United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-92/191 December 1992
i& EPA Project Summary
Guidance for Research House
Studies of the Florida Radon
Research Program
Kenneth J. Gadsby and T. Agami Reddy
Although there are many areas of
the country in which various radon re-
search efforts in houses have been on-
going, there has not been a coordinated
approach to study these houses with
the objective of developing construc-
tion codes and standards. The soils,
construction styles, and techniques in
Florida are somewhat different from
those found in the areas where most of
the research data have originated. The
Florida Radon Research Program
(FRRP) put in place a research strategy
where most of the factors that influ-
ence the transport and entry of radon
into these houses would be studied.
The research house component of
this program would use four to six un-
occupied houses in three areas to study
the radon entry effects in different types
of construction, soil conditions, and
climate common in Florida where el-
evated indoor radon had been experi-
enced. There would also be one or two
occupied existing houses in New Jer-
sey where house construction prac-
tices, subsoil characteristics, and
equipment impacts may be different.
Southern Research Institute, University
of Florida, Florida A&M University/
Florida State University, and Princeton
University made up the four involved
research teams.
Research plans included specifics in
regard to common (between groups)
and specialty experiments, standard-
ized instrumentation requirements,
characterization of the house and site,
and quality assurance. One goal was
to develop an integrated study in which
experiments would be performed in well
characterized houses where conditions
could be normalized so that data from
each research group can be compared.
The report provides guidance and a
readily available reference to the re-
search house groups. Comprehensive
lists of parameters for high and low
resolution measurements (continuous
and periodic) were generated. Proto-
cols were given for the characteriza-
tion and specialty measurements. Data
storage variable assignments were pro-
vided so that researchers could have
access to a standardized data set. An
example of an approved Quality Assur-
ance Project Plan was also included.
Individual research plans linked to the
various FRRP objectives and commit-
tees were developed to ensure that the
research goals would be met.
This Project Summary was devel-
oped by"EPA's Air and Energy Engi-
neering Research Laboratory, Research
Triangle 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).
Introduction and Background
Elevated indoor radon levels that ex-
ceed the EPA guideline of 4 pCi/L have
been observed in houses in various Florida
locations. Some of these houses are lo-
cated in or near phosphate mining areas
and may be built over mining-residue-filled
or reclaimed land. Other houses are lo-
cated in sections of the state where par-
ticular geologic formations have significant
radium concentrations. In an effort to re-
duce human exposure to radon in houses
Printed on Recycled Paper
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the State of Florida, through a non-resi-
dential new construction fee, authorized
research, Florida Radon Research Pro-
gram (FRRP), that would have as its goal
the development of radon resistant con-
struction codes.
Specific Objectives of FRRP
Develop, test, and evaluate quantitative
specifications for building components.
Develop for testing/use in newly con-
structed Florida houses. These include
research houses and new houses con-
structed in accordance with the Florida
draft code.
a. protocols for experiments and
testing
b. assessment tools
c. models
Develop correlations and indices of per-
formance leading to construction code
and standards development.
a. Major house subsystems to be
regulated by the code are: Barri-
ers, Subslab suction systems,
Heating, ventilation, and air-con-
ditioning (HVAC) specifications,
and Foundation fill materials. In
addition, performance standards
will be mandated (long-term av-
erage vs. short-term measure-
ments). All experiments or
models should be explicitly re-
lated to one or more of the above
topics.
Overall Goal of Research House
Study
Research House Study—an approach
to the study of a house, the adjacent soil,
local weather conditions, and space condi-
tioning appliances as a system. The inter-
actions of components of the house system
have a major impact on radon entry into
the house. The goal of this integrated study
is to develop techniques to control radon
entry by modification of components of this
system.
General Strategy
Given that the number of research
houses is small (four to six), similar experi-
ments will be conducted in each house in
an effort to identify key quantitative perfor-
mance characteristics and normalize any
differences in the housing that would affect
the results of each group. Examples would
include comparison of the University of
Florida's (UFs) house dynamics results
with Southern Research Institute's (SRI's)
results from their research houses, radon
availability at various depths and distances,
and leakage areas of the slabs, walls, and
bypasses. This would be done before any
protocols were passed on to Florida's New
House Evaluation Program (NHEP) or stan-
dards development activities. A serious
look at the extra amount of effort and/or
costs and any scheduling changes will have
to done before committing to such testing.
Methodology
Where new research houses are being
built, the construction will be monitored by
researchers and any faults corrected. De-
signed and well characterized (quantified)
faults, as representative of typical con-
struction, w|ll then be installed for the ex-
periments. These modifications may include
openings through the slab and intentional
supply or return leaks in the heating and
air-conditioning (HAG) ductwork. Subslab
instrumentation tubing and probes will be
installed before the slab is poured.
House and Site Characterization
Measurements (Before and
During Construction)
The building site should be character-
ized using FRRP protocols, including the
native soil, fill, or any backfill used. Data
should be mapped.
During Construction (for CMU—
Concrete Masonry Unit—
Construction)
Any faults found during these in-
spections should be remedied before
the next construction sequence covers
them or otherwise makes them inacces-
sible.
The subslab instrumentation installa-
tion should be checked for integrity, espe-
cially just before the slab is poured.
Construction should be monitored and
any faults corrected in order to make the
house conform to the code. Critical areas
include ductwork installation and air leak-
age sites that may be difficult to get to after
completion of the structure. In the case of
an existing new building, areas of the
house may have to be opened for in-
spection to verify systems integrity.
House and Site Characterization
Measurements
(After Construction)
FRRP Protocol 2.4.1 plus infrared scan-
ning/blower door depressurization to lo-
cate air leakage sites in the thermal
envelope. Leakage distribution is required
for inputs for most models.
Low Resolution Measurement
Most would be repeated quarterly dur-
ing the experimental period. These tests
are to determine whether the baseline con-
ditions have changed due to settling, shrink-
age, or changes in the moisture levels in
the soils, substructure, or superstructure.
Support lumped parameter or simple mod-
els.
Site characterization—(same grid pat-
tern as before construction where pos-
sible)
House characterization
Low Resolution Measurements—
Multi-day Averages
Radon entry rate determination with
the use of radon measurements and
perfluorocarbon tracer (PFT) derived air
infiltration measurements. (Aggregated
measurement as described in Appendix E
of Volume 1.)
Radon Protocols
High Resolution Measurement
Continuous—These fundamental pa-
rameters are measured continuously on a
real-time basis to provide the dynamic data
that describe the operation and interac-
tions of the various components and natu-
ral phenomena that affect radon entry. This
high resolution data can then be totaled or
averaged over half-hour or longer periods
as required for various modeling efforts.
Core Measurements—Fundamental
parameters that affect radon entry.
(Appendix F)
Specialty Measurements—Answer key
questions.
FRRP Research House Program
Overview
Unoccupied Research Houses
Four to six unoccupied research houses
in three areas will be used to study the
radon entry effects in different types of
construction, soil conditions, and climate
common in Florida where houses with el-
evated indoor radon levels are located.
Occupant effects would be eliminated thus
providing a cleaner data set. This is an
integrated study in which common and
specialty experiments will be performed in
well characterized houses where condi-
tions can be normalized so that data from
each research group are comparable.
SRI—One or two newly constructed, to
the Florida draft code, slab-on-grade
houses in the Tampa (southern Florida)
area built on reclaimed phosphate mining
lands.
Major research areas include:
(1) Barrier effectiveness evaluation.
(2) Protocol development.
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(3) Radon entry model.
(3a) Radon availability model vali-
dation.
(4) Alternate performance standard
support measurements.
(5) Subslab depressurization (SSD)
system effectiveness.
UF—One or two existing new slab
houses in the Gainesville (central Florida)
area built on native soil with fill.
Major research areas include:
(1) Evaluation of the effects of house
dynamics on indoor radon.
(2) HVAC system effects model.
(3) Protocol development.
(4) Radon entry.
Florida A&M University/Florida State
University (FAMU/FSU)—One or two newly
constructed, to the Florida draft code,
crawlspace structures built in the Tallahas-
see (northern Florida geology) area.
Major research areas include:
(1) Crawlspaces as a radon source.
(2) Plumbing and electrical penetra-
tion effects.
(3) HVAC location and operation ef-
fects.
(4) Modeling of indoor radon entry.
(5) Modeling of house dynamics.
Occupied Research Houses
Princeton University (PU)—One or two
existing houses in New Jersey where house
construction practices, subsoil characteris-
tics, and equipment impacts may be differ-
ent than those in Florida.
Major research areas include:
(1) Experimentally backed macro-
scopic model development.
(2) Ventilation and its effects on in-
door radon.
(3) Evaluation and modeling HVAC
effects on radon entry.
(4) Alternate data analysis to reduce
uncertainties in predicting long-
term radon levels from screen-
ing measurements.
Examples of Experiments
With the intention of being able to ex-
trapolate results, similar experiments will
be performed on each house. Results will
be compared and pooled, if appropriate, in
order to support more general conclusions.
One example of a HAC experiment
would be one where various pressure dif-
ferences are imposed on the house in
order to investigate the correlation between
pressure magnitude and radon entry (in-
door radon levels). These tests would be
for time periods of several hours for each
pressure in order to ensure achieving
steady-state conditions.
Piedmont study results indicate that
radon levels, in a basement with a leaky
return system, rose by a factor of about
2. Completely sealed systems would
not eliminate all of the radon.
Another example of a HAC experiment
would be to modify, in a quantitative way,
the operation and performance of the HAC
system to pressurize the building as a
method of radon entry control. The effects
of this technique on moisture migration
into the structure and occupant impacts on
the operation of the system will have to be
evaluated.
Experiments to quantify the average
radon entry rate, calculated from tracer-
gas-derived air infiltration rates and aver-
aged measured radon concentrations, can
be used to validate theoretical radon entry
models.
FRRP and Research House
Group Objectives Linkage
Charts
FRRP Objectives and
Committee Symbols
(See Table 1).
Objectives
I. Develop for testing/use in newly con-
structed Florida houses:
la. Protocols for experiments and
testing.
Ib. Assessment tools (hardware, de-
vices).
Ic. Models.
lla. Develop correlations leading to
construction code and standards
development.
lib. Develop indices of performance
leading to construction code and
standards development.
Committees
A. Improved Floor Barriers
B. Subslab Suction System Design
Criteria
C. HVAC Specifications
D. Foundation Fill Material Specifi-
cations
E. Alternate Performance Standard
F. New House Evaluation Program
G. Radon Potential Mapping
H. Research House
Numbers
1 = Keyed to deliverables.
2 = Coordination or joint effort.
Research Group Identification
F = FAMU/FSU
U = UF
S = SRI
P = PU
A similar chart is needed to link each
research group's specific experiments,
FRRP objectives, and committees.
Each research group's specialty ex-
periments should be marked (S), and the
common experiments (C).
Florida A&M University/Florida
State University
School of Engineering
Florida Radon Research
Modules—Transport Dynamics
and Modeling
1.0 Goals and Objectives
The fundamental purpose of this radon
research is to protect the public from the
health hazard of excessive radon con-
centration in the indoor air, by develop-
ing building standards for radon-resistant
residential construction. In order to
achieve this goal, it is necessary that
three technical objectives be accom-
plished:
1. To develop an understanding of the
mechanisms of radon transport and
entry into houses.
2. To develop mathematical models
for predicting the temporal and spa-
tial variation of radon concentra-
tions in houses as affected by local
meteorologic and surficial geologic
conditions, building materials, de-
sign, and construction details.
3. To evaluate techniques for inter-
rupting and controlling the trans-
port of radon into houses, taking
into account effectiveness, cost, and
reliability.
1.1 Radon Research Module Project
Objectives
The Leon County radon research house
project will additionally undertake the fol-
lowing (the letter in parentheses after
each objective denotes whether the task
involves specialty measurements unique
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Table 1. FRRP Research House Program Summary
1.
2.
Task Areas
Develop, Test, and Evaluate Ra-
don Transport and Entry Model
Evaluate Barrier Effectiveness,
Including Superstructure
FRRP Objectives
la Ib
S,P S
U
S.P P
U,F
Ic
S,P
U.F
S.P
U.F
Ha
S.P
U
S
F
lib
P
F
P
U.F
A
S
U,F
S,P
U,F
B
S,P
U
U
FRRP Committees
C
S
U,F
U.F
D
S
U
S
E
S,P
U
F
S.P
F
S,P
U,F
G
S.P
U.F
S.P
U.F
H
F.U
S
S.P
U.F
(Correlations ofleakiness,
air Infiltration, and radon entry)
3. HVAC Evaluation (Design
parameters tied to radon entry)
S,P S S.P S,P P
F U,F U.F U,F
S
U
S,P
U,F
S,P
U.F
U.F
4. Macroscopic Model RD&D
s,p s.P s.p: S.P
U.F
S.P
P.U
5. Ancillary Supporting Studies
P.U P.U
P.U
P.U P.U
P,U
to this project [S], or common measure-
ments conducted in all Florida Radon
Research House Study projects [C]):
1. Develop, test, and validate a math-
ematical model for radon transport
from a ventilated crawlspace and
into a building. [S]
2. Determine the effect of sealing
points of air leakage at various lo-
cations in the building envelope, on
radon transport from the crawlspace
into the building, temperature dif-
ferences, and building pressure dif-
ferences (neutral plane). [S]
2a. Determine the effect of air-han-
dier operation on radon trans-
port from the crawlspace into
the building, and on radon con-
centration within the building.
[C]
2b. Determine the effect of air-han-
dler and duct location and duct
construction and leakage on ra-
don transport from the
crawlspace into the building
and on radon concentrations
within the building. [S]
1.2 Long-Term Leon County Research
Project Objectives
While there is a well defined set of fun-
damental objectives, other longer range
objectives could not be met within the
scope of the proposed project. Among
the longer range objectives are:
3. Determine the height above ground,
ventilation area, and vent configu-
ration necessary for satisfactory
control of radon by passive ventila-
tion of crawlspaces.
3a. Develop and validate optimized
design parameters, including
height above ground, ventila-
tion area, and vent configura-
tion necessary for satisfactory
control of radon by active ven-
tilation of the crawlspace.
4. Validate laboratory procedures used
for quantifying the radon-resistance
of specific building materials and
assemblies by incorporating them
full-scale into the research mod-
ules.
5. Validate optimized design param-
eters for sub-membrane soil-de-
pressurization systems developed
by related projects within the FRRP.
2.0 Project Rationale
The radon research house project is con-
ceived as part of an ongoing compre-
hensive effort by the State of Florida to
develop practical means for lowering av-
erage radon concentrations in new build-
ings, and to incorporate applicable
methods into statewide minimum build-
ing codes when appropriate. This effort
began in September 1988 with the ap-
pointment of the State University Sys-
tem Radon Advisory Board. Research
projects, funded through this Board and
completed by various state universities,
focused on:
1. Characterization of soils and fill ma-
terials as related to their interaction
with sub-slab depressurization sys-
tems.
2. Development of an analytical model
for design and evaluation of sub-
slab depressurization systems.
3. Long-term (1 -year) evaluation of the
sub-slab environment in houses
with active sub-slab depressuriza-
tion systems.
4. Development of a laboratory proce-
dure and equipment for evaluating
the effectiveness of various con-
struction techniques and assemblies
as radon barriers.
5. A field validation of houses built in
voluntary compliance with existing
guidelines for radon-resistant new
residential construction.
6. Incorporation of techniques similar
to those suggested for control of
radon in residences into a large-
scale building.
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University of Florida Radon
Research Houses
House Dynamics and Modeling
1.0 Strategy
A. Utilize unoccupied houses for con-
trolled experimental conditions.
B. Develop protocols to be used for
evaluating building codes (through
the New House Evaluation Pro-
gram—NHEP).
1. Develop and test protocols in
research houses.
2. Modify NHEP criteria as nec-
essary following evaluation in
the NHEP.
C. Incorporate special features into
new research houses during con-
struction as appropriate.
D. Develop models for indoor radon.
1. Individual components will be
developed by research groups
with different emphasis areas.
2.0 Objectives
A. Develop and test protocols for the
NHEP and building code develop-
ment.
B. Develop predictive models for in-
door radon.
C. Recommend and evaluate compo-
nents of the building code based
on experiment and predictive mod-
els.
3.0 Protocols
•A. Endpoint Protocols for the NHEP.
1. Stress Test.
2. HVAC Evaluations.
Duct leakage.
Pressurization and depressur-
ization of zones.
3. Slab Entry Area/Soil Gas.
4. House Leakage Area.
B. Experimental Protocols To Be De-
veloped and/or Utilized.
1. Radon Supply.
2. Slab Leakage Area and Loca-
tion.
3. House Leakage Area and Lo-
cation.
4. Forced Air Distribution System
Leakage.
5. HVAC Pressurization/Depres-
surization.
6. Radon Entry.
a) Gross Entry.
b) Entry Rate and Entry Po-
tential for Different Loca-
tions.
c) Gross Entry Potential.
7. Air Mixing and Characteristic
Times.
Resulting from HVAC Effects.
8. Zonal Characterization of
Houses.
9. Radon Transport Between
Zones.
10. Barrier Effectiveness.
Southern Research Institute
Polk County Research House
Studies
The objectives and specialty experiments
of the Polk County Research House
Project are listed below.
1.0 Project Objectives
1. Validate the effectiveness of "bar-
rier" construction features.
2. Make detailed measurements rel-
evant to radon transport and entry
for model testing and validation.
3. Develop transferable protocols rel-
evant to depressurized radon mea-
surement.
4. Provide test site for HVAC, subslab
ventilation (SSV), and other stud-
ies.
2.0 Specialty Experiments
1. Document response of subslab
pressure field, radon concentration
to environmental driving forces.
(1a) Short term, depressurized
house.
(1b) Long term, environmental driv-
ing forces.
2. Optimize whole house depressur-
ization; and radon test as basis for
radon potential and entry efficiency
protocols.
3. Develop zonal depressurization
techniques to characterize and lo-
calize radon entry.
Princeton University
Indoor Radon and its Control by
Modification of Building
Dynamics
1.0 Objectives
The final objective of the Princeton Uni-
versity study (as also that of FRRP con-
tractors involved in the research house
effort) is to develop alternate perfor-
mance standards for radon resistant
building construction and equipment op-
eration.
In order to fulfill this, the following objec-
tives have been identified:
(a) Seek to understand how residences
should be constructed and HVAC
and other equipment should be op-
erated to achieve maximum radon
resistance.
(b) Evaluate the potential of natural
ventilation to decrease indoor ra-
don levels.
(c) Assess alternate data analysis tech-
niques to decrease uncertainties as-
sociated with predicting long-term
indoor radon levels from short-term
screening tests.
(d) Develop an experimentally backed
physical macroscopic radon entry
model to identify leakage pathways
through the building substructure
and superstructure.
2.0 Rationale
This research effort is an ideal opportu-
nity for Princeton University to: perform
and extend the types of statistical and
physical modeling approaches used in
New Jersey houses, to evaluate differ-
ences between houses in New Jersey
and Florida, and to identify likely causes
for these differences. The wider repre-
sentation in building construction types,
soil conditions, and equipment operation
would additionally be beneficial to both
EPA and the Florida radon research pro-
grams in terms of optimal deployment of
time and money. This dovetailing of ex-
periments should expedite EPA's radon
mitigation research since technology
transfer between the participants of the
combined research effort would be ex-
pedited.
3.0 Methodology
It is proposed that the final objective be
satisfied by: (i) formulating a general
macroscopic model for radon entry and
indoor air dynamics, (ii) using this model
framework to develop an experimental
protocol to identify important radon entry
paths, and (iii) using model parameters
identified in a number of research houses
as specified inputs to comprehensive
computer codes to develop alternate per-
formance standards for radon resistant
building construction and equipment op-
eration.
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4.0 Overall Experimental Approach
The approach adopted is to instrument
two New Jersey research houses along
the same lines as those done in previ-
ous years by Princeton University. The
instrumentation package will enable vari-
ous climatic, house operation, and ra-
don parameters to be recorded remotely
on a continuous basis (reported at a
half-hour time interval) during the re-
search study periods. The parameters
are essentially the core measurements
listed in Volume 1. Specialty experi-
ments, each lasting typically for 3-4 days,
would then be performed to identify/quan-
tify different factors affecting radon en-
try. These experiments would be
repeated during different periods of the
year so as to include seasonal effects.
The specialty experiments pertinent to
Princeton University specifically involve
HAG effects, air infiltration, and HVAC
measurements.
An important component of the experi-
mental study is to evaluate the effects of
natural and forced ventilation as a mitiga-
tion scheme for low radon houses ( >30
pCi/L). This would involve collection of core
measurements, subsoil pressure field mea-
surements (six to eight points), and two-
tracer gas PFT measurements in a house
baseline case and then repeat the test with
the ventilation strategy in place.
•U.S. Government Printing Office: 1992 — 750-071/60155
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Kenneth J. Gadsbyand T. AgamiReddy are with Princeton University, Princeton,
NJ 08544
David C. Sanchez is the EPA Project Officer (see below).
The complete report consists of two volumes, entitled "Guidance for Research
House Studies of the Florida Radon Research Program:"
Volume 1. "Research Plan" (Order No. PB93-100907/AS; Cost: $27.00; subject to
change)
Volume 2. "Model-backed Experimental Protocol for Determining Radon" (Order
No. PB93-100915/AS; Cost: $19.50; subject to change)
The above reports will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-437-4650
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
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-92/191
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