United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-93/211 January 1994
<&EPA Project Summary
Case Studies Of Radon
Reduction Research In
Maryland, New Jersey, and
Virginia Schools
David W. Saum
This report details the radon mitiga-
tion research in school buildings in
Maryland, New Jersey, and Virginia that
was conducted during 1991 and 1992.
One school in each state was selected
for the research. In two schools, the
objective was to evaluate the potential
for modifying the school ventilation
system to control radon concentra-
tions. The other school was newly con-
structed with radon resistant features,
and the objective was "to evaluate the
effectiveness of those features.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research Tri-
angle Park, NC, to announce key find-
ings of the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Paramount Elementary School
School mitigation research to date has
emphasized reduction of radon levels us-
ing active subsiab depressurization (ASD).
Although ASD has proven successful in a
number of schools, alternative techniques
may be required in some schools: one
promising alternative is modifying the heat-
ing, ventilating, and air-conditioning
(HVAC) system in the school to provide
radon mitigation. The Paramount Elemen-
tary School in Hagerstown, MD, was se-
lected because it was a typical older school
with a unit ventilator HVAC system, and it
had an ASD radon control system.
The unit ventilator HVAC system in one
wing was modified, and its radon mitiga-
tion potential was tested under a number
of conditions. Several problems in provid-
ing radon mitigation with unit ventilators
were encountered at Paramount: unit ven-
tilators do not generally provide a con-
stant ventilation rate, their ventilation ca-
pability may be reduced to achieve in-
creased energy conservation, or they may
be poorly maintained. However, when
these problems were corrected at Para-
mount, the radon mitigation performance
was comparable to that of the previously
installed ASD system. Unfortunately, the
radon mitigation performance observed at
Paramount was probably enhanced by the
passive stack action from the two ASD
stacks that were unsealed, although their
fans were turned off.
Desmares Elementary School
The Francis A. Desmares Elementary
school near Flemington, NJ, completed in
September 1991, was selected because
the 1989 building design included a
rough-in of an ASD system with 10 stacks
and a network of perforated pipes in the
subsiab aggregate. Subsiab pressure field
measurements after construction indicate
that one or two stacks equipped with ex-
haust fans would probably provide ad-
equate radon mitigation performance, and
that one active stack can depressurize at
least 50,000 ft2 (4645 m2) if subsiab barri-
ers are absent. The Desmares subsiab
depressurization was achieved without sig-
nificant additional slab sealing. The
$25,000 cost of this system could prob-
ably be reduced to about $5,000 by re-
ducing the number of stacks and using
less expensive subsiab perforated piping.
The report also describes a simple
method of characterizing pressure field
extension (PFE) data, a method that was
Printed on Recycled Paper
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used to analyze PFE data from the
Desmares school and compare it with an-
other building. Test equipment to simplify
PFE measurements is described.
Dranesville Elementary School
The Dranesville Elementary school in
Herndon, VA, was selected because it
had a modern variable air volume (VAV)
HVAC system that could be compared
with the standard ASD radon mitigation
technique. The school also has an ASD
radon control system. The school was built
in 1987 near houses with elevated radon
levels, and the school design incorporated
features for easy radon mitigation with
ASD. When 1991 radon tests showed el-
evated concentrations in one wing, a
single-stack ASD system was installed by
school personnel.
During the summer of 1991 when the
school was generally unoccupied, the ASD
system was shut down and the HVAC
system operation was changed in a con-
trolled manner over several weeks. The
data collection included continuous mea-
surements of radon, pressures, and tem-
peratures. The results show that the in-
door radon concentrations were very low
during the weekdays under all VAV op-
eration modes, while higher radon levels
were measured on the weekends. Two
factors are suspected to have caused the
low radon levels:
1) unanticipated increased ventilation
because school personnel corrected
an error in their HVAC control strat-
egy just before the experiment
started, and
2) reverse stack pressures in the build-
ing because the summer outdoor
temperatures were generally higher
than the inside temperatures.
Unfortunately, the radon levels in this
school were too low during the summer to
be useful in evaluating VAV HVAC modifi-
cation as a radon mitigation tool. The re-
verse stack effect in this building sug-
gests that summer indoor radon concen-
trations may be quite different from winter
radon concentrations. The subslab radon
concentration neasurements suggest that
large variations in these levels make it
difficult to interpret spot measurements.
. GOVERNMENT PRINTING OFFICE: 1994 - 5SO-067/HOU2
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D. Saum is with Infiltec, Falls Church, VA 22041.
Kelly W. Leovic is the EPA Project Officer (see below).
The complete report, entitled "Case Studies of Radon Reduction Research In
Maryland, New Jersey, and Virginia Schools," (Order No. PB94-117363; Cost:
$27.00; 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 and Energy Engineering 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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