United States
Environmental Protection
Agency
National Risk Management
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-97/051 July 1997
SEPA Project Summary
Large Buildings Characteristics as
Related to Radon Resistance: A
Literature Review
Ronald A. Venezia
This report presents results of a lit-
erature review to identify the database
for specific large building characteris-
tics that is available regarding radon
entry. The primary sources for the re-
view were the Ei Compendix database
(235 abstracts) and a database con-
sisting of literature related to indoor air
work by EPA's Air Pollution Prevention
and Control Division.
This Project Summary was developed
by EPA's National Risk Management
Research Laboratory's Air Pollution
Prevention and Control Division, Re-
search 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).
Introduction
Radon can enter a building in several
ways. When there are no pressure differ-
ences, radon can enter buildings by diffu-
sion-driven transport. Radon can be emit-
ted from well water directly supplied to a
building from radium-bearing formations.
Building materials can also be a source of
radon. However, it is uncommon that any
significant radon concentration would oc-
cur in large buildings by these mecha-
nisms. Pressure-driven transport, occur-
ring when a lower indoor air pressure
draws air containing radon from soil or
bedrock into the building, is the most com-
mon way radon enters large buildings.
This occurs in many large buildings when
they operate at an indoor air pressure
lower than that of the subsoil. The follow-
ing four conditions must exist if radon is to
enter a building through pressure-driven
transport: 1) radon in the subsoil, 2) a
pathway from the source through the sub-
structure into the building, 3) radon entry
points and 4) a driving force into the build-
ing.
Prior to 1993, most radon research in
large buildings focused on developing di-
agnostic and mitigation techniques for
school buildings. The belief exists that
techniques developed for school buildings
can be used as the basis for developing
diagnostic and mitigation techniques for
other types of large buildings. The com-
plexity and diversity of large building de-
signs is an added complication in radon
mitigation. Much in the available literature
on large building characteristics is directed
toward energy conservation and heating,
ventilation, and air-conditioning (HVAC)
system design and operation. The devel-
opment and application of energy conser-
vation techniques for large buildings have
been vigorously pursued since the mid-
1970s and have resulted in significant en-
ergy savings. Some of these techniques
may have contributed to sick building syn-
drome, building related illness, and a gen-
eral decrease in indoor air quality.
Radon diagnostic and mitigation strate-
gies are needed for large buildings. Stud-
ies are in progress to develop, validate,
and provide guidance for radon diagnostic
procedures and radon mitigation strate-
gies applicable to a variety of large build-
ings commonly found in the State of
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Florida. To help meet these needs, an
understanding of existing characteristics
of large buildings is necessary.
Summary of Findings
Few large building studies have evalu-
ated radon entry and/or mitigation. Most
large building characterization studies are
related to energy conservation. Environ-
mental studies have centered on indoor
air quality (IAQ) as it relates to sick build-
ing syndrome and building related illness.
Large building characteristics of impor-
tance in relation to radon entry include:
HVAC system operation and maintenance,
building foundation, floor space to foot-
print ratio, separation of lower level from
upper floors, floor bypasses, and location.
Location has been suggested as the most
important characteristic related to radon
entry. The literature provided information
on HVAC system operation and mainte-
nance mostly in large building character-
ization studies that were related to energy
conservation. There were minimal data on
other radon related characteristics. One
author concluded, "...a significant body of
knowledge exists about the infiltration, air
leakage, and ventilation characteristics of
residential buildings, however, little mea-
sured data exists on the quantities for
commercial buildings."
Large buildings have diverse character-
istics which make it difficult to place them
into a manageable number of categories
for radon mitigation studies. The Depart-
ment of Energy characterized nearly four
million commercial buildings, one million
of which may be considered to be large,
greater than 10,000 ft2 (929 nf). Average
footprint size was available for buildings
up to three stories tall. It was not possible
to determine from the data the footprint
size for buildings taller than three stories.
This is significant because the building
characteristic that is most strongly linked
to radon entry is location. The much higher
floor space to footprint ratio for large mul-
tistory commercial buildings over small
buildings may account for the low inci-
dence of high radon levels in large build-
ings. Of the 80,000 building measurements
conducted in federal buildings, 95% were
under 4 pCi/L.
Approximately half of the commercial
buildings (large and small) surveyed in
the U.S. incorporate characteristics that
could increase radon entry if the radon
source was present and the pathway avail-
able. For example, basement substruc-
tures may significantly contribute to radon
infiltration. The use of National Institute of
Standards and Technology parameters for
describing building and HVAC character-
istics developed in conjunction with IAQ
investigations may provide some insight
relative to radon entry into large buildings
especially as it relates to operation and
maintenance of HVAC systems.
An extensive search for literature on
large buildings in Florida concluded that
little information relevant to commercial
building characteristics in regard to radon
was available. Because of Florida's warm
climate, high humidity, high water table,
and the scarcity of sources for aggregate
for construction, large buildings in Florida
generally differ from those built in other
states.
HVAC systems have a significant im-
pact, positive or negative, on radon con-
centrations in large buildings because of
pressurization or depressurization, intro-
duction of dilution air, and air distribution.
Well designed and installed HVAC sys-
tems can be adjusted to effectively miti-
gate radon in large buildings. However, a
bias toward energy conservation, poor
maintenance, and inefficient operation of
these complex systems can negate any
potential for radon mitigation. HVAC sys-
tem performance characteristics are typi-
cally measured in terms of a number of
different parameters such as air distribu-
tion, ventilation effectiveness, thermal com-
fort, building pressurization, energy and
maintenance costs, and outdoor air ex-
change rates. Experience has shown that
a properly designed, well-constructed,
properly functioning, and well-maintained
HVAC system will minimize most IAQ and
comfort complaints, but may not be suffi-
cient to solve all strong source/open path-
way situations.
Energy use is a factor in radon entry as
it relates directly to whether or not the
building is under positive or negative pres-
sure. Energy use is significantly influenced
by occupancy, building shell, mechanical
equipment, and weather. Evaluation of
end-use electrical consumption at com-
mercial sites may give some insight to
HVAC system operation and maintenance
which can be inferred to impact on radon
entry. Information may relate to energy
conservation, ventilation, and building de-
pressurization. Protocols, standards, and
codes which guide and regulate the de-
sign, installation, commissioning, opera-
tion, and maintenance of HVAC systems
(considering both radon infiltration/mitiga-
tion and IAQ) are unavailable.
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Ronald A. Venezia, EPA Consultant, Gary NC 27511.
David C. Sanchez is the EPA Project Officer (see below).
The complete report, entitled "Large Buildings Characteristics as Related to Radon
Resistance: A Literature Review,"(OrderNo. PB97-167134; Cost: $25.00, subject
to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
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
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
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