United States
Environmental Protection
Agency
National Kisk Management
Research Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-95/174 January 1996
& EPA Project Summary
HVAC Systems as a Tool in
Controlling Indoor Air Quality; A
Literature Review
Max M. Samfield
The report gives results of a review
of literature on the use of heating, ven-
tilation, and air-conditioning (HVAC)
systems to control indoor air quality
(IAQ). The review covers the years 1988
through 1993, and involved 60 refer-
ences, 32 of which are cited in the
report.
This Project Summary was developed
by the National Risk Management Re-
search Laboratory's Air Pollution Pre-
vention and Control Division, Research
Triangle Park, NC, to announce key
findings of the research project that is
fully documented in a separate report
of the same title (see Project Report
ordering information at back).
Although significant progress has been
made in reducing the energy consumption
of HVAC systems, the role of HVAC sys-
tems in affecting indoor air pollution is not
fully understood. It is apparent that the
HVAC systems themselves very often con-
tribute to the indoor air pollution problem
because: (a) maintenance of the system
is poor, (b) the design limitations of the
building and the HVAC system have gradu-
ally, over time, been exceeded either
through overcrowding or the introduction
of new, pollution-generating sources within
the building, and (c) the outdoor air in-
takes are located near ambient pollution
sources.
IAQ problems frequently manifest them-
selves through Sick Building Syndrome or
Building Related Illness (SBS or BRI).
These can cause a loss in employee pro-
ductivity. It is now recognized that there
must be a trade-off between energy con-
servation and employee productivity. In
addition, building owners and managers
now recognize that failure to pay attention
to IAQ problems may result in expensive
litigation. The National Institute of Occu-
pational Safety and Health (NIOSH) in a
recent survey determined that in over 50%
of the cases where IAQ problems existed,
poor and inadequate ventilation was the
problem. In cases where pollutants ema-
nate from soil gases (e.g., radon), the
installation and operation of an HVAC sys-
tem can alter the IAQ.
Since the entry of soil gas is, to a large
extent, dependent on the pressure differ-
ential between the soil and the structure,
HVAC system operation can have a sig-
nificant effect. Before an HVAC system is
designed and installed, all operations in
the building should be thoroughly exam-
ined with regard to potential pollution
sources and a determination should be
made whether local exhaust systems (such
as hoods) need to be installed at the pol-
lution source. Proper installation of local
exhaust systems may significantly reduce
the need for general ventilation.
Two primary types of HVAC systems
are in use: (a) constant air volume sys-
tems and (b) variable air volume (VAV)
systems. VAV systems compensate for
variations in heating or cooling load by
regulating the volume of air supplied to
each zone. Energy conservation as well
as improved controls and equipment have
made VAV an increasingly popular option.
The American Society of Heating, Re-
frigerating and Air-Conditioning Engineers
(ASHRAE) has revised Standard 62-1981,
replacing it with Standard 62-1989. The
revised standard now includes an updated
and revised IAQ procedure for which a
model has been developed, and equa-
-------
tions for calculating the amount of recircu-
lation needed.
Numerous modeling schemes have
been developed; however, little informa-
tion has been published regarding the rela-
tive merits of the different models.
Contents of this report are based on a
literature survey covering primarily 1988
through 1993 and a survey of 60 refer-
ences, 32 of which are cited in this report.
Author M. Samfield, now deceased, was a consultant with the Agency. For report
details, contact the project officer.
David C. Sanchez is the EPA Project Officer (see below).
The complete report, entitled "HVAC Systems as a Tool in Controlling Indoor Air
Quality; A Literature Review," (Order No. PB96-140561; Cost $17.50, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air Pollution Prevention and Control Division
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection Agency
National Risk Management Research Laboratory (G-72)
Cincinnati, OH 45268
Official Business
Penalty for Private Use $300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-95/174
------- |