EPA/600/A*93/186
STATUS OF ASHRAE STANDARD 62-
VENTILATION FOR ACCEPTABLE INDOOR AIR QUALITY
W. Gene Tucker, Chairman ASHRAE SSPC62
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina, USA
ABSTRACT
This paper briefly describes the purpose, history, and major features of American Society of
Heating, Refrigerating and Air-conditioning Engineers (ASHRAE) Standard 62. The
primary focus of the paper is on the status of the review and revision process as of January
1993. The current working outline of the revised standard is presented and discussed. The
complementary roles of ventilation, source management, and air cleaning are emphasized.
Extending the standard beyond ventilation system design to include operation and maintenance
of buildings and ventilation systems is also projected.
INTRODUCTION
ASHRAE Standard 62 contains design procedures and guidelines for ventilation rates in "all
indoor or enclosed spaces that people may occupy, except where other applicable standards
and requirements dictate larger amounts of ventilation than this standard." Standard 62 is the
basis for ventilation requirements in many codes for commercial, institutional, and residential
buildings in North America. The Standard is reviewed every 5 years or less, then updated
as needed to incorporate new information or improve its usefulness to building designers and
code officials. The initial version of the standard was issued in 1973 (1). It was updated in
1981 (2), and most recently in 1989 (3). Distinctions among those versions of the standard
are summarized elsewhere (4,5).
ASHRAE has formed a new committee—SSPC62~to review and update Standard 62. This
paper highlights some of the key features of the current standard and summarizes the status
of the review process.
THE CURRENT STANDARD: 62-1989
The purpose of Standard 62-1989 is "to specify minimum ventilation rates and indoor air
quality that will be acceptable to human occupants and are intended to minimize the potential
for adverse health effects." While this standard is primarily considered a design standard for
heating, ventilating, and air-conditioning (HVAC) systems, the foreword to the document
states: "...the conditions specified by this Standard must be achieved during the operation of
buildings as well as in the design of the buildings if acceptable indoor air quality is to be
achieved." To facilitate this, the standard requires that ventilation design documentation be
provided as guidance for ventilation system operation.
For purposes of this standard, acceptability of indoor air is based on both health and comfort
considerations (the comfort term refers to sensory rather than thermal comfort). The
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foreword of the standard states: "For substantive information on health effects, the Standard
must rely on recognized authorities and their specific recommendations. Therefore, with
respect to tobacco smoke and other contaminants, this standard does not, and cannot, ensure
the avoidance of all possible adverse health effects, but it reflects recognized consensus
criteria and guidance." Health-based criteria and guidelines are listed for the following
contaminants: sulfur dioxide, particulate matter smaller than 10 micrometers in diameter
(PM10), carbon monoxide, ozone, nitrogen dioxide, lead, chlordane, and radon. The single
contaminant listed for sensory comfort criteria-carbon dioxide (CO2)-is listed as a surrogate
for human (body) odor. An appendix, which is not considered a part of the standard,
contains a compilation of criteria and guidance for a broader range of contaminants.
The Ventilation Rate Procedure prescribes the rate at which ventilation air must be delivered
to a space and various means to condition that air. Ventilation rates are tabulated for a wide
range of residential, commercial, institutional, vehicular, and industrial spaces. These rates
are described in terms of either liters/second of outdoor air per person of occupancy, or
liters/second per square meter of floor area. The tabulated ventilation rates are derived from
physiological considerations, subjective evaluations, and professional judgements.
The tabulated values of outdoor air requirements "prescribe supply rates of acceptable outdoor
air required for acceptable indoor air quality. These values have been chosen to control CO2
and other contaminants with an adequate margin of safety and to account for health variations
among people, varied activity levels, and a moderate amount of smoking." An appendix
contains a discussion of the basis for the absolute minimum value of 7 liters/second (15 cubic
feet/minute) per person, to maintain indoor CO2 levels below the 1,000 parts per million
concentration that is associated with acceptability of occupant odor.
The Ventilation Rate Procedure also includes a statement that is often overlooked: "Where
unusual indoor contaminants or sources are present or anticipated, they should be controlled
at the source or the procedure of 6.2 shall be followed." The procedure of Section 6.2 is the
Indoor Air Quality Procedure.
The Indoor Air Quality Procedure is presented as an alternative to the Ventilation Rate
Procedure. Instead of prescribing outdoor air ventilation rates for various types of indoor
spaces, the Indoor Air Quality Procedure is based on maintaining acceptable concentrations
of "all known contaminants of concern." In principle, this procedure provides a better basis
for protecting public health. However, it requires knowledge of contaminants that will be
present, acceptable concentrations of these contaminants to protect health and ensure sensory
comfort, and sources of these contaminants. Furthermore, Standard 62 contains very little
information on how to use this procedure.
Use of the Indoor Air Quality Procedure is very limited at present. Consensus on acceptable
concentrations is available for only a very limited number of contaminants, and there are very
limited data on emission rates of contaminants from sources. As more information becomes
available on sources and their emissions, and the health and comfort effects of those
emissions, use of this procedure may very well increase. With further development it could
be a very useful design tool for evaluating trade-offs between increased ventilation, source
management, and air cleaning as options for achieving occupant health and comfort.
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STATUS OF REVIEW AND REVISION
As part of ASHRAE's policy to review standards every 5 years, a new committee was
formed in January 1992 to review Standard 62-1989, and to develop revisions as needed.
The committee consists of 25 designers, equipment manufacturers, regulators, and researchers
(5).
Special emphasis is being placed on reviewing the scientific information that can be used as
the basis for the health and sensory comfort guidance that the document uses to define
acceptable indoor air quality. Another special emphasis is on making clearer links between
sources of contaminants and control of indoor air quality by ventilation, source management,
or air cleaning. Progress in these two areas is key to improving the soundness and usefulness
of the two design procedures.
Figure 1 shows the current working outline for the body of a revised Standard 62. As
currently envisioned, the Foreword will note changes from 62-89, which might include
Foreword
1. Purpose
2. Scope
3, Definitions
4. General Requirements
5. Design Procedures for Commercial-Institutional Buildings
5.1 Determining the Design Ventilation Rate
5.2 Procedure for Minimum Ventilation Rates
5.3 Procedure for Additional Ventilation Rates
6. Design Requirements for Residential Buildings
6.1 Single-Family Residences
6.2 Multiple-Family Residences
7. Documentation of Design and Operational Guidelines
8. Operating and Maintenance Procedures
8.1 HVAC System
8.2 Building Operation and Maintenance Activities
9. References
Figure 1. Working Outline for Revision of the Body of Standard 62
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separate treatment of residential buildings; new emphasis on source management, air cleaning,
and operations and maintenance over the life cycle of the building; and use of code language
to facilitate adoption in building codes. Sections 1 and 2 will likely be modified slightly to
better reflect the relationship between ventilation and indoor air quality, and to incorporate
any changes in the concept of acceptability of indoor air quality.
Section 4 is designed to present the general principles of ventilation, define the role it plays
in providing and maintaining air quality, and summarize good engineering practice in
designing and operating buildings for good indoor air quality. The purposes of ventilation,
its positive and negative impacts on indoor air quality, and the distinction between dilution
ventilation and exhaust ventilation will be explained. General guidance will be given on such
topics as exhausting air near strong sources of contaminants, transferring air from low-
concentration to higher-concentration areas in a building, locating air intakes to provide good-
quality outdoor air, and operation of the ventilation system during transient occupancies and
periods of high emissions such as maintenance activities. Design and operational guidance
on how to prevent conditions that promote growth and dispersion of microbials will be made
more explicit than in the current version of the standard.
Section 5 will describe the design procedures for determining ventilation rates for commercial
and institutional buildings. The design ventilation rate is expected to be defined as the sum
of a minimum rate and an additional rate. The first step of the procedure will be to
determine the minimum ventilation rate (i.e., amount of outdoor air) for each occupied space
in the building. This step is the same as using the Ventilation Rate Procedure in the current
standard. It accounts for contaminants emitted by occupants and sources unique to particular
spaces (e.g., stoves in kitchens, dry cleaning machines in dry cleaning establishments). The
second step will be to determine whether additional ventilation is required for any of the
spaces, using the approach implied by the current Indoor Air Quality Procedure. Sources
with potentially high emission rates of contaminants will be listed, along with default emission
rates and simple equations to calculate additional ventilation rates. The possibility of allowing
use of certified low-emission products instead of additional ventilation is being considered.
In any event, the designer has an incentive to consider source management as an alternative
to additional ventilation.
Section 6 will deal with residential buildings, both single- and multiple-family. Buildings
with and without mechanical ventilation systems will be covered. This section will expand
on the limited guidance in Standard 62-1989 and make it more prominent..
Section 7 will greatly expand the requirements of the current standard for documenting the
bases and assumptions used in designing the building and the ventilation system. It will likely
include a requirement to document instructions on how to operate the HVAC system. This
section will most likely include a checklist or a format of items to be documented. This
requirement is important in enabling proper operation and maintenance of the building, which
can have major impacts on indoor air quality.
Section 8 will emphasize the importance of building (and HVAC) operation and maintenance.
It is expected to cover such topics as HVAC system operation during transient occupancy and
building maintenance activities, maintenance of key HVAC system components, and
monitoring environmental conditions. This section, new to Standard 62, will convey the
importance of attending to indoor air quality beyond the design stage, through the entire life
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of the building.
Figure 2 shows the working outline for the appendices of the standard. Although not
traditionally considered an official part of Standard 62, appendices may have new standing
in the revised version because ASHRAE is considering classifying appendices (or annexes)
as "informative" or "normative"; the normative appendices would have essentially the same
authoritative status as the body of the standard.
Appendices
A-Conversion Factors
B- Positive Combustion Air Supply
C- Health and Comfort Criteria
D-Rationale for Ventilation Rate Procedure
E- Design Guidelines for Ventilation Effectiveness
F- Design Guidelines for Transient Occupancy
G- Method for Determining Rate of Outdoor Air Delivered to a Space
H- Example Calculations of Design Ventilation Rates
Figure 2. Working Outline for Revision of the Appendices of Standard 62
Primary changes from appendices in the current standard are an updating of health and
comfort criteria (appendix C), specification of method(s) for measuring the outdoor air rate
to a space (G), and example calculations of ventilation design rates (H). The example
calculations will cover various typical scenarios of building type, HVAC system type, and
climate. For each scenario, the selection of minimum ventilation rate, calculation of
additional ventilation rate for spaces with strong sources, and determination .of design
ventilation rate will be illustrated. Options for source management and air cleaning will be
presented for scenarios requiring large amounts of additional ventilation.
SUMMARY
Standard 62-1989 provides state-of-knowledge guidance on ventilation system design and
operation practices that will help provide good air quality in commercial and residential
buildings. This standard is being continually reviewed and updated to reflect new
information, especially on public health aspects of indoor air and sources of indoor
contaminants.
The current review is focused on issues that have been raised over the past several years in
various technical meetings and in feedback to ASHRAE from the design community. It is
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unreasonable to expect ventilation, which acts primarily by dilution and displacement of
indoor contaminants, to provide acceptable indoor air quality by itself. Special emphasis is
therefore being given to the health and comfort basis of the standard and to describing the
complementary roles of source control and air cleaning for providing good indoor air quality.
The review committee is also committed to simplifying and clarifying the standard where
possible, in response to requests from design engineers and building code officials.
The primary changes from Standard 62-1989 that are currently being considered are to
provide separate sections for residential buildings and design documentation; new material
on operations and maintenance and design calculations; more explicit treatment of source
management and air cleaning as options to ventilation for ensuring acceptable indoor air
quality; and clarifications or modifications to the Ventilation Rate and Indoor Air Quality
Procedures. It is also the revision committee's intention to use "code language" to make
Standard 62 easier to adopt by governmental bodies that establish legal specifications (codes)
regarding design and operation of buildings and their HVAC systems. An alternative may
be to prepare a specification version for code officials, and a more extensive version with
guidance for designers and building owners and operators.
Other ventilation standards and guidelines (6,7) are being reviewed for ideas on how Standard
62 should be structured. Under the European ventilation guidelines, three design levels are
offered for perceived indoor air quality (which is similar to sensory comfort, as used in this
paper). Ventilation rates are calculated separately for health and perceived air quality; the
higher rate is recommended for design. These and other approaches will be considered by
the SSPC62 committee.
REFERENCES
1. ASHRAE standard 62-73 (ANSI B 194.1-1977), standards for natural and mechanical
ventilation. American Society of Heating, Refrigerating and Air-conditioning
Engineers, Inc. Atlanta, 1977.
2. ASHRAE standard 62-1981, ventilation for acceptable indoor air quality. American
Society of Heating, Refrigerating and Air-conditioning Engineers, Inc. Atlanta, 1981.
3. ASHRAE standard 62-1989, ventilation for acceptable indoor air quality. American
Society of Heating, Refrigerating and Air-conditioning Engineers, Inc. Atlanta, 1989.
4. Janssen, JE. 1989. Ventilation for acceptable indoor air quality. ASHRAE Journal,
31(10):41-48.
5. Tucker, WG. 1992. ASHRAE standard 62: ventilation for acceptable indoor air
quality. In: Proceedings on Indoor Air Quality, Ventilation and Energy Conservation
of the 5th International Jacques Cartier Conference, Center for Building Studies,
Concordia University, Montreal, pp. 211-219.
6. Guidelines for ventilation requirements in buildings. European concerted action-
indoor air quality and its impact on man, report no. 11. Commission of the European
Community, publication EUR 14449 EN. Luxembourg, 1992.
7. Australian standard AS 1668.2-1991, the use of mechanical ventilation and air-
conditioning in buildings, part 2: mechanical ventilation for acceptable indoor-air
quality. Standards Association of Australia. North Sydney, 1991.
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AEERL-P-1036
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before comp
1. REPORT NO.
EPA/600/A-93/186
2.
4. TITLE AND SUBTITLE
Status of ASHRAE Standard 62- Ventilation for
5. REPORT DATE
Acceptable Indoor Air Quality
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
W. Gene Tucker
8. PERFORMING ORGANIZATION REPORT NO,
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
See Block 12
11. CONTRACT/GRANT NO.
NA (Inhouse)
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Air and Energy Engineering Research Laboratory
Research Triangle Park, North Carolina 27711
13. TYPE OF REPORT AND PERIOD COVERED
Published paper; thru 1/93
14. SPONSORING AGENCY CODE
EPA/600/13
15. SUPPLEMENTARY NOTES
AEERL project Qfficer is w> GeneTicker, MailDroP54, 919/541-
2746, Indoor Air '93, Helsinki, 7/4-8/93.
16. ABSTRACT
The paper briefly describes the purpose, history, and major features of
ASHRAE (American Society of Heating, Refrigerating and Air-conditioning Engin-
eers) Standard 62. The primary focus of the paper is on the status of the review and
revision process as of January 1993. The current working outline of the revised
standard is presented and discussed. The complementary roles of ventilation,
source management, and air cleaning are emphasized. Extending the standard be-
yond ventilation system design to include operation and maintenance of buildings and
ventilation systems is also projected.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Pollution
Ventilation
Standards
Pollution Control
Stationary Sources
Indoor Air Quality
13 B
13 A
14 G
8. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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