonal incident solar radiation should

not be less than 80 percent of the radiation for the same period that would be received at the optimum orientation. In

general, stationary 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 com- bined space and water heating. Single-axis tracking collectors

may be oriented north-south or east-west, depending on site and

and system requirements.

High-rise buildings with small roof areas or unfavorable

building orientation may require special architectural

integration and preclude thermally-optimum orientation of

collectors, yet the solar systems may be technically and

economically appropriate.

Tilt deviations of +15 degrees from the above values and

azimuth deviations of 20 degrees east and 30 degrees west of

true south will not likely decrease performance by more than

10 percent. Local conditions such as shading or fog, or the

particular advantage of emphasizing morning or afternoon gain

should be considered. It is often desirable to orient the

collectors toward the east of due south when the collected

solar energy can be used during the daytime.

2.4.2

Criterion Individual collector performance . The thermal efficiency of

the individual collectors as installed in the array shall not

differ significantly, relative to single-collector tests, due

to flow rate or fluid properties over the design operating

range

.

Evaluation Procedures equivalent in accuracy to ASHRAE Standard 93-77,

Reference [35] , shall be used to determine the efficiency curve

of the single-collector test. Post-stagnation test as given in

Section 10 of Appendix A (modification of test in NBSIR

78-1305A, Reference [36]), is required.

2-18
Three primary factors must be taken into consideration when

calculating array performance relative to the single-collector

test. First, the average flow rate through the array may differ

from the test flow rate. Second, the flow rate through the

lowest-flow collector in the array may be less than the average

flow rate due to imbalance of flow among the collectors. Third,

the heat transfer properties of the actual collection fluid may

differ from the properties of the fluid used in the

single-collector test. Each of these three factors shall be

evaluated.

Determination of the flow rate through the lowest-flow

collector in the array is difficult, and there are no readily-available, simple methods for doing this. Some collector manufacturers have empirical data for flow rate through

each collector in certain array configurations. Some engineering firms and collector manufacturers have computer programs

for performing the iterative calculations necessary to determine the flow rates through all collectors in the array, but

agreement with measured data is not always good. The viscosity

of some fluids changes with temperature in the collector operating range, and the transition between laminar and turbulent

flow cannot easily be predicted for many situations.

Reference [6], pages 236-244 and 266-268, may be used to

'^ determine loss in efficiency due to flow rate and fluid

property changes. Reference [37] gives the effect of flow rate

on a typical air-type collector and also gives typical collector efficiency curves. A revised collector efficiency curve

for an average-flow-rate collector and one for the lowestflow-rate collector in the array shall be constructed.

Any significant decrease in performance in the design operating

range shall be justified on the basis of rational system design

trade-offs. Such trade-offs may include the following conditions : Use of a liquid with a lower specific heat than water

may be necessary for freeze protection or for corrosion prevention. Lower average flow rate may result in significant

reduction in operating power for fluid circulation (see

Criterion 2.6.2). Variable-flow collection systems may be very

energy efficient, although the flow rate may not equal that

used for the single panel test at all times.

Commentary The performance of the average-flow-rate panel as installed

in the array will be required as an input to the system performance calculation under Requirement 2.9.

The middle collectors in parallel arrays tend to have reduced

flow and therefore run hot. To alleviate this, a high ratio of

pressure drop across any collector to the pressure drop across

the manifold is required. The minimum flow through a collector

2-19
is important, but it is not necessary to have equal flow to all

collectors in the array. In large arrays, acceptable flow

variations may be as great as 3 to 1 in individual collectors,

while maintaining the required minimum flow in the lowest-flow

collector. Reverse return arrangement of manifolds helps to

balance the flow to individual collectors. Too many collectors

in series tend to increase the inlet temperature of the last

collectors and should be avoided. Experimental studies,

Reference [38] 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. Experience in the

National Solar Demonstration Program has shown cases of

extremely low flow rates in central collectors in parallel

arrays, resulting in hot conditions that caused permanent

damage to the collectors.

In the case of site-built collectors for which no test data

are available, the flow rate at each major branch in the array

should be documented and balanced. The methods given in

Reference [39] may be used to predict the performance of the

collector array. The balance of flow to all parts of a sitebuilt array is important whether individual collectors are used

or the array is built as one unit, such as an integral part of

a building roof.

2.4.3

Criterion Manifold thermal loss . Under typical conditions during the

coldest month of system operation, the rate of thermal loss from

pipes or ducts within the collector array shall not exceed 10

and 15 percent of the solar energy collection rate for liquid

and air systems, respectively.

Evaluation This is an instantaneous calculation. Both the rate of thermal

loss and the solar energy collection rate must be calculated

for the following conditions :

1. Time of year: coldest month of system operation, usually

January in most of the continental United States.

2. Solar irradiance : 70 percent of the clear sky value at noon for the coldest month.

3. Anbient temperature : normal high for the month as given

in the U. S, Climatic Atlas,

4. Collector fluid inlet temperature: minimum usable

storage temperature or use temperature.

Additional information to be provided by the designer includes

the collector efficiency curve, the air leakage rate (for air

systems), and insulation thickness and conductivity. The solar

2-20
energy collection rate can be calculated as the product of the

solar irradiance on the collector surface, the collector area,

and the instantaneous collector efficiency (at the given fluid

inlet temperature, ambient air temperature and collector orientation) . The collector efficiency curve shall be based on flow

rates and fluid properties as discussed under Criterion 2.4.2,

Individual collector performance . Thermal loss from the manifolds shall be calculated using standard procedures such as given by ASHRAE, Reference [20].

Commentary The collector array includes all collector panels and

associated piping or ducts to the point where there is only

one inlet and outlet. Thermal 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 manifold thermal 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). Maintaining a slightly subatmospheric

pressure in the collector array, resulting in air leakage into

,^ the array, causes less decrease in thermal performance than

leakage out of the array. Reference [40]. Reference [41]

provides a simple analytical technique for analyzing the

thermal effects of collector air leakage. A similar procedure

for analyzing the effect of thermal loss from collector supply

and return ducts or pipes on system performance is described in

Reference [42] . Chapter 9 of Reference [43] recommends suitable insulation type and thickness for collector array manifold

pipes and ducts. Reference [44] describes methods for determination of economically optimum insulation thickness. The

solar irradiance value of 70 percent of the noon clear sky

level represents approximately the average value over the day.

(For a sinusoidal function, the average power is equal to 0.707

times the peak amplitude. Clear-sky solar irradiance follows

approximately a sinusoidal function over the day.)

2.4.4

Criterion Thermal loss during noncollection periods . During the coldest

month of system operation, daily thermal loss from the collector array and all exterior pipes or ducts, when not in a heat

collection or rejection mode of operation, shall not exceed

10 percent of the daily collected solar energy.

Evaluation This is a cumulative energy calculation over a typical 24-hour

day during the coldest month of system operation, which is

usually January. Thermal loss from the collector panels, pipes

or ducts exterior to the building, must be included. Thermal

loss due to thermosiphoning, capacitance effects (cool down at

2-21
night), and freeze protection shall be evaluated separately and

then totaled. If the collectors are above the storage, remain

filled, and the configuration permits thermosiphoning , check,

valves or backdraft dampers must be present to prevent reverse thermosiphoning when the collectors are colder than storage.

When the collection fluid remains in the collector during operation, daily thermal loss due to capacitance effects must be

calculated. Thermal loss due to capacitance effects is equal

to the product of fluid mass in the collectors and exterior

piping or ducts, fluid heat capacity, and the difference

between the temperature of the hot fluid at the time of system

shutdown and the temperature to which it cools (normal ambient

low for the month). It can be assumed that the collection

system will shut down once a day. Thermal loss due to freeze

protection (draindown, fluid circulation, etc.) shall be calculated for an average day in the coldest month. If circulation

of liquid from storage is used as the freeze protection method,

thermal loss from collector and exterior piping shall be calculated for the length of time liquid is circulated. Reasonable values shall be assumed for ambient temperature, storage

temperature, insulation of pipes or ducts, and the thermal loss

factor of the collectors. The time of freeze control circulation shall be calculated based on control strategy, length of

day, percent possible sunshine, and statistical ambient temperature data. Reference [45] gives mean number of days having

minimum temperature of 32° F (O^C) and below for the month of

January for various locations. Energy loss due to other

methods of freeze protection such as heat tapes shall be

included. Energy collected for the day shall be calculated on

the basis of average conditions of solar irradiance and ambient

temperature. Collection fluid inlet temperature shall be

assumed to be equal to the minimum usable storage temperature.

Commentary Some collector designs reduce the possibility of thermal loss

due to reverse thermosiphoning; for example, those having inlet

and outlet at the same elevation. Draining of all liquid from

collectors and exterior piping to the storage tank when energy

is not available (collector drain back system) eliminates thermal loss due to thermosiphoning, capacitance and freeze protection and is recommended for many applications. The effect of

leakage past dampers in air type systems is discussed in Reference [46]. Leakage past dampers that 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 noncollection period addressed

in this criterion does not include shutdown for servicing or repairs.

This criterion is directed toward active collector systems but

consideration must be given to losses from thermal mass

2-22
collector/storage components, such as Trombe walls. Guidelines

for such components have not yet been developed but the principles governing energy transfer during application should be

addressed in estimating actual performance of such components

during non-collection periods.

2.4.5

Criterion Thermal energy dissipation . Collectors used for thermal energy

dissipation shall be capable of dissipating thermal energy at

the required rate.

Evaluation Collector thermal loss rate may be estimated using the slope of

the ASHRAE 93-77, Reference [35], test efficiency curve, and

adjusted for the effect of the collector loop heat exhangers,

if any. The slope of the collector efficiency curve, FrUl,

multiplied by the collector area and the difference between

ambient and fluid temperatures, will give a conservative value

of the rate of thermal energy dissipation, and is satisfactory

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

energy dissipated may be calculated using more refined analyses

that consider the effective temperature of the night sky, if

thermal energy dissipation occurs at night. Compliance must be

demonstrated for the time of day and time of year that represent

the most demanding performance as specified in the design.

Commentary Collectors may be used as a thermal sink for heat pumps

operating in the cooling mode. They may also be used to cool

the system at night to dump thermal energy that is not needed.

For example, collectors in a solar heating system may be operated to collect thermal energy during summer days and reject it

at night to prevent the collectors from reaching extremely high

temperatures. See Criterion 2.6.5 for provisions covering noncollector thermal energy rejection equipment such as cooling

towers. See Criteria 3.5.3 and 4.3.2 for provisions regarding

system pressure and temperature relief controls.

Efficient solar collectors are inherently inefficient thermal

rejectors, especially designs utilizing selective coated

absorbing surfaces, multiple glazings or evacuated tubes. It can be difficult to reject at night the amount of thermal

energy collected during a typical sunny day.

2.5

Requirement Thermal storage . The thermal storage subsystem shall be

capable of efficiently accepting thermal energy, storing it,

and releasing it to partially or fully satisfy the space

heating, space cooling, and/or water heating load(s).

Commentary Refer to Section 2.8 for criteria concerning the

thermal storage and its effect on system performance.

size of

2-23
2.5.1

Criterion

Evaluation

Thermal energy loss . Thermal energy loss from thermal storage

shall not exceed 15 percent of the energy input to the storage

subsystem for any month in which the load exceeds the collected

solar energy.

Conductive thermal loss or gain through insulation, losses

through storage container structural supports, and losses due

to air leakage shall be examined and documented. Underground storage containers must be insulated. For purposes of

calculation of energy loss, the storage temperature may be

assumed to be the minimum usable storage temperature.

Commentary

For other than service hot water storage only and when such

thermal loss does not have an 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 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 insulation requirements.

Typical measured values in the demonstration program show

thermal loss as low as five percent of the energy input to

storage during the heating season for liquid collection and

storage systems. Reference [26], page 19, gives a simple calculation procedure for determining the required insulation

to limit thermal loss to two percent in 12 hours.

It may be justifiable to keep thermal losses from storage well

below the levels specified by this criterion, so that the

adverse effect on the cooling load during summertime operation

will be kept small.

The high temperature of active cooling system hot storage

places extra emphasis on thermal energy loss. Delivery of

solar energy directly to the chiller, bypassing storage,

reduces storage losses and delivers higher temperatures. For

cooling systems that provide a small fraction of the cooling

load with solar energy, it is possible to design the system

without large hot water storage tanks, using only a small buffer tank to prevent frequent cycling of the absorption chiller.

For applications dominated by cooling loads, hot storage should

be outside of the conditioned space. Experience in the National

Solar Demonstration Program, Reference [31], shows that cold

storage energy gains offset savings accrued by means of off-peak

electric chiller operation.

2-24
Thermal energy transferred from space heating and hot water

systems to the conditioned space during the summer months must

be accounted for in the calculation of design cooling load for

the mechanical cooling system (see Criterion 2.3.2, Cooling

system design capacity).

2.5.2

Criterion

Evaluation

Thermal stratification . Means to promote thermal stratification

in the hot thermal storage subsystem shall be used to increase

overall system efficiency whenever practical.

The shape, number, and arrangement of the storage container(s)

shall be examined. The location of inlets and outlets and

the velocity of heat transfer fluids into and out of the con- tainer shall be designated on the drawings. The direction of

fluid flow, especially through rock bins for air systems, shall

be noted in the documentation for each mode of system operation. Baffles in tanks and the location of auxiliary heat

input to the storage container shall be examined.

Commentary 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. Con-

^ sideration should be given to trade-offs between stratification and thermal losses from a second tank in the case

of solar water heaters. F-CHART, Reference [34], assumes fully

mixed storage; however, improved thermal performance may be

achieved in practice with stratified storage.

It has been shown that the thermal performance of a well-insulated tank in the demonstration program could be

greatly improved by eliminating short-circuiting from inlet

to outlet by means of baffles.

In single-tank HW systems, the auxiliary heating unit 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 [47] describes the effect of stratification by use

of mathematical models.

Gas-fired water heaters are becoming available with the heater

placed midway up the tank to allow thermal stratification for use with small solar energy systems.

In existing buildings, it may not be practical to make full use of thermal stratification due to physical space restrictions. For example, a horizontal tank may be more practical

than a vertical one.

2-25
It is good practice for air system rock beds to have the

vertical dimension as large as practical, and supply hot air to

the top as well as draw hot air from the top for heating purposes. When vertical construction is not possible, horizontal

rock beds can be stratified horizontally with proper flow

directions of hot and cooler air.

The dependence of collector array efficiency on thermal

stratification and hence, inlet temperatures to the collector

array has been indicated by a statistical analysis of storage

temperatures and corresponding collector array efficiencies.

Average storage temperatures in space heating systems with

better than average collector array efficiency was 102° F,

whereas systems with worse than average collector array efficiency had storage temperatures averaging 112°F, Reference [48].

2.5.3

Criterion Auxiliary energy to thermal storage . Auxiliary

to the solar energy storage container shall not

reduce system performance.

energy added

significantly

Evaluation If auxiliary energy is added to the thermal storage container,

it must be shown that any reduction in collector performance

will be offset by reduced thermal energy loss due to fewer numbers of storage containers, less surface area for energy loss,

or the ability of the collectors to provide thermal energy to

reduce standby losses that would otherwise have been made up

using auxiliary energy. Stratification must be maintained in

the storage container to prevent auxiliary/heated fluid from

being transferred directly to the collector inlet.

Commentary The addition of auxiliary energy to thermal storage containers

can severely decrease collection efficiency by increasing

collector inlet temperature.

It is advisable to keep the solar and auxiliary systems

separate, and in parallel, if possible. Auxiliary energy may

be added to thermal storage if thermal stratification is

preserved.

See Criterion 2.5.2 for discussion of stratification.

2.6

Requirement Energy transport . The energy transport system shall be capable

of efficient transfer of thermal energy among the various

components and subsystem.s.

Commentary The energy transport system typically consists of insulated

pipes or ducts, pumps or blowers, heat exchangers, and a working fluid such as water or air.

2-26
Efficient energy transfer requires low thermal losses (or

gains), low operating power to move fluids, and proper sizing

of heat exchangers.

2.6.1

Criterion

Evaluation

Thermal energy loss . During normal operation, the rate of

thermal energy loss from any energy transport subsystem shall

not exceed 15 percent of the rate of energy input to that

subsystem.

The energy loss from the energy transport subsystem shall be

calculated and documented to be less than or equal to the

allowable limit established in the above criterion. Energy

input to the collector-storage loop, for example, can be calculated by multiplying the temperature difference between the

inlet and outlet to the beat exchanger on the storage side by

the mass flow rate and specific heat of the fluid. Fluid

temperature shall be assumed to be the highest (lowest for cold

fluids) that would occur during normal operating conditions.

Ambient temperature to which thermal energy is lost shall be

assumed to be average room temperature if in a conditioned

space, average expected temperature if in a semiconditioned

space, and average monthly outdoor temperature for the coldest

month if outside. This is an instantaneous calculation similar

to Criterion 2.4.3, not a cumulative energy calculation as for

Criterion 2.4.4.

For other than service hot water systems and when such thermal

loss does not have adverse effects 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.

Commentary It has been found in air systems that there may be

approximately a one-to-one correspondence between the percent

of air leakage and the loss of thermal efficiency of the system, based on computer modeling of a typical residential aircollection heating system. Reference [40]. In other words, a

10 percent rate of air leakage could increase the energy use of

the solar energy system by about 10 percent relative to a zero- leakage system. This may apply to small commercial buildings

with similar solar energy system designs.

This criterion does not apply to the air distribution system — within the conditioned space (see Reference [49], Sections

5.10 and 5.11 for pipe and duct insulation guidelines).

Typically, thermal 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

2-27
losses for systems in the Federal Demonstration Program are as low as 3 percent of the collected solar energy. Reference

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

thermal performance of solar energy systems. Chapter 9 of

Reference [43] indicates insulation thickness for pipes and

and ducts for residential applications, which may be applicable

to commercial buildings.

There is concern that thermal loss from the energy transport

system, especially by means of 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 upon the system to meet the cooling load during

any summertime operation should be acceptably low.

2.6.2

Criterion Operating power . During normal operation, operating power for

circulating the solar collector heat transfer fluid shall not

exceed 10 percent of the rate of solar energy collected.

Evaluation Steady state heat transfer calculations are required to document that the operating power limit is not exceeded. This is an instantaneous calculation (as in Criteria 2. A. 3 and 2.6.1),

not a cumulative energy calculation (as in Criteria 2.4.4 and

2.5.1). Power is energy per unit time. Pump or blower electric input power is a function of the volumetric fluid flow

rate, the differential pressure across the pump or blower, the

pump or blower efficiency, and the electric motor efficiency.

Typical pump or blower efficiencies are about 50 to 70 percent,

and motor efficiencies are from 80 to 95 percent. Alternatively, the pump or blower manufacturer's power curve can be

consulted at the proper flow rate and differental pressure.

For example, to evaluate operating power for the solar collector

subsystem, the rate of collection of solar energy is calculated

based on the following conditions:

1. Time of year: coldest month of normal system operation,

usually January.

2. Solar irradiance: 70 percent of clear-sky irradiance at

solar noon.

3. Ambient outdoor temperature: normal daily high for the

month.

4. Collector inlet temperature: minimum usable storage or use temperature.

2-28
Additional information to be provided by the designer includes

the collector efficiency curve, the air leakage rate (for air

systems), and insulation thickness and conductivity. The solar

energy collection rate can be calculated as the product of the

solar irradiance on the collector surface, the collector area,

and the collector efficiency (at the given fluid inlet temperature and ambient air temperature). The collector efficiency

curve shall be based on actual flow rates and fluid properties

as discussed under Criterion 2.4.2, Individual collector performance. The rate of solar energy collection is a power quantity.

Commentary Under normal operating conditions, operating power should not

exceed 5 percent of the rate of energy collection for liquid

systems or 10 percent for air systems. Reference [51] includes

values for operating power in thermal performance analysis of

selected projects in the National Solar Demonstration Program.

The use of thermosiphon loops can be very effective in

reducing operating power where feasible.

Typically near the end of the day, just prior to collection

system shutdown, there may be a very small temperature differential between collector array inlet and outlet, and the rate

of collection of solar energy may be only slightly greater than

the collection loop operating power. This is in accordance

with proper design practice, and is not intended to be prevented by this criterion. This criterion only applies to the

specific conditions specified under the evaluation above.

2.6.3

Criterion Collector loop energy transfer . If a heat exchanger is used

in the solar collection loop, the energy transfer surface area

shall be compatible with the energy to be collected and allow

the collectors to operate in an effective manner.

Evaluation The heat exchanger effectiveness shall be reviewed under

average operating conditions and peak design conditions. Factors such as the heat transfer fluid flow rate, fluid

properties, average and peak solar irradiance on the collection

surface, collector area, collector efficiency curve, and storage or use temperature shall be considered as these variables

influence overall performance, Reference [52]. For thermosiphon

or drain-down systems, fluid flow rates shall be estimated

considering the piping size, height of storage above the collectors, and the collector hydraulic characteristics.

Commentary Reduced collector loop energy transfer rate will result in high

collector temperature, and hence reduced collection efficiency.

The approach temperature difference for the heat exchanger

should be as low as practical, 5°F-15°F (3°C-8°C), as recommended in Reference [53]

.

2-29
The presence of a heat exchanger between storage or load and

the collectors effectively increases the temperature of the

fluid entering the collectors, and therefore reduces collection

efficiency. The effect can be particularly significant in the case of air-to-liquid heat exchangers. Air-type collectors

should only be used when air can be supplied to the load or storage, as for space heating systems. Preheating of make-up

air directly is a very efficient strategy because no heat

exchanger is required.

2.6.4

Criterion Energy transfer to 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 for

transfer of energy at a rate to satisfy the design load.

Evaluation Heat transfer surface area, fluid flow rates, and design load

shall be reviewed. Design loads as determined under Criteria

2.3.1, 2.3.2, and 2.3.4 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 readily available from manufacturers on heat

exchanger performance parameters. Typically, the temperature

ranges will be somewhat lower for solar applications and

should be reflected in the calculations and documentation.

2.6.5

Criterion Thermal energy rejection . Thermal energy rejection equipment

shall be capable of rejecting thermal energy at the required

rate.

Evaluation Compliance must be demonstrated for the time of day and time

of year that represents the most demanding thermal energy

rejection requirement as specified in the design of the system.

It shall be shown that under these conditions the equipment

will operate within the range specified by the manufacturer.

Commentary This criterion covers non-collector thermal energy rejection

equipment such as cooling towers. See Criterion 2.4.5 for

provisions regarding the use of solar collectors as thermal

energy rejectors. Thermal energy rejection equipment may be

located within the collector array or external to it. One of

the main purposes of this type of equipment in solar energy

systems is to protect the solar collectors from overheating

when they are not designed to stagnate. When storage is at its

2-30
maximum allowable temperature, any thermal energy collected

must be able to be rejected by the thermal energy rejection

equipment. Therefore, this equipment should be capable of

dissipating thermal energy at the maximum solar energy collection rate, and for the maximum allowable temperature conditions

(storage, collectors, or specific equipment limitations).

2.7

Requirement Controls . The control subsystem shall be capable of proper

and efficient regulation of other components of the system to

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

system requirements.

Commentary Simpler control subsystems have been found to be as efficient

as complicated ones and are often less prone to malfunctions.

Extensive coverage of control system design is presented in

Reference [54]. For commercial buildings with cooling capability the complexity of the control system will generally

increase.

2.7.1

Criterion Sensor location . Control sensors shall be located and

installed so that they will accurately measure the desired

variable for correct system operation.

Evaluation Examine the placement of sensors and their installation

details. The presence or absence of flow past the sensor

location should be checked and noted. Check for backflow or thermosiphon effects during non-operation periods and determine

the 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.

Thermosiphon or backflow in an idle loop can cause sensors to

give erroneous indications of system operating conditions.

Proper placement or insulation from external conditions, or the use of check valves or backdraft dampers will reduce sensor susceptibility to the influence or detrimental, extraneous or uncontrolled heat flows. Reference [55] discusses the implications of sensor location on system performance.

2.7.2

Criterion Collector circulation set points . Collection loop set points

shall be selected so that the collection fluid will only circulate when the rate of collection of solar energy exceeds the

operating power required for fluid transport thermal energy,

except when circulation is reruired for freeze protection or thermal energy dissipation.

2-31
Evaluation Since normally the turn-on set point is greater than the

turn-off set point for a typical differential controller, it is

important to check the turn-off set point of the controller to ensure that the temperature differential allows a solar energy

collection rate at least equal to the pump or blower power. See

Criterion 2.6.2 for procedures for calculation of pump or blower power. For variable-flow systems, the pump or blower

power requirement at the time of collection loop shutdown shall

be computed. The rate of solar energy collection at the time of

system shut-down can be calculated by multiplying the turn-off

set point temperature differential by the collection fluid mass flow rate and heat capacity.

Commentary Collector pump or blower cycling can be reduced by proper

deadband in on/off controllers or use of time delays. Studies,

References [54, 56], have shown that proportional controllers

are not substantially more effective than on/off controllers.

Typical set points for a liquid collection system are 10°

F

(6°C) between storage and collector temperature for start-up

and 3°F (2°C) for shut-down. Higher temperature differentials

should be used for air collector systems. References [54]

and [56] provide useful information for the determination of

set points.

2.7.3

Criterion Leakage past valves and dampers . Leakage past control valves

and dampers shall not significantly degrade the thermal

performance of the system.

Evaluation Control logic, operation of control dampers and valves, and

potential flow paths and temperature of leaking fluids shall be

examined. Manufacturers' specifications for leakage rate of

valves and dampers shall be examined. Low- leakage dampers

shall be specified.

Commentary As described in Reference [46] , it is important that dampers in

the air collection loop close tightly. Large thermal losses

can occur because of thermosiphoning from storage to collectors at night if valves or dampers do not close tightly. This can also cause freezing of liquids in air-to-liquid and liquidto-liquid heat exchangers.

Valves that open to allow flow of thermal energy rejection

devices (such as cooling towers) must close tightly. Particular

attention should be directed toward valves that, for safety

reasons, are normally open to the thermal energy rejection

device, and are held closed during system operation by the

control circuit. Leakage past these valves can cause considerable thermal losses and decrease system performance

significantly.

2-32
See Criterion 3.3.3 for specification of allowable damper

leakage.

The effect of leakage on the temperature of the conditioned

space should be considered. Leakage past valves or dampers

must not cause the temperature in conditioned spaces to exceed

the limits specified under Requirement 2.1, Design conditions.

2.7.4

Criterion

Evaluation

Commentary

Priority of energy use . Only when sufficient solar energy is

not available to meet the load shall the control system allow

auxiliary energy to be used.

Control logic, system configuration, sensor locations and type,

and operation of thermostats shall be examined.

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. Twostage thermostats are recommended so that the auxiliary energy

system is applied after the solar energy, if the solar energy

system cannot maintain the temperature in the desired range.

In this way, the control system prioritizes 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.

This criterion is not intended to prevent the simultaneous use

of solar and auxiliary energy. The most important consideration is to conserve depletable energy resources.

2.8

Requirement Component/ system integration . All components in the system

shall be selected and integrated into the system for proper and

efficient function of the system as a whole.

2.8.1

Criterion Collector selection. The solar collector shall be selected

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

is delivered.

Evaluation Post-stagnation test data. References [35, 36] shall be

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

may utilize low-loss collectors. Low temperature applications

2-33
(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 are discussed in

Chapter 3 of Reference [39].

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 [53] gives useful information and discussion.

2.8.2

Criterion Storage size . The minimum storage size shall be that which,

when starting from a discharged state, will provide storage for

the thermal energy from the collector which exceeds operational

requirements for a clear-sky day of full system operation

during the peak-load month.

Evaluation The peak-load month shall be determined and a typical day of

operation defined. Solar energy shall be collected and the

load shall be calculated on an hourly basis throughout the

24-hour day. dear-sky conditions shall be assumed. The

collector inlet temperature may be assumed to be the average

storage temperature, and the ambient outdoor temperature may be

assumed to be equal to the normal daily high throughout the day.

The minimum size storage needed to allow storage of excess collected solar energy for the day shall be calculated as follows.

Assume the storage is fully discharged in the morning. At some

' time during the day the rate of solar energy collection may

exceed the load. (If it does not, storage may not be needed.)

Add the surplus solar energy for each hour in which the collected solar energy exceeds the load. The daily total stored

energy will be equal to the capacity of the minimum storage

2-34
size. The design storage size shall not be smaller than the

calculated size. More detailed calculations may be provided

by the designer.

Commentary Storage need not be provided (see Requirement 2.5). Storage

size affects collection efficiency, temperature stability of

the subsystem, and cycling of equipment, especially absorption

chillers. Too small storage can result in inefficient use of

solar collectors. Too large storage can result in unacceptably

high losses (see Criterion 2.5.1) or too low temperatures to

offset the load. Proper size storage depends on the magnitude

of the load and collectable solar energy, and the time relationship between the two. If all collectable solar energy can

be used immediately, for all, or most times during the year

when a load exists, storage is not required. This may be the case for cooling systems that operate seven days a week. For

systems in which the load is out of phase with the solar energy

system input, such as a space heating system, storage is almost

always required. Ifowever, if solar energy is used only to preheat outside ventilation air during occupied daytime hours,

then storage may not be needed except perhaps to reduce maximum

supply temperatures.

The minimum allowable storage should be selected on the basis

of minimum acceptable thermal performance, that is, full utilization of collectable solar energy during the month of peak

load. The intent of this criterion is not to optimize the

storage size, but to specify the smallest recommended size.

The largest reasonable storage size would be that which can store the collected solar energy for two consecutive clear-sky

days when there is no load. This may be desired, for example,

so that collectable solar energy is not wasted during a two-day

weekend when there is little or no space conditioning load for

a commercial office building or school. Results from a comparative analysis of National Solar Demonstration Program space

cooling systems indicate that cold storage does not improve

system efficiency relative to having hot storage only.

Reference [31] . However, Reference [57] includes the following

conclusions:

"Cooling storage is more important for residential

applications simply because the cooling load and solar

availability are not coexistent as they are for commercial

buildings. Of all of the storage options investigated,

cold-side latent storage appears most promising for com- mercial absorption and Rankine systems, and residential

absorption system in cooling dominated climates."

2-35
2.8.3

Criterion

Evaluation

Commentary

Fluid flow rates . The flow rates through all components in

each circuit shall be compatible and shall be within the ranges

specified by the equipment manufacturer.

Documentation shall be provided to show that the flow rates of

the design and the manufacturers ' specified range or operation

limits are compatible. Heat exchanger performance must meet

design specifications for the flow rate specified. Each fluid

flow loop or circuit shall be evaluated separately. Pumps and

fans shall be selected to operate at or near their best efficiency point. Variable-flow systems must meet this criterion

at all flow rates. Equipment configuration shall incorporate

provisions for balancing the flow to all components on the same

circuit, (fine Criterion 2.4.2 for balance of flow through

collector panels.)

Overall system efficiency can suffer due to specification of

equipment requiring different flow rates in the same loop.

Equipment sizes and arrangements (in series or parallel) should

be chosen considering compat Lbllity of flows and heat transfer

rates. Heat transfer capability of heat exchangers varies

considerably with flow rate. See Criteria 3.2.1 and 3.3.1 for

provisions regarding fluid velocities in pipes and ducts.

2.8.4

Criterion

Evaluation

Auxiliary equipment selection. Auxiliary energy equipment

shall be selected and integcai.ed into the system to minimize

the use of depletable energy on an annual basis.

The auxiliary energy source, equipment location, equipment

efficiency ratings, suitability of the equipment to the local

climatic area, and controls and operating proced.ires shall be

evaluated.

Commentary P.ir.illel solar/auxiliary heat pumps may not be efficient in

cold climates. In this arrangement, the heat puiap uses outside

air as an energy source when the solar portion of the system

cannot supply the load. Since the heat pump coefficient of

performance and capacity are reduced at low source temperatures, this arrangement is not always advantageous.

The effect of a large ruuiber of solar conditioned buildings on central power facilities could be substantial and must be con- sidered in the selection of auxiliary energy sonrc-^s, and

design of the system and controls for times of peak auxiliary

energy use. Energy sources that can be stored on-site such as oil or gas are preferred to those thcii" cannot be stored such

as electricity direct from a utility. Conversion of electricity to a storable form of energy is acceptable provided

energy losses from storage are not high.

2-36
In the case of solar-powered absorption chillers, auxiliary

electric chillers may aggravate loads on electric utilities

during peak cooling power requirements. Auxiliary energy used

to heat water for operation of the absorption chiller may

result in reduced solar collector efficiency and not provide

back up cooling in case of failure of the absorption chiller.

Careful design trade-offs must be made, such as dual storage

tanks, auxiliary energy input location, physical size of system

components, etc.

Experience gained from the National Solar Demonstration Program

indicates that loading and operating procedures are more important to overall absorption chiller performance than the

hot water inlet temperature. Frequent cycling of the chillers

should be avoided (see Criterion 2.8.2).

2.9

Requirement System performance . The total building system, including

passive and active solar components, the mechanical system,

and lighting, shall be designed to conserve depletable energy.

Commentary In addition to meeting peak load conditions and having

well-designed and properly integrated components, the solar

energy system must have adequate overall performance. The purpose of this requirement is to provide a means to describe and

verify overall system performance. This requirement applies

only to those space heating, cooling or water heating systems

that utilize solar radiation received at the building site as an energy source. The system performance indicator is

"depletable energy use." Other indicators such as solar

fraction, solar savings fraction, solar contribution, or energy

savings, should not be used. Depletable energy can be calculated equally for passive or active systems, and for standard

or innovative systems, and can be used as a basis for deciding

among various alternative building or system designs. No maximum level of depletable energy use is required. To set such a level would be beyond the scope of these criteria, since that

is primarily an economic issue, not a thermal one. Only the

accurate statement and verification of system performance is

required. For solar space conditioning systems, lighting

energy is included in the energy calculation to promote the use

of sunlight to offset the high electrical energy requirements

and thermal output associated with artificial lighting systems.

2.9.1

Criterion Depletable energy use . The annual depletable energy use for

lighting, space conditioning, and/or water heating systems shall

be determined and shall not exceed the limit established by

the owner, designer, or local jurisdiction as applicable.

2-37
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 thermal 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.

The energy use calculation shall be based on operating

conditions provided by the applicable authority including occu- pancy schedule, temperature set points for day/night and

summer/ winter, and ventilation schedule. Emergency Building

Temperature Restrictions, Reference [58], is one example of

legislated operating conditions. Energy records of comparable

buildings may be used to substantiate calculated energy use.

The annual depletable energy use for space conditioning systems

shall specifically include energy for lighting purposes.

Depletable energy includes coal, oil, natural and manufactured

gas, other petroleum products, electricity, and wood.

Depletable energy does not include solar energy converted to

thermal energy or electricity at the building site or thermal

energy extracted from the groundwater, or ground at the site.

Electricity produced off-site from any source including 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 Examples of applicable authorities responsible for determining

the depletable energy use limit may include building codes.

Reference [59], states, local or regional jurisdictions, legislative action (such as the proposed BEPS, Reference [60]), or the building owner.

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 can be used to calculate

the performance over the full range of operating conditions.

2-38
All systems that provide the functions of heating and/or

cooling require a building thermal load analysis to determine

the energy demand on the mechanical equipment. This analysis

can vary from simplified methods such as described in Chapter

43 of the ASHRAE Systems Handbook, Reference [6] , and based on

the modified degree-day method for heating and the equivalent

full-load hour method for cooling, to sophisticated computer

programs such as NBSLD, Reference [61], which perform dynamic

simulation of hourly thermal loads for each building zone for an entire year. Reference [62] provides a summary of computer

programs available for heating and cooling thermal load determination. Refinements to the simplified energy calculation

procedures, Reference [63], are currently being developed to

include elements deemed essential to the accuracy of the calculation procedure. The choice of a particular method used to

calculate building thermal load depends on the specific application. Buildings containing two or less zones and not utilizing passive solar components can usually be evaluated using

the simplified procedures; however, larger, multiple-zoned

buildings and buildings having passive solar components should

utilize the more comprehensive methods.

The annual thermal performance of all heating, cooling,

lighting, and hot water 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

[34], varying from handbook calculation procedures to interactive computer programs. Reference [64], are suitable for many

smaller active solar energy systems. The f- Chart method is

based on a correlation of detailed simulation of 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

suitable for use with:

passive components

tracking collectors

space cooling systems

heat pumps

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.

2-39
SOLCOST, Reference [65] , 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 solar-assisted 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 [14], 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 [66],

and a more comprehensive summary of calculation procedures is

described in Reference [67] .

Although the thermal performance of buildings containing

passive solar components such as direct-gain buildings can usually be calculated using the previously described building

thermal load techniques, thermal network analysis techniques

may be required for buildings having indirect-gain features

such as Trombe walls. General purpose analyzers such as S INDA,

Reference [68] , or specialized programs such as PASOLE,

Reference [13], are available for these types of buildings.

Hand calculation procedures such as the Solar/ Load Ratio,

Reference [69], method are also available. Reference [19] 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 the National

Bureau of Standards, Reference [70], 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 Demonstration Program, References

[71,72].

2-AO
Chapter 2 References

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Passive and Hybrid Heating and Cooling Systems," SER l/TP-6 3-218 , Solar

Energy Research Institute, Golden, CO, August 1979_'

.

2. Handbook and Product Directory , Applications, ASHRAE, 1982j^/.

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4. lES Lighting Handbook, Reference Volume , John E. Kaufman, Ed,,

Illuminating Engineering Society of North America, 345 E. 47th Street,

New York, New York, 1981.

5. lES Lighting Handbook, Applications Volume , John E. Kaufman, Ed.,

Illuminating Engineering Society of North America, New York, New York,

1981.

6. Handbook and Product Directory Systems , ASHRAE, 1980j^/.

7. Energy in Design , American Institute of Architects, Washington, DC,

1981.

8. Energy Graphics , U.S. Department of Energy, Washington, DC, 1981^'.

9. TEANET; A Numerical Simulation of System Behavior Using Thermal Network

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

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

Energy Group. Princeton, New Jersey.

11. Bryan, Clear, Rosen, and Selkowitz, "Ouicklite 1, A Daylighting Program

for the TI-59 Calculator," LBL-12248, W-80, EEB-W-81-01, Lawrence Berkeley

Laboratories, Berkeley, CA, 1981.

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

of Texas, Austin, Texas, May 1978.

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Energy," Los Alamos Scientific Laboratory Internal Report, LA-7473-MS,

Los Alamos, New Mexico, October 1978.

14. Klein, S., et al., "TRNSYS - A Transient Simulation Program," Report 38-10

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Laboratory, University of Wisconsin, Madison, Wisconsin, June 1978.

15. CALPAS 3 , Berkeley Solar Group, 2140 Grove Street, Berkeley, California,

October 1980.

16. SUNCODE , Ecotope, Inc., 2332 E. Madison, Seattle, Washington, February 1981.

2-41
17. DoE-2 Solar Simulator , Los Alamos Scientific Laboratory, Mail Stop 985,

liOS Alamos, New Mexico, 1979.

18. lUMEN II Lighting Analysis Computer Program , Smith, Hinchman, and

Grylls Associates, Inc., October 1978.

19. Solar Passive Building Design Computer Programs ; A Brief Survey With

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U.S. Department of Commerce, Washington, DC, October 1976.

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26. Cole, R. , et al., "Design and Installation Manual for Thermal Energy

Storage," ANL 79-15, Argonne National Laboratory, January 1980_'

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ASHRAE, 1977j_/.

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Experience Handbook," Preliminary Draft. DoE/CS-0045/0, U.S. Department of

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31. "Comparative Report: Performance of Active Space Cooling Systems," Vitro

Laboratories, 1980.

2-42
32. Final Proceedings of the Second SHAG Demonstration Program Contractor's

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33. Final Proceedings of the Third SHAG Demonstration Program Contractor's

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35. Method of Testing to Determine the Thermal Performance of Solar

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Department of Mechanical Engineering, February 1979^/.

2-43
45. Climatic Atlas of the United States , National Oceanic and Atmospheric

Administration, 1974, Asheville, NC.

46. "The Effect of Air Damper Leaks on Solar Energy System Performance,"

Solar/0012-78/29, National Solar Data Program, U.S. Department of Energy,

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Testing and Materials, 1916 Race Street, Philadelphia, PA 19103.

48. "Comparative Report, Performance of Active Solar Space Heating Systems,"

Vitro Laboratories, 1980.

49. Energy Conservation in New Building Design , Standard 90A-80, ASHRAE, 1980£/.

50. Ward, D., Solar Heating and Cooling System Efficiency as a Function of

Design and Installation , Solar Energy Applications Laboratory, Colorado

State University, Fort Collins, Colorado, September 1978.

51. "Volume One: Federal Program Presentations and National Solar Data

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Heating Systems," Solar Energy , Vol. 17, p. 335 (1975).

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and Gossett ITT, Morton Grove, Illinois, 1977.

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Cooling Applications," Final Report, SAN-1592-1, U.S. Department of Energy,

Washington, DC, 1978^/.

55. Waterman, R. E., "Analysis, Simulation and Diagnosis of Solar Energy

Control System Anomalies," Solar/0005-81/80, National Solar Data Program

Performance Results, Volume II, Vitro Laboratories, 1981^'.

56. 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, Orlando, Florida, New

York, New York, June 4-6, 1979.

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Cooling Applications," SERI/TR-09033-1 , Science Applications, Inc., for

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No. 130, pp. 39354-39369, July 5, 1979.

2-44
59. The Code for Energy Conservation in New Building Construction , National

Conference of States on Building Codes and Standards, December 1977.

60. "Energy Performance Standards for New Buildings, Proposed Rule," Federal

Register , Vol. 44, No 230, Office of Conservation and Solar Energy, U.S.

Department of Energy, Washington, DC, November 28, 1979.

61. Kusuda, T. , "NBSLD, The Computer Program for Heating and Cooling Loads in

Buildings," NBS Building Science Series 96, National Bureau of Standards,

U.S. Department of Commerce, Washington, DC, July 1976_'.

62. Bibliography on Available Computer Programs in the General Area of Heating , Refrigerating, Air Conditioning and Ventilation , ASHRAE, October 1975^^.

63. Kusuda, T. , Saitch, T., "Simplified Heating and Cooling Energy Analysis

Calculations for Residential Applications," NBSIR 80-1961, National Bureau

of Standards, U.S. Department of Commerce, Washington, DC, July 1980.

64." F-Chart Version 3.0 Users Manual , Solar Engineering Laboratory, University

of Wisconsin, Madison, Wisconsin, June 1978.

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

Guide , Martin Marietta Aerospace, Denver Division, P.O. Box 179, Denver,

Colorado, April 1978.

66. Conservation and Renewable Energy Inquiry and Referral Service, Box 8900,

Silver Spring, MD 20907.

67. 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, Georgia, May 28 - June 1, 1979^'T

68. SINDA - Systems Improved Numerical Differencing Analyzer , available from

COSMIC, the University of Georgia, Athens, Georgia.

69. Balcomb, J., et al .

, "Passive Solar Design Handbook, Volume Two of Two

Volumes: Passive Solar Design Analysis," DoE/CS-0127/2, Los Alamos

National Laboratory, for the U.S. Department of Energy, Washington, DC,

January 1980^/.

70. 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, Georgia, May 28 - June 1, 1979^^.

71. Shenfish, K., "Solar Energy System Performance Evaluation - Scattergood

School Recreation Center, West Branch, Iowa," June 1978 through April 1979,

SOLAP/2003-79/14, U.S. Department of Energy, Washingtion, DC, 1979£/.

72. Shenfish, K., "Solar Energy System Performance Evaluation - Northview

Elementary School (Howard's Grove) Howard's Grove, Wisconsin," September

2-45
1978 through April 1979, SOLAR/2041-79/14, U.S. Department of Energy,

Washington, DC, 1979.

73. Gillette, Gary, "A Dayllghting Model for Building Energy Simulation,"

Building Science Series 152, National Bureau of Standards, U.S. Department

of Commerce, Washington, DC, March 19832.'.

]j American Society of Heating, Refrigerating and Air Conditioning Engineers,

Inc., 1791 Tullie Circle, NE, Atlanta, Georgia 30329.

£' Technical Information Center, P.O. Box 62, Oak Ridge, Tennessee 37830.

^ Superintendent of Documents, U.S. Government Printing Office, Washington,

D.C. 20402.

^' National Technical Information Service, 5285 Port Royal Road, Springfield,

Virginia 22161.

£/ AS/ISES, 1230 Grandview Avenue, Boulder, Colorado 80302.

2-46
CHAPTER 3

MECHANICAL

Page

3.0 Introduction 3-1

3.1 System design conditions 3-1

3.1.1 Solar collectors 3-2

3.1.2 System balancing 3-2

3.1.3 Insulation 3-3

3.1.4 Structural deflection 3-3

3.2 Liquid systems 3-A

^3.2.1 Piping design 3-4

3.2.2 Leak testing 3-5

3.2.3 Liquid quality 3-6

3.2.4 Thermal expansion of fluids 3-7

3.2.5 Draining and filling 3-7

3.2.6 Entrapped air 3-8

3.2.7 Vacuum relief 3-8

3.2.8 Thermal expansion of materials 3-8

3.2.9 Valves 3-9

3.2.10 Pumps 3-9

3.3 Air systems 3-10

3.3.1 Duct design 3-10

3.3.2 Sealing of air systems 3-11

3.3.3 Damper leakage 3-14

3.3.4 Air leak testing 3-14

3.3.5 Air quality 3-16

3.4 Building solar (passive) components 3-17

3.4.1 Energy transport and distribution 3-17

3.4.2 Movable insulation 3-18

3.5 Control system 3-19

3.5.1 Inhabited space temperature control 3-19

3.5.2 Service hot water temperature 3-19

3.5.3 System temperature and pressure limit control 3-20

3.5.4 Temperature sensor installation 3-20

3.5.5 Auxiliary system control 3-21

3.5.6 Tracking collector controls 3-21

3.5.7 Control wiring 3-23

3-a
CHAPTER 3 - (Continued)

MECHANICAL

Page

3.6 Freeze protection 3-22

3.6.1 Antifreeze concentration 3-22

3.6.2 Dralndown, dralnback systems 3-22

3.6.3 Power operated protection 3-24

3.6.4 Freeze tolerant designs 3-25

References 3-26

3-b
CHAPTER 3

MECHANICAL

3.0

Introduction

3.1

Requirement

Commentary

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.

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 (U.L.1279-PROPOSED)

.

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 service of solar heating systems (H),

Reference [2] and installation guidelines for solar hot water

systems (HW), Reference [3] have been prepared. Although

specific to residential application, they may be of assistance

for commercial use.

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

3-1
3.1.1

Criteria

Evaluation

Commentary

Solar collectors . The solar collectors shall be designed to

accommodate the specified pressure drops and to resist 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.

3.1.2

Criterion

Evaluation

Commentary

System balancing . The energy transport system shall be designed with provisions for measuring and 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, 2.6.3, 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/min'ft^ (0.014 L/s*m2)

of collector (range 0.01 to 0.03 gal/min'ft^, typical).

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^/min'ft^ (0.01 m^/s'm^) of collector is

typical (range 1-4 ft^/min-ft-, typical).

Balancing dampers placed in ducts having excessive air flow

rates is a common means of balancing air systems. Means should

be provided to mark and/or lock the flow set point indicators.

Flow rates and velocities for thermosiphon systems will vary

3-2
dynamically and will not necessarily fall within stated

ranges

.

3.1.3

Criterion

Evaluation

Commentary

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.

Review drawings and specifications. Insulation design and

installation shall be in accordance with ASHRAE, Reference [8],

Chapter 20. Factory manufactured insulated ducts shall satisfy

the requirements of UL 181, Reference [9]. Fibrous glass ducts

shall satisfy SMACNA requirements. Reference [10].

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 R-value. Requirements for resistance to weathering exposure are contained in

Criteria 5.1.1, 5.1.2, and 5.1.3, 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 subsurface

drainage are highly recommended. Construction in high watertable 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.

3.1.4

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

3-3
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 conventional 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

Commentary

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.

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. 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

3-4
Evaluation

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.

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].

" Velocity limits to prevent erosive wear are given for selected

materials in Tables 5.3 and 5.4 of Chapter 5.

A therraosiphon 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 surfaces

from sagging, vibration, and thermal cycling. Support and

anchorage systems are illustrated in Reference [21]. 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) intervals for threaded pipe, one to two foot

(.3-. 6 m) intervals for rigid plastic pipe, and six foot

(1.3 m) for aluminum tubing. For larger size piping, greater

than 2 inches (5.08 cm), it is recommended that the manufacturers recommendations be obtained for spacing of anchors and

allowances for thermal expansion.

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

Evaluation

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.

Review specifications and testing. The portions of the H/C/HW

systems that contain pressurized liquid heat transfer fluids

3-5
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 minimxm of 15 minutes,

when filled with a recommended testing fluid. Those portions

of the system designed to operate at, or close to, 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 connected 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"? (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, sweating 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 relief devices should be considered to

avoid damage of these components during pressure testing.

3.2.3

Criterion Liquid quality . The systems shall have strainers, filters, or other means to collect particulate matter that could impair

heat transfer or the flow of the heat transfer fluid and result

either in a reduction of system efficiency or deterioration of

system components beyond acceptable limits.

Evaluation Review drawings and specifications.

Commentary The piping in some solar collectors and heat exchangers may

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

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

3-6
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, stainless steel, or monel screen should be installed ahead of the

pumps and control valves to remove foreign matter that might

damage the pump, clog collector or heat exchanger passages,

cause galvanic corrosion in the system, or cause valve malfunction. The change in pH of some heat transfer fluids due to

their decomposition at elevated temperatures 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 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.

Evaluation Review drawings, specifications, and design calculations.

Expansion tanks shall be sized in accordance with ASHRAE

Handbook/Systems, Reference [16].

Commentary 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. 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.

3.2.5

Criterion 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, specifications, and maintenance instructions.

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

3-7
6.2.1 and 3.2.3 for further discussion of

quality of heat transfer liquids.

maintaining the

Water wall units , barrels , columns, and other collector/storage

assemblies may require draining and filling provisions for the

individual liquid containers.

3.2.6

Criterion 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.

Evaluation Review drawings and specifications.

Commentary 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 and operated as directed by the manufacturer.

3.2.7

Criterion

Evaluation

Commentary

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.

Review drawings and specifications.

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 is 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

Evaluation

Commentary

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 or other fittings

that will occur over the service temperature range.

Review drawings, specifications, and calculations.

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.

3-8
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 lateral

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 component 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.

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 fail-safe 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 shutoff. 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

preventors 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.

3.2.10

Criterion 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.

3-9
Evaluation Review drawings, manufacturer's literature, and specifications

for compliance with Hydraulic Institute Standards, referenced

above.

Commentary 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 or start-up 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 can 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.

In draindown systems, the pump must be a certain distance below

the minimvim water level i^ the receptor tank to retain prime

and provide adequate positive suction head. Running air-bound

for short periods of time may damage the pump.

3.3

Requirement 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.

Commentary 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, 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]

3-10
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/mln (3.6-4.6 m/s). References [19, 26]. Lower velocities

may be desired If quieter operation Is required. 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 pressure

loss, which should be kept to a minimum In order to reduce

blower operating cost. Blowers sized near the center of their

performance curves 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 manlfold-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 (SDSS) 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 non3-11
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 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 is

commonly done in passive applications. Sealing shall

include joints in thermal storage, duct, and access

openings.

(d) 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. A.

Commentary These requirements may appear to be excessive, 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 principles 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

3-12
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 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 service 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 con- trol is very important because the surface areas involved

in passive air transporting assemblies are sometimes

very large and contain many sources for air leakage.

3-13
3.3.3

Criterion Damper leakage . 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 constructed to ensure tight cutoff

of the air stream.

Evaluation Review drawings and specifications to determine that

correct damper type is specified.

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 service 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 tight 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.

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 randomly 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.

Evaluation For active systems, leak testing shall be performed in

accordance with SMACNA High Pressure Duct Construction Systems,

Reference [27] as applicable.

3.3.4

Criterion

3-14
The following threshold leakage limits are based on the achievable levels noted in Criterion 3.3.2 for each portion of the

system.

Nondetrimental

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

There are no criteria yet established for air leakage in passive systems. See Commentary following for subjective evaluation of passive system leakage using 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 (see

Criterion 3.3.2). References [34, 36] discuss certain 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.

* 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
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%).

3.3.5

Criterion Air quality . Adequate 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 material 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 A.l.A.

ASTM C33-81, "Standard Specification for Concrete Aggregate,"

Reference [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 con- tainers 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 of the rock bed.

In some air collectors, performance reduction due to

accumulation of dirt from the system on the coverplate 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 is very

desirable.

A similar situation may exist in passive systems with air circulation (Trombe walls, air thermosiphons, etc.) where dirt

3-16
3.4

Requirement

Commentary

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.

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.

References [38, 39, 40] provide a full discussion of the

technical aspects of passive solar design.

3.^.1

Criterion

Evaluation

Commentary

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 constructed 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 suc- tion 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 inadequacy of such devices

should be noted:

3-17
(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.

(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

Evaluation

Commentary

Movable insulation . Manual or automatic movable insulation

shall be designed and installed for proper perimeter sealing

and reliable manipulation, operation, and storage.

Review drawings and specifications, especially for details of

fit and closure of insulation at the perimeter of glazed openings.

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 reduce

its ineffectiveness. 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 well 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.

3-18
3.5

Requirement

For further discussion Including guidelines and assessment

methods, see References [38, 39].

Control system. The control system shall be designed to operate

the solar and auxiliary H/C/HW system In a proper and efficient

manner.

Commentary See Criteria 2.7.1 through 2.7.4. 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.

3.5.1

Criterion Inhabited space temperature control . Each space conditioning

system or zone 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

(n^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.

Evaluation Review drawings and specifications.

Commentary 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 Criterion 2.3.1 for requirements for auxiliary heating systems

size.

3.5.2

Criterion Service 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.

Evaluation Review drawings and specifications. Review mechanical design

for compliance with Criterion 4.3.4.

Commentary Service hot water 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).

3-19
3.5.3

Criterion 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.

Evaluation

Commentary

3.5.4

Criterion

Evaluation

Commentary

Review drawings and specifications.

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 com- ponents 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.

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.

Review drawings, specifications, and system diagrams.

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.

3-20
The sensor should be in direct contact with the measured object

or substance. Heat transfer pastes may be used to increase

thermal contact. Sensors for sensing fluid temperatures should

be immersed directly in fluids or in direct contact with the

containment device or pipe. Insulation of sensors from extraneous heat flows can increase the accuracy of the readings

obtained from them. 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 Auxiliary system control . Provisions shall be made in the

control system to allow separate operation of the auxiliary

system.

Evaluation Review drawings, specifications, and control system.

Commentary 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 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.

Evaluation Review past performance data, drawings, and specifications.

Commentary 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.

3-21
3.5.7

Criterion

Evaluation

Commentary

Control wiring . Control wiring designed for exterior use shall

be suitable for weather exposure or protected from weathering.

Control wiring shall be selected and installation specified to

prevent damage and breakage of wiring.

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.

3.6

Requirement 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.

Commentary Various methods of freeze protection are available including

the use of freeze-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].

3.6.1

Criterion

Evaluation

Commentary

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 recom- mendations for antifreeze systems.

3.6.2

Criterion Draindown, drainback systems . Systems using automatic draindown for freeze protection shall provide for complete and

timely drainage of components exposed to freezing condi3-22
tions 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. Bi air-assisted

draindown systems, moisture-laden 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 generally 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. It is

important that pipes passing through unheated spaces be con- sidered as potential freeze problems. Such locations could be

well below freezing and create problems even though the control

sensor may not indicate the need for draindown.

3-23
The hardness or mineral content of the water used in draindown

systems should be evaluated for the potential build-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.

Backup 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 manual drain method would

be justified. For small HW systems, manual methods might be

considered acceptable for somewhat more frequent freezing

recurrence intervals. Judgment 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 backup provisions such as automatic draindown

or possibly even stand-by electrical generation. Backup standby power is probably most feasible where it is being considered

for other back-up reasons as well.

Reference [46] contains a detailed discussion of freeze protection for warm climates.

3-24
3.6.4

Criterion

Evaluation

Commentary

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.

Review drawings and specifications. Freeze tolerance of collectors shall be tested in accordance with test method 7.6 of

NBSIR 78-1305A, Reference [4].

Stresses in collector assemblies caused by differential thermal

expansion and contraction and by freezing of heat transfer

fluids, if any, can cause permanent damage: distortions, 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 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 backup.

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.

3-25
Chapter 3 References

1. Handbook and Product Directory Equipment , ASHRAE, 1979.2./

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

Systems for One and Two Family Dwellings , MSI/ASTM E683-79 (1979).^^

3. "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, Washington, D.C., April 1979._^'

4. "Provisional Flat Plate Solar Collector Testing Procedures," First Revision,

NBSIR 78-1305 A, PB 272 500, National Bureau of Standards, U.S. Department

of Commerce, Washington, DC, June 1978 ._^/

5. Methods of Testing to Determine the Thermal Performance of Solar Collectors , Standard 93-77, ASHRAE, 1977.£/

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.^^

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 .^^

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," LA-UR 81-3339, Los Alamos

National Laboratory. -^^Z

13. "Performance Criteria Resource Document for Binovatlve Construction,"

NBSIR 77-1316, National Bureau of Standards, U.S. Department of Commerce,

Washington, DC, November 1977.^/

14. Building Code Requirements for Reinforced Concrete , ACI 318-77, American

Concrete Institute, P.O. Box 19150, Redford Station, Detroit, MI 43219,

1977.

3-26
15. National Standard Plumbing Code , as recommended by the National Association

of Plumbing-Heating-Cooling Contractors, Appendix B, 197 1._^'

16. Handbook and Product Directory, Systems , ASHRAE, 1980,£/

17. Baughn, J. W, and Dougherty, D. A., "Experimental Investigation and

Computer Modeling of Solar Natural Circulation System," Prpceedings of the

1977 American Section of ISES Annual Meeting , Orlando, fTT^

18. Applications of Solar Energy for Heating and Cooling of Buildings , GRP

170, ASHRAE, 1977.j_/

19. Heating and Air-Conditioning Systems Installation Standards for One- and

Two-Family Dwellings and Multi-Family Housing Including Solar , SMACNA,

1981.^/

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

Energy, Washington, D.C., October 1979.'

Associates, Inc., The Ehrenkrantz Group, for the U.S. Department of

22. Windenburg, D. , "Vessels Under External Pressure," Mechanical Engineering , pp. 601-607, January 1937.^/

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.^0/

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 the U.S. Department of Energy, Washington, D.C., January 1978.^/

27. High Pressure Duct Construction Standards , Third Edition, 1975, SMACNA.^/

28. Low Pressure Duct Construction Standards , Fifth Edition, 1976, SMACNA.^,'''

29. "Thermal Performance Guidelines for One- and Two-Family Dwellings," NAHB

Research Foundation, Inc., P.O. Box 1627, Rockville, MD 20850.

30. BOCA Basic Energy Conservation Code - 1977 , Building Officials and Code

Administrators International, Inc., 1313 East 60th Street, Chicago, IL

60637.

31. Energy Conservation in New Building Design , Standard 90A-1980, ASHRAE.^/

3-27
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, Rockville, 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.^/

35. "The Effects of Air Damper Leaks on Solar Energy Systems Performance,"

Solar/0012-78/29, U.S. Department of Energy, Washington, D.C., 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.^/

37. Tamura, G. , "Measurement of Air Leakage Characteristics of House Enclosures,

ASHRAE Transactions , Vol. 81, Part 1, pp. 202-211, 1975.£/

38. Balcomb, J., et. al. , "Passive Solar Design Analysis," Vol. Two,

DOE/CS-0127/2, Dist. Cat. UC-59 , U.S. Department of Energy, Washington,

D.C.^/

39. "The First Passive Solar Home Awards," HUD-PDR-376, GPO 023-000-00517-4,

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

1979.£/

40. Mazria, E., The Passive Solar Energy Book , Rodale Press, Emmaus, PA, 1979.

41. Britnell, C, "Thermal Performance Analysis of Space Heating Systems in

the National Solar Data Network," IBM, Solar/0025-78/42, U.S. Department

of Energy, Washington, D.C, 1979.£/

42. Pejsa, J., et. al., "Cost Effective Control Systems for Solar Heating and

Cooling Applications," Final Report, SAN-1592-1, U.S. Department of Energy,

Washington, D.C, 1978, ^Z.

43. Waite, E., et. al. , "Reliability and Maintainability Evaluation of Solar

Control Systems," ANL/SDP-TM-79-5, Argonne National Laboratory, ^/.

44. National Electric Code , NFPA No. 70, National Fire Protection Association,

470 Atlantic Avenue, Boston, MA 02210, 1981.

45. Chopra, P. and Wolosewicz, R. , "Reliability and Maintainability Evaluation

of Freezing Solar Systems," ANL/SDP-TM-78-3, Argonne National Laboratory,

1978.2/

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.

3-28
47. Oil Burning Equipment , NFPA No. 31, 1974 (Also ANSI Z951). ^Q»J-^/

48. Gas Appliances and Gas Piping Installation , NFPA No. 54, 1974. (Also ANSI

Z21.22 and ANSI Z83.1, 1972) 7-^^^^7^17

49. Standard Specification for Concrete Aggregates , ASTM C33-81.^/

}j American Society of Heating, Refrigerating and Air Conditioning Engineers,

Inc., 1791 Tullie Circle, N.E. Atlanta, GA. 30329.

£/ American Society for Testing and Materials, 1916 Race Street, Philadelphia,

PA 19103.

2.' Superintendent of Documents, U.S. Government Printing Office, Washington,

DC 20402.

£/ National Technical Information Service, 5285 Port Royal Road, Springfield,

VA 22161.

£/ National Association of Plumbing-Heating-Cooling Contractors, 1016 20th

Street, N.W. , Washington, DC 20036.

£/ AS/ISES, 1230 Grandview, Avenue, Boulder, Colorado 80302.

iJ Sheet Metal and Air Conditioning Contractors National Association, Inc.

,

P.O. Box 70, Merrifield, VA 22116.

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

2J The American Society of Mechanical Engineers, Inc., 345 East 47th Street,

New York, NY 10017.

^Q/ National Fire Protection Association, Battery March Park, Quincy, MA 02269.

^^' American National Standards Institute, Inc., 1430 Broadway, New York, NY

10018. ^' Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545.

3-29

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 4-13

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 4-15

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 4-17

4.5.3 Electrical wiring 4-18

4-a
CHAPTER 4 - (Continued)

SAFETY AND HEALTH

Page

4.6 Structural safety 4-18

4.6.1 Structural resistance of H/C/HW systems 4-19

References 4-23

4-b
CHAPTER 4

SAFETY AND HEALTH

4.1

Requirement

4.1.1

Criterion

Evaluation

Commentary

4.1.2

Criterion

Evaluation

Contamination hazards . No material, form of construction,

fixture, appurtenance, or item of equipment shall be employed

that will support the growth 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.

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.

Review of plans and specifications. The quality of the

water shall be in compliance with the National Interim

Primary Drinking Water Regulation, Reference [1].*

This criterion is not intended to preclude using dyes suitable

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

in the system.

Separation of circulation loops . 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.l/

1/

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

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.

4-1
Commentary 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 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.J_' These data do not indicate the cut-off points at

which various degrees of protection must be taken; however,

consensus standards (in development )_^' 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 contamination

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

potable water system shall be prevented in a by the applicable authority.

fluids into the

manner approved

Evaluation Review drawings

systems

.

and specif iciations. Inspect assembled

Commentary Pollution of the potable water supply can occur by way of

backflow caused by back pressure and/or backsiphonage 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

^/ 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]

.

^' 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

protection provided.

the extent of

4-2
systems. A check valve is not a substitute for an approved

backflow preventor and should not be used in its place.

Reference [5] provides discussion as well as evaluation of some

of the many backflow prevention devices available. However,

without proper routine maintenance, any backflow prevention

device can fail. The false sense of security imparted by an expensive, yet failed, backflow preventer may permit nonpotable

or even lethal quantities of fluid to be ingested.

4.1.4

Criterion 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.

Evaluation Review drawings and specifications.

Commentary 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.

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, noncorrosive heat exchangers. The use of heat exchangers will

penalize the thermal performance of the system to some degree.

4.1.5

Criterion 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.

4-3
Evaluation 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.

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

Commentary

4.2.1

Criterion

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.

See the Terminology section for the definition of "hazardous

substances" and the indicated reference providing guidelines to

regulations regarding such substances.

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 com- pilation 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

4-4
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

antifreeze/water mixtures or to water may affect toxicity

characteristics

.

4.2.2

Criterion

Evaluation

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 summarizing 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].

Commentary The original fluid containers will frequently be discarded

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

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

point at which the owner or service personnel are most likely

to contact the heat transfer fluid and permanent labeling

should be retained at that point. Identification may be provided by attaching a tag containing the required information

such as may be supplied by the heat transfer fluid

manufacturer.

4.2.3

Criterion 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.

Evaluation Review drawings and specifications. Test detection and warning

system(s), i.e., visibility of a dye or operation of warning

device.

Commentary 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

4-5
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.

4.2.4

Criterion 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.

Evaluation Review

tions.

drawings and specifications and local disposal regulaCommentary 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.

4.3

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

create a hazard to people greater than those found in conventional buildings where solar energy equipment or design concepts are not used.

4.3.1

Criterion 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.

4-6
Evaluation 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.

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 con- sidered 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

4-7
falling or blowing of

safety glazing or be

from falling.

broken pieces or shards shall consist of

protected against breakage or restrained

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 conventional

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.

4-8
Potential safety hazards should be considered in areas exposed

to frequent hail storms, falling limbs or other projectiles

with regard to installation of skylights, 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 . 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 2.1.3.

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 temperatures. It is

generally suggested that mixing or tempering valves are the

most cost effective means for providing for protection from

scalding. The +5"! (+3°C) margin is given to allow a reasonable margin of error for the design temperature capability that

must be provided (see Criterion 2.1.3) and the temperature

limitations of this section.

4-9
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 general

use 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 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.

Evaluation Review drawings and specifications.

Commentary 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

Evaluation

Commentary

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.

Review drawings and specifications.

Solar system components may often include smooth slippery

surfaces located in elevated positions at steep angles. These

elements may heat up rapidly and loosen masses of snow or ice

which may slide off. Means should be provided to prevent a hazard to people or property. Methods such as deflectors,

restraints, low friction materials, or design of "safe fall" areas (pedestrian or vehicular routes located away from the

building) should be considered. This criterion is not intended

4-10
4.3.8

Criterion

Evaluation

Commentary

4.4

Requirement

Evaluation

Commentary

to apply to areas where snow and freezing conditions do not

normally occur.

Lightning . As applicable, lightning protection shall be

provided in accordance with the NFPA No. 78 Lightning Protection

Code, Reference [15].

Review of calculations, drawings, and specifications.

Damage to control components and the potential of fire are

major concerns for lightning protection.

used as grounding for lightning

a continuous electrical path to

If solar system piping is

protection, there must be

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.

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, and smoke generation will be considered in assessing the potential fire

hazards.

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

4-11
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:

A temperature of 50°F (28°C) above the design

flow temperature of the fluid in the solar system;

maximum

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

described in NFPA No. 321, "Basic Classification of Flammable

and Combustible Liquids," Reference [26]. 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 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.

4-12
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

[26].

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 [27].

4.4.2

Criterion

Evaluation

Commentary

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].

Review specifications or code compliance.

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.

4.4.3

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*

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

Insulation," Federal Register , Volume 43, No. 153, P. 35240, became effective

on September 8, 1978 and supersedes these requirements for cellulose insulation where applicable. Modifications to this standard are under consideration by CPSC.

4-13
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 E8A, 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 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 £84. 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 "non-combustible."

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.

4.4.4

Criterion 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-asphaltlc 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 thermal barrier having a finish rating of not less than 15 minutes as determined by NFPA 251, Reference [28]. Thermal barriers shall

be installed in a manner such that they will remain in place

for a minimum of 15 minutes under the same test conditions.

Installed insulation and vapor barriers shall not make contact

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

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

producing appliances are specifically designed and rated for

that purpose.

Evaluation Review 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 construction and

insulation materials, and to preclude any Increased fire hazard

4-14
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 firefightlng.

4.4.5

Criterion 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.

Evaluation Review drawings and specifications. Testing to show compliance

in accordance with NFPA 251, Reference [28] and applicable

standards.

Commentary Solar components may form the load bearing elements of

walls, roofs, etc. In addition, the presence of solar components (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 elements.

Large expanses of combustible glazing or other components used

In wall and roof elements may significantly reduce the fire

resistance of these components.

4.4.6

Criterion 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.

Evaluation Review drawings and specifications. Testing when necessary to

show compliance shall be in accordance with NFPA 256, Reference

[23] 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.

4-15
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 [29], 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:

Installation Clearances

Maximum Surface

Temperature (°F)

less than 200

200 to 250

250 to 500

over 500

Required Clearance

(inches)

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 selfignition 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 (lOO^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

* 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.

4-16
specified by a nationally recognized testing laboratory may be

used.

4.5

Requirement

Commentary

4.5.1

Criterion

Evaluation

Commentary

4.5.2

Criterion

Evaluation

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.

Identification and location of controls. Main shutoff

valves and switches should be conspicuously marked and placed

in locations that are readily accessible to those personnel

who would normally be expected to operate them in the event of

an emergency. These valves and switches shall be located in

the same manner as specified in 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.

4-17
The location of solar equipment on a roof could reduce the

usability of that roof for fireflghting 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.

4.5.3

Criterion

Evaluation

Commentary

4.6

Requirement

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.

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 branch circuit

wiring in spaces that will experience elevated temperatures

that may require a special type wire be used, or the type

generally used wire, having a thermal limit of 140*'F (60*'C) be

derated. Recent studies. References [47, 48] have shown that

the 140**? (60**C) limit can be reached when 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.

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 inservice 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

4-18
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 nonconventional elements. Elements with a structural support

function will generally be conventional.

4.6.1

Criterion 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.

4-19
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 provisions, the value of "Cp" (horizontal force factor) shall

be taken as 1.0. Reference [38] 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. The 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 [29] 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.

4-20
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 address 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 (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 workmian

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

4-21
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. 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.

(7) 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.

4-22
Chapter 4 References

1. National Interim Primary Drinking Water Regulations , 055-000-00157-0,

Environmental Protection Agency, Office of Water Supply, Washington, DC,

1977.£/

2. Gosselln, Hodge, Smith and Gleason, Clinical Toxicology of Commercial

Products , 4th Edition, Williams and Wllklns Co., 428 E. Preston St.,

Baltimore, MD 21202, 1975.

3. Durham, W. , "Toxicology" In Dangerous Properties of Industrial Materials , Sax, N., ed. Van Nostrand Relnhold 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, Sandla Laboratories, Albuquerque, NM, June

1978.£/

5. Sherlln, G. , Beausollel, R. , "Evaluation of Backflow Prevention Devices:

A State-of-the-Art Report," NBSIR 76-1070, National Bureau of Standards,

U.S. Department of Commerce, Washington, DC, 1976.2_'

6. Kusuda, T., Hunt, C, McNall, P., "Radioactivity (Radon and Daughter

Products) as a Potential Factor In Building Ventilation", ASHRAE Journal , July 1979.^/

7. Johnson, J. and Olson, H. , "Measurement of 222j^ 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,

U.S. Department of Energy, Washington, DC, July 1979.

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

181, Underwriters Laboratories, 333 Pflngsten 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.£/

11. HUD Minimum Property Standards, Multlfamlly Housing , No. 4910.1, U.S.

Department of Housing and Urban Development, Washington, DC, 1973, revised

1976,

y

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

16, Part 1500.1/

4-23
13. "Federal Mandatory Standard for Architectural Glazing Materials," 16 CFR

1201, Federal Register , January 6, 1911 ,}_f

14. Performance Specification and Method of Test for Safety Glazing Material

Use in Buildings , ANSI Z97. 1-1975, American National Standards Institute.^/

15. Lightning Protection Code , NFPA No. 78, 1977 ._^/

16. Clearances, Heat Producing Appliances , NFPA No. 89M, 1976 ._^/

17. Air-Conditioning and Venting Systems , NFPA No. 90A, 1981._^/

18. Warm Air Heating and Air Conditioning , NFPA No. 90B, 1980._^/

19. Chimneys, Fireplaces and Vents , NFPA No. 211, 1977 ._^/

20. Gas Appliances gnd Gas Piping Installation , NFPA No. 54, 1974 (also ANSI

Z83.1, 1972). ^»o/'

21. Flammable and Combustible liquid Code , NFPA No. 30, 1977.^/

22. Oil Burning Equipment , NFPA No. 31, 1974 (also ANSI Z95.1)._^/

23. Fire Tests of Roof Coverings , NFPA No. 256, 1976 (also ASTM E108, 1975^^/

and UL 790)._^/

24. National Electric Code . NFPA No. 70, 1978 (also ANSI CI, 1978). ^»^/

25. Surface Burning Characteristics of Building Materials, Test for , ASTM

E84-77, 1977.f_/

26. Basic Classification of Flammable and Combustible Liquids , NFPA No. 321,

1976._^/

27. 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, U.S. Department of Commerce, Washington, DC, November, 1979 ._^'

28. Standard Methods of Fire Tests of Building Construction and Materials , NFPA No. 251, 1972 (also ASTM El 19 and UL 263) .^ >'^/'

29. "Provisional Flat Plate Solar Collector Testing Procedures," First Revision

NBSIR 78-1305 A, National Bureau of Standards, U.S. Department of Commerce,

Washington, DC, June 1978._^/

30. Ufe Safety Code , NFPA No. 101, 1976._^/

31. Building Code Requirements for Reinforced Concrete , ACI 318-77, American

Concrete Institute, P.O. Box 19150, Redford Station, Detroit, MI 43219,

1977.

4-24
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, U.S. Department of Commerce,

Washington, DC, November 1977._^'

36. American National Standard for Minimum Design Loads for Buildings and Other

Structures , ANSI A58. 1-1982, American National Standards Institute, 1982.^/

37. 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, U.S. Department of Commerce, Washington, DC,

February 1981.2^

39. "Design of Steel Transmission Pole Structures," ASCE Journal of the

Structural Division , American Societ> of Civil Engineers, New York, NY,

December 1974

.

40. Tieleman, H. , Sparks, P., Akins, 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. , Filliben, J., "Extreme Wind Speeds at 129 Stations

in the Contiguous United States," BSS 118, National Bureau of Standards,

U.S. Department of Commerce, Washington, DC, 1979._^'

42. Wood Handbook , p. 4-32, 4-40, Forest Products Laboratory, P.O. Box 5130,

North Walnut Street, Madison, WI 53705, 1974.

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,

U.S. Department of Commerce, Washington, DC, 1981.^'

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.

4-25
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, U.S. Department of Commerce, Washington, DC, 1978.^'

48. Faison, T.K. , "Field Measurement of Branch Circuit Wire Temperatures,"

NBSIR 81-2347, National Bureau of Standards, U.S. Department of Commerce,

Washington, DC, 1981.^^

49. Walton, William D., "Solar Collector Fire Incident Investigation," NBSIR

81-2326, National Bureau of Standards, U.S. Department of Commerce,

Washington, DC, 1981.3/

^ Superintendent of Documents, U.S. Government Printing Office, Washington,

DC 20402.

2; American Society for Testing and Materials, 1916 Race Street, Philadelphia,

PA 19103.

£/ National Technical Information Service, 5285 Port Royal Road, Springfield,

VA 22161.

21 American Society of Heating, Refrigerating and Air Conditioning Engineers,

Inc., 1791 Tullie Circle, N.E. Atlanta, GA 30329.

V American National Standards Institute, Inc., 1430 Broadway, New York, NY

10018.

£/ National Fire Protection Association, Battery March Park, Quincy, MA 02269.

^' The American Society of Mechanical Engineers, Inc., 345 East 47th Street,

New York, NY 10017.

4-26

i
CHAPTER 5

DURABILITY/RELIABILITY

Page

3.0 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 5-4

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 5-9

5.3.1 Materials/transfer fluid degradation 5-9

5.3.2 Dissimilar metals degradation 5-12

5.3.3 Compatibility of adjacent organic materials 5-13

5.4 Effect of wear 5-13

5.4.1 Degradation by wear 5-13

References 5-26

5-a

CHAPTER 5

DURABILITY/RELIABILITY

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 aid to

identifying the need for assessing properties of materials.

These tables do not relate directly to specific criteria, but

5-1
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 estimate if satisfactory performance can be 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.

Evaluation Compliance may be documented with data on satisfactory longterm performance under in-service 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 E7 65-80, "Standard

Practice for Evaluation of Cover Materials for Flat Plate

5-2
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 con- trolling entrance of sunlight (shutters, shades, drapes, blinds,

etc.), reflectors, and collector casing assemblies. Combinations of materials (e.g., dissimilar metals) may give rise to

corrosion 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.

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

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

5-3
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 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.

Efflorescence on the absorber surface of masonry walls such as greenhouse and Trombe walls can cause the deterioration of the

absorber coating. Efflorescence occurs when water-soluble

salts are absorbed by water passing through a cementitious surface. The salts crystallize on the surface coating causing a chalky deposit provided that the coating is permeable. If the

coating is not permeable, the salts seep out beneath the coating, thus causing it to lose adhesion. If there is no water

passage, efflorescence can be avoided.

5.1.3

Criterion Pollutant degradation . Solar components and materials that are exposed to regionally prevalent air pollutants such as photo5-4
chemical 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 longterm 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 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 plates, deterioration

of coupling hoses, exposed seals, and corrosion of metallic

elements

.

5-5
5.2

Requirement

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.

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 longterm performance under in-use conditions or engineering analysis. Evaluation may occur at the collector, component 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 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

* Maximum and minimum service temperatures are defined in Section 1 of Appendix

A.

5-6
Seals Used in Concentrating Solar Collectors", Reference [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", Reference [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 for 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-term 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 con- tainers, 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.

Outgassing of condensible volatiles from components inside the

collector could lead to deposits on the underside of the collector glazing reducing glazing transmissivity 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 by-products and

formations which create scale and sludge within the system.

Because of this concern, it is recommended that a maintenance

program be developed and implemented to monitor and correct

corrosion and scaling problems in order to achieve the desired

lifetime of the system.

If not considered in the design, viscosity changes in heat

transfer fluids may lead to pumping problems, such as excessive

5-7
pumping power requirements or fluid thickening.

overheating due to heat transfer

5.2.2

Criterion

Evaluation

Commentary

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.

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.

This criterion is intended to identify potential problems that

may occur as a result of differential thermal movement. Physical restraints (including support conditions) that will be

imposed on the system in actual use shall be considered when

testing is required. Permanent dimensional 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

5-8
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 longterm 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.

For collectors not capable of withstanding cold fill under

stagnation conditions, this provision may be waived, if the

collector is protected with means of preventing circulation of

cold fluid in the hot collector.

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 sign5-9
iflcantly impaired under in-use conditions during their design

life.

Evaluation Compliance may be documented with data or satisfactory longterm 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 E7 12-80, "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 shall

be conducted using the methodology outlined in Section 7 of

Appendix A or other methods which can be shown 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, con- nectors, 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

5-10
[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 be used to maintain a suitable

pH balance but buffering will eventually be exhausted. Changes

in pH indicate the loss in buffering capacity and the transfer

fluid, or at least the buffers, must be renewed. However,

simply adding a buffer is not adequate unless it can also be

determined that the corrosion inhibitors have not been

depleted. In addition, the concentration of corrosion inhibitors present in the system should be checked periodically.

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.

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, crevice corrosion cells may be

set up at plastic/metal fittings. The physical and mechanical

5-11
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, delamlnate, soften, crack, become brittle,

lose strength, etc. The specific response Is dependent upon

the combination of polymer and heat transfer fluid. The UniBell 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.

5.3.2

Criterion 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.

Evaluation Compliance may be documented with data on satisfactory longterm 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.

Commentary The use of dielectric fittings that electrically isolate dissimilar metals is desirable. When using an electrically con- ductive 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, but the

problem can be alleviated by alternate grounding system.

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.

There is need to examine materials compatibility beyond the

component level to assure that the total system is engineered

with regard to reasonable life expectancy. The design life

must take into account the long term materials compatibility,

maintenance and operation, along with the desired thermal

performance.

5-12

I
5.3.3

Criterion

Evaluation

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.

Compliance may be documented with data on satisfactory longterm performance under in-use conditions or engineering analysis. For compatability of collector components and thermal

insulation used in the collector, ASTM E861-82, "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 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.

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 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.

5.4.1

Criterion Degradation by wear . Dampers, check valves, pressure

regulators, pumps, control devices, collector tracking

mechanisms, insulation movement mechanisms and assemblies, and

similar components shall be capable of operating under in-use

conditions without exhibiting wear or fatigue that would

significantly impair their ability to perform their intended

function over their design lives.

5-13
Evaluation Compliance may be documented with data on satisfactory longterm 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 is 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 applications and careful evaluation is desirable. Components containing 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 Conditionsi/

Altiffllnun

1. 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.

3. 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).

4. 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).l/

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.

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.

7. 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.

JL' 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.

]J 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 it/a (1.83 m/s).!/

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 contact with aqueous 1. liquid containing copper ions.

2. When in direct contact with aqueous 2. liquid with pH <8 or >12.

3. When in direct contact with aqueous

liquid with a temperature >131°F (55°C).

When adequate cathodic protection of

the galvanized parts is used (practical

only for storage tanks).

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 dezincification 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.

U 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.

±' 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 Paraneters: Generally Acceptable and Unacceptable Use Conditions for Metals in Direct Contact with Heat Transfer Liquids

Generally Unacceptable Use Conditions Generally Acceptable Use Conditional.'

AlumlnuB

1. When In direct contact with untreated,

uninhibited tap water with pH <5 or >9.

2. vrhen in direct contact with uninhibited

aqueous liquid containing copper, iron, or hallde ions.

When in direct contact with distilled

or delonized 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).

Copper

1. When in direct contact with an aqueous

liquid having a velocity greater than

4 ft/s (1.22 m/s).!/

2. When in contact with a chemical that can form copper complexes such as anmonium

compounds

.

When in direct contact with untreated

tap, distilled, or delonized water.

When in direct contact with stable

anhydrous organic liquids.

When indirect contact with aqueous

liquids which do not form complexes

with copper.

Steel

1. When in direct contact with untreated

tap, distilled, or delonized 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). 2/

1. When in direct contact with untreated

tap, distilled, or delonized 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

1. When the grade of stainless steel

selected is not corrosion resistant

in the anticipated heat transfer

liquid.

2. When In direct contact with a liquid

which is in contact with corrosive

fluxes.

1. When the grade of stainless steel

selected is resistant to pitting,

crevice corrosion, intergranular

attack, and stress corrosion cracking

in the anticipated use conditions.

2. When In direct contact trlth 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.

y 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 CondltlonajL'

Galvanized Steel

1. When In direct contact with water of 1. When In contact with water of pH >8

pH <8 or >12. but <12.

2. When In direct contact with an aqueous

liquid with a temperature >131'P (55°C)

Brass and Other Copper Alloys

Binary copper-zinc brass alloys (CDA 2XXX series) exhibit generally the same behavior

as copper when exposed to the. same conditions. However, the brass selected shall

resist dezlnclflcatlon 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.

ll 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 sy9tem. 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.-^/

2. Standard Practice for Exposure of Cover Materials for Solar Collectors to

Natural Weathering Under Conditions Simulating Operational Mode , ASTM

E782-81.£/

3. Standard Practice for Evaluating Solar Absorptive Materials for Thermal

Applications , ASTM E744-80.^/

4. Standard Practice for Evaluating Absorptive Solar Receiver Materials When

Exposed to Conditions Simulating Stagnation in Solar Collectors with Cover

Plates , ASTM E781-81.^/

5. "Provisional Flat Plate Solar Collector Testing Procedures," First Revision,

NBSIR 78-1305A, National Bureau of Standards, U.S. Department of Commerce,

Washington, DC, June 1978, PB 283-721.£/

6. Standard Method for Testing Coated Metal Specimens at 100 Percent Relative

Humidity , ASTM D2247-68 (1973).^^

7. Standard Practice for Evaluating Thermal Insulation Material for Use in

Solar Collectors , ASTM E861-82.1/

8. HUD Minimum Property Standards, One-and Two-Family Dwellings , No. 4900.1,

U.S. Department of Housing and Urban Development, Washington DC, 1973.^'

9. ASHRAE Handbook of Fundamentals - 1981.^/

10. Standard Specification for Rubber Seals Used in Flat Plate Solar Collectors , ASTM D3667-78.j^/

11. Standard Specification for Rubber Seals Used in Concentrating Solar

Collectors , ASTM D3771-79.^/

12. Standard Specification for Rubber Seals Contacting Liquid in Solar Energy

Systems , ASTM D3832-79.^/

13. Standard Specification for Rubber Seals Used in Air-Heat Transport of

Solar Energy Systems , ASTM D3903-80.^/

14. Standard Specification for Rubber Hose Used in Solar Energy Systems , ASTM

D3952-80._|^/

15. "Air Quality Data - Annual Statistics Including Summaries with Reference

Standards," EPA-450-2-78-040.5/

5-26
16. Standard Practice for Nonoperatlonal Fxposure and Inspection of a Solar

Collector . ASTM E823-81.1/

17. Standard Practice for Laboratory Screening of Metallic Containment Materials

for Use with Liquids In Solar Heating and Cooling Systems. ASTM ¥.712-fi0.1.^

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 £745-80.1/

19. Standard Practice for Screening Polymeric Containment Materials for the

Effects of Heat and Heat-Transfer Fluids In Solar Heating and Cooling

Systems . ASTM £862-82.1^

20. Prevention of Corrosion of Metals , Society of Automotive Engineers,

Standard J447a, 1964.^/

21. Metz, F. E. and Orloskl, M. J., " State-of-the-Art Study of Heat Exchangers

Used with Solar Assisted Domestic Hot Water Systems," NBSIR 78-1542,

National Bureau of Standards, U.S. Department of Commerce, Washington, DC,

June 1978, PB287-410.2./

22. Handbook of PVC Pipe Design and Construction .Z/

JL' American Society for Testing and Materials, 1916 Race Street, Philadelphia,

PA 19103.

2./ National Technical Information Service, 5285 Port Royal Road, Springfield,

VA 22161.

2.' Superintendent of Documents, U.S. Government Printing Office, Washington,

DC 20402.

A' American Society of Heating, Refrigerating and Air Conditioning Engineers,

Inc., 1791 Tullie Circle, N.E., Atlanta, GA 30329.

A' U.S. Environmental Protection Agency, Office of Air Quality Planning and

Standards, Monitoring and Data Analysis Division, Research Triangle Park, NC

27711.

§J Society of Automotive Engineers, Inc., Two Pennsylvania Plaza, New York, NY

10001.

Z/ Unl-Bell Plastic Pipe Association, 2655 Villa Creek Drive, Suite 164, Dallas,

TX 75234.

5-27
CHAPTER 6

OPERATION 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 6-7

6.3.1 Checkout 6-7

6.3.2 Minimum operating information 6-8

6.3.3 Access for system monitoring 6-8

References 6-10

6-a
CHAPTER 6

OPERATION AND SERVICING

6.0

Introduction

6.1

Requirement

Commentary

6.1.1

Criterion

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

containing instructions for the installation, operation and

maintenance of the H/C/HW systems and components. The extent of

detail of the manuals shall be consistent with the need for

descriptive information to properly operate and maintain the

system.

This 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 conversely 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
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

Commentary

6.1.2

Criterion

Evaluation

Commentary

6.1.3

Criterion

Review installation instructions.

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 projectspecific 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. Although

these guidelines were developed for residential application, they should provide assistance in working with small

commercial systems.

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. For example, the manual should specify

acceptable methods of cleaning glazed surfaces.

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.

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

6-2
Evaluation Review of maintenance plan.

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 111 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

In the manual.

6.1.5

Criterion

Evaluation

Flushing of liquid system. The manual shall provide Instructions for Initial flushing as required and periodic flushing

(cleaning). If required, of the liquid passages.

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 crevices. 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
Evaliiatlon Review Installation and maintenance Instructions.

Commentary 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. The Instructions should

Indicate where 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.

6.1.7

Criterion 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.

Evaluation Review operation Instructions.

Commentary 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 dally

and seasonal basis Including times of building vacancy.

6.2

Requirement 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.

6.2.1

Criterion 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.

Evaluation Review specifications and monitoring of the heat transfer

liquid for pH, buffering capacity, viscosity, and concentration

of heat transfer fluid components.

Commentary Experience from demonstration programs Indicates the Importance

of heat transfer liquids and their quality In preventing f reezeups 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 Association Industry Standards S-100-75 and S-200-73 should be provided. Reference [3].

6-4
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 and <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 nonadjacent 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, monitoring, adjusting,

and balancing. Information on access provisions is provided in

Reference [5].

6-5
6.2.3

Criterion

Evaluation

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

,

manuals.

specifications, and service instruction

Commentary

6.2.4

Criterion

Evaluation

Commentary

The complexity and design of certain components may require

their removal and replacement to accomplish repair of the system. Routine servicing of systems should 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,

system drawings.

site plans, and building and solar

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.

6.2.5

Criterion 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.

Evaluation Review drawings and specifications.

Commentary 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:

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.

6-6
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

qxiantities 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.

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.

6.3

Requirement System monitoring . Provision shall be made for system monitoring in accordance with the specifications of the operation

and maintenance manual.

6.3.1

Criterion 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.

6-7
Evaluation 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, the manuals and instructions

defined in Requirement 6.1.

Commentary 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.

6.3.2

Criterion Minimum operating information . Provisions shall be made to

indicate to the user when the collector loop and/or the auxiliary energy system is operating.

Evaluation Review drawings, specifications, and operation instructions.

Commentary A minimum level of information is essential to the user to assure that the solar system is functioning as intended.

Monitoring means may involve 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

6-8
voltages are of concern In this provision. Access for the

monitoring of flow, either liquid or alr» should be considered

and the access point should be located so that upstream disturbances do not affect the measurements. Ports should be available for monitoring the quality of the heat transfer fluid.

Charging ports are probably adequate for this purpose If

located In an active portion of the transport network. Corrosion monitoring may be Important for particular systems and

provisions for Installation of coupons, probes, and/or corro- sion fuses should be considered In the layout of the system.

6-9
Chapter 6 References

1. "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, Washington, DC, April 1979.2_'

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- 100-7 5 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/SDP-TM-79-6,

SOLAR/0904-79/70.£/

5. Uniform Mechanical Code , International Conference of Building Officials,

5360 South Workman Mill Road, Whittier, CA 90601, 1982.

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, U.S. Department of Commerce,

Washington, DC, 1980.2/

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

^' Superintendent of Documentrs, Government Printing Office, Washington,

DC 20402

6-10
APPENDIX A

Page

INTRODUCTION A-c

Section 1 Temperature Conditions A-1

2 Evaluation Methods A-8

3 Test Methodology; Criterion 5.1.1 Solar Degradation A-8

Aging Procedure 1 (Simulated Laboratory Exposure) A-8

Aging Procedure 2 (Outdoor Exposure Using Concentrated

Natural Radiation) A-8

Aging Procedure 3 (Natural Weathering) A-9

Property Assessment A-10

Commentary A-10

4 Test Methodology; Criterion 5.1.3 Pollutant Degradation A-IO

Aging Procedure 1 (Resistance to Ozone) A-IO

Aging Procedure 2 (Resistance to Salt Spray) A-IO

Aging Procedure 3 (Resistance to SO2 and NO^) A~ll

Property Assessment A-1

1

Commentary A-11

5 Test Methodology ; Criterion 5.2.1 Thermal Degradation A-U

Aging Procedure 1 (Resistance of Fluids to Maximum

Service Temperature) A-12

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-13

6 Test Methodology; Criterion 5.2.2 Thermal Cycling

Degradation A-13

Aging Procedure 1 (Resistance of Components and Materials to

Thermal Cycling) A-13

Property Assessment A-13

Commentary A-13

A-a
APPENDIX A (Continued)

Page

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-15

8 Test Methodology; Criterion 5.3.2 Dissimilar Metals

Degradation A-15

Aging Procedure 1 (Resistance of Metallic Containment

Materials to Liquids) A-15

Aging Procedure 2 (Resistance to SO2 and NOx) A-15

Property Assessment Arl5

Commentary A-15

9 Test Methodology; Criterion 5.3.3 Compatibility of

Adjacent Organic Materials A-15

Aging Procedure 1 (Compatibility of Adjacent Organic

Materials) A-15

Property Assessment A^16

10 No-Flov 30-Day Degradation A-16

COMMENTARY A-20

REFERENCES A-22

A-b
INTRODUCT ION

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 con- cern 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 given 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. Many analytical models rest on the implicit

assumption that heat transfer fluid is flowing through the collector; these models cannot be used directly to calculate no-flow

temperatures. An acceptable alternative for most collector

designs is to calculate the collector temperatures under stagnation conditions. (A solar collector is said to be in stagnation

when heat transfer fluid is flowing through the collector but

because of the elevated collector temperatures the efficiency is

zero.) This calculation has been performed for ten typical flat

plate collector designs to provide assistance in establishing the

maximum service temperatures of critical collector components.

The absorber and cover plate temperatures calculated for two such

flat plate collectors in stagnation are plotted as a function of

A-1
ambient temperature In figure A. 1. The results for all ten

collectors are given in table A.l, which contains the mean plate

temperature for the absorber along with the corresponding temperature for the cover plate(s) at two ambient temperatures* These

data were generated using the analytical model developed by

Thomas, Reference [!]•* The fixed and varied parameters used in

the model calculations are listed in tables A.2-A.5. Some of the

key fixed parameters established for the modeling are: zero wind

speed; a low fluid flow rate (0.01 kg wT^a'^); beam radiation

normal to the collector surface; 45" collector tilt; a constant

irradiance value of 1070 Wm'*^, Collector cover plate and absorber

temperatures, under conditions of stagnation can be determined

for other ambient temperatures within the range of temperatures

indicated in table A.l by linear interpolation.

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. In addition, unconventional collector

designs that include heat pipes, stagnation prevention devices

and the like may not be amenable to this kind of modeling analysis. It is recommended that the temperature of critical components be experimentally established for a particular collector

design whenever possible.

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

A-2
250

(482)

200

(392)

1 j.b_sorberi?^^^^^

"

oo 150 —

HI

- (302)

(32)

T—rn—

r

T—I—I—I—I—I—I—

r

AbsorberJCase J L.

Case 1: Absorber - flat black, cover plate - glass

Case 2: Absorber - black chrome, cover plate - glass

J I I L J \ I L J I I L

-17.8

(0)

-6.7

(20)

4.4

(40)

15.6

(60)

26.7

(80)

37.8

(100)

AMBIENT TEMPERATURE. ^C (^F)

Figure A. 1. Calculated surface temperatures of absorber and collector cover

plate(s) under conditions of stagnation. Fixed meteorological,

operational and optical parameters are given in tables A.

2

through A. 5. The surface temperatures for the absorber and cover

plates are also presented in table A.l at ambient temperatures

of -17.8 and 37.8°C.

A-3
TABLE A.l

CALCULATED ABSORBER AND COVER PLATE TEMPERATURES FOR FLAT-PLATE SOLAR

COLLECTORS UNDER STAGNATION CONDITIONS [Ija

Ambient Absorber Inner Outer

Collector Identification Temp. Mean Plate

Temp. (*C)

Cover

Temp. CC)

Cover

Case Absorber Cover Plated Temp. CO

1 Flat Black Glass -17.8 125 f 67

1 Flat Black Glass 37.8 157 f 106

2 Black Chrome Glass -17.8 185 f 57

2 Black Chrome Glass 37.8 226 f 98

3 Flat Black Glass, Glass -17.8 154 114 59

3 Flat Black Glass, Glass 37.8 185 149 101

4 Black Chrome Glass, Glass -17.8 208 100 49

4 Black Chrome Glass, Glass 37.8 245 136 93

5 Flat Black FRPC -17.8 112 f 59

5 Flat Black FRP 37.8 146 f 100

6 Black Chrome FRP -17.8 171 f 52

6 Black Chrome FRP 37.8 214 f 94

7 Flat Black PVpd -17.8 102 f 49

7 Flat Black PVF 37.8 136 f 91

8 Black Chrome PVF -17.8 179 f 53

8 Black Chrome PVF 37.8 220 f 94

9 Flat Black FEP^, PVF -17.8 114 76 42

9 Flat Black FEP, PVF 37.8 146 114 86

10 Black Chrome FEP, PVF -17.8 195 85 34

10 Black Chrome FEP, PVF 37.8 233 122 79

Notes: (a) See Tables A. 2 through A. 5 for parameters used in the referenced

model calculations.

(b) For double glazed collectors, the inner cover plate material is

listed first.

(c) FRP - Fiber reinforced plastic

(d) PVF - Poly( vinyl) fluoride

(e) FEP - Fluorinated (ethylene propylene)

(f) Single glazed collector

A-4
TABLE A. 2

FIXED METEOROLOGICAL CONDITIONS AND OPERATIONAL PARAMETERS

Irradiance 1070 Wm"2 (340 Btu/hr"^ ft"^)

Diffuse Fraction 0.15

Angle of Incidence C

Collector Tilt 45"

Wind Speed ms~^

Fluid Flow Rate 0.01 kgm~2s"l

A-5
Table A. 3. Dimensions and Heat Transfer Properties for Flat Plate Collector*

Used in Stagnation Temperature Calculations

Absorber

Effective Length 1.72 m

Effective Width 0.81 m

Thickness 0.9 mm

Thermal Conductivity 45.0 Wm-2»C-1

Flow Configuration Parallel

Flow Tubes : Number 10

O.D. 8.1 mm

Hydraulic Diameter 4.9 mm

Wetted Perimeter 15.4 mm

Emittance

Solar Absorptance

Cover Assembly

Number of Covers

Air Space between first cover

and absorber

See Table A. 4

See Table A.

4

1 or 2

37 mm

Air space between first and

second cover, if two covers

Thickness

Infrared Emittance

fiifrared Transmittance

Index of Refraction

Extinction Coefficient

25 mm

See Table A. 5

See Table A. 5

See Table A. 5

See Table A.

5

See Table A. 5

Insulation

Thickness : Back

Edge

Conductivity Back

Edge

89.0 mm

25.4 mm

0.040 Wm"l*C~l

0.040 Wm^l^C"^

Area

Aperture

Gross

1.39 m2

1.67 m2

* Representative of collector

Program [3] , [4] ,

'D" in the NBS Durability and Reliability

A-6
TABLE A.

4

ABSORBER PLATE PROPERTIES

Material Absorptance Emlttance

Flat Black Paint^

Black Chrome^

0.98

0.97

0.92

0.07

Notes: (a) Collector "C" as described in

reference [2] . (b) Collector "D" as described in

reference [2]

.

TABLE A.

5

COVER PLATE PROPERTIES

Low Iron

Etched Glass

Fiber

Reinforced

Plastic

Fluorinated

(Ethylene

Proplyene)

Poly(Vinyl)

Fluoride

Factor [3,4]' FRP [3,4]^ FEP [3,4]' PVF [5]

In/rared Emittance

Infrared

Transmittance

Index of Refraction

Extinction

Coefficient (inm"^)

Thickness of Cover

Plate (mm)

0.88

0.00

1.30

0.0095

3.175

0.84

0.07

1.54

0.0565

0.965

0.33

0.60

1.33

0.0658

0.0254

0.57

0.35

1.46

0.078

0.102

Notes: (a) Collector "D" (Outer Cover) as described in references [3,4]

(b) Collector "E" as described in references [3,4]

(c) Collector "H" (Inner Cover) as described in references [3,4]

A-7
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 026-77, Operating

Light Exposure Apparatus (Xenon-Arc Type) With and Without Water

for Exposure of Non-Metallic Metals, Reference [6] or ASTM

D2565-79, Operating Xenon Arc-Type (Water Cooled) Light and Water

Exposure Apparatus for Exposure of Plastics, Reference [7].

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.

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

[8] expose components or materials to concentrated natural solar

radiation until they have received a total Incident radiant exposure of 5. A X 10^ Btu/ft^ (6.0 GJ/m^). Exterior surfaces exposed

A-8
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/mln. ft^

(1.18 X 10"^ L/s,wr) +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 [8]

.

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 dally 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/ft^ (14.8 Mj/m^).

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 Solar 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

Exterior Paints ASTM D1014-66 Standard Method of Conducting

(Not Absorber (Reapproved 1973) Exterior Exposure Tests of

Coatings) Paints on Steel

Adhesive

Joints

ASTM D1828-70

(Reapproved 1976)

Standard Recommended Practice

for Atmospheric Exposure of

Adhesive Bonded Joints and

Structures

Plastics ASTM D1435-75

(Reapproved 1979)

Standard Recommended Practice

for Outdoor Weathering of

Plastics

A-9
Non-Metallic ASTM G7-77a

Materials

Standard Practice for

Atmospheric Environmental Exposure Testing of Non-Metallic

Materials

Pipeline

Coatings

ASTM Gll-79

Any material ASTM G24-73

(Reapproved 1980)

Standard Test Method for

Effects of Outdoor Weathering

on Pipeline Coatings

Standard Recommended Practice

for Conducting Natural Light

Exposures Under Glass

Property

Assessment

Commentary

Section 4

Aging

Procedure 1

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.

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.

Test Methodology; Criterion 5.1.3 Pollutant Degradation

(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

D1149-78a, "Rubber Deterioration Surface Ozone Cracking in a Chamber (Flat Specimens)", Reference [9]. Specimens should be

stressed to simulate service conditions.

Aging

Procedure 2 (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 [10]

A-10
Aging

Procedure 3 (Resistance to SO2 and NOx)

Coupon specimens of components

closed chamber having openings

tained at a temperature of 73.

of 21 days. An amount of (SO2

the volume of the test chamber

ber each working day. A small

at the bottom of the chamber.

shall be supported vertically in a for gas inlet and outlet and roain4 + 3.6°F (23 + 2*'C) for a period

or NOx) equivalent to 1 percent of

shall be introduced into the chamamount of water is to be maintained

Property

Assessment 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.

Commentary

Section 5

These tests are intended to determine

components to airborne pollutants.

Test Methodology; Criterion 5.2.1

the resistance of

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 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)

Standard Method of Test for

Effects of Heat Aging on Weight

Loss, Cracking and Chalking of

Elastomeric Sealants

Rubber ASTM D454-81 Standard Test Method for Rubber

Deterioration by Heat and Air

Pressure

Plastic ANSI/ ASTM D794-68

(Reapproved 1977)

Standard Recommended Practice for

Determining Permanent Effect of

of Heat on Plastics

Plastic ANSI/ ASTM D1042-51

(Reapproved 1978)

Standard Test Method for linear

Dimensional Changes of Plastics

Under Accelerated Service

Conditions

A-11
Plastic ANSI/ASTM D1204-78

Plastic ANSI/ASTM D1299-55

(Reapproved 1979)

Plastic ANSI/ASTM D1203-67

(Reapproved 1974)

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 ffethod 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. 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.

Aging

Procedure 2 (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.

Aging

Procedure 3 (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.

Property

Assessment 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

A-12
both aged and unaged specimens to establish a basis for

comparison.

Commentary 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.)

Section 6 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).

Aging

Procedure 1 (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

mlnlmiim service temperature for a total of 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 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.

Commentary These tests are Intended to permit estimations to be made of the

effect of thermal cycling In degrading collector components

and materials.

Section 7 Test Methodology; Criterion 5.3.1 Materials/ Transfer Fluid

Degradation . Metallic containment materials used with nonaqueous

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 tfetalllc 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.

A-13
The primary sample typically consists of a 36 in, (914 mm) length

of tubing bent around an 8 in. (203 mm) diameter mandrel 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, degree of fluid

aeration, and surface area ratios of the dissimilar metals shall

be included in the test. Protective coatings shall form a part

of the test specimen if they are used in the actual system.

Testing shall be followed by visual inspection. With appropriate modification. Standard TM-01-71, "Autoclave Corrosion

Testing of Metal in High Temperature Water", Reference [11]

of the National Association of Corrosion Engineers for materials

used in pressurized systems or ASTM D1384-80, "Corrosion Test

for Engine Coolants in Glassware", Reference [12] 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 [13] or ASTM D1239-55( 1971) , Reference [14]. 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 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.

A-14
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 used 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.

Aging

Procedure 1 (Resistance of Metallic Containment ^felterials 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.

Aging

Procedure 2 (Resistance to SO2 and NOx)

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 A.

Property

Assessment 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.

Commentary

Section 9

These tests are intended to permit estimations to be made of

the effect of corrosion on non-isolated dissimilar metals.

Test Methodology

;

Organic Materials

Criterion 5.3.3 Compatibility of Adjacent

Aging

Procedure 1 (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.

A-15
Property

Assessment 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.

Section 10 No-Flow 30-Day Degradation

Testing Procedure

Evaluation of changes in collector materials or performance due

to environmental conditioning shall be determined in accordance

with the test procedure described in ASHRAE Standard 93, Reference [15], 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 water_^' following which the inlet shall be

sealed and the outlet provided with a pressure relief

valve set to a value between 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 water_' following which the fluid shall

be allowed to gravity drain for 15 minutes with the collector mounted at a A5° tilt angle. The collector inlet

^1 Manufacturer's/designer's recommended fluid shall be used in those instances

when they specifically prohibit the use of distilled water,

A-16
shall then be protected to prevent entry of dirt or precipitation. The collector shall also be vented to

prevent buildup of pressure.

C. Exposure Conditions ;

1. Exposure conditions shall consist of 30 days of cumulative

exposure to a minimum daily incident solar radiation

flux of 1500 Btu/ft2»day (17,000 kj/m2»day) as measured

in the plane of the collector aperture.^'

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 summarized in the table of paragraph D.4. 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/ft^'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/ft^^h exposure period.

Solar irradiance measurements shall be performed in

the plane of the collector to verify that the irradiance does not vary by more than 10 percent over

the collector aperture and that the minimum

instantaneous flux requirement is met.

c. A transparent enclosure may be used to raise the

ambient temperature around the collector. The

1/ 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 the day of exposure. 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 *
enclosure material shall have a total solar transmittance of at least 0.85 and a spectral transmittance of at least 0.80 in the wavelength band from

0.3 to 0.4 ym. If used, the pyranometer shall be

mounted within the enclosure and within the plane

of the collector for measurement of the solar

irradiance.

D. 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 conducted

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"? (30°C). A complete description of the apparatus and procedure is presented in

NBSIR 78-1305 A, Reference [16].

4. Test requirements and options ; Specific test

requirements for exposure conditions and options are summarized in the following table.

A- 18
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A-19
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/ft2«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 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 com- mensurate 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 con- ditions 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

A-20
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-21
REFERENCES

1. Thomas, W.C., "Solar Collector Test Procedures: Development of a Method

to Refer Measured Efficiencies to Standardized Test Conditions,"

NBS-GCR-84-459, Virginia Polytechnic Institute and State University,

Report No. VPI-E-80.23, National Bureau of Standards, U.S. Department of

Commerce, Washington, D.C., 1984.J^/

2. Streed, E. and Waksman, D., "NBS Solar Collector Durability/Reliability

Test Program Plan," NBS Technical Note 1136, National Bureau of Standards,

U.S. Department of Commerce, Washington, D.C., 1980._^'

3. Streed, E. and Waksman, D. , "Uncertainity in Determining Thermal Performance

of Liquid-Heating Flat-Plate Collectors," NBS Technical Note 1140, National

Bureau of Standards, U.S. Department of Commerce, Washington, D.C., 1981._^'

4. Dawson, A.G. Ill and Thomas, W.C., "Stagnation Temperature Methods for

Determining Solar Collector Thermal Performance Degradation," Interim

Report (DOC NBS Grant NBS 79NADA0022) Virginia Polytechnic Institute and

State University, 1981.

5. Clark, E.J., Roberts, W.E., Grimes, J.W., and Embree, E.J., "Solar Energy

Systems - Standards for Cover Plates for Flat-Plate Solar Collectors," NBS

Technical Note 1132, National Bureau of Standards, U.S. Department of

Commerce, Washington, D.C., 1980.J_'

6. Standard Recommended Practice for Operating Light-Exposure Apparatus

(Xenon Arc Type) With and Without Water for Exposure of Nonmetallic

Materials , ANSI/ASTM G26-77.^/^/

7. Operating Xenon-Arc Type (Water Cooled) Light- and Water- Exposure

Apparatus for Exposure of Plastics , ANSI/ASTM D2565-79.^^

8. Standard Practice for Performing Accelerated Outdoor Weathering Using

Concentrated Natural Sunlight , ASTM E838-81.^^

9. Standard Test Method for Rubber Deterioration - Surface Ozone Cracking in

a Chamber (Flat Specimens) , ANSI/ASTM D1149-78a.^^^/

10. Standard Method of Salt Spray (Fog) Testing , ASTM B117-73 (1979).£/

11. Autoclave Corrosion Testing of Metal in High Temperature Water , NACE

TM-01-71.f/

12 * Standard Method for Corrosion Test for Engine Coolants in Glassware , ANSI/ASTM Dl 384-80 .f/f_/

13. Standard Test Method for Resistance of Plastics to Chemical Reagents , ANSI/ASTM D543-67 (1978).^/5/

A-22
14. Standard Test Method for Resistance of Plastic Films to Extraction by

Chemicals , ANSI/ASTM D1239-55 (1971).^/^^

15. Methods of Testing to Determine the Thermal Performance of Solar Collectors , Standard 93-77, ASHRAE 1977.^^

"

16. Provisional Flat Plate Solar Collectors Testing Procedures , First Revision,

NBSIR 78-1305A, National Bureau of Standards, U.S. Department of Commerce,

Washington, D.C., June 1978, PB 283-721.1/

U National Technical Information Service, 5285 Port Royal Road, Springfield,

VA 22161.

^' American Society for Testing and Materials, 1916 Race Street, Philadelphia,

PA 19103

2.' National Association of Corrosion Engineers, Box 1499, Houston, TX 77001.

2J American Society of Heating, Refrigerating and Air Conditioning Engineers,

Inc., 1791 Tullie Circle, N.E., Atlanta, GA 30329.

_^' American National Standards Institute, Inc., 1430 Broadway, New York, NY

10018.

A-23

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

REFERENCES B-8

ABBREVIATIONS B-9

SI CONVERSION UNITS B-10

B-a
INTRODUCTION

Appendix B contains tables which have been complied 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.

B-b
Table B.l List of Test Properties, Test Method Designations and Titles

Property

Test Method

Designation Number Title

VISUAL OBSERVATION

Chalking ASTM D659-80 Standard Method of Evaluating

Degree of Chalking of Exterior

Paints

Checking ASTM D660-44

(Reapproved 1976)

Standard Method of Evaluating

Degree of Checking of Exterior

Paints

Cracking ASTM D661-44

(Reapproved 1975)

Standard Method of Evaluating

Degree of Cracking of Exterior

Paints

Blistering ASTM D7 14-56

(Reapproved 1974)

Standard Method of Evaluating

Degree of Blistering Paints

OPTICAL PROPERTIES

Solar

Transmittance

Solar

Reflectance

Emittance

ASTM E424-71

ANSI Z138. 7-1973

ASTM E424-71

ANSI Z138. 7-1973

ASTM E408-71

(Reapproved 1980)

ASTM E434-71

(Reapproved 1980)

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 Inspection-Meter Techniques

Standard Test Method for

Calorimetric Determination of

Hemispherical Emittance and the

Ratio of Solar Absorptance to

Hemispherical Emittance Using

Solar Simulation

Hardness

PHYSICAL PROPERTIES

ANSI/ASTM D785-65

(Reapproved 1976)

Standard Test Method for Rockwell

Hardness of Plastics and Electrical Insulating Materials

B-1
Table B.l (Continued)

Property

Test Method

Designation Number Title

Hardness

Dimensional

Stability

Tensile Strength

Tensile Strength

Tensile Strength

Tensile Strength

Tensile Strength

Loading or Compression

Strength

Loading or Compression

Flexure Strength

Flexure Strength

Flexure Strength

ANSI/ASTM D2583-75

ANSI/ASTM D2122-76

Standard Test Method for

Indentation Hardness of Rigid

Plastics by Means of a Barcol

Impressor

Standard Method of Determining

Dimensions of Thermoplastic Pipe

and Fittings

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

ANSI/ASTM D2412-77

ANSI/ASTM C158-80

ASTM C393-62

(Reapproved 1980)

ANSI/ASTM D790-80

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

B-2
Table B.l (Continued)

Test Method

Property Designation Number Title

Fatigue ANSI/ASTM D671-71 Standard Test Method for

(Reapproved 1978) Flexural Fatigue of Plastics by

Constant Amplitude of Force

Burst or Rupture ANSI/ASTM D1598-76 Standard Test Method for Tlmeto-Fallure of Plastic Pipe Under

Constant Internal Pressure

Burst or Rupture ANSI/ASTM D1599-74 Standard Test Method for Short-

(Reapproved 1980) Time Rupture Strength of Plastic

Pipe, Tubing and Fittings

Burst or Rupture ANSI/ASTM D2143-69 Standard Test Method for Cyclic

(Reapproved 1976) Pressure Strength of Reinforced

Thermosetting Plastic Pipe

B-3
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B-4
Table B.3 Characteristics of Absorptive Coatlngal/

Property

Material

Absorptancel.^ Ealttance

e Breakdoim

Teaperature

•F CC)

Coaaents

Anodic Alualnua

.94-.96 .3-.8 1.2-3 May be Influenced by aoisture

Black Chroae .87-.93 .1 ~9

Alkyd Enaael .9 .9 1 Durability Halted at high teaperatures

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 ealttance

for thicknesses >10wa

Flat Black

Paint

.95-. 98 .89-. 97 -1

Ceraalc Enaael .9 .5 1.8 Stable at high

teaperaturea

Black Zinc .9 .1 9

Copper Oxide over Alualnua.93 .11 8.5 392 (200)

Black Copper

over Copper

.85-. 90 .08-. 12 7-11 842 (450) Patlnates with

aoisture

Black Chroae over Nickel

.92-. 94 .07-. 12 8-13 842 (450) Stable at high tevaratures

Black Nickel

over Nickel

.93 .06 15 842 (450) May be influenced by aoisture at elevated

Ceaperature*

Nl-Zln-S over

Nickel

.96 .97 14 536 (280)

Black Iron over Steel

.90 .10 9

i/ These values iiere obtained froa the following references:

G. E. McDonald, "Survey of Coatings for Solar Collectors', NASA TNX-71730, paper presented at Workshop on Solar Collectors for Heating and Cooling of Buildings, Noveaber 21-23, 1974, New

York City.

G. E. McDonald, "Variation of Solar-Selective Properties of Black Chroae with Plating Tlae", NASA TMX-71731, May 1975.

S. W. Moore, J. D. Balcoab, J. C. Hedstroa, "Design and Testing of a Structurally Integrated

Steel Solar Collector Unit Based on Expanded Plat Metal Plates", IA-OR-74-1093 , paper presented

at U.S. Sectlon-ISES Meeting, Ft. Collins, Colorado, August 19-23, 1974.

D. P. Grlaaer, S. H. Moore, "Practical Aspects of Solar Heating: A Review of Materials Used la Solar Heating Applications", U-UR-75-1952, paper presented at SAMPB Meeting, October 14-16, 1975, Hilton Inn, Albuquerque, MN.

R. B. Toenjes, "Integrated Solar Energy Collector Final Suaaary Report", LA-6143-MS, tos Alaaos Scientific Laboratory, Los Alaaos, New Mexico, Noveaber 1975.

G. L. Merrill, "Solar Heating Proof-of-Concept Bxperlaent for a Public School Building", Honeywell

Inc., Minneapolis, Minnesota, National Science Foundation Contract No. C-870.

D. L. Klrkpatrick, "Solar Collector Design and Perforaance Experience", for the Grover Cleveland

School, Boston, Massachusetts, paper presented at Workshop on Solar Collectors for Heating and Cooling of Buildings, Noveaber 21-23, 1974, New York City.

a Dependent on thickness and vehicle to binder ratio. B-5
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B-6
Table B.5 Typical Properties of Selected Building Materials for Solar Application*

Property

Material

Absorptance Eaittance

Specific Heat Theraal

Afflbient Density lb/ft5 Conductivity

Btu/(lb)CF) Btu in/h'ft2.«F

[J/(Kg-K)l (Kg/m3) IW/(»2.K)]

Expansion

Coefficient in/in/°Fxl0-6

[cn/cn/'CxlO-*)

MASONRT

Brick***

(Glazed, white to cream) 0.26 to 0.35 0.92 0.22

[921) 130(2080)

1.3 to 3.8

(0.19 to 0.55)

5 to 9 [0.72 to 1.30)

3.6 to 8.5

(6.5 to 15.3)

Brick***

(Cooaon, light red to red) 0.52 to 0.68 0.93 0.22[921) 120(19201 Same Same

Brick***

(Malted purple to blue)

0.77 to 0.89 0.22

[921) 130(2080) SaM Same

Concrete, stone aggregate

(Soooth, light) 0.60 to 0.65 0.88 0.20[834) 120

(1920

to 140

to 2440) 0.9 to 12.0

[0.13 to 1.73) 5.5[9.91

Concrete, stone aggregate

(Rough, light) 0.60 to 0.85 0.94 0.20

[834) 120

[1920

to 140

to 2240)

Same Sane

Concrete, stone aggregate

(Pigmental, dark)

0.85 to 0.91 0.97 0.20

(834) 120

(1920

to 140

to 2240) Same Same

Stone

(Light color) 0.35 to 0.54 0.36 0.21 to 0.25

[880 to 1050)

117 (1870

to 187 to 3000)11 to 20 [1.59 to 2.88) 3.6 to 22 (6.5 to 39.6]

Stone (Dark color) 0.50 to 0.73 0.90 0.21 to 0.25

[880 to 1050]

117 [1870

to 187

to 3000) Same Same

Clay Floor Tile

(Light color) 0.20 to 0.50 0.19

(800)

12 to 20

(1.73 to 2.88)

Clay Floor Tile

(Dark color) 0.50 to 0.80 0.19

[8001 Same

METALS

Aluminum (Polished) 0.10 to 0.40 0.03 0.21 (880) 171 (2740) 1404 (202.5) 13.9 [25.0]

Aluminum (Dull) 0.40 to 0.65 0.09 0.21 (880) 171 (2740) 1404 [202.51 13.9 (25,0)

Copper (Bright) 0.18 to 0.40 0.07 0.09 (380) 556 (8910) 2688 [387.7) 9.2 [16.6]

Copper (Tarnished) 0.40 to 0.64 0.20 0.09 (380) 556 (8910) 2688 (387.7) 9.2 (16.6)

Iron (Oxidized) 0.80 to 0.92 0.94 0.12 [5001 (212*F)

450 (7210) 384 ( 55.4) 6.7 (12.1)

Steel - - 0.12 (500) 489 (7830) 314 [ 45.3) 9.6 [17.31 WOOD

Hardwood 0.90 0.06 (2510) 23 1 [370 1to 70

CO 1120) 0.8 to 1.8[0.12 to 2.6)

1.1 to 5.3

[2.0 to 9.6)

Softwood 0.60 0.06 to 0.7 (2510 to 2930)

22 1 [350 1Co 46

to 740) 0.7 to 1.1

[0.10 to 0.161

Same

WATER

Clear

Black (1/2 percent carbon suspension)

1.00

1.00 (4.19) 62.4 [1.001

1.00 (4.19) 62.4 [1.00]

4.1

4.1

Varies (Water expands

about 4Z in volume

from 40 to 200°F)

* These values were taken from different sources, as referenced below, and are meant to serve as a guide only. U "Handbook of Air Conditioning, Heating and Ventilating', Clifford Strock and Richard L. Koral, Industrial Press, Inc., New Tork, NT, Second Edition, 1965.

1/ "Handbook of Fundamentals", American Society of Heating, Refrigerating and Air Conditioning Engineers, 1791 Tullle

Circle, Atlanta GA 30329. ASHRAE 1977.

}LI 'Building Construction Handbook", Chapter 2, McGraw-Hill Book Company, Third Edition.

zl "Journal of Research of the National Bureau of Standards", Volume 6, page 1003. U 'Concrete Manual". Bureau of Reclamation, D.S. Department of Interior

** May vary with the water containment device.

*** For additional information on the properties of brick, see Technical Notes on Brick Construction . 43 D Sept/Oct 1980. "Brick Passive Solar Heating Systems - Material Properties - Part N". Brick Institute of America, McLean, Virginia.

B-7
ABBREVIATIONS (Code Groups, Associations and Gov't. Agencies)

AABC

AASHTO

ACCA

AIA

AIAA

ANL

ANSI

ARI

ASHRAE

ASME

ASPO

ASSE

ASTM

AWWA

BOCA

CABO

CDA

CPSC

DOE

EPA

FHA

FSEC

HUD

lAPMO

ICBO

ISES

LANL

NACE

NAHB

NASA

NBS

NCSBCS

NEBB

NFPA

NOAA

NWTI

ORNL

SAE

SAMPE

SBCC

SEIA

SERI

SEREF

SMACNA

UL

Associated Air Balance Council

American Association of State Highway and Transportation Officials

Air-Condi tioning Contractors of America

American Institute of Architects

American Industrial Arts Association

Argonne National Laboratory

American National Standards Institute, Inc.

Air-Conditioning and Refrigeration Institute

American Society of Heating, Refrigerating and Air-Conditioning

Engineers, Inc.

American Society of Mechanical Engineers, Inc.

American Society of Planning Officials

American Society of Sanitary Engineers

American Society for Testing and Materials

American Water Works Association

Building Officials and Code Administrators International, Inc.

Council of American Building Officials

Copper Development Association

Consumer Product Safety Commission

U.S. Department of Energy

U.S. Environmental Protection Agency

Federal Housing Administration

Florida Solar Energy Center

U.S. Department of Housing and Urban Development

International Association of Plumbing and Mechanical Officials

International Conference of Building Officials

International Solar Energy Society

Los Alamos National Laboratory

National Association of Corrosion Engineers

National Association of Home Builders

National Aeronautics and Space Administration

National Bureau of Standards

National Conference of States on Building Codes and Standards, Inc.

National Environmental Balancing Bureau

National Fire Protection Association

National Oceanographic and Atmospheric Agency

National Wood Tank Institute (ceased operations, standards

available)

Oak Ridge National Laboratory

Society of Automotive Engineers, Inc.

Society for the Advancement of Material and Process Engineering

Southern Building Code Congress International, Inc.

Solar Energy Industries Association, Inc.

Solar Energy Research Institute

Solar Energy Research and Education Foundation

Sheet Metal and Air-Conditioning Contractors' National

Association, Inc.

Underwriters Laboratories, Inc.

B-8
SI CONVERSION UNITS

Length

1 in = 0.0254 meter (exactly)

1 ft = 0.3048 meter (exactly)

Area

1 in2 = 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"^ meter^

Mass

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

1 pound-mass (avoirdupois) = 0.4536 kilogram

Pressure or Stress (Force/Area)

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

1 pound-force/ inch'^(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 103 j/kg»K (specific heat)

1 langley = 4.184 x 10^ J/m2 = 1 cal/cm2 = 3.69 Btu/ft2

B-9
/
COMPOSITE 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 2.3.1

HW load 2.3.4

Performance 2.8.4

Priority 2.7.4

AUXILIARY SYSTEMS

Controls 2.7.4

Cooling (sizing) 2.3.2

Service hot water 2.2.4, 2.3.4

BACKFLOW

Prevention 4.1.3

BACKSIPHONAGE

Prevention 4.1.3

BLOWERS

Operating energy 2.6.1, 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

Overheating 2.1.1, 2.1.2

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

Design Conditions 2.1

Natural factors 1.1

Orientation 1.2

Site Consideration 1.2

CALCULATION, SOLAR CONTRIBUTION

Heat loss 2.2.1, 2.3.1

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

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

COLLECTORS

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

Cleaning glazing 3.3.5

Degradation by wear 5.4.1

Effect of roof deterioration

6.2.5

Energy transfer rate 2.6.3

I-l
COLLECTORS (Continued) COMPUTER PROGRAMS

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) 2.4.1

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 2.5

Structural safety 4.6

Thermal cycling degradation 5.2.2

Thermal degradation 5.2.1

COLLECTORS, PASSIVE

CALPAS 2.2.1, 2.2.2

DALITE 2.2.1, 2.2.2, 2.2.3

DEROB 2.2.1, 2.2.2

DoE-2 2.2.1, 2.2,2

F-Chart 2.9.1

LUMEN II 2.2.1, 2.2.2, 2.2.3

NBSLD 2.9.1

PASOLE 2.2.1, 2.2.2

PEGFIX/PEGFLOAT 2.2.1, 2.2.2

Quicklite I 2.2.1, 2.2.2, 2.2.3

SINDA 2.2.1, 2.9.1

SOLCOST 2.2.1, 2.9.1

SUNCODE 2.2.1, 2.2.2

TEANET 2.2.1, 2.2.2

TRNSYS 2.2.1, 2.2.2

CONDENSATION

Adverse effects (building or

site) 1.2, 1.3, 1.4

Performance of components or materials 5.1.2

Trombe walls 1.3, 1.4, 2.1.1

Water walls 1.3, 1.4, 2.1.1

Windows 1.3, 1.4, 2.1.1

COMBUSTIBLE LIQUID

CONDITIONED SPACE

Overheating 2.1.2

Shading 1.3

Thermal condition 2.1.1

Drain and filling 3.2.5

Handling 4.4.2

Liquid flash point 4.4.1

COMBUSTIBLE MATERIALS

CONTAINERS, STORAGE

Safety hazards 4.2

CONTAMINATION

Adjacent to high temperature

components 4.4.7

Flame spread of insulation 4.4.3

Warning to maintenance personnel

6.1.4

COMFORT CONDITIONS

Occupied space 2.1.1

COMPONENT/ SYSTEM

Air 4.1.4, 4.1.5

Backflow preventor 4.1.3

Dyes 4.1.1

Growth of fungi 4.1, 4.1.5

Hazards 4.1

Heat exchanger 4.1

National Interim Primary Drinking

Water Regulat ion 4.1.1

Potable water 4.1.1

CONTROLS

Interaction 1.4, 2.8

Thermal expansion 3.2.8

Auxiliary energy 2.7.4, 3.5.5

Service hot water 3.5.2

1-2
CONTROLS (Continued) DAMPERS

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

Performance 2.7, 3.5

Priority of energy use 2.7.4

Protection during installation

and shutdown for maintenance

3.5.3, 6.1.6, 6.1.7

Sensor location 3.5.4

System checkout 6.3.1

Temperature and pressure limit

3.5.3

Tracking 3.5.6

CORROSION

Air pollution 1.1, 5.1.3

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

COVER PLATES

Exposed to pollutants 1.1, 5.1.3,

Injuries due to accidental

contact 4.3.3

Materials 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

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, 2.7.3, 3.3.3

Operating conditions 3.3.3

Sealing 3.3.3

Sizing 3.3.1

Thermos iphoning 2.7.3

DEFLECTION

Caused by loads 3.1.4, 4.3.3

Cover plates 4.3.3

Draindown systems 3.6.2

Ponding 4.6.1

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 2.2.1, 2.2.2,

2.2.3, 2.9.1

DESIGN LIFE

Effect of temperature 5.2

Thermal degradation 5.2.1

DIAGRAMS

Flow and wiring 6.1.2

DRAINBACK 3.6.2

DRAINDOWN 3.6.2

1-3
DUCTS

Air leakage 2.4,3, 2.6.1, 3.3.2,

3.3.4,

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

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 2.6.2, 2.9.1

Depletable energy use 2.2.1, 2.2.2,

2.2.3, 2.9.1

Dumping 2.4.5, 4.3.2

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 (Dissipation) 2.4.5

Requirements for mechanical space

cooling system 2.2.2, 2.3.2

Requirements for mechanical space

heating 2.2.1, 2.3.1

Transfer rate 2.6.4

ENERGY TRANSPORT

Air leakage 2.6.1

Combustible liquids 4.4.2

Flash point 4.4.1

Liquid quality 6.2.1

ENERGY TRANSPORT (Continued)

System balancing 3.1.2

ENVIRONMENT

External factors affecting

solar systems 1.1, 1.2, 5.1

EXCESS HEAT

Dissipation 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

Checkout 6.3.1

Collector efficiency 2.4.2

Collector loop 2.6.3

Heat transfer fluid 2.8.3

Liquid velocities 3.1.2, 3.2.1

1-4
FLOW RATE (Continued) GLAZING (Continued)

Operating energy 2.6.2

System design 3.1

Variations 2.4.2, 2.8.3, 3.1.2

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 2.7.2

Hot water 2.2.4

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

GLAZING

Acceptable methods of cleaning

6.1.2

Compatability of adjacent

materials 5.3.3

Condensation 3.4.2, 5.1.2

Deflection 4.3.3

Dirt deposits 1.1, 1.3, 3.3.5

Reduce risk and injuries from

accidental contact 3.1.4,

4.3.3

Safety (See "Safety of Building

and Site")

Temporary coverings 6.1.6

Thermal degradation 3.1.1, 5.2.1

Transmissivity 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, 2.6.5, 2.8.3

System balance 3.1.2

HEAT LOSSES

Collector-to-storage 2.6.1

Due to freeze protection 2.4.4

During non-collection periods 2.4.4,

From thermal storage 2.5.1

Manifold losses 2.4.3

Thermos iphoning, reverse 2.4.4,

2.7.3

HEAT TRANSFER FLUID

Degradation 5.3.1

Quality 6.2.1

Velocity 2.8.3, 3.2.1, 3.3.1

Viscosity changes 5.2.1

HEATING SYSTEM

Auxiliary heating system sizing

2.3.1, 2.8.4

Building heat loss calculation 2.2.1

1-5
HEATING SYSTEM (Continued)

Design load calculation 2.2.1

HOSES

Compatibility with transfer

fluids 5.3.1

Exposed to pollutants 5.1.3

HOT WATER SYSTEM (see "Service

Hot Water")

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 2.2.1, 3.4.2, 4.4.4,

6.1.7

Protection of exposed pipe and duct

3.1.3, 3.2.1, 4.4.4

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 2.7.3

Dampers 2.4.4, 2.7.3

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

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

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

1-6
MANIFOLD (Continued) OPERATING ENERGY

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 2.3, 2.8.4

MECHANICAL SYSTEM

System sizing 2.3, 2.8.4

MOISTURE DEGRADATION

Collectors 5.1.2

Efflorescence 5.1.2

MONITORING

Access for system 6.3.3

NO-FLOW

Aging procedure 5.2.1

Excessive pressure and

temperature 4.3.1, 4.3.2

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 2.4.4, 2.4.5

Radiation 2.3.2, 2.4.4, 2.4.5

OCCUPANT

Manual of instruction 6.1.7

Required activity 6.1.7

Blowers, pumps, and valves

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

Desiccant cooling 2.3.2

Evaporation 2.3.2

Nocturnal radiation 2.3.2

PASSIVE SOLAR

Classification 2.0

Components 3.4

Contribution to conditioned space

2.1

Movable insulation 3.4.2

Net solar contribution 2.2

Overheating 2.1.2

Panels - protection from

accidental contact 4.3.3

Reduce space condition

energy requirement 2.2

Seasonal contribution 2.2

Shading 1.3, 2.2.2

PENETRATIONS

Buildings 1.4

Fire resistance 4.4.5

Roof 6.2.5

PERFORMANCE

Collector panel 2.4.2

Efficiency curves 2.4.2

1-7
PERFORMANCE (Continued) PUMPS (Continued)

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

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

components 5.3

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

Collector selection 2.8.1

Conversion to thermal energy 2 .4

,

2.4.1

Nocturnal 2.3.2

No flow conditions 4.3.2,

Appendix A, Section 10

Shading devices 1.3, 2.2.2

Site considerations 1.2

Solar degradation 5.1.1, 5.1.3

Thermal storage exposure 2.1.1,

2.2.1, 2.8.2

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 2.5.2

Cleanliness 4.1.4

Size 2.5.2

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

1-8
SAFETY PROVISIONS (Continued) SHADING

Lightning 4.3.8

Liquid flash point 4.4.1

Structural 4.6

SAFETY OF BUILDING 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

SERVICE HOT WATER

Auxiliary system 2.2.4, 2.3.4

Daily water use rate 2.1.3, 2.3.4

Energy use 2.9.1

Fail-safe 3.5.2

Limits controls 3.5.3

Recovery rate (hourly) 2.1.3, 2.3.4

Scalding 4.3.4

Storage 2.1.3

Tap temperature 2.1.3, 4.3.4

Temperature control 3.5.2

SETPOINTS

Collection loop 2.7.2

Devices to reduce cooling load

1.3, 2.2.2

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

Lightning protection 4.3.8

Usability of roof for firefighting or egress 4.5.2

SOLAR SYSTEM/ BUILDING

INTERACTION 1.4, 2.8

SPACE COOLING SYSTEM

Maintain comfort conditions

2.1.2

SPACE HEATING SYSTEM

Auxiliary design 2.3.1, 2.8.4

Measured performance (F-Chart)

2.9.1

Operation and maintenance 6.1.2

SPACE, INTERIOR

Planning and coordinating 1.3

SPACE, OCCUPIED

Design conditions 2.1.1, 2.1.2

STORAGE CONTAINERS

Air leakage 2.5.1

1-9
STORAGE CONTAINERS (Continued)

Chemical compatibility of

components 5.3.1, 5.3.3

Corrosion 4.3.6

Drainage provisions 3.3.5

Energy loss 2.5.1

Glazing 4.3.3

Hazards 4.3

Insulation 3.1.3

Sizing 2.5, 2.8.2

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

3.1.4, 4.3.3, 4.6.1

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

STRUCTURAL DESIGN LOADS (LOADS,

STRUCTURAL) (Continued)

Snow and ice 4.6.1

Wind 4.6.1

TEMPERATURE

Comfort 2.1.1, 2.1.2

Design 2.1

Effect 5.2

Hot water at tap 2.1.3, 4.3.4

Overheating 2,1.2

THERMAL DESIGN LOADS (LOADS,

THERMAL)

Hot water 2.1.3, 2.2.4

Space cooling 2.2.2

Space heating 2.2.1

THERMAL PROPERTIES

Storage materials (Appendix B)

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

Effect of interior items 1.4

Energy loss 2.5.1

Hot water load 2.3.4, 2.5

In building mass 2.2.1

Insulation 2.5.1

Performance 2.5

Potential for fungus growth

4.1.5

Sealing 3.3.2

Size 2.8.2

Stratification 2.5.2

Thermally-coupled area 2.1.1, 2.2.1

Trombe walls 2.1.1

Use of building mass 2.2.1

I- 10
THERMOSIPHON TRANSPORT SYSTEM (Continued)

Collection loop 2.4.4, 2.6.3, 2.7.3

Hot water system 2.2.4, 2.6.3,

3.2.1

Non-collection period losses

2.4.4, 2.7.1, 2.7.3

Prevention 2.7.2, 2.7.3

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 5.1, 5.2, 5.3

TRANSMITTANCE

Glazing 5.1, 5.2, 5.3

TRANSPORT ENERGY

Collector loop rate 2.6.3

Load transfer rate 2.6.4

Losses 2.6.1

Passive 3.4.1

Performance 2.6

TRANSPORT SYSTEM

Balancing 3.1.2

Energy loss 2.6.1

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, 3.3.4

TROMBE WALLS

Application 2.1.1

Efflorescence on absorber surfaces

5.1.2

Provision for recoating 6.2.2

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-building 2.2.2

VENTING

Draindown systems 3.6.2

Piping, during filling operation

3.2.2, 3.2.6

Thermal expansion of fluids 3.2.4

I-U
VISCOSITY

Heat transfer fluids 2.4.2, 2.6.2

Pump selection 3.2.10

WALLS, THERMAL STORAGE

Trombe walls 2.1.1

Water walls 2.1.1

WATERPROOFING

Exposed insulation 5.1.2

WEAR

Degradation 5.4.1

WINDOWS

Impact on space cooling loads

1.3, 2.2.2

Solar radiation 2.2.1, 2.2.2

WINDS, WINTER

Protection 1.1, 1.2, 1.3

^U.8. OOVERNMENT PRINTINO OFFICE: 198«» •20 997 96

1-12
NBS-n4A (REV. 2^0)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBS TN 1187

2. Performing Organ. Report No. 3. Publication Date ;^il 1984

4. TITLE AND SUBTITLE

Performance Criteria for Solar Heating and Cooling Systems in

Commercial Buildings

5. AUTHOR(S)

Center for Building Technology Staff

6. PERFORMING ORGANIZATION (/f joint or other than NBS, see ;n struct/on s) NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No. DE-AI01-76PRO6010

8. Type of Report & Period Covered

Final

Office of Solar Heat Tex^hnologies

U.S. Department of Energy

Washington, DC 20585

10. SUPPLEMENTARY NOTES

r~| Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual sun\mary of most significant Information. If document includes a significant

bibliography or literature survey, mention it here)

This document establishes baseline criteria for the design, development,

technical evaluation and procurement of solar heating and cooling systems for

commercial buildings. These performance criteria were developed in accordance

with Public Law 93-409 the "Solar Heating and Cooling Demonstration Act of

1975." The document is intended as a resource for use in establishing minimum

acceptance levels of performance for solar heating and cooling systems. Criteria which deal with public health and safety are in compliance with general

building 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 for conventional space conditioning equipment. By the use of performance language in the

document, it is believed that sufficient latitude has been provided to allow

innovation and flexibility that is essential for the stimulation of a viable

solar Industry.

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

I I For Official Distribution. Do Not Release to NTIS

fvl Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

I I Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

229

15. Price

USCOMM-DC e043-P80





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systems, and whole structures. The series presents research results,

test methods, and performance criteria related to the structural and

environmental functions and the durability and safety characteristics of building elements and systems.

Technical Notes—Studies or reports which are complete in themselves but restrictive in their treatment of a subject. Analogous to_ monographs but not so comprehensive in scope or definitive in treatment of the subject area. Often serve as a vehicle for final reports of work performed at N BS under the sponsorship of other government agencies.

Voluntary Product Standards—Developed under procedures

published by the Department of Commerce in Part 10, Title 15, of

the Code of Federal Regulations. The standards establish nationally recognized requirements for products, and provide all concerned interests with a basis for common understanding of the

characteristics of the products. N BS administers this program as a supplement to the activities of the private sector standardizing

organizations. Consumer Information Series—Practical information, based on N BS research and experience, covering areas of interest to the con- sumer. Easily understandable language and illustrations provide

useful background knowledge for shopping in today's technological marketplace. Order the above NBS publications from: Superintendent of Documents. Government Printing Office. Washington. DC 20402. Order the following NBS publications—FlPS and NBSIR's—from

the National Technical Information Service, Springfield, ^A 22161.

Federal Information Processing Standards Publications (FIPS

PUB)—Publications in this series collectively constitute the Federal Information Processing Standards Register. The Register

serves as the official source of information in the Federal Govern- ment regarding standards issued by NBS pursuant to the Federal Property and Administrative Services Act of 1949 as amended,

Public Law 89-306 (79 Stat. 1127), and as implemented by Executive Order 11717(38 FR 12315, dated May II, 1973) and Part 6 of Title 15 CFR (Code of Federal Regulations).

NBS Interagency Reports (NBSIR)—A special series of interim or

final reports on work performed by NBS for outside sponsors

(both government and non-government). In general, initial dis- tribution is handled by the sponsor: public distribution is by the National Technical Information Service , Springfield, VA 22161,

in paper copy or microfiche form.
U.S. Department of Commerce

National Bureau of Standards

Washington, D.C. 20234

Official Business

Penalty for Private Use S300