KPi\-600/R-S7-064a
July 1997
RADON DIAGNOSTIC MEASUREMENT GUIDANCE FOR
LARGE BUILDINGS
Volume 1. Technical Report
By
Marc Y. Menetrcz
and
Russell N. Kulp
U.S. Environmental Protection Agency
Air Pollution Prevention and Control Division
National Risk Management Research Laboratory
Research Triangle Park, North Carolina 27711
Prepared for
U.S. Environmental Protection Agency
Office of Research and Development
Washington, DC 20460
Florida Department of Community Affairs
Codes & Standards Division
2740 Centerview Drive
Tallahassee, Florida 32399
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NOTICE
This document has been reviewed in accordance with U.S. Environmental
Protection Agency policy and approved for publication. Mention of trade
names or commercial products does not constitute endorsement or
recommendation for use.
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FOREWORD
The U. S. Environmental Protection Agency is charged by Congress with pro-
tecting the Nation's land, air, and water resources. Under a mandate of national
environmental laws, the Agency strives to formulate and implement actions lead-
ing to a compatible balance between human activities and the ability of natural
systems to support and nurture life. To meet this mandate, EPA's research
program is providing data and technical support for solving environmental pro-
blems today and building a science knowledge base necessary to manage our eco-
logical resources wisely, understand how pollutants affect our health, and pre-
vent or reduce environmental risks in the future.
The National Risk Management Research Laboratory is the Agency's center for
investigation of technological and management approaches for reducing risks
from threats to human health and the environment. The focus of the Laboratory's
research program is on methods for the prevention and control of pollution to air,
land, water, and subsurface resources; protection of water quality in public water
systems; remediation of contaminated sites and groundwater; and prevention and
control of indoor air pollution. The goal of this research effort is to catalyze
development and implementation of innovative, cost-effective environmental
technologies; develop scientific and engineering information needed by EPA to
support regulatory and policy decisions; and provide technical support and infor-
mation transfer to ensure effective implementation of environmental regulations
and strategies.
This publication has been produced as part of the Laboratory's strategic long-
term research plan. It is published and made available by EPA's Office of Re-
search and Development to assist the user community and to link researchers
with their clients.
E. Timothy Oppelt, Director
National Risk Management Research Laboratory
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ABSTRACT
The purpose of this study was to develop radon diagnostic procedures and mitigation strategies
applicable to a variety of large non-residential buildings commonly found in the State of Florida.
The investigations document and evaluate the nature of radon occurrence and entry mechanisms for
radon, the effects of heating, ventilating, and air-conditioning (I IV AC) systems configuration and
operation on radon entry and dilution, and the significance of occupancy patterns, building height,
and other building construction features. A primary focus of this project was the effect of the HVAC
systems of a large building in influencing the transport, entry, and hopefully the minimization of
indoor radon in the building. Two buildings were investigated, both of which showed an inverse
relationship between dedicated ventilation air and indoor radon concentrations, as was expected.
Both also showed signs of aberrant HVAC design, operation, and maintenance that presumably
adversely affected indoor radon and other indoor air quality variables. The second building showed
clear indications of foundation design elements that contributed to radon entry. Some
recommendations relevant to building standards can be concluded from this project. First, design
and construction should concentrate on elimination of major soil gas pathways such as hollow walls
and unsealed utility penetrations. Second, HVAC system design should include strategies designed
to minimize depressurized zones adjacent to the soil. Third, while increased supply ventilation is
generally helpful for radon control, it is clearly not the most cost-effective solution or prevention tool
once the requirements of occupant comfort and general indoor air quality have been met.
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TABLE OF CONTENTS
Section Page
Abstract iv
List of Figures vi'1
List of Tables xii
Metric Equivalents x -j ^ j
Glossary x1ii
Acknowledgements xjV
1.0 Introduction 1
2.0 Conclusions and Recommendations 2
3.0 Background: HVAC Systems and Radon in Large Buildings 3
3.1 HV AC Systems Background 3
3.2 HVAC System Demands 9
3.3 Radon Entry Mechanisms Relevant to Large Buildings 12
4.0 Project Objectives and Experimental Plan 19
5.0 Experimental Procedures 24
5.1 Data Station Equipment 24
5.2 Tracer Gas Measurements 25
5.3 Diagnostic Measurements 27
6.0 Radon Case Study 1: Financial Center North .. ..: 30
6.1 Building and HVAC System Description 30
6.2 Experimental Plan: Outdoor Air Variations 34
6.3 Data and Analysis 35
7.0 Radon Case Study 2: Polk County Life and Learning Center 39
7.1 Building and HVAC System Description 39
7.2 Initial Building Inspection and HVAC Modifications 41
7.3 1993 Parametric Study 48
7.4 1994 Phase II Study 75
8.0 Quality Assurance 104
8.1 Data Quality Objectives and Achievements 104
8.2 Data Quality Indicators 104
8.3 Data Reviews 112
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TABLE OF CONTENTS (continued)
8.4 Identification of Corrective Actions 112
9.0 References 113
Appendix
I Financial Center North Initial Engineering Report Vol. 2
II Financial Center North 11VAC Syslem(s) Test & Balance Reports Vol. 2
III Southern Research Institute Deerfield Beach Analysis Vol. 2
IV Polk Life & Learning Center Initial Engineering Report Vol.2
V Polk Life & Llearning Center HVAC System Test & Balance Report
Phase I & II, Prebalance System Survey Vol. 2
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LIST OF FIGURES
Number Page
1 Average radon concentrations at Financial Center North during
parametric study of outdoor air variations 37
2 Floor plan of LLC showing locations of EPA data loggers, tracer gas
system and weather station data logger 40
3 Results of the Phase 3 radon tests at Polk County Life and Learning
Center as carried out by the Radiological and Occupational Health
Section. Polk County Public Health Unit during the 1990-91 and
and 1991-92 school years 43
4 Frequency histogram of the radon levels measured at Polk County
Life and Learning Center 44
5 Locations of the radon values shown in Table 2 as measured
in the Phase 3 testing program 45
6 Average of the continuous radon levels as measured in Rooms 109, 102,
Cafeteria, and Conference Room (excluding Audiology) along with the
5-day moving average values over the testing period 52
7 Test Week #1 continuous radon levels, 20 cfm/person OA, HVAC on
from 6 am to 6 pm seven days/week, all exhaust fans off from
3 pm Friday (2/5) to 3 pm Saturday (2/6) and all fans on over the
period from 3 pm Saturday (2/6) until about 7 am Monday (2/8),
during weekdays (2/8-2/12) exhaust fans at normal operation 53
8 Test Week #2 continuous radon levels, 0 cfni/person OA, HVAC on
from 6 am to 6 pm seven days/week, all exhaust fans off from 3 pm
Friday (2/12) to 3 pm Saturday (2/13) and all on over the period from
3 pm Saturday (2/13) until 7 am Monday (2/15), during weekdays (2/15-
2/19) exhaust fans at normal operation 54
9 Test Week #3 continuous radon levels, 8 cfm/person OA, HVAC on
from 6 am to 6 pm seven days/week, all exhaust fans off from 3 pm
Friday (2/19) to 3 pm Saturday (2/20) and all on over the period from
3 pm Saturday (2/20) until 7 am Monday (2/22), during weekdays (2/22-
2/26) exhaust fans at normal operation 55
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LIST OF FIGURES (Continued)
Number Page
10 Test Week #4 continuous radon levels, 5 cfm/person OA, HVAC on
from 6 am to 6 pm seven days/week, all exhaust fans off from 3 pm
Friday (2/26) to 3 pm Saturday (2/27) and all on over the period from
3 pm Saturday (2/27) until 7 am Monday (3/1), during weekdays (3/1 -
3/5) exhaust fans at normal operation 56
11 Test Week #5 continuous radon levels, because of equipment failure
the test from the previous week was repeated during this week 57
12 Test Week #6 continuous radon levels, repeat the test of Test Week # 1,
20 cfm/pcrson OA, HVAC on from 6 am to 6 pm seven days/week, all
exhaust fans off from 3 pm Friday (3/12) to 3 pm Saturday (3/13) and
all on over the period from 3 pm Saturday (3/13) until 7 am Monday
(3/15). during weekdays (3/15-3/19) exhaust fans at normal operation 58
13 Test Week #7 continuous radon levels, 15 cfm/person OA, HVAC on
from 6 am to 6 pm seven days/week, all exhaust fans off from 3 pm
Friday (3/19) to 3 pm Saturday (3/20) and all on over the period from
3 pm Saturday (3/20) until 7 am Monday (3/22), during weekdays (3/22-
3/26) exhaust fans at normal operation 59
14 Test Week #8 continuous radon levels, 15 cfm/person OA, IIVAC on
from 6 am to 6 pm seven days/week, all exhaust fans off from 3 pm
Friday (3/26) to 3 pm Saturday (3/27) and all on over the period from
3 pm Saturday (3/27) until 7 am Monday (3/29), during weekdays (3/29-
4/2) exhaust fans at normal operation 60
15 Test Week #1 averaged continuous radon levels, 20 cfm/person OA., HVAC
on from 6 am to 6 pm seven days/week, all exhaust fans off from
3 pm Friday (2/5) to 3 pm Saturday (2/6) and all fans on over
the period from 3 pm Saturday (2/6) until about 7 am Monday (2/8),
during weekdays (2/8-2/12) exhaust fans at normal operation 61
16 Test Week #2 averaged continuous radon levels, 0 cfm/person OA, HVAC on
from 6 am to 6 pm seven days/week, all exhaust fans off from 3 pm
Friday (2/12) to 3 pm Saturday (2/13) and all on over the period from
3 pm Saturday (2/13) until 7 am Monday (2/15), during weekdays (2/15-
2''19) exhaust fans at normal operation 62
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LIST OF FIGURES (Continued)
Number Page
17 Test Week #3 averaged continuous radon levels, 8 cfm/person OA, HVAC on
from 6 am to 6 pm seven days/week, all exhaust fans off from 3 pm
Friday (2/19) to 3 pm Saturday (2/20) and all on over the period from
3 pm Saturday (2/20) until 7 am Monday (2/22), during weekdays (2/22-
2/26) exhaust fans at normal operation 63
18 Test Week #4 averaged continuous radon levels, 5 cfm/person OA. HVAC on
from 6 am to 6 pm seven days/week, all exhaust fans off from 3 pm
Friday (2/26) to 3 pm Saturday (2/27) and all on over the period from
3 pm Saturday (2/27) until 7 am Monday (3/1), during weekdays (3/1-
3/5) exhaust fans at normal operation 64
19 Test Week #5 averaged continuous radon levels, because of equipment failure
the test from the previous week was repeated during this week 65
20 Test Week #6 averaged continuous radon levels, repeat the test of Test Week #1,
20 cfm/person OA, HVAC on from 6 am to 6 pm seven days/week, all
exhaust fans off from 3 pm Friday (3/12) to 3 pm Saturday (3/13) and
all on over the period from 3 pm Saturday (3/13) until 7 am Monday
(3/15), during weekdays (3/15-3/19) exhaust fans at normal operation 66
21 Test Week #7 averaged continuous radon levels, 15 cfm/person OA, HVAC on
from 6 am to 6 pm seven days/week, all exhaust fans off from 3 pm
Friday (3/19) to 3 pm Saturday (3/20) and all on over the period from
3 pm Saturday (3/20) until 7 am Monday (3/22), during weekdays (3/22-
3/26) exhaust fans at normal operation 67
22 Test Week #8 averaged continuous radon levels, 15 cfm/person OA, HVAC on
from 6 am to 6 pm seven days/week, all exhaust fans off from 3 pm
Friday (3/26) to 3 pm Saturday (3/27) and all on over the period from
3 pm Saturday (3/27) until 7 am Monday (3/29), during weekdays (3/29-
4/2) exhaust fans at normal operation 68
23 Average building daytime (8 am-4 pm) radon levels in LLC as a function
of the outdoor air flowrate 69
24 Comparison of indoor average radon levels with those measured outdoors
at ground level and 8 ft above the ground for the period from
4/16/93 to 4/23/93 HVAC on from 6am to 6pm, 15 cfm/person 70
ix
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LIST OF FIGURES (Continued)
Number Page
25 Comparison of indoor average radon levels with those measured outdoors
at ground level and 8 ft above the ground for the period from
4/23/93 to 4/30/93 HVAC on from 6am to 6pm except for Saturday and Sunday,
4/24 and 4/25 when the HVAC was on continuously for testing purposes,
15cfm/person 71
26 Comparison of indoor average radon levels with those measured outdoors
at ground level and 8 ft above the ground for the period from
4/30/93 to 5/7/93 HVAC on from 6am to 6 pm, 15 cfm/person 72
27 Comparison of indoor average radon levels with those measured outdoors
at ground level and 8 ft above the ground for the period from
5/7/93 to 5/12/93 HVAC on from 6am to 6pm, 15 cfm/person 73
28 Blower door test results on Life and Learning Center using four blower
doors. Airtightness is 18,047 CFM50 and 4.9 ACH50 77
29 Infiltration rate of the building with all mechanical air moving systems
turned off is 0.08 ach. Radon levels increase from about 2 pCi/L to
about 10 pCi/L during this 13 hour period 79
30 Airtightness curves for the Conditioned Space and the Attic return
Plenum space (including the mechanical room). Building leakiness is
approximately evenly split between the conditioned space and the
attic plenum 82
31 Outdoor air radon levels during the LLC radon experiments at three
locations: roof level at the OA intake. 4 feet above the ground,
and at ground level (3 inches). A charcoal filter was placed at the
inlet to the 4 foot CRM for 2 days and then removed and placed at the
inlet of the roof CRM for 2 days 86
32 Differential pressure of LLC zones to cafeteria during the period
4/13-4/22/94 87
33 Differential pressure of LLC zones to cafeteria during the period
4/23-4/30/94 88
34 Differential pressure of LLC zones to cafeteria during the period
5/3-5/10/94 89
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LIST OF FIGURES (Concluded)
Number Page
35 Differential pressure of LLC zones to cafeteria during the period
5/9-5/17/94 90
36 Differential pressure of LLC zones to cafeteria during the period
5/21-5/28/94 91
37 Radon in cafeteria and mechanical room during the period 4/13-
4/22/94. Also plotted is SF6 concentration in cafeteria 92
38 Radon in cafeteria and mechanical room during the period 4/23-
4/30/94. Also plotted is SF6 concentration in cafeteria 93
39 Radon in cafeteria and mechanical room during the period 5/3-
5/10/94. Also plotted is SF6 concentration in cafeteria 94
40 Radon in cafeteria and mechanical room during the period 5/9-
5/17/94. Also plotted is SFh concentration in cafeteria 95
41 Radon in cafeteria and mechanical room during the period 5/21 -
5/28/94. Also plotted is SF6 concentration in cafeteria 96
42 Radon concentrations in block wall section and outdoor air at roof
level during the period 4/13-4/22/94 97
43 Radon concentrations in block wall section and outdoor air at roof
level during the period 4/23-4/30/94 98
44 Radon concentrations in block wall section and outdoor air at roof
level during the period 5/3-5/10/94 99
45 Radon concentrations in block wall section and outdoor air at roof
level during the period 5/9-5/17/94 100
46 Radon concentrations in block wall section and outdoor air at roof
level during the period 5/21-5/28/94 101
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LIST OF TABLES
Number Page
1 Average Radon Measured al the FCN under Range of
Operating Modes 36
2 Polk County Life and Learning Center Phase 3 Testing Results
1990-91 and 1991-92 School Years 42
3 Locations and Data Sampled at the LLC 47
4 Test Matrix for LLC revaluation 48
5 Comparison of Radon Levels Inside and Outside the LLC Building
Over the Period April 16,1993 to May 12, 1993 75
6 Supply Airflows at LLC 78
7 Outdoor Airflows at LLC 80
8 Exhaust Airflows at LLC 80
9 Building and Ceiling Plenum Pressures (exhaust fans off) 83
10 Results from Replicate Placement of CRMs 105
11 Results of the Bias Determinations for the CRMs 106
12 Results of the E1C Calibration Check 109
13 Calibration Results for the Grab Cells from 1991 and 1993 110
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METRIC EQUIVALENTS
Nonmetric units are used in this report for the reader's convenience. Readers more familiar
with the metric system may use the following factors to convert to that system.
Nonmetric
Multiplied bv
Yields Metric
cfm
0.0283
m3/min
ft
0.305
m
fe
929
cm2
op
(9/5) C + 32
°C
in
2.54
cm
in WG
249
Pa
pCi/L
37
Bq/m3
ton
907
kg (metric ton)
GLOSSARY
ACH
Air Changes per Hour
ACH50
Air Exchange Rate at ± 50 pascals
AH
Air Handler
CATS
Capillary Absorption Tube Samplers
CFM50
Cubic ft/min at ± 50 pascals
CMU
Concrete Masonry Units
CRM
Continuous Radon Monitor
HLA
Effective Leakage Area
EMS
Energy Management System
EPERM
Iligh Sensitivy. Standard Chamber
EqLA
Equivalent Leakage Area
FCN
Financial Center North
FRRP
Florida Radon Research Program
FSEC
Florida Solar Energy Center
FIRS
Health and Rehabilitative Services
1IVAC
Heating, Ventilating and Air-Conditioning
LLC
Polk County Life and Learning Center
MBH
Million BTU/IIr
NEBB
National Environmental Balancing Bureau
NPP
Neutral Pressure Plane
OA
Outdoor Air
OAR
Outdoor Air Riser
PFT
Perfluorocarbon Tracer
PRV
Power Roof Ventilator
RPP
Radon Proficiency Program
TAB
Test and Balance
VAV
Variable Air Volume
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ACKNOWLEDGEMENTS
The authors would like to acknowledge the efforts made by Ashley D. Williamson, Bobby E. Pylc,
Susan F. McDonaough and Charles S. Fowler of Southern Research Institute, and for their endless
energy and enthusiasm. Our thanks also extend to the Polk County Schools and their Facilities and
Operations Divisions, for their time, efforts and cooperatioon in this project. The project was funded
by the U. S. Environmental Protection Agency and the Florida Department of Community Affairs.
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SECTION 1
INTRODUCTION
This report describes the results of a project conducted by Southern Research Institute and other
organizations for the U.S. Environmental Protection Agency on behalf of the Florida Department
of Community Affairs. The purpose of this study is to develop radon diagnostic procedures and
mitigation strategies applicable to a variety of large non-residential buildings commonly found in
the State of Florida. To accomplish this, it was necessary to perform detailed field investigations
and parametric studies in a variety of buildings that have elevated levels of radon. The investigations
document and evaluate the nature of radon occurrence and entry mechanisms for radon, the effects
of heating, ventilating, and air-conditioning (HVAC) systems configuration and operation on radon
entry and dilution, and the significance of occupancy patterns, building height, and other building
construction features.
Elevated levels of radon have been found in large buildings in Florida. These have generally been
in the same areas of the state that were identified by the Florida Statewide Radiation Survey (Nag
87) as having high radon potentials. To date, the greatest effort in the research of radon in large
buildings has been to develop radon diagnostic and mitigation techniques for school buildings
throughout the U.S. Experience in other types of large non-residential buildings was limited at this
time, although there are a number of similarities between school buildings and other types of large
buildings. Diagnostic and mitigation techniques developed by the U.S. EPA and used in school
buildings were used as the basis for developing suitable diagnostic and mitigation techniques for
large buildings in Florida.
A primary focus of this project was the effect of the HVAC systems of a large building in
influencing the transport, entry, and hopefully the minimization of indoor radon in the building. The
report contains a discussion of HVAC systems and their effects, followed by a description of case
studies in two large buildings in the state of Florida. Conclusions and recommendations address
elements of significance to proposed statewide standards for radon resistance in new large building
construction.
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SECTION 2
CONCLUSIONS AND RECOMMENDATIONS
The two case studies in this report present some insight which can be generalized to other structures.
The first building was a structure that had apparently been successfully mitigated by passive
techniques, so would not normally be considered a "problem" structure. In this building, variations
in outdoor air flow control dampers produced ventilation rate changes within the typical range [0.2
to 0.6 air changes per hour (ACH)] resulting in variations in indoor radon concentrations over a
comparable range (a factor of 2.6). The second building had much higher radon levels, which could
not be reduced below the 4 pCi/L radon standard without introducing outdoor air at a rate in excess
of American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standard
requirements, not to mention the energy management priorities of the owner. Both buildings
demonstrated an inverse relationship between dedicated ventilation air and indoor radon
concentrations, as was expected. Both also showed signs of aberrant HVAC design, operation, and
maintenance which presumably adversely affected indoor radon as well as other indoor air quality
variables. The second building showed clear indications of foundation design elements which
contributed to radon entry; elimination of these entry paths at the time of construction would have
been by far the most cost-effective remedy for the building.
Some recommendations relevant to building standards can be concluded from this project. First,
design and construction should concentrate on elimination of major soil gas pathways such as hollow
walls and unsealed utility penetrations. It is less clear from this study how much benefit can be
derived from sealing of minor cracks and joints. Second. HVAC system design should include
strategies designed to minimize depressurized zones adjacent to the soil. Such zones could be
caused by flow imbalance in the air distribution system, inadequate sealing of major duct leaks, or
imbalance of supply and exhaust ventilation airflow. The combination of depressurized areas and
poor barriers is particularly undesirable, especially if the depressurizing element is the return air
portion of the air handling system. Third, while increased supply ventilation is generally helpful for
radon control, it is clearly not the most cost-effective solution or prevention tool once the
requirements of occupant comfort and general indoor air quality have been met.
Further studies to extend the information base would be of value. In particular, future studies could
include monitoring of the radon in new buildings constructed on high radon potential soil according
to radon control guidelines.
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SECTION 3
BACKGROUND: HVAC SYSTEMS AND RADON IN LARGE BUILDINGS
3.1 HVAC SYSTEMS BACKGROUND
Heating, ventilating, and air-conditioning (HVAC) systems have two distinct primary functions: a)
provision and maintenance of specific environmental conditions; and b) occupant or space
ventilation for the provision and maintenance of acceptable indoor air quality. Specified
environmental conditions are typically for occupant comfort, but special environmental conditions
can also be needed for a process or a product. In all cases, the HVAC system must provide the
occupant or process with the proper conditions (dry-bulb temperature, relative humidity, etc.). The
primary purpose of ventilation is the controlled introduction, and exhaust or recirculation of air in
a given space. Research indicates that the required amount of outdoor air is dependent on the rate
of contaminant generation and the maximum acceptable contaminant level. Understanding this is
important to HVAC system designers since confusion can lead to designs that are energy wasteful
(too much outdoor air) or that provide poor indoor air quality (too little outdoor air).
There exists a wide variety of design situations for these two basic functions. These include
commercial and manufacturing applications, general office space, educational and institutional
facilities, and special purpose space, such as laboratories and clean rooms. These diverse
environmental conditions require a wide range of equipment types and sizes for HVAC systems for
the creation and maintenance of a controlled environment. For purposes of simplicity, all HVAC
systems fall into one of the following four major categories: ALL-AIR SYSTEMS, AIR-WATER
SYSTEMS, ALL-WATER SYSTEMS, and UNITARY SYSTEMS. These system types are
distinguished from one another based on their terminal-cooling medium:
An ALL-AIR SYSTEM is defined as an HVAC system that provides complete
sensible and latent cooling capacity in the cold air supplied by the system. No
additional cooling is required at the zone. Heating may be accomplished by the same
air stream either in the central system or at a particular zone. In some applications,
heating is accomplished by a separate air, water, steam, or electric heating system.
An AIR-WATER SYSTEM is one in which both the medium of air and water are
distributed to each space to perform the cooling function. In virtually all AIR-
WATER SYSTEMS, both cooling and heating functions are carried out by changing
the air or water temperatures (or both) to permit control of the space temperature
during all seasons of the year.
An ALL-WATER SYSTEM is one with fan-coil units, unit ventilators, or valance-
type room terminals having unconditioned ventilation air supplied by an opening
through the wall or by infiltration. Cooling and humidification are provided by
circulating chilled water or brine through a finned coil in the unit. Heating is
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provided by supplying hot water through the same or a separate coil using a piping
distribution system from a central boiler plant. Electric heating or a separate steam
coil may also be used.
A UNITARY SYSTEM consists primarily of conditioning equipment that is
factory-matched with refrigerant-cycle components for inclusion in air-conditioning
systems that are field designed to meet the needs of the user. Heating is
generally accomplished by the use of electric coils.
3.1.1 ALL-AIR SYSTEMS
ALL-AIR SYSTEMS may be briefly classified in two basic categories: a) single-path systems, and
b) dual-path systems. Single-path systems are those which contain the main heating and cooling
coils in a series flow air-path, using a common duct distribution system at a common air temperature
to feed all terminal apparatus. Dual-path systems are those that contain the main heating and cooling
coils in a parallel flow, or series parallel flow air-path, using either a separate cold and warm air duct
distribution system, which is blended at the terminal apparatus (dual-duct systems), or a separate
supply duct to each zone with blending of warm and cold air at the main supply fan. These
classifications may be broken down as follows:
Single-Path Systems
Single Duct, Single Zone, Constant Volume
Single Duct, Variable Volume
Single Duct, Variable Volume Induction
Single Duct Zoned Reheat
Dual-Path Systents
Dual-Duct (including Dual-Duct, Variable Volume)
Multizone
The ALL-AIR SYSTEM may be adapted to all types of air-conditioning systems for comfort and
ventilation. It is used in buildings requiring individual control of conditions within a multiplicity
of zones, such as office buildings, schools and universities, laboratories, hospitals, stores, and hotels.
An ALL-AIR SYSTEM is also used for many special applications where a need exists for close
control of temperature and humidity, including clean rooms, computer rooms, hospital operating
rooms, and textile factories. In general, ALL-AIR SYSTEMS offer the following advantages:
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• Centralized location of major equipment allowing operations and maintenance in
unoccupied spaces.
• Greatest number of potential cooling season hours when outdoor air can be used for
cooling in lieu of mechanical refrigeration.
• Wide choice of zone-ability, flexibility, and humidity control under all operating
conditions with simultaneous availability of heating and cooling to the extent
required, even during off-season periods.
• Readily adaptable to heat-recovery systems.
• Best suited for applications requiring abnormal exhaust makeup.
• Adaptable to winter humidification.
Some of the disadvantages of ALL-AIR SYSTEMS are:
• Plenum space for the duct distribution system can be very expensive.
• System designs can be difficult to keep in air balance, requiring balancing as often
as once a year.
• Accessibility to equipment and room terminal units can be difficult if not closely
coordinated between the architect and the mechanical engineer.
• Some ALL-AIR SYSTEMS are not energy efficient.
Four types of ALL-AIR SYSTEMS that are commonly found in buildings today are:
Reheat Systems
The purpose of this system is to permit zone or space control for areas of unequal loading; or to
provide heating or cooling of perimeter areas with different exposures; or for process or comfort
applications where close control of space conditions is desired. These cases arise in some hospitals,
laboratories, office buildings, or spaces where wide load variations occur.
Variable Volume Systems
The Variable Air Volume (VAV) system is a central HVAC system that compensates for varying
cooling load by regulating the volume of air being supplied to the space through a single duct. Of
significant advantage are the low initial and operating costs associated with the VAV system. The
system is far lower in first cost in comparison to other systems that provide individual space control
because it requires only single runs of duct and a simple control at the room terminal unit. Also,
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where diversity of loading occurs, smaller equipment can be used. Applications of VAV exist for
office buildings, hotels, hospitals, apartments, and schools.
Dual or Double-Duct Systems
In a dual-duct system, the central station equipment supplies warm air through one duct and cold air
through the other. The temperature in an individual space is controlled by a thermostat that mixes
the warm and cool air in proper proportion. Many dual-duct systems are installed in office buildings,
hotels, hospitals, schools, and large laboratories. With the simultaneous availability of warm and
cool air from the room-terminal unit at all times, this system provides great flexibility in satisfying
multiple loads and in providing prompt and opposite temperature response as required.
Multizone Systems
The multizone system provides a single supply duct for each zone and obtains zone control by
mixing warm and cool air at the central unit in response to room or zone thermostats. For a
comparable number of zones, this system provides greater flexibility than the single-duct system and
involves lower cost than the dual duct-system, but it is physically limited by the number of zones
that may be supported by the equipment.
3.1.2 AIR-WATER SYSTEMS
In ALL-AIR SYSTEMS, the spaces within the building are cooled and heated solely by the air
supplied to them from the central air-conditioning equipment. In contrast, an AIR-WATER
SYSTEM is one in which both air and water are distributed to each space to perform the cooling and
heating functions. The water side of the system consists of a distribution system of piping and
pumps that carries the hot and cold water to the space room terminal unit to perform the heating and
cooling functions. The air side to the system consists of central air-conditioning equipment and a
duct distribution system connected to the same space room terminal unit. The air side is constant
volume and often referred to as primary air to distinguish it from room air which is recirculated over
the coil in the room terminal unit. The common room terminal unit associated with these systems
is the air-water induction unit. In virtually all AIR-WATER SYSTEMS, both cooling and heating
are carried out by changing the air or water temperature (or both) to permit control of space
temperature during all seasons of the year. A number of reasons exist for the use of this type of
system:
(1) Water has a greater specific heat and density than air; consequently, the mechanical
space required for the water-piping system to accomplish the same cooling effect as
the air-duct system is much less.
(2) The air side of this type of system can be designed as a high velocity system further
reducing the mechanical space required.
(3) Since the water side of this system does most of the heating and cooling, energy
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consumption is reduced since pump horsepower is more efficient than fan
horsepower.
AIR-WATER SYSTEMS are primarily applicable to multiple perimeter spaces where a wide range
of sensible loads exist and where close control of humidity is not required. Systems of this type have
been commonly applied to office buildings, hospitals, hotels, schools, some apartment buildings, and
laboratories. The mechanical space savings associated with these systems make them especially
beneficial for use in high-rise structures.
3.1.3 ALL-WATER SYSTEMS
ALL-WATER SYSTEMS are those with fan-coil, unit ventilator, or valance-type room-terminal
units with unconditioned ventilation air supplied by an opening through the wall or by infiltration.
Cooling is provided by circulating chilled water or brine through a coil in the room terminal unit.
Heating is provided by supplying hot water through the same or separate coil. Heating could also
be supplied by a separate electric or steam coil.
Most of the ALL-WATER SYSTEMS that are installed do not meet the criteria for this type of air-
conditioning system as stated in ASHRAE Standard 55 (ASH 92) because they lack humidity control
and because the quantity of outdoor air is limited by the effectiveness of mechanical exhaust fans
within the room and by the size of the wall opening. These systems also fail to meet the ventilation
requirements of ASHRAE Standard 62 (ASH 89). There is no positive ventilation unless wall
openings are used, and the effect of these openings depends on wind pressures and stack action on
the building.
The greatest advantage of the ALL-WATER SYSTEM is its flexibility for adaptation to many
building module requirements. A fan-coil system applied without provision for positive ventilation
or taking ventilation air through an aperture is one of the lower first-cost central-station perimeter
systems in use today. It requires no ventilation air-duct work, is comparatively easy to install in
existing structures, and (as with any central-station perimeter system utilizing water in pipes instead
of air ducts) offers considerable space saving throughout the building.
On the other hand, maintenance and service work have to be done in the occupied areas, and as the
units become older, the fan noise can become objectionable. Each unit requires a condensate drain
line that periodically has to be flushed out and cleaned. It can be very difficult to limit bacterial
growth in these units. In extreme cold weather, it is often necessary to close the outdoor air dampers
to prevent freezing of coils, reducing ventilation air to that obtained by infiltration.
3.1.4 UNITARY SYSTEMS
UNITARY SYSTEMS include air-conditioning equipment consisting of factory-matched refrigerant
cycle components for inclusion in air-conditioning systems that are field designed to meet the needs
of the user. These fundamentally simple systems are characterized by the use of split-system
configuration utilizing an air-cooled condensing unit. The nearly infinite combinations of coil
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configurations, evaporator temperatures, air-handling arrangements, refrigerating capacities, and
variations thereof, which are available in central systems, are rarely possible with UNITARY
SYSTEMS. Consequently, in many respects, a higher level of design ingenuity and performance
is required to develop superior system performance using UNITARY SYSTEM equipment than for
central systems.
UNITARY SYSTEM equipment tends to fall into a zoned system category with each zone being
served by its own unit. For large single spaces, where central systems are at their best advantage,
application of multiple units often finds advantage due to movement of load sources within the
larger space, giving the flexibility of many smaller interlocked and independent systems instead of
one large central system. Typical examples of systems in this category are:
Window Air Conditioners
Packaged Terminal Air Conditioners
Rooftop Split Systems
Unitary Air Conditioners
Water-loop Heat Pumps
Multiple-unit systems generally have the following advantages over central system alternatives:
• Individual room control provided simply and inexpensively.
• Individual air distribution system for each room, usually with convenient, simple
adjustment provided by the occupant.
• Individual ventilation air provision, normally operating whenever the
conditioner is operating.
• Manufacturer-matched components ensure consistent performance.
• Manufacturer assembly and connection of components allow easier quality control
and improved reliability.
• Heating and cooling capability is provided at all times, independent of the mode of
operation of other spaces in the building.
• Only one terminal zone or conditioner affected in the event of equipment
malfunction.
• Usually some space saving.
• Usually lower initial cost.
• Equipment serving spaces that become vacant can be turned off locally without
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affecting occupied spaces.
This class of HVAC system typically finds application in small to medium commercial buildings,
some smaller multistory office buildings, and schools.
3.2 HVAC SYSTEM DEMANDS
An HVAC system is an assemblage of equipment components, such as fans, heating and cooling
coils, filtration devices, and ductwork, with the primary function of:
(a) providing an acceptable level of indoor air temperature and control so that the
occupants perceive that they are comfortable;
(b) maintaining relative humidity levels that are not detrimental to human health or
processes, yet positively interact with temperature ranges to enhance comfort;
(c) effectively cleaning the indoor supply air of contaminants and odors generated
outdoors and contaminants originating indoors;
(d) distributing and circulating the room air supply in such a way that air-flow patterns
ensure mixing in all comfort zones; and
(e) providing building ventilation systems that distribute the required amounts of
outdoor air to the comfort zones in a manner that ensures proper pressure
relationships throughout the entire system.
Research has shown that the comfort and health of building occupants can be greatly impacted,
depending on the ability of the HVAC system to perform according to each of the system's demands.
Complete, properly designed and installed HVAC systems have the ability to meet and control all
of these and many other factors. It is possible for a system to react accordingly to each system
function.
Why then are many indoor air-quality problems associated with newly constructed or renovated
HVAC systems? The answer to this question may well be found by investigating the planning,
development, and selection process. Reports of investigations of large buildings indicate that many
indoor air problems exist because of misapplication of the HVAC system, poor maintenance born
out of faulty design, lack of system control, poor construction and installation techniques, or
deficient commissioning practices.
Many problem systems can be associated with the lack of initial consideration of system demands
and performance characteristics by the design engineer. Quite a few cases exist that indicate that the
designer overemphasized first cost as the most important factor when evaluating and selecting the
HVAC system, or failed to properly evaluate the quality of the system.
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The practice of being guided primarily by first cost can prove to be false economy. Problem HVAC
systems can cause future losses associated with worker productivity, possibly poor indoor air quality
litigation, and costs associated with increased operation and maintenance. Additionally, considering
first cost only ignores other important factors such as life expectancy, ease of maintenance, and even
to some extent, energy efficiency, though most energy codes require a minimum efficiency rating.
Most professionals involved in the design, construction, and maintenance of HVAC systems would
agree that prevention is the least expensive way to go. The expense and effort required to prevent
indoor air quality problems is much less than the expense and effort required to resolve problems
after they develop.
It seems that in many cases the design engineer is not aware of the important factors in the
development and selection stage of HVAC system design. Technologies have changed greatly in
the past few years. We now know more about the demands of HVAC systems and their ultimate
effect on indoor air quality and energy usage if proper consideration is not given to design in the
earliest steps of HVAC system development. As research is done, we continue to learn in this area.
A more valued and complete approach to system development and selection is to consider and
evaluate the following criteria:
(a) Comfort requirements must be evaluated, including indoor air quality. This primarily
involves defining the goals and objectives of the indoor air requirements.
Consideration should be given to the building type and number of occupants. A
thorough knowledge of the activities of the occupants and equipment or devices they
may employ in their everyday activities is necessary for thorough evaluation. These
considerations can sometimes help in identifying possible indoor sources of
contaminants and their classifications. Once this type of information and knowledge
is gained, the design engineer can more expertly apply relevant codes and standards.
Many problems can be anticipated and resolved using this technique, and HVAC
system configuration options can be developed and evaluated for maximum impact.
After the options are defined, the final decision concerning the type system needed
can be made much more effectively.
Occupant comfort is generally easy to define and evaluate since this involves
providing the occupants with proper temperature and relative humidity levels
Engineering procedures for accomplishing this are well defined in design manuals
and textbooks. However, problems can arise when not enough detailed consideration
is given to methods of providing and controlling relative humidity levels.
Humidification can be a very serious cause of occupant health related issues. Low
humidity results in eye and throat irritation. High humidity encourages
biocontaminant growth, which is also a health hazard. Occupant comfort is closely
tied to air movement and circulation. Many occupant-related problems occur when
the design engineer performs insufficient design analysis to ensure good mixing and
distribution of air.
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(b) Energy usage actually refers to the efficient use of energy as it relates to the total
building. Total building energy usage includes many factors, the most dominant
being operation and maintenance aspects of HVAC systems. It is well known that
certain aspects of HVAC systems can have a great impact on total building energy
usage; two of these are ventilation and comfort control. Many concerns surface, and
questions are raised when discussing the potential costs associated with increased
outdoor air ventilation rates required by indoor air standards. Additionally, energy
cost associated with comfort control (temperature and relative humidity) can be
substantial, depending upon the systems application and building process. Total
building energy usage is estimated to account for 30% of all energy consumed.
Obviously, great initial savings, as well as life-cycle savings, can be realized by
closely controlling energy costs associated with ventilation and comfort control.
Energy savings at the expense of ventilation and comfort can result in a deterioration
of indoor air quality. Design decisions that impact and reduce this usage and that
are relative to the previous discussions are: construction of the building shell and its
associated thermal and air-barrier performance, HVAC system type and class, and
HVAC operational demands and duty cycle. A reasonable plan for evaluating energy
aspects should be developed. The design engineer must look at the building, evaluate
its use, determine the type and source of energy available, and develop an energy-
reduction plan that maintains the best building environment for all anticipated
circumstances.
(c) First cost and life-cvclc costs are critical design variables. Providing the building
owner with a well designed and efficiently operating HVAC system is the intent of
all design engineers. Unfortunately, this is not enough. The systems must be
economical. The best intentions of the design engineer will quickly be lost if the
system is not economically balanced with respect to first-cost, operating cost, and
maintenance cost. It is not easy to determine the economy of a system. The process
of evaluation is wrought with many complex parameters, such as varying equipment
costs related to different system types, various energy sources and usage rates, tax
codes and structures, the time value of money, building-life expectancy, asset
depreciation, and varying levels of insurance needs. As stated before, it is easy for
the design engineer to overemphasize the importance of first-cost in evaluating
different systems. It is imperative that a successful design include a thorough life-
cycle analysis. Different systems can be realistically evaluated and compared by
converting all system costs to "present worth values."
(d) System maintenance is a critical and important consideration in system selection and
design. Very often design engineers give little thought to this factor even though the
long term satisfaction of the owner and the occupants is at stake. A basis towards
poor maintenance of a complex system can negate any potential for radon mitigation
(Sau 93). It is the responsibility of the design engineer to determine the amount of
space that will allow maintenance personnel to perform their job of maintaining the
system. The design engineer must also make the architect aware of the importance
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of providing the proper space to meet these needs. This applies not only to the
obvious spaces, such as mechanical equipment rooms, but also to ceiling plenums
and interstices. This will allow proper maintenance of the control and distribution
systems.
(e) System operations, along with system maintenance, is an important but often over-
looked design and selection factor. The design engineer must consider and design
HVAC systems that are easily understood and that can be operated in accordance
with design intent. This means that, with proper training, the operating engineer(s)
can operate the system to meet the demands for which it was designed. Simplicity-
is the rule that the design engineer should follow. Do not overly complicate the
system or its controls. Additionally, simple systems are the easiest to commission.
Commissioning involves testing and balancing the final installation to certify that it
can meet the environmental design parameters that it was intended to fulfill, such as
temperature, relative humidity, and air movement.
3.3 RADON ENTRY MECHANISMS RELEVANT TO LARGE BUILDINGS
Radon entry into large buildings can be influenced by the effect of either ventilation air or infiltration
air. These are two important types of entry-influencing mechanisms that contribute to the driving
forces causing soil gas to enter a building. Outdoor air is generally used to dilute indoor air
contaminants, pressurizing the building interior thus creating a driving force that impedes entry,
while the energy associated with heating or cooling this outdoor air can have a significant impact
on space-conditioning, energy-loading factors.
The generally accepted definition of ventilation air is the intentional and controlled introduction of
outdoor air into occupied space. Further, ventilation air can be either natural or forced. Natural
ventilation is unpowercd airflow through open windows, doors, and other intentional openings in
the building envelope. Forced ventilation on the other hand is the intentional, powered air exchange
by a fan or blower with intake and/or exhaust vents that are specifically designed and installed for
the introduction of outdoor air. Designers of heating, ventilation, and air-conditioning systems
utilize design standards to determine the correct amount of outdoor air to introduce into the occupied
space. The current standard used by designers is The American Society of Heating, Refrigerating
and Air-Conditioning Engineers (ASHRAE) Standard 62-1989 (ASH 89). "Ventilation for
Acceptable Indoor Air Quality." Under ASHRAE Standard 62-1989, the minimum ventilation rate
can be defined by two approaches. The primary approach is a specification standard calling for the
provision of minimum amounts of clean, conditioned, outdoor air. The alternative method is a
performance standard whereby the minimum outdoor air quantities need not be met but the quality
of the indoor air must conform to established guidelines. Either approach is acceptable; however,
the alternative approach generally results in a lower ventilation rate. This means that less ventilation
air (outdoor air) is being brought into the building, which could have an adverse impact on the
HVAC system's ability to control radon entry. In building design, the key factors influencing radon
entry from soil are the design and operation of the ventilation system, which affects pressures driving
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bulk airflow through soil, and the design and construction of the building substructure, which
controls the degree of movement between the air in the soil and the air in the building.
Infiltration is the unintentional and uncontrolled introduction of outdoor air into the building through
cracks and openings in the shell or envelope of the building. Infiltration is uncontrolled airflow
through cracks, interstices, and other unintentional openings that occur in the envelope of the
building and seem to be a general result of construction practices. Both infiltration and natural
ventilation airflows are caused by pressure differences due to wind, indoor-outdoor temperature
differences, and equipment operation.
3.3.1 Radon Entry
Most large buildings are built with the lowest floor made of poured concrete and in direct contact
with underlying soil (basement or slab-on-grade), or in some cases, suspended above the soil (crawl
space). The building substructure influences radon entry by the degree of coupling between indoor
air and soil air, and the size and location of openings, penetrations, joints, and cracks in the slab,
through the substructure. The degree of coupling is a result of the underlying layer, which can act
to distribute soil gas (such as gravel) or provide minimum gaseous communication (such as clay or
tight sand) beneath the slab and the building to subslab differential pressure providing the convective
driving force. In addition to buildings with slab-on-grade or basement construction of the
foundation, crawl space substructures can be well coupled when crawl space vents are not installed.
Penetrations in the building shell of greatest importance are those in the floor and. in the case of
basement substructures, openings in the wall below soil grade. In addition, the rate at which soil-gas
moves through soil may be the limiting factor when slab openings are not minor in size.
In buildings, a possible additional source of entry are building materials, which can contribute to
the total indoor radon concentrations but are easily controllable. Intended building materials should
be investigated on the basis of their properties as sources of radon. Materials high in radon
concentration should not be used.
3.3.2 Ventilation Air
In the previous discussion of heating, ventilating, and air-conditioning systems, it was stated that one
of the primary purposes of HVAC systems is for space ventilation, specifically for the provision of
acceptable indoor air quality. Ventilation is best described as the action of replacing indoor air with
outdoor air; this occurs either naturally or intentionally. A primary use of ventilation air for
acceptable indoor air quality is the introduction of outdoor air for the purpose of controlling building
depressurization. Building depressurization occurs when the indoor building pressure is less than
the outdoor atmospheric pressure.
Research has indicated that the infiltration of pollutants (e.g., soil gases) in large buildings increases
as building depressurization increases. Building depressurization can be caused by a number of
driving mechanisms. Wind pressure on the outside of the building, temperature differences between
indoors and outdoors (stack effect), and the operation of combustion devices and mechanical
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ventilation systems are the primary factors affecting building depressurization. Building
depressurization can also have a great impact on energy usage in a building, as well as on the general
quality of the indoor environment. When a building experiences depressurization energy costs can
rise since the air entering via infiltration is unconditioned. Additionally, infiltration air can also have
an adverse effect on the indoor air quality since it is essentially untreated. Ideally, the designer of
building systems will want to control the level of building depressurization; however, this is not an
easy task since the driving forces are not easily controlled.
During the early 1970s, energy conservation was a primary goal of building designers. Buildings
were built with airtight envelopes to lessen the intrusion of infiltrating air. We now know that this
practice has led to poor indoor air quality since infiltrating air can help to dilute and remove indoor
air pollutants.
3.3.3 Wind Pressure
Building depressurization can be caused by wind pressure when the wind impinges on a building,
setting up a distribution of static pressures on the building's exterior surface. The degree of pressure
difference is dependent on the direction of the wind and varies with the location on the building
exterior. These static pressure distributions are dependent on the pressure inside the building. For
large buildings that are very tall and have relatively porous exteriors, the effect of building
depressurization due to wind pressure can be very significant. The static-pressure distributions will
cause outdoor air to infiltrate the building through openings in the windward walls and exfiltrate
through wall openings in the leeward wall of the building. In order to overcome the wind pressure
infiltration, the HVAC design must be such that a positive pressure is maintained in the building
with respect to outside the building. This, of course, is accomplished by using a system design that
introduces outdoor air in a controlled and conditioned fashion. Not all HVAC systems meet both
of these requirements. Even with HVAC systems that have outdoor air capability, wind pressure is
not easily overcome.
3.3.4 Stack Effect
Stack effect is the term used to describe the entry mechanism of outdoor air into a building due to
a temperature difference. The temperature difference is primarily between the indoor air
temperature and the outdoor air temperature. These temperature differences between indoor and
outdoor air tend to cause density variations between the indoor air and the outdoor air. The density
variations are then translated into pressures differences that cause outdoor air to infiltrate the
building structure. When the HVAC system is in the heating mode, it supplies warm air to the
building. This warm air has less density than the colder outdoor air and will naturally tend to rise
inside the building. In large and tall buildings, the warm air rises through stairwells, elevator shafts,
and utility corridors. Flow has also been shown to occur through pipe penetrations in floor slabs.
As it rises, warm air eventually will flow out of the building at the upper floors through openings
and cracks in the building envelope or through mechanical penthouses located on the roof. As this
air is exfiltrating at the upper floors, it is replaced by unconditioned, untreated, outdoor air at the
bottom floors. This phenomenon occurs primarily at the base of the building. The air finds its way
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into the building through the action of opening doors, through the building loading dock, or through
cracks and openings in the envelope.
During the cooling season, the flow directions are reversed, and air will enter at the top of the
building and be exfiltrated at its base through the doors and other openings. During the cooling
season, the stack effect is generally less than that found during the heating season. This is because
stack effect is driven by a density variation caused by the indoor air and the outdoor air temperature
differences. In the cooling season, this temperature difference is smaller than is experienced during
the heating season.
There is a point in the height of the building where the exterior and interior pressures are equal. This
point in the building is commonly referred to as the Neutral Pressure Plane (NPP). Above this
neutral pressure plane, (during the heating season), the pressure inside the building is greater than
the pressure outside of the building. Therefore, air will tend to flow from the building above the
NPP. Below the NPP, the inside pressure is less than outdoors, and air will tend to flow into the
building. The determination of the location of the NPP at zero wind speed depends upon a number
of factors:
(1) The vertical distribution of openings along the shell of the building; are the openings
and cracks in the shell evenly or unevenly distributed?
(2) The level of resistance of the openings to airflow; are the windows well sealed and
caulked?
(3) The resistance to vertical airflow within the building: is the interior of the building
constructed so that air can easily flow from one floor to another? Are stairwell doors
well sealed and gasketed? Are utility penetrations in the floors well sealed?
If the openings in the building shell are uniformly distributed vertically, and there is no internal
airflow resistance, the NPP is naturally found at the mid-height of the building. If there is only one
opening, or an extremely large opening relative to any others, the NPP is at or near the center of this
opening. Internal partitions, stairwells, elevator shafts, utility ducts, chimneys, vents, and
mechanical supply and exhaust systems complicate the analysis of NPP locations. Chimneys and
openings at or above the roof height raise the NPP in small buildings. Exhaust systems increase the
height of the NPP, while outdoor air supply systems lower it.
3.3.5 System Operation
Previous studies have shown that radon entry into large buildings can be reduced by reducing the
amount of building depressurization that occurs. By decreasing the building depressurization, entry
mechanisms, such as wind pressure and stack effect, can be de-emphasized. The heating, ventilating,
and air-conditioning system can play an important role in the depressurization of the building by
controlled use of ventilation air. By introducing more outdoor air through the HVAC system than
is removed through the building exhaust systems, the building can be pressurized with respect to the
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outdoors. Ideally, under building pressurization, indoor air exfiltrates rather than outdoor air
infiltrating. A properly operating HVAC system with outdoor air provision need only maintain a
pressure differential of 1-4 pascals. Not all HVAC systems encountered in large buildings are
capable of providing a level of building pressurization that is required to mitigate radon entry.
System configuration, type of HVAC system, building porosity, or some other factor may affect a
desired degree of building pressurization. The ability to pressurize a space or a building depends
upon the following factors:
Type of HVAC System
The system characteristics and features of various types and classes of HVAC systems were
discussed in previous sections. From the discussion, it is obvious that not all HVAC systems will
provide building pressurization. Many of the ALL-AIR SYSTEMS and some of the AIR-WATER
SYSTEMS are desirable for building pressurization. These classes of systems can provide outdoor
air in specific quantities to offset the forces that defeat pressurization. Many of the UNITARY
SYSTEMS and all of the ALL-WATER SYSTEMS do not allow pressurization because outdoor air
is not a feature of these types of systems.
Room or Building Porosity
Generally, the designs of building envelopes are successful in meeting structural and porosity
requirements. However, poor envelope construction can adversely affect the ability of the HVAC
system to maintain building pressurization. Many of these practices include inadequate sealing and
caulking around window frames or the installation of window and door systems that do not meet
tight construction standards. Another construction feature that can greatly affect envelope porosity
is the air barrier. The purpose of the air barrier is to prevent air from flowing through the building
shell itself. This means that outdoor air should be prevented from flowing into the building through
the walls, roof, and fenestrations. Conversely, flow of indoor air to the outdoors should also be
discouraged. These types of air leakages lead to excessive energy usage, poor thermal performance,
and poor indoor air quality, as well as interfere with the normal operation of the HVAC system.
Ductwork System
Leakage in duct systems is responsible for most major problems in air distribution systems. Poor
construction practices can cause leakage rates of up to 50%. This means that only half of the air that
enters the supply duct will reach the intended occupied zone. With this level of loss, it is virtually
impossible to maintain any degree of building pressurization. To avoid these leakage rates, HVAC
systems should be designed to operate at the lowest acceptable supply pressure. High pressure in
ducts only serves to encourage leakage. In existing systems, duct joints should be sealed. A number
of accepted sealing techniques can be used.
Automatic Control Methodology
The degree of building pressurization achievable will be directly proportional to the HVAC system's
ability to control and balance the introduction of outdoor air with the amount of air removed from
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the building. This can only be accomplished by satisfactory operation of the automatic control
system for the HVAC system. There are three primary control methodologies in use today:
pneumatic, electric, and digital. All three of these methodologies have proven to be effective as
control systems. There are many advantages as well as disadvantages to each. It is incumbent upon
the system designer to evaluate these and select the most advantageous system for pressurization,
ventilation, and comfort control.
System Return-Air Fans
In some HVAC system configurations and designs, it is necessary to incorporate a return-air fan in
the system. This is particularly true in variable air volume systems and dual-duct systems where the
return-air system has a high pressure loss. The difficulties involved with return-air fans and the
ability of the HVAC system to maintain building pressurization center around maintaining the
synchronization of the return-air-fan operation and the system supply fan. If the supply fan and the
return fan do not operate in harmony, imbalances in airflow can result. In the extreme case, these
imbalances allow the building pressure to swing from positive to negative. Controlling these fans
in order to eliminate imbalances in airflow is a difficult task. It is not enough to match fan speeds,
since these fans operate with different characteristics, making speed an insufficient measure for
balance. Usually, total flow or pressure is used to correct the imbalance. This practice is not without
problems, however, because the question arises as to the best point in the total system at which to
measure flow or pressure. The general design rule is to avoid using return-air fans if at all possible.
However, as the building becomes larger in size, a return-air-fan will be required. Proper balancing
of the return and supply air flows during the building commissioning, prior to first occupancy, is
critical. Also, continued maintenance and regular calibration and testing of the return and supply
fans and dampers are essential to avoid a negative pressurization.
Building Exhaust Fans
Powered exhaust systems are usually a requirement of building codes. Toilets, bathrooms, kitchens,
workshops, and similar areas are required to be exhausted. In many buildings, the very nature and
operation of individual exhaust systems defeat the HVAC system's ability to maintain building
pressurization. The best practice is to design central exhaust systems. With central systems, the
designer has the ability to provide some level of control over the operation of the exhaust systems.
Building Systems
The entire range of ALL-AIR category HVAC systems, by their very nature, will allow building
pressurization. These systems have as a major feature the ability to provide and control wide ranges
of outdoor air. It is not a difficult task to select and design an ALL-AIR system based upon the idea
that it will provide building pressurization. It is an entirely different task to implement that design.
Many of the obstacles that need to be considered and overcome were previously discussed.
The AIR-WATER SYSTEM is somewhat less acceptable for building pressurization. This is
because the heating and cooling medium is a combination of air and water, and this means that the
type of terminal units used will depend upon the amount of outdoor air used. If less outdoor air is
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used, then less control of building pressurization will be realized.
The ALL-WATER SYSTEM provides no means of outdoor air introduction. With this type of
system, no means of providing pressurization for the building exists. Typically, buildings that are
served by this type of system operate under depressurization, or negative pressure. Generally, this
depressurization is the result of a combination of a lack of outdoor air and the operation of exhaust
fans associated with toilets and bathrooms.
On the other hand, the UNITARY SYSTEM can be made to operate with the full range of outdoor
air introduction and control available in the ALL-AIR SYSTEM.
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SECTION 4
PROJECT OBJECTIVES AND EXPERIMENTAL PLAN
In accomplishing the project objectives the following activities have been included: (1) identification
of candidate buildings, (2) selection of a representative subset of buildings for diagnostics and
mitigation research. (3) developing standard diagnostic protocols applicable to large buildings, and
(4) conducting diagnostic measurements and research in two selected buildings. The elements of
this study plan are described below.
In preparation for the field study, the EPA, Southern Research Institute, and GEOMET made
contacts to identify candidate buildings and contact building owners and/or managers to obtain
agreements with regard to study participation and availability of buildings. Only those buildings
whose owners agreed to full and continued participation were considered for selection.
The following basic criteria were used to select candidate buildings for evaluation:
(1) Large buildings which are representative of the Florida building stock and have radon levels
higher than 4 pCi/L.
(2) Buildings with a minimum area of 10,000 square feet or three floors (excluding basements).
(3) Buildings and HVAC systems characteristic of Florida building stock.
(4) Buildings with owners/mangers willing to participate in the study and support study
activities.
Preference was to be given to buildings with:
• Radon levels significantly higher than 4 pCi/L.
• Facilities (or Energy) Systems which are computer based and from which HVAC operating
parameters may be recorded and reported.
• Owners willing to support or cost share in measurement and/or mitigation activities.
Standardized information relative to each building's construction type, HVAC type and operating
procedures was collected to aid in the screening process. Short-term radon measurements were made
in these buildings to verify elevated radon conditions. Measurements were carried out in accordance
with "Indoor Radon and Radon Decay Product Measurement Device Protocols" (EPA92). From
these measurements, a subset of preferred candidates were determined.
The exclusion of many buildings was necessary to accomplish study results which could be
meaningful and consistent. The screening of a large number of buildings produced three buildings
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recommended for inclusion in this research project. Of these, two were used for the case studies
reported in Sections 6 and 7.
Southern Research and the EPA selected three buildings, screened as described above, for more
detailed diagnostic and mitigation strategy research. A team of building researchers conducted a
preliminaiy site assessment of each of these buildings. The visit consisted of a walk-through of the
facility and a review of all available building information and plans.
The preliminary assessment provided: verification of previously obtained information, more detailed
information on type of building and occupancy patterns, and specifics on HVAC system
configuration, air handlers, air supply, and operating schedules. Further, the team attempted to
identify potential radon entry routes, and noted information on possible sampling locations and
procedures. In view of the limited number of buildings available for study, it was important to select
buildings which gave complementary information regarding construction or HVAC type. The two
buildings that were selected to be studied consist of one unitary constant-volume flow system
(having 23 separate air handlers), and one variable air volume control system (having one air
handler).
The diagnostic measurements were a part of an experimental plan to develop a diagnostic protocol,
identify radon mitigation strategies, and provide test data for the calibration of the Florida Radon
Research Program (FRRP) integrated radon entry and building performance model "Florida
Software for Environment Computation - User's Manual Version 3.0" [FSEC 3.0] (FSE92). The
following data as core measurements were gathered in each building during the early stages of the
field study:
(1) Verification of building data collected during the first site visits.
(2) Radon subslab sniffs to evaluate the radon source strength and the relationship between
subslab and indoor radon levels.
(3) Pressure differential measurements throughout the building (to the outdoors and to the
subslab) for various HVAC system operating conditions, (e.g.. outdoor damper open and
closed, exhaust systems on and off).
(4) Ventilation rate measurements via flow hood and duct traverses to determine the effect that
various operating conditions of the HVAC systems have on radon levels in the buildings.
(5) Infiltration rate measurements using tracer gas to determine the effects that air infiltration
rates have on diluting radon that enters buildings.
(6) Determination of the operating parameters for HVAC systems and the data logging
capabilities of the building Energy Management Systems (EMS), if available.
In preparation for the parametric evaluations, a thorough survey of the flow patterns and balance of
the HVAC system was performed. The measurements of the HVAC system were made by a certified
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Test and Balance (TAB) Contractor of the National Environmental Balancing Bureau (NfiBB) or
other equally qualified TAB company.
After each building was evaluated based on the core measurements, a detailed measurement plan was
developed for that building. This plan consisted of systematic study of the building over a range of
HVAC settings. Depending on the types of HVAC systems available in the study buildings, it was
necessary to override the normal system operation in order to simulate various operating modes.
These modes of operation include:
(a) Adjustment of outdoor air (OA) intake from 0 to as much as 20 cfm/person, if possible under
equipment and operation limitations.
(b) Control of the duty cycle operation of HVAC fans, including air handlers (AH), OA. and
exhaust fans. Defined periods of on, off, and intermittent operation are necessary to test
conditions driving HVAC system employment.
These HVAC operation modes were coordinated with the building managers and thus limited to
weekends only. Each of these operation modes was allowed to run for at least 4 full days. Each
building was fitted with sensors and data collectors to collect the following information at each
building:
(a) Pressure differentials across the building shell and the building slab.
(b) Radon levels in the building, subslab, and ambient air.
(c) Flowrate measurements of outdoor air or outdoor air damper positions (calibrated to the
outdoor air flow).
(d) Indoor air quality measurements of temperature, relative humidity, and carbon dioxide.
(e) Ventilation rates using tracer gases.
(f) Data on the HVAC system fan duty cycle operations and flowrates (taken by TAB company).
These data would include run schedules, setpoints, and input and output data (temperatures,
control signals, etc).
(g) Data on weather conditions at the building location.
These measurements were made in order to identify radon entry points and sources of pressure
driven flow, to quantify the overall ventilation rate of the space, and to measure the impact of the
HVAC systems operation on radon levels, ventilation rate, and pressure differentials. Data from
these measurements were provided to Florida Solar Energy Center (FSEC) to be used in the model
analysis to verify' model predictions.
Measurements were completed on two large buildings in Florida. Section 6 describes the first study
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at the Financial Center North (FCN) Building located in Deerficld Beach. This building has a
unitary HVAC system with 23 separate AHs, two outdoor air intakes; and contains office areas on
three floors. Multiple zone measurements of radon, carbon dioxide concentrations, temperature,
humidity, pressure differentials across the building shell and subslab areas, and outdoor air intake
flowrates were collected over an 8 week period. The outdoor air intake was adjusted from 0 to 20
cfm/person (ASIIRAE recommended levels) as a modification of pressurization and dilution of the
indoor air conditions. Passive perfluorocarbon tracer (PFT) gas emitters were placed in all rooms,
and detector sets were placed in all zones for each outdoor air intake level. Short term EPERM
detectors were also used as an integrated sampling for each outdoor air intake level.
The second case study, described in Section 7, was conducted at the Polk County Life and Learning
Center (LLC), located in Bartow. The same conditions and measurements described above were
also made at LLC. with five data stations and a weather station installed and operated for 6 months.
All stations were downloaded by phone modem and are collecting data analogous to those collected
at the Decrfield Beach site.
Obviously, the findings of two case studies must be generalized to provide useful conclusions for
a broad range of large building types. In each case study, data synthesis must be performed to find
if correlations are observed which provide implications for mitigative strategies and could be used
to guide design or operation of HVAC systems. To apply this information to a better understanding
of all large buildings a unifying comprehension of all dynamic conditions must be achieved. This
comprehensive understanding can only be achieved through the application of a computer model
to study the many types and variations of HVAC systems.
Computer modeling of building dynamics is a viable tool in completely understanding the actions
and interactions of various building components on indoor air quality. The use of building models,
including those for zonal transport, ventilation, soil gas entry, and energy, is desirable and could
enhance and extend the results of this study. Models such as FSEC 3.0 (FSE92), CONTAM (Axl
90) and COMIS (Feu 90) require extensive data input to produce successful results. An effort in
modeling the study buildings was conducted in a parallel study by the Florida Solar Energy Center
for the Florida Department of Community Affairs (DCA). The data from our studies have been
processed through the FSEC 3.0 model and the correlations between exhibited and predicted
examined. The validation of the model to predict large building responses to changes in design or
operational controls and the limits of the ability to predict these responses was investigated (Gu 96).
Results of the FSEC evaluation of the second case study of this project (LLC) are published in a
separate report, "Analysis of the Polk Life and Learning Center (PLLC)," FSEC - CR-739-94
(Gu96). In view of the applicability of this model to this and other studies, it is described briefly
below.
One of FSEC 3.0's major features is its ability to solve user-defined systems of governing equations.
Up to 250 coupled differential equations and their corresponding boundary conditions may be either
selected from libraries or defined by the user. The equations may be linear or nonlinear, spatially
lumped or spatially distributed, steady-state or transient, ordinary or partial. The structure of the
software also allows users to incorporate their own routines or programs. Thus, researchers may
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define a specific problem and incorporate it into general software that provides the numerical
framework for detailed computer simulation.
The software allows combined heat, moisture, and contaminant transport and system simulations at
different levels of detail. For example, in considering a building that is composed of several solid
and air interfaces where the solids include the envelope, internal walls, or furniture, and the air is
either indoor or outdoor, spatially lumped or distributed equations may be used to define the
characteristics of the solid and air domains.
FSEC 3.0 incorporates the necessary macrolevel and microlevel models needed for simulating radon
in large buildings. In addition, several component level models are available to assemble different
HVAC systems. These include models built from manufacturers' data and those obtained from other
codes. Models to simulate VAV box performance have been also added.
A unique feature of FSEC 3.0 is that the user is not limited to any specific type of HVAC system.
Rather, the user has the option to assemble individual components such as ducts, fans, fittings, coils,
chillers. VAV boxes, and control elements and construct the desired HVAC system to be simulated.
This was seen as a critical feature for the type of modeling required in this large building radon
study.
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SECTION 5
EXPERIMENTAL PROCEDURES
This project is examining how radon concentration and indoor air quality levels are affected by
building ventilation dynamics and building air system conditions, including mixing and leakage rates
of typical residential, commercial, and public structures, and HVAC components. The ventilation
dynamics inherent to a building to dilute radon and indoor air pollution, and overcome soil gas entry
forces, are being analyzed in an effort to develop diagnostic and mitigation protocols.
Large buildings, being complex in character, raise imposing demands on data needs. Project
demands to measure many data parameters over time made it necessary to either utilize numerous
individual monitoring sensors or develop a new data collection station system. Individual sensor
units would put large demands on field personnel in time and individuals needed to collect data, and
would have created quality control concerns. A centralized data collection system was needed to
reduce technical support time and streamline data collection. Extensive data collection
microcontroller requirements consisting of four 12 bit channels, seven 8 bit channels, three pulse
channels, and three switch channels, and the high cost of existing centralized data collection systems
made the development of a new system important to the project success.
Measurements required for this project include radon and carbon dioxide concentrations,
temperature, humidity, pressure within indoor building zones and subslab areas, and outdoor air
intake flowrates. The general experimental procedure includes adjustment of the outdoor air intake
from levels of no outdoor air to recommended ASHRAE levels while monitoring pressurization and
dilution of the indoor air conditions. Weather station information was recorded continuously on a
separate data logging system. Real time data from instruments are downloaded by computer modem
connection to allow for prompt evaluation and analysis, and minimize on-site time demands.
5.1 DATA STATION EQUIPMENT
The Large Building Instrumentation System is based on the Blue Earth Research Micro-440
microcontroller system. This device is designed for compact, low power (or battery-operated)
applications, and contains the core hardware and software in the main unit. The only additional
required hardware units are the 4-input 12-bit A/D converter and a power supply. A 12-volt
rechargeable batter)' pack is included in the power supply to provide for continued operation during
brief power failures. The built-in memory is large enough to save 20 days of data. If a longer period
between downloading of data is desired, an additional memory module may be added to the system
to give an extra 28 days of data storage. The devices are installed in a metal cage to give mechanical
protection.
Each instrumentation node serves as a stand-alone system, requiring only electrical power to operate.
A built-in battery allows the system to withstand brief power failures without loss of operation.
Data may be downloaded on site with a portable computer used as a terminal or by using the built-in
modem; the data may be accessed by telephone.
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The microcomputer controlling the Blue Earth system uses a 1-second clock interrupt to pace data
acquisition. It counts to 7 seconds and then reads each A/D converter and samples the input switch
lines. The readings are added to averaging buffers which hold the intermediate values. After 256
loops the contents of the buffer are averaged and converted to one or two bytes of data. The 12- bit
A/D converter values result in two bytes of data each, the 8-bit A/D converters and the switch
registers produce one byte of data each, and the counter registers which are read at this time produce
two bytes each. The elapsed time for the loop is 1792 seconds (7 X 256), so an added delay of 8
seconds before beginning the next loop produces sampling periods of 30 minutes (1800 seconds).
The real time clock is read at this time and the month, day, hour, and minute values are used to form
the header for the data block, which is stored in the battery-backed RAM which is available in the
system. The 4 date/time numbers and the 20 data value numbers are stored as a block in the next
available space in memory.
The system contains rechargeable batteries which will provide about 8 hours of operation with the
external power off. This will permit data acquisition to continue during brief power outages. If the
power is off for a longer interval, data acquisition will stop but the data taken up to that point will
be saved in internal battery-backed RAM. When power is reapplied, the system will reset and start
taking data from that time. The system will operate automatically without any operator intervention.
For system control and data downloading, a computer configured as a terminal is connected to the
RS-232 connector. The terminal operates at 2400 baud. Any one of the data channels can be
checked for operation or calibrated via the RS-232 input. The channel number and the number of
repetitions of the test are entered, and then that channel is exercised and the results printed out. with
a delay between each repetition of the test.
The blocks of data stored in memory are identified by the month and day of acquisition. The month
and day of the first data block to be downloaded are entered at the prompts, then the system searches
memory for the first data block for that month and day. There are 48 blocks in each full day of data.
When downloading starts, all of the data from the entry date to the current block are downloaded.
Several input channels are dedicated to the internal instruments on the data station, including a
continuous radon monitor (FemtoTech Model R210F), a carbon dioxide monitor, two differential
pressure transducers (Modus, typically -25 to +25 Pa full-scale), and temperature and relative
humidity transducers. Additional pulse counting, A/D, and switch monitoring channels are available
for other instruments if required.
5.2 TRACER GAS MEASUREMENTS
A number of techniques both passive and active are available for characterizing airflow and transport
in a building by use of tracer gas. Perfluorocarbon tracer (PFT), devised at Brookhaven National
Laboratories, is a passive method of characterization of airflow patterns in residential, large
industrial, commercial, and office buildings using five varieties of gas and common detectors. The
five types of passive emitter gases allow five zones to be monitored simultaneously for interzonal
mixing, yielding an integrated average for the sampling period. With this technique, natural and
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mechanical ventilation rates and efficiency, natural infiltration, and overall HVAC system
performance can be measured. Capillary adsorption tube samplers adsorb the steady state gases and
are analyzed at Brookhaven. This type of measurement technique was used in FCN.
The most widely used and simplest technique is the tracer gas decay method which was employed
at LLC. In this method a tracer gas is injected into a well-mixed zone of the building. Once the
sulfur hexafluoride (SF6) concentration becomes uniform, the injection is stopped and the
concentration of gas is periodically sampled over a period of several hours. From the decaying
concentration information the zone (or building) ventilation rate can be calculated. This technique
is simple to perform and requires little expensive equipment. However, the measurements are not
continuous, and the assumption of a well-mixed zone (or building) is often not realized. Also,
although it is possible to perform multizone decay tests, the amount of time required for a single
tracer gas is often over 8 hours, and the analysis is difficult and prone to errors.
Active multigas analyzers can give comparable data, but on a real time basis, reporting information
several times each hour in four or more zones. The time between buildup and decay of tracer gas
is minimized allowing multiple tests to be run and variation in HVAC control to be incorporated.
The constant injection technique is a very powerful but complex method. In this method, several
different tracer gases are constantly injected into the building with each gas going into a different
zone. Simultaneously, the concentrations of all the gases are measured in all of the zones on a
continuous basis. For the case where the building can be considered a single zone, the air infiltration
rate is simply a function of the rate of change of the concentration and the tracer injection rate,
When more than one zone is called for, the equations governing the level of tracer gases are a series
of coupled first order differential equations. The advantage of the constant in jection method is the
ability to continuously measure the air flowrates (interzonal and infiltration) in a multizone building.
PFT measurements were used at the Florida Financial Center Building while active continuous
measurements were used at the Polk County Life and Learning Center.
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5.3 DIAGNOSTIC MEASUREMENTS
A series of tests were done by FSEC at the LLC to characterize building airtightness, air flowrates,
and pressure differentials. These measurements assist in understanding the driving forces for radon
entry (pressure differential) and dilution (infiltration/ ventilation rate), and form the basis for much
of the LLC computer modeling effort. While this information is also included by FSEC in their
project report (Gu 96), their participation provided significant input to these project goals.
Accordingly, sections of their procedures will be reproduced here and some of their results in Section
7 of this report.
5.3.1 Airtightness
Building or zone airtightness was done using blower doors; FSEC, like Southern Research, uses
Minneapolis Blower Door Model 3. These units come from the factory with a rated accuracy of
+5%. FSEC has performed calibration checks on their blower doors since the fall of 1993, and have
found them to be within the factory specifications. One of the FSEC blower doors was sent to the
factory for a more precise calibration in early 1994.
The "Fan Pressurization" test method is essentially that used in ASTM Standard E779-87 (AST87).
However our tests are done exclusively in the depressurization mode, because we believe that this
more typically represents the true airtightness characteristics of the building. If a building is
pressurized to +50 pascals, it is common for windows, exhaust fan dampers, dryer dampers,
skylights, etc. to push open and thereby overrepresent the true leak area of the building. Also,
repeating the test in the pressurization mode consumes more time and yields little additional useful
information.
We obtain six or more "pressure versus air flow" data points, and do a best-fit curve to those points.
The FSEC test data are input directly to a Quattro Pro file, which automatically calculates and plots
the Q - C(AP)" curve, the goodness of fit (r), CFM50, ACH50, EqLA, and ELA. Sample data are
shown in Section 7. Because the results are computed instantaneously, we are able to assess the
goodness of the test and repeat the test if necessary.
5.3.2 Air Flows
Air Ho ws are measured by air flow hood, pitot tube traverse, or tracer gas injection. The air flow
hood used by both FSEC and Southern Research is a Shortridge ADM-860. The FSEC hood was
calibrated during the third quarter of 1993 using a bench-top TSI wind tunnel as the standard. Air
coming from supply registers or going into return or exhaust registers is measured by placing the
hood over the register/grill.
We use a pitot tube in conjunction with the ADM-860 micromanometer/computer and sample in
a matrix of 5 by 5 (25 data points for the rectangular outdoor air ducts). In the round supply trunk
ducts we used a cross section sampling technique of 10 points vertically and 10 points horizontally
(20 data points). These points arc averaged to obtain an average velocity, and this is multiplied by
the cross-section area of the duct to obtain the volumetric air flowrate.
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Tracer injection is also used by FSEC as a method for measuring air flows within a duct. They
used tracer injection to measure the airflow rate of outdoor air. the two major supply trunks, and the
total supply air through the air handler. A Gilmont (Cole-Parmer cat.#L-03202-00) flow meter,
calibrated to either nitrous oxide (N20) or SF6, was used to inject gas into the air stream. A Miran
101 was used to read the concentration of tracer gas downstream.
The flowrate of air can be calculated by knowing the injection rate and the gas concentration
downstream, assuming that the gas is well-mixed in the air. Mixing is enhanced by injecting the gas
in a distributed manner. For example, when injecting gas into the outdoor air stream at the LLC,
FSEC divided the gas stream four ways and injected at four sides of the outdoor air intake fan (the
fan would provide further mixing, as well). As the test is run, FSEC inputs the data directly into a
Quattro Pro program which immediately calculates the air flowrate. By repeating the test 3 to 5
times, they are able to check for internal consistency and then average the values to reduce
inaccuracy.
5.3.3 Pressure Differentials
Digital micromanometers are used to measure pressure in various zones of the building. Two types
of instruments are primarily used: single-channel micromanometers from the Energy Conservator)'
(EC) or EDM, Inc. and a six-channel micromanometer with computer interface. The EC
micromanometers have several features which make them ideal for use in measuring the small
pressures which exist in buildings. They have resolution to 0.1 pascal and they have time averaging:
5 seconds. 10 seconds, or long term. When pressure differentials are small, say less than 1 pascal
and there is fluctuation in pressures due to the wind, then the long-term averaging feature is
invaluable. It provides a running average from the time of turn-on. By watching the value displayed
on the screen stabilize, the observer knows when a good value has been achieved, often after a period
of 5 to 10 minutes. We last calibrated these micromanometers during the fourth quarter of 1993,
against an inclined manometer, several ADM-860 micromanometers, and against each other
(typically agree within ± 0.1 pascal). These instruments have been found to be very accurate, and
stable over time.
The six-channel micromanometer can measure all six channels simultaneously, plot them to a real-
time screen display, average over specified time increments, and record them to computer memory.
Plastic tubing can be attached to each of the six pressure ports, and run to distributed locations which
are of measurement interest. This six-channel uses Modus micromanometers. Because their zero
is subject to thermal drift, the assembly has been designed to rezero at each reading, about every 15
seconds. This procedure is also used by Southern Research Institute (with a 30 minute zeroing
frequency).
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5.3.4 Infiltration Rate
FSEC uses tracer gas decay tests of the type discussed in Section 5.2 to determine the infiltration
rate/ventilation rate of the building. The gas detectors are Miran 101 s and Bruel and Kjaer 1305.
Two Miran 101s are available which can read SF6 and N20, respectively. 1'he Bruel and Kjaer can
read both SF6 and N?0, simultaneously. The tests at the LLC were done with N20 as the tracer gas,
with both the Bruel and Kjaer and the Miran instruments.
The FSEC test method is as follows. We inject the tracer gas into the return air side of the air
distribution system with the air handler operating. This distributes the gas. We then leave the unit
on for a period of about 30 minutes to achieve good mixing. At the end of this mixing period, we
typically take readings of indoor air concentration at 10 minute intervals and at a representative
number of locations throughout the building. Tests at the LLC were done with sampling at four
distributed locations throughout the building.
The air exchange rate is calculated based on the formula
60
C
i
ach
In
min
C
where
ach = air changes per hour
min = length of test period, minutes
Cj = initial tracer gas concentration, ug/m3
Cf = final tracer gas concentration, ug/m3
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SECTION 6
RADON CASE STUDY 1: FINANCIAL CENTER NORTH
The first large building selected for a radon case study is the Financial Center North (FCN) Building
in Deerfield Beach, Florida. This is a privately owned building that is presently being leased to the
General Services Administration (GSA) for purposes of housing Financial Center North of the
Internal Revenue Service (IRS). The Crown Diversified Industries Corporation presently owns the
building.
6.1 BUILDING AND HVAC SYSTEM DESCRIPTION
The building is a combination office and warehouse/maintenance facility. It is constructed in two
wings that form the shape of an L. Each of the two wings is three floors, with each floor in the north
wing measuring approximately 5600 gross square feet (112 x 50 feet), and approximately 6200 gross
square feet (124 x 50 feet), in the east wing floors. The warehouse/maintenance portion of the
facility is located in the crook of the L shape. It is predominantly a two-story high bay space. This
area of the building is primarily used by a maintenance staff that services an adjacent apartment
complex also owned by Crown Diversified Industries Corporation. The maintenance/warehouse area
measures approximately 10,450 gross square feet (110 x 95 feet). The entire building measures
approximately 46,000 gross square feet and houses approximately 125 occupants.
The IIVAC systems are of the UNITARY SYSTEM type and rely on 22 separate direct expansion
split systems for primary cooling to the office spaces. All of the condensers are frame mounted and
located on the roof. The system evaporators arc located in ceiling hung air handler (AH) units in/or
near the comfort zone being served. In addition to housing the evaporator, all of the AHs contain
electric reheat coils that provide space heating. The AHs are also provided with a system of
distribution ductwork consisting of supply, return, and outdoor air connections. Cooling and heating
of the occupied space is controlled by wall mounted thermostats. Each AH is provided with its own
individual thermostat. The heating and cooling capacities of each split system range in size from
2.91 tons cooling/7.2 kW heating to 9.16 tons cooling/15 kW heating.
Air is exhausted from the building primarily by three roof mounted power roof ventilators (PRVs),
as well as toilet exhaust fans. The original HVAC design called for the outdoor air to be provided
through two outdoor air risers (OARs) that, through a system of ductwork, were connected to the
suction side of each AH. None of the OARs were originally powered by a fan. The introduction of
OA was reliant on the ability of the AH fan to inject OA from the roof level down the OARs and
into the intake of the AH. The original design specified that a total of 4500 cfm of outdoor air be
introduced to the building. This quantity of outdoor air represents 10% of the total building supply
air.
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The building was designed to operate under a slightly positive pressure; that is, the outdoor air is
being introduced at a greater rate (4,500 elm) than the quantity of air being exhausted (2,310 cfm).
This is a desirable mode of operation since outdoor contaminants can not infiltrate the building (see
Appendix I, Financial Center North Initial Engineering Report).
6.1.1 HVAC Svstcm - Diagnostics and Modifications
in May 1991. the building owner hired Bailey Engineering Corporation (BEC), a certified HVAC
TAB firm, to perform the following evaluations of the HVAC systems:
(a) Compare the original design criteria to current standards for ventilation requirements.
(b) Determine if the systems conform to the design drawings and specifications.
(c) Evaluate the actual system performance against the design and current requirements of
ventilation as related to indoor air quality.
From this evaluation the following observations were made by BEC:
(a) The installation of the HV AC systems closely follows the original design configuration.
(b) Most of the All thermostats are not being operated in a proper mode. Most are in the
"auto" mode which cycles the All off when space conditions are satisfied. When the
Al l is off, no outdoor air can be introduced into the building. Obviously this condition
can reverse the building from positive pressure to negative pressure. This is an
undesirable condition.
(c) Dampers installed in the OARs are all in the open position.
(d) Outdoor air quantities appear to be more than sufficient to satisfy ASHRAE Standard
62-1989 "Ventilation for Acceptable Indoor Air Quality" (ASH89). The design
quantities would support 100 occupants per floor. This population is never realized.
(c) All HVAC equipment operates 24 hours a day.
BEC reported the following conclusions:
(a) Operating the AHs in the "auto" mode will not allow the HVAC systems to perform
as intended by the original design.
(b) The building actually operates in a negative mode rather than a positive mode. This
creates a situation where unfillered, untreated infiltration air is brought into the space
along with unwanted humidity and contaminants.
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(c) Without performing a complete test and balance of all components, it is not possible
to determine how closely the systems are performing to the original design parameters.
(d) The exhaust systems may very well be exhausting more air than was designed.
(e) It is unlikely that the low static pressure produced in the return air plenum of the AHs
is capable of overcoming the static resistance of the OARs. This would result in less
outdoor air being brought in than was intended by the original design.
Based on these observations and conclusions, BEC made the following recommendations:
(a) Operate all systems with the AHs in the "ON" mode to ensure constant AH operation.
(b) Perform a complete test and balance of each of the systems to verify that design
requirements are met.
(c) Install time clocks on the exhaust fans to prevent unnecessary ventilation during the
unoccupied hours.
(d) Install motorized dampers on the fresh air intakes that operate in concert with the
exhaust fans.
(e) Energy savings can be realized by putting all AH operation on a time clock. This
would prevent after hours operations.
(f) BEC should be provided with the energy history of the building from the last 24 months
for determination of the potential energy savings.
In June 1991 the building owner continued the services of BEC to perform item b of the
recommendations cited above. The complete test and balance of the HVAC systems was to be
earned out in three phases:
Phase I Preliminary testing
Each system AH was to be tested to determine the following:
- total air flow (cfm)
- return air flow (cfm)
- outdoor air volume (cfm/occupant)
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Phase II
Engineering of system modifications
Design criteria was to be determined from the results of Phase 1 for the following
required system components:
- new outdoor air fans
- automated dampers and actuators
- control system to interlock all system components for balanced ventilation
Phase III Final testing and balancing
After all system modifications were complete, a final test and balance was to be
performed to ensure that proper ventilation standards are maintained and that control
strategies are functioning as designed.
In June 1991 BEC began Phase I, and their primary finding was that the outdoor air actually being
introduced to the building by the AHs was 21% of the volume called for in the original design. This
quantity of outdoor air satisfies the GSA lease requirements of 5 cfm per person occupancy. The
actual tested volume of outdoor air would be sufficient for 192 occupants but not sufficient to meet
the ASHRAE Standard 62-1989 requirement of 15 cfm/person occupancy. BEC also reported that
the low volume of outdoor air is not sufficient to offset the volume of exhaust air. This creates the
undesirable condition of building negativity mentioned previously. BEC recommended that the
following additional engineering items be required before the systems could perform as designed:
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(a) New outdoor air supply fans were to be installed on the OARs.
(b) Motor operated dampers were to be installed on the OARs to close when the supply
fans are not in operation. This would prevent uncontrolled outdoor air from entering
the building during unoccupied hours.
(c) The new outdoor air fans were to be controlled by time clocks to operate only during
occupied hours. The existing exhaust fans were to be controlled by the same time
clocks on the same operating schedule.
The building owner complied with all of these recommendations and in January 1992, the final test
and balance was performed. BEC found that the new outdoor air fans that they recommended were
not operating to specified catalog specifications. BEC measured the outdoor air quantities at about
3000 cfm total being introduced by the new outdoor air fans. The new outdoor air fans raised the
level of outdoor air from 21% to about 66% of design. Using the ASI IRAE Standard 62-1989, this
new quantity of outdoor air would support 200 occupants (3000 cfm/15 cfm per occupant). BEC
reports no more than 102 occupants in the building at any time (17 occupants per floor x 6 floors).
At the time of our study, the building was being operated in this mode (see Appendix II, Financial
Center North IIVAC System(s) Test and Balance Reports).
6.2 EXPERIMENTAL PLAN: OUTDOOR AIR VARIATIONS
For the purposes of this part of the study, it was agreed that the primary feature of the HVAC
systems in mitigating radon is pressurization of the building.
It was decided to operate the HVAC systems in four different modes of building pressurization while
collecting data. These modes of operation were determined by our ability to vary and control the
amount of outdoor air allowed to be introduced into the building while maintaining supply and
exhaust at known quantities.
The four modes are:
Mode 1 Operate the system(s) with no outdoor air from the outdoor air supply fans. No changes
in the supply or exhaust air quantities.
Mode 2 Operate the system(s) so as to provide 5 cfm/occupant. No changes in the supply or
exhaust air quantities.
34
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Mode 3 Operate the system(s) so as to provide 15 cfm/occupant. No changes in the supply or
exhaust air quantities.
Mode 4 Operate the system(s) so as to provide 20 cfm/occupant. No changes in the supply or
exhaust air quantities.
These predetermined modes of operation describe situations from complete system shutdown of OA
quantities to those recommended in ASHRAE Standard 62-1989. Mode 1, no OA, would be
considered the worst case scenario. Under this mode of operation, the building is under complete
negative pressure and all OA is through infiltration. As OA supplied to the AH increases, infiltration
decreases resulting in no change in supply or exhaust quantities, although increasing OA causes
increased pressurization throughout the building. Mode 2 would simulate the OA requirements
illustrated in the Florida Administrative Code chapter 6A-2 (FAC94) that controls the amount of
outdoor air to 5 cfm/occupant. Modes 3 and 4 would be variations on the ASIIRAE Standard 62-
1989 (ASH 89) using 15 and 20 cfm/occupant, respectively.
The following schedule indicates the time-frame of data collection for each mode of operation:
Mode 1 data were collected from July 3 to 6,1992.
Mode 2 data were collected from July 6 to 15, 1992.
Mode 3 data were collected from June 16 to July 3, 1992.
Mode 4 data were collected from July 15 to 27, 1992.
For Mode 1, the BF.C closed the outdoor air intakes with polyethylene to ensure a complete
nonporous seal. Mode 1 was accomplished over a weekend since the building owner would not
permit the HVAC systems to be operated without outdoor air during normal working hours.
For Mode 2, BEC balanced the HVAC systems so that the measured outdoor air intake was actually
5.5 cfm/occupant. Mode 3 was measured at 13.6 cfm/occupant. Mode 4 was 19.5 cfm/occupant (see
Appendix II, Financial Center North HVAC System(s) Test and Balance Reports).
6.3 DATA AND ANALYSIS
Data were collected from the data stations by downloading data files through the internal modem by
telephone connection. The information was converted into usable numbers, calibrated, and put into
graphs and tables. Data files were analyzed and compared to other information, such as maintenance
practices.
35
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The FCN data are limited in scope due to instrumentation difficulties that were later corrected for
the second case study. FCN results are limited to radon concentrations and some PFT tracer gas
measurements. A description of part of the resulting data follows. The current extent of the data
analysis is limited to a qualitative discussion of carbon dioxide levels and a quantitative comparison
of radon levels and building HVAC activity. The FCN building is used as office space and as such
was occupied largely during weekday periods from 8 AM to 5 PM. Carbon dioxide levels as
expected peaked during the weekday periods. Radon correlated to outdoor air levels, temperature,
pressure, and relative humidity, and PFT analysis from Brookhaven National Laboratory are
included in graph and table form respectively in Appendix 111.
6.3.1 Radon
The FCN had initially exhibited radon levels of approximately 10 picocuries per liter (pCi/L), during
GSA screening measurements, which are above the EPA action level guideline of 4 pCi/L. In early
1992, Radon Environmental Testing Corporation was requested to provide radon measurement and
mitigation service to the building management. Passive sealing of slab cracks and penetrations was
provided as well as increasing the level of outdoor air by installing supply fans. This reduced radon
levels to below the 4 pCi/L guideline and generally subjectively improved indoor air quality. By
intentionally reducing the outdoor air intake an increase in radon concentrations was exhibited to a
peak level above 4 pCi/L throughout the building (see Appendix III for all data). Distinct average
levels of radon can be identified from the graphs for a consistent level of outdoor air intake. A
comparison of radon levels versus outdoor air intake flowrate is evident in Figure 1. The building
average concentration at 0 cfm (per occupant) was 2.6 pCi/L as compared to 1.8 pCi/L at 5.5 cfm.
1.2 pCi/L at 13.6 cfm. and 1.0 pCi/L at 19 cfm. These values are shown in Table 1.
TABLE 1. AVERAGE RADON MEASURED AT THE FCN
UNDER RANGE OF OPERATING MODES
Outdoor
Air Input
(cfm/'pp)
Building
Ventilation
(ACH)
Average
1st Fl.
Radon
(pCi/L)
Average
2nd Fl.
Radon
(pCi/L)
Average
3rd Fl.
Radon
(pCi/L)
Average
Building
Radon
(pCi/L)
0
0.2
2.5
2.6
2.6
2.6
5.5
0.4
1.5
1.8
2.2
1.8
13.6
0.5
1.1
1.4
1.2
1.2
19.0
0.6
0.9
1.0
1.2
1.0
36
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Financial C«ntar Building, D«erfi«ld B«aeh, 7L
Average Radon LavaIs, All Floors
022ACH
6JSACH
t C-Ifl ACH
0.47 ACH
OS ACH
06/15
06/25
07/05
07/15
07/25
06/20
06/30
07/10
Oet«
07/20
07/30
1»t floor — 2nd Fleer ¦ 3rd Floor
Figure 1. Average radon concentrations at Financial Center North during parametric
study of outdoor air variations.
37
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A reduction correlated with increased OA is present; however, due to imprecision in measurement
and expected fluctuations in radon concentrations it is not possible to clearly use this result as a basis
for forming conclusions. These results are shown in Figure 1 where the average radon values are
plotted as a function of time (date) along with the levels of OA and the results of the tracer
measurements (ventilation rates).
6.3.2 Tracer Gas
A number of techniques both passive and active are available for characterizing airflow and transport
in a building by use of tracer gas. Perfluorocarbon tracer (PFT), devised at Brookhaven National
Laboratories, is a passive method of characterization of airflow patterns in large industrial,
commercial, and office buildings using five varieties of gas and common detectors. The five types
of passive emitter gases allow five zones to be monitored simultaneously for interzonal mixing,
yielding an integrated average for the sampling period. With this technique natural and mechanical
ventilation rates and efficiency, natural infiltration and overall HVAC system performance can be
measured. Capillary adsorption tube samplers (CATS) adsorb the steady state gases and are
analyzed at Brookhaven.
Enclosed in Appendix III are the results of the six measurement periods performed in FCN plus a
general description of the output data. The interzonal flow results in the building are of less interest
than the overall building ventilation results. These are shown in Table 1. The ventilation in terms
of building air changes per hour (ACH ) correlate quite well with the measured OA flowxates.
38
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SECTION 7
RADON CASE STUDY 2: POLK COUNTY LIFE AND LEARNING CENTER
The second case study in this project was conducted at the Polk County Life and Learning Center
(LLC). While some of the same measurement techniques were used at this building as for the
previous study at the FCN, the experimental and analytical sequences were much more detailed.
The LLC consists of three buildings: The Center for the Trainable Mentally Handicapped, the
Severely Handicapped Center (two classroom addition), and the Greenhouse. The Center for the
Trainable Mentally Handicapped and the Greenhouse were designed in 1974 and built in 1975. The
Severely Handicapped Center was designed in 1984 and constructed in 1985. This study focuses
entirely on the LLC Center for the Trainable Mentally Handicapped.
7.1 BUILDING AND HVAC SYSTEM DESCRIPTION
The LLC building is a single-story training/school building of approximately 18,000 gross square
feet in size. It consists of staff office space, classrooms, a large multipurpose room, a kitchen,
janitorial closets, and a woodshop. The facility houses 103 students daily along with 22 staff
members for a total of 125 occupants. Architecturally, the building is constructed as a slab-on-grade.
The slab is 4-inch reinforced concrete on compressed fill and provided with a vapor barrier. The
vapor barrier is assumed to be polyethylene (the drawings are not specific). The walls of the Center
are 8-inch CMUs (concrete masonry units; i.e., blocks) with stucco exterior and 5/8-inch gypsum
board on 1- x 2-inch furring strips on the interior. The roof system coasists of wood truss
construction with asphalt shingle roof tiles over the majority of the roof. However, in some areas
the roofing consists of rolled mineral roofing material. The interior ceilings are either lay-in tile or
painted gypsum board. All windows are either aluminum frame single hung or bay windows. The
interior walls are gypsum board on wood sluds with interior ceiling heights of typically 9 feet except
for the central area used as a caleteria;auditorium. The LLC is divided into four fire control zones
by means of rated 5/8-inch gypsum board that extends to the tectum decking below the roof.
However, numerous openings between zones (some as large as 2 x 4 feet) tend to merge the separate
zones into one or two larger zones. 'l"he floor plan of the LLC is shown in Figure 2, which shows
the locations of the fire walls which divide the building into roughly four zones (although the zones
appear to be well coupled).
The LLC is heated and cooled by an ALL-AIR system composed of a single main air handler (AH)
unit. The AH provides cooling to the Center by means of a 21 ton (252.0 MBH) direct expansion
split system and a distribution system of supply ductwork. The system is low pressure (2.5 inch
WG) and utilizes a single supply duct and a ceiling plenum return air system. The individual rooms
and zones are environmentally controlled by variable-air-volume (VAV) boxes mounted above the
ceiling in the return plenum. Wall-mounted thermostats control the VAV boxes.
39
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1 00 feet
o
L
HVAC
O ©
Rm "K09
Audio
Rm 1 05
o
- WS(Datalogger)
Q Cafeteria o
Conf
Rm 102
Porch
Tracer Gas
o Samp.Loc.
$ Inj. Loc.
Fire Walls
Figure 2. Floor plan of LLC showing locations of EPA data loggers (DS), tracer gas system
(TGS), and weather station (WS) data logger.
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The introduction of outdoor air is controlled by a roof-mounted supply fan (F-l). This fan initially
could provide up to 1200 cfm of unconditioned outdoor air (OA) directly to the AH return air
plenum. Refer to Appendix IV. The OA then mixes with the building return air. The AH has the
capacity to supply 5620 cfm at conditions of 57°F dry bulb/56 °F wet bulb which gives the machine
a rating of approximately 21 tons. This is approximately 1.2 tons per 1000 ft2 which constitutes a
greatly oversized capacity. Based on the Florida Administrative Code, Chapter 6A-2 requirements
of 5 cfm per occupant, the Center could house 240 occupants. The actual occupancy of 120 people
increases the OA per occupant to 10 cfm per occupant (1200 cfm/120 occupants).
Heat for the LLC building (via AH) is provided with a 15 kW strip heater. In addition, each VAV
box that serves a space that is adjacent to an exterior wall is provided with an additional strip heater.
VAV box strip heaters are controlled by the room wall-mounted thermostat. The building is served
by a total of 26 VAV boxes that are sized for a full air-conditioning load of 11,305 cfm. The boxes
are set for a minimum setting of 40% of full load. The diversity factor (100 times the ratio of the
sum of the individual VAV box capacities divided by the AH capacity, i.e., 100 x [5620/11,305])
is calculated to be approximately 50% for the VAV box operation.
Exhaust air from the LLC is through the use of 14 exhaust fans located in the toilets, bathrooms,
janitor closets, workshop, and kitchen. The total design building exhaust from these 14 fans is 2350
cfm when all are operating.
Initial radon measurements were made at the LLC by the Polk County Health Unit during the 1990-
91 and 1991-92 school years. The results are summarized in Table 2 and shown graphically in
Figure 3. From Figure 3 it can be seen that the radon levels are fairly independent of the seasons and
most always lie above the EPA guidelines. In Figure 4 the measured radon levels in the LLC building
are plotted as a frequency histogram. It is seen in this figure that the average level shifts somewhat
toward higher values during the Fall compared to the values measured in the Spring. However,
overall the readings are fairly constant. The locations of the annual average radon levels listed in
Table 2 are shown schematically in Figure 5.
7.2 INITIAL BUILDING INSPECTION AND HVAC MODIFICATIONS
Based upon inspection of the design plans for the building, it was easy to see that this building may
have been operated in an undesirable HVAC negative pressure mode. Since the maximum outdoor
air quantity was 1200 cfm and the exhaust quantity was 2350 cfm, the building may have been
operated negative by about 1150 cfm or less. To compound this imbalance, the outdoor air fan was
set to shut off when the return air temperature was below 70°F or above 80°F. The fan controls
would only allow the outdoor air fan to operate when the return air temperature was in the range of
70-80 °F. This condition of little or no outdoor air also violates the minimum outdoor air
requirements of Chapter 6A-2 of the Florida Administrative Code, paragraph 6A-2.066 Ventilation,
subparagraph (2)a-2 (FAC94), that calls for a minimum of 5 cfm of outdoor air per occupant at all
times of occupancy.
41
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TABLE 2. POLK COUNTY LIFE AND LEARNING CENTER
PHASE 3 TESTING RESULTS
1990-91 AND 1991-92 SCHOOL YKARS
Fa!!
Radon
Sample Level
Location (pCi/L)
Winter
Radon
Level
(pCi/L)
Spring
Radon
Level
(pCi/L)
Annual
Average
Radon
Level
(pCi/L)
1
12.9
10.9
8.3
10.7
2
12.2
9.9
9.2
10.4
3
11.1
9.6
8.5
9.7
4
6
1,1.7
14.0
%9
8.4
10.2
it
8.9
10.6
1$4
7
12.6
8.1
9.0
9.9
8
12.3
9.8
8.2
10.1
9
11.4
8.5
9.1
9.7
10
12.7
5.7
7.4
8.6
11
14.0
7.6
8.8
10.1
12
14.4
7.9
6.8
10.4
13
*
7.5
8.6
*
14
12.8
9.6
8.4
10.3
15
12.4
9.3
8.9
10.2
16
13.6
10.8
9.5
11.3
17
18.7
19.1
13.1
17.0
18
11.6
9.0
8.7
9.8
19
13.2
10.5
7.1
10.3
20
11.4
9.7
8.0
9.7
21
. 12.0
10.0
10.0
10.7
22
12.6
10.9
8.8
10.8
23
12.8
9.3
6.9
10.3
24
11.7
8.7
7.6
9.3
Blrfe. Average
12.8
9.6
8.9
10.4
High
18.7
19.1
13.1
17.0
Low
11.1
5.7
7.1
8.1
Std.Dev.
1.6
2.4
1.2
1.6
CV (%)
12.1
24.7
13.0
15.1
» Data not available.
CV - Coefficient of Variation
42
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Fall
Sample Location
Figure 3. Results of the Phase 3 radon tests at Polk County Life and Learning Center as carried
out by the Radiological and Occupational Health Section, Polk County Public Health
Unit during the 1990-91 and 1991-92 school years.
43
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w
u
Q)
GO
rail
Annual
Radon Level (pCi/L)
Figure 4. Frequency histogram of the radon levels measured at Polk County Life and Learning
Center.
44
-------
10.6
8.6
10.1
-/
-L
10.7
9.7
10.8
1041 mo.4
_ } \9.9\
10.4
1
10.3
j 9.3
10.7
9.7
10.3
17.0
9.8
10.4
10.3 10.2
1 1.3
Annual Average
Radon Levels
(pCi/L)
Figure 5.
Locations of the radon values shown in Table 2 as measured in the TIC. Phase 3 testing
program.
-------
In order to ready the LLC for instrumentation, a certified HVAC Test and Balance (TAB) firm was
contracted (the Phoenix Agency, Inc.) to perform the following steps:
1. Building Pre-Balance Survey
a. Review the design plans and become familiar with the design of the HVAC
systems.
b. Visit the site and evaluate the condition of the HVAC system and determine
what components of the HVAC system are in need of replacement, repair,
or renovation in order for the system to operate as desired.
c. Develop a "punch list" of repair items for the Polk County authorities
who will provide all repairs and maintenance.
2. Building Pre-Balance Survey: Re-visit the LLC after all repairs are made to confirm
that the systems are ready for final air balancing.
3. Building Air Balancing: Air balance the HVAC systems.
On November 5,1992, the Phase 1 System Survey was performed by the test and balance firm (The
Phoenix Agency, Inc.) and the complete results of this survey are included as APPENDIX V. Some
of the more serious deficiencies found were that the outdoor air fan (F-l) was installed backwards
on the motor shaft, and the motorized damper for the OA fan was frozen in the closed position.
Other deficiencies identified include: leakage from the supply air on both sides of the VAV boxes;
in the main supply duct feeding all the VAV boxes, several of the VAV control mechanisms were
inoperative; and four exhaust fans were inoperative. A list of the building deficiencies was sent to
school officials on about November 10,1992. It was agreed that the Polk County School System
would fund all "punch list" items and the EPA would fund the TAB fee and fan replacement.
The LLC was instrumented with five of the EPA data logging systems on October 27-29, 1992.
School maintenance personnel implemented a repair procedure at the LLC to correct the deficiencies
detected in the building during the walk-through on November 5, 1992, and as described in the
building pre-balance survey carried out by the TAB company. These repairs were completed during
the latter part of January 1993. During December, the Phoenix Agency, Inc. (PAD replaced the
outdoor air supply fan and damper. The as-found condition of the building was such that little or no
OA was being supplied to the building. The only ventilation was through openings in the building
shell. This was evident from the odors that persisted in several of the rooms and in particular in
Room 105. The new OA fan is capable of supplying 3000 cfm of outdoor air. Also during the last
week of January, repairs were carried out to correct a problem in the EPA data loggers. This
involved shorting out a base resistor in the solenoid-zero circuit in order to increase the current flow
to the zeroing solenoids. Also during this time, an additional Campbell 21X data logger was
installed in LLC to carry out parallel measurements of some of the parameters measured by the EPA
data loggers. Additional parameters were also measured by this data logger.
46
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The data taken at the LLC include:
• Data sampled as summarized in Table 3, which include continuous radon at six
locations, subslab to room pressure differences at five locations, room to outdoor
pressure differences at seven locations, ambient outdoor temperature, RH, wind
parameters, local barometric pressures, temperatures in the building at seven
locations, outdoor air (OA) flowrates into the HVAC system, and operation of
bathroom exhaust fans in five locations.
• Air movements within the building and infiltration/exfiltration measurements using
Southern Research's multi-gas tracer system.
TABLE 3. LOCATIONS AND DATA SAMPLED AT THE LLC
Room
102
Room
104
Room
109
Cafe
Conf
Mech
Room
RA
Plenum1
Continuous Radon Levels
*
*
*
*
*
*
Ap Room to RA Plenum
*
*
*
+
*
*
*
Ap Subslab to RA Plenum
*
*
*
*
*
Ap to Outdoors
*
*
Temperature
*
*
*
*
*
*
*
Relative Humidity
*
*
*
~
*
CO,
*
*
*
*
*
Exhaust Fan Operation
*
*
*
*
«
'The RA Plenum includes the entire attic area above the suspended ceilings.
47
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7.3 1993 PARAMETRIC STUDY
7.3.1 Experimental Sequence
Testing at the LLC was carried out using the matrix of conditions shown in Table 4. Generally, each
OA flowrate condition occupied a week of testing. The exhaust-fan-on condition was maintained
over 1-1/2 days of the weekend, and the exhaust-fan-off condition at nights and the remainder of
the weekend. Typically, the HVAC fan operated on a 12 hour on/12 hour off cycle each day.
TABLE 4. TEST MATRIX FOR LLC EVALUATION
HVAC (ON/OFF)
BATHROOM FANS
OA FLOWRATE
(ON/OFF)
(CFM/PERSON)
OFF
OFF
0
OFF
ON
0
ON
OFF
0
5
10
15
20
ON
ON
0
5
10
15
20
Final balance of the HVAC system in the LLC was carried out on February 4,1993, by The Phoenix
Agency, Inc. Tesiing was begun on Friday, February 5th, with the Outdoor Air (OA) damper set to
deliver approximately 3000 cfm (or 20 cfm/person based on an occupancy of 150 persons) OA into
the building. The HVAC system was also set up to come on at 6:00 am and go off at 6:00 pm. Over
the weekend days. Saturday and Sunday (the 6th and 7th of February), the exhaust fans in the
restrooms of the building were set first to be off from Friday around 5 pm until Saturday about 3 pm
at which time all operable fans were turned on until Monday morning when the teachers arrived and
turned them off. This procedure was followed during each weekend of the testing period. On
Friday, February 19th, the OA damper was closed and the OA fan turned off to create the condition
of 0 OA intake. The exhaust fans were operated as described above. Data were downloaded from
the five EPA data loggers and the Campbell 21X at least once per week for later analysis. The
specific schedule of experiments is as follows:
48
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Testing of the LLC building continued during March. On March 5th, the OA damper was set to
provide roughly 750 cfm of outdoor air, or approximately 5 cfm/person. This test was plagued with
problems with the data loggers, the tracer gas system, and the HVAC system itself. Consequently,
the same test conditions were run the following week, of March 12th. On March 19th, the OA
damper opening was increased to 3000 cfm (20 cfm/person). The building was operated in this
condition until March 26th when the OA damper opening was reduced to 2250 cfm or 15
cfm/person. The building was operated in this manner until April 2, 1993.
Jan 18-22
Polk County personnel complete repairs to the HVAC system in the Life & Learning Center
(LLC).
Jan 29-Feb 1
Southern Research Institute work on EPA data loggers to improve Dp cell zero, and install
Campbell based data logger to supplement EPA data loggers.
Feb 3-4
TAB company (PAI) return to LLC to carry out rebalancing of system.
Feb 5-12
Test Week #1, 20 cfm/person OA, HVAC on from 6 am to 6 pm seven days/week, run
building with all exhaust fans off from 3 pm Friday (2/5) to 3 pm Saturday (2/6) and all fans
on over the period from 3 pm Saturday (2/6) until about 7 am Monday (2/8), during
weekdays (2/8-2/12) exhaust fans at normal operation, perform radon grabs under slabs in
each data location on Friday and read EPERMs.
Feb 12-19
Test Week #2, 0 cfm/person OA, expose EPERMs (2/15-2/19), run tracer gas system.
HVAC on from 6 am to 6 pm seven days/week, run building with all exhaust fans off from
3 pm Friday (2/12) to 3 pm Saturday (2/13) and all on over the period from 3 pm Saturday
(2/13) until 7 am Monday (2/15), during weekdays (2/15-2/19) exhaust fans at normal
operation, perform radon grabs under slabs in each data location on Friday and read
EPERMs.
Feb 19-26
Test Week #3, 8 cfm/person OA. expose EPERMs (2/22-2/26), run tracer gas system,
HVAC on from 6 am to 6 pm seven days/week, run building with all exhaust fans off from
3 pm Friday (2/19) to 3 pm Saturday (2/20) and all on over the period from 3 pm Saturday
(2/20) until 7 am Monday (2/22). during weekdays (2/22-2/26) exhaust fans at normal
operation, perform radon grabs under slabs in each data location on Friday and read
EPERMs.
Feb 26-Mar 5
Test Week #4, 5 cfm/person OA. expose EPERMs (3/1-3/5), run tracer gas system. HVAC
on from 6 am to 6 pm seven days/week, run building with all exhaust fans off from 3 pm
49
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Friday (2/26) to 3 pm Saturday (2/27) and all on over the period from 3 pm Saturday (2/27)
until 7 am Monday 3/1, during weekdays (3/1-3/5) exhaust fans at normal operation, perform
radon grabs under slabs in each data location on Friday and read EPERMs.
Mar 5-Mar 12
Test Week #5, because of equipment failure the test from the previous week was repeated
during this week.
Mar 12-Mar 19
Test Week #6, repeat the tests of Test Week #1,20 cfm/person OA, expose EPERMs (3/15-
3/19), run tracer gas system, HVAC on from 6 am to 6 pm seven days/week, run building
with all exhaust fans off from 3 pm Friday (3/12) to 3 pm Saturday (3/13) and all on over the
period from 3 pm Saturday (3/13) until 7 am Monday (3/14), during weekdays (3/15-3/19)
exhaust fans at normal operation, perform radon grabs under slabs in each data location on
Friday and read EPERMs.
Marl9-Mar26
Test Week #7, 15 cfm/person OA, expose EPERMs (3/22-3/26), run tracer gas system,
HVAC on from 6 am to 6 pm seven days/week, run building with all exhaust fans off from
3 pm Friday (3/19) to 3 pm Saturday (3/20) and all on over the period from 3 pm Saturday
(3/20) until 7 am Monday (3/22), during weekdays (3/22-3/26) exhaust fans at normal
operation, perform radon grabs under slabs in each data location on Friday and read
EPERMs.
Mar 26-Apr 2
Test Week #8, 15 cfm/person OA, HVAC on from 6 am to 6 pm seven days/week, run
building with all exhaust fans off from 3 pm Friday (3/26) to 3 pm Saturday (3/27) and all
on over the period from 3 pm Saturday (3/27) until 7 am Monday (3/29), during weekdays
(3/29-4/2) exhaust fans at normal operation. This period was used to carry out special tests
for Florida Solar Energy Center to assist in their model development and validation. This
period was also used to validate data to determine if any tests needed to be repeated.
Apr 2-Apr 9
HVAC on from 6 am to 6 pm seven days/week, 15 cfm/person OA. This period was used
to carry out special tests for Florida Solar Energy Center to assist in their model development
and validation.
Apr 9-Apr 16
IIVAC on from 6 am to 6 pm except for Saturday and Sunday, 4/10 and 4/11, when the
IIVAC was on continuously for testing purposes.
Apr 16-Apr 23
HVAC on from 6 am to 6 pm seven days/week, 15 cfm/person.
50
-------
Apr 23-Apr 30
HVAC on from 6 am to 6 pm except for Saturday and Sunday, 4/24 and 4/25, when the
HVAC was on continuously for testing purposes, 15 cfm/person.
Apr 30-May 7
HVAC on from 6 am to 6 pm, 15 cfm/person.
May 7-May 12
HVAC on from 6 am to 6 pm, 15 cfm/person, all equipment removed from building on
5/12/93.
7.3.2 Data and Analysis
The radon levels in the LLC building were significantly reduced from the levels first measured in
December 1992. In Figure 6 the averaged radon levels measured in Rooms 102,109, Cafeteria, and
Conference room (excluding Audiology) with the Femto-Tech continuous monitors attached to the
EPA data loggers located in those rooms are plotted as functions of time. Several aspects of the data
are apparent. First, the levels measured during December 1992 and January 1993 were much higher
than those measured by the Polk County Health Unit shown in Figures 3-5. The reasons for this
large difference are not known. Second, the overall levels show a steady decrease as shown by the
5-day moving (un-weighted) average line. This is due primarily to the replacement of the OA fan
and damper, and to the consistent operation of this fan. Also, the new OA fan has greatly reduced
the level of offensive odors noticed in Room 105 in October 1992. The second interesting aspect
of Figure 6 is the fine structure or daily variations in the radon levels. These are caused primarily by
the daily cycling of the HVAC system from daytime use to nighttime setback.
Radon data from this test series are summarized in Figures 7 through 14. In Figures 7 through 14
are plotted the continuous radon levels as measured in Rooms 102, 109, the Conference room, the
Cafeteria, and in the Audiology room over the 8 week testing period. Also shown in these figures
are the outputs read from the x-type annubar installed in the OA duct (after conversion to cfm air
flow). In Figures 15 through 22 the averaged radon levels in all rooms except Audiology are plotted
along with the OA flowrates. Several aspects of these plots were readily apparent:
1. The radon levels generally increase overnight until the HVAC system comes on.
2. Once the HVAC system turns on, the levels drop rapidly.
3. As the HVAC system operates, the levels drop but seldom go below 4-5 pCi/L. The rate
of drop and the limiting radon level depend as expected on the OA flowrate. The
variation of average daytime radon levels with OA is shown is Figure 23.
51
-------
V/1
to
0. 25
® 20
>
« 10
1
12/22 01/3.1 03/12
01/11 02/20 04/01
Date
04/21
05/31
05/11
Building Average (ex.Audiology) —— Moving Average (5 Day)
Figure 6 Polk Life & Learning Center, Lakeland, FL. Average of the continuous radon levels as
measured in Rooms 109, 102, Cafeteria, and Conference Room (excluding Audiology)
along with the 5-day moving average values over the testing period.
-------
KS\
UJ
ffl 40
a
o 30
/05 02/06 02/07 02/08 02/09
Date
02/10
02/11
3000
- 2500
2000
1500
1000
500
02/12
U
o
O
#2-Room 109 —— #4-Room 102 #3-Conf.Room
#6-Cnfe #7-Audiology jdk. Outdoor Air
Figure 7, Polk Life & Learning Center, Lakeland, FL
Test Week #1 continuous radon levels, 20 cfm/person OA,
HVAC on from Sam to 6pm seven days/week, ell exhaust fans
off from 3pm Friday (2/5) to 3pm Saturday (2/6) and all
fans on over the period from 3pm Saturday (2/5) until
about 7am Monday (2/8), during weekdays (2/8-2/12) exhaust
fans at normal operation.
-------
.u
r. 60
O 30
02/12
02/13
02/14 02/15 02/16
Date
02/17
02/18
3000
-2500
2000
g
o
1500 £
O
•H
1000 o
500
02/19
#2-Room 109 — #4-Room 102 #3-Conf.Room
—— #6-Cafe #7-Audiology ~4kr Outdoor Air
Figure 8. Polk Life & Learning Center, Lakeland, FL
Test Week -2 continuous radon levels, 0 cfm/person OA,
HVAC on from 6an Co 6pm seven days/week, all exhaust fans
off from 3pm Friday (2/12) to 3pm Saturday (2/13) and all
on over the period from 3pre Saturday (2/13) until 7am
Monday (2/15), during weekdays (2/15-2/19) exhaust fans" at
normal operation.
-------
r* 60
-------
o\
® 40
o 30
Hr
03/05
3000
-2500
2000
02/26
02/27
02/28
03/01 03/02
Date
03/03
03/04
o
1500 ?
O
rH
fa
1000 o
- 500
#2-Room 109 #4-Room 102 #3-Conf.Room
#6-Caf« #7-Audblogy lAr Outdoor Air
Figure 10. Polk Life & Learning Center, Lakeland, FL
Test Week #4 continuous radon levels, 5 cfm/person OA,
HVAC on from Sam to 6pra seven days/ueek, all exhaust fans
off from 3pm Friday (2/26) to 3pm Saturday (2/27) and all
on over the period from 3pm Saturday (2/27) until 7am
Monday 3/1, during weekdays (3/1-3/5) exhaust fans at
normal operation.
-------
-4
® 40
03/05
03/06
03/07
03/08 03/09
Date
03/10
03/11
3000
2500
2000
n
o
1500 5
o
- 1000
500
<
o
03/12
#2 Room 109 —— #4-Room 102 #3-Conf.Room
#6-C«fe #7-Aud»logy Outdoor Air
Figure 11. Polk Life & Learning Center, Lakeland, FL
Test Week "5 continuous radon levels, because of equipment
failure the test from the previous week was repeated
during this week.
-------
oo
•H
O
04
-------
LA
vo
r? 60
ffl 40
0 30
03/19
3000
2500
h 2000
e
o
1500 &
0
1000 o
500
03/20
03/21
03/22 03/23
Date
03/24
03/25
03/26
#2-Room 109 #4-Room 102 #3-Conf.Room
#6-Cafe #7-Audiology Outdoor Air
Figure 13. Polk Life & Learning Center, Lakeland, FL
Test Week #7 continuous radon levels, 15 cfm/person OA,
HVAC on from 6am to 6pm seven days/week, all exhaust far.s
off from 3pm Friday (3/19) to 3pni Saturday (3/20) and all
on over the period from 3pm Saturday (3/20) until 7am
Monday (3/22) , during weekdays (3/22-3/26) exhaust fans at
normal operation.
-------
3000
ON
o
- 2500
2000
1500
© 40
1000 O
a
o 30
03/26 03/27
03/28 03/29 03/30
Date
03/31
04/01 04/02
#2-Room 109 #4-Room 102 - #5-Conf.Room
#6-Caf« #7-Aud»fogy A. Outdoor Air
Figure i>. Polk Life & Learning Center, Lakeland, FL
Test Week #8 continuous radon levels, 15 cfm/person OA,
HVAC on Crom 6am ro 6pm seven days/week, all exhaust fans
off from 3pm Friday (3/26) to 3pm Saturday (3/27) and all
on over the period from 3pm Saturday (3/27) until 7am
Monday (3/29), during weekdays (3/29-4/2) exhaust fans at
normal operation.
-------
3000
40
"2500
2000 e
<4-4
25
1000
r 500
02/05
02/07
02/09
02/11
02/06 02/08 02/10 02/12
Date
-Er- Building Average #7-Audiology -air Outdoor Air
Figure 15. Polk Life & Learning Center, Lakeland, FL
Test Week #1 averaged continuous radon levels, 20 cfin/person
OA, HVAC on from 6am to 6pm seven days/week, all exhaust
fans off from 3pm Friday (2/5) to 3pm Saturday (2/6) and all
fans on over the period from 3pm Saturday (2/6) until 7am Monday
(2/8), during weekdays (2/8-2/12) exhaust fans at normal operation.
61
-------
3*
aits
c 10
K
3000
2500
2000 e
4-1
1500
1000
r 500
3
0
In
<
o
02/12 02/14 02/16 02/18
02/13 02/15 02/17 02/19
Date
-sr~ 3uilding Average ~~ #?-Audiology
¦ Outdoor Air
Figure 16. Polk Life & Learning Center, Lakeland, FL
Test Week #2 averaged continuous radon levels, 0 cfm/person OA,
HVAC on from 6am to 6 pm seven days/week, all exhaust fans off
from 3pm Friday (2/12) to 3pm Saturday (2/13) and all on over the
period from 3pm Saturday (2/13) until 7am Monday (2/15), during
weekdays (2/15-2/19) exhaust fans at normal operation.
62
-------
i-9
¦A
U
a
0
>
a>
a
o
•c
-------
U
a
>
ai
J
o
"O
<0
0£
•>£; ~=*5 «~.f < ' 'T?'•
; ¦¦' v-^y ; jggr- j;
3000
2500
2000 g
M-4
c
1500 ?
1000
500
02/26 02/28 03/02 03/04
02/27 03/01 03/03 03/05
Date
Building Avarnga #7-Audiology -Jk~ Outdoor Air
Figure 18. Polk Life & Learning Center, Lakeland, FL
Test Week #4 averaged continuous radon levels, 5 cfm/person OA,
HVAC on from 6am to 6pm seven days/week, all exhaust fans off
from 3pm Friday (2/26) to 3pm Saturday (2/27) and all on over the period from
3pm Saturday (2/27) until 7am Monday 3/1, during weekdays (3/1-3/5) exhaust
fans at normal operation.
64
-------
i 1- ,
I SEE1! -i
a'.*
U
EL
>
(1)
c 15 W\ 1
Fi13
V t i
* 10 ]
K
3000
-2500
^2000 E
«w
1500 3
c
•—i
&U
1000 g
- 500
03/05 03/07 03/09 03/11
03/06 03/08 03/10 03/12
Date
¦ Building Average #7-Audiclogy
Outdoor Air
Figure 19. Polk Life & Learning Center, Lakeland, FL
Test Week #5 averaged continuous radon levels, because of equipment
Failure the test from the previous week was repeated during this week.
65
-------
o
cu
«
>
V
c
0
13
c
S
SO
80
70
60
50
40
30
20
10
1 1 rn. M. 1 +
A
j
r*<\
w
-
A
4
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-
i
i
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i 4
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I
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1
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i
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if
I 1 ;
i
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j i
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A i
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k
-
it*"",
1
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k
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ft ! I
s
\m
ai
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; :t
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u
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a
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w
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i
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ifS
1 +T* Lu
I ~ ! /T%f*
[» 1 ji^
3.
J"
J*.
T!
"^SbhjST J
*! 1_4*
rs
0
03/12
03/14
03/16
03/18
3000
2500
2000
1500 S
o
1000
r 500
<
o
03/13
03/15
Date
03/17
03/19
Building Average ——¦ #7-Audioiogy -At Outdoor Air
Figure 20. Polk Life & Learning Center, Lakeland, FL
Test Week #6 averaged continuous radon levels, repeated the tests of
Test Week #1,20 cfm/person OA, HVAC on from 6am to 6pm seven
days/week, all exhaust fans off from 3pm Friday (3/12) to 3pm Saturday (3/13)
and all on over the period from 3pm Saturday (3/13) until 7am Monday (3/14),
during weekdays (3/15-3/19) exhaust fans at normal operation.
66
-------
u
a
v
>
l|H«i iWlll «
03/21 03/23
03/20 03/22
Date
03/24
03/25
03/26
£
U-l
U
1500 3
0
I—f
III
iooo 5
Building Average #7-Audiology -Jc- OutCoor Air
Figure 21. Polk Life & Learning Center, Lakeland, FL
Test Week #7 averaged continuous radon levels, 15 cfin/person OA,
HVAC on from 6am to 6pm seven days/week, all exhaust fans off from 3pm
Friday (3/19) to 3pm Saturday (3/30) and all on over the period from 3pm
Saturday (3/20) until 7am Monday (3/22), during weekdays (3/22-3/26) exhaust
fans at normal operation.
67
-------
3000
2500
50
J?
B 40
a
2000 g
1000 <
§ 20
¦3
CO
cs
500
o •#*¦»
03/26
03/28
03/30
04/01
03/27 03/29 03/31 04/02
Date
-rr- Building Average — Outside 8* #7-Audiclogy -Ar Outaoor Air
Figure 22. Polk Life & Learning Center, Lakeland, FL
Test Week #8 averaged continuous radon levels, 15 cfm/person OA, HVAC on
from 6am to 6pm seven days/week, all exhaust fans off from 3pm Friday (3/26)
to 3pm Saturday (3/27) and all on over the period from 3pm Saturday (3/27) until
7am Monday (3/29), during weekdays (3/29-4/2) exhaust fans at normal operation
68
-------
30
Rn (pCi/L) = 19.3 - 0.61 OA(cfm^er perscri)
R ^ 2 = 0.94
20
15-
10"
•3 5
0 T 1 1 1 r~~
0 5 10 15 20 25
OA Flovrate PSC9CT\)
Figure 23. Polk Life & Learning Center, Lakeland, FL
Average building daytime (8 am - 4 pm) radon levels in LLC as a function
of the outdoor air flowrate.
69
-------
3000
u
04
rH
ID
>
33
A
C
0
V
a
pi
2500
2000
1500 5
0
1000 <
O
04/16 04/18 04/20 04/22
04/17 04/19 04/21 04/23
Data
~ ¦ BuBdSng Avtrsg* — Gnd.Ltvil Avtrsgt 1 >K Outdoori Ond.Leve!
Outdoors 8' Outdoor Air
Figure 24 Polk Life & Learning Center, Lakeland, FL. Comparison of indoor average radon levels
with those measured outdoors at ground level and 8 ft above the ground for the period
form 4/16/93 to 4/23/93. HVAC on from 6 am to 6 pm, 15 cfm/person.
70
-------
3000
v
Ck
r-j
ID
>
ffl
a
c
0
•a
es
CC
2500
2000
1500 3
o
1000 <
o
04/23 04/25 04/27 04/29
04/24 04/26 04/28 04/30
Date
¦3- Building Avtrege Gnd.U*v«l Avtragt )K Outdoors Gnd. Level
QjtdoOCS 8* -Jr- Outdoor Air
Figure 25 Polk Life & Learning Center, Lakeland, FL. Comparison of indoor average radon levels
with those measured outdoors at ground level and 8 ft above the ground for the period
from 4/23/93 to 4/30/93. HVAC on from 6 am to 6 pm except for Saturday and Sunday,
4/24 and 4/25, when the HVAC was on continuously for testing purposes, 15
cfm/person.
71
-------
3000
•H
V
&
H
0
c
0
*0
-------
3000
2500
2000 E
w 12
1500 S
fej
1000 <
o
par
\il
^ \
05/09
05/11
05/13
05/10
05/12
Date
05/07
05/08
-E- Building Average Gnd.Uvtl Averng* ' Outdoors Gnd. Level
Qjtcbars 8' -Jkr Outdoor Air
Figure 27 Polk Life & Learning Center, Lakeland, FL. Comparison of indoor average radon levels
with those measured outdoors at ground level and 8 ft above the ground for the period
from 5/7/93 tto 5/12/93. HVAC on from 6 am to 6 pm, 15 cfm/person.
73
-------
4. When the exhaust fans are run continuously, the radon levels do not increase to nearly
as high levels with the HVAC system off as they do when the fans are left off.
5. The radon levels in the Audiology room do not always follow the rest of the building.
The levels here are usually higher than the building as a whole.
From these observations several conclusions appear obvious. The ITVAC system is assisting in
lowering the radon levels even without the intentional introduction of OA. A significant factor is
almost certainly the enhanced ventilation rate induced by the system. Pressure differences across
the building shell will enhance infiltration through shell openings, especially when exhaust fans are
operating. This infiltrating air is difficult to measure and changes the definition of "no OA" to mean,
"no OA actively supplied by the OA supply fan." l"he peak radon levels reached in the building just
before the HVAC system comes on do depend somewhat on the amount of OA introduced into the
system during the previous HVAC operation cycle and on the length of time that has transpired since
the HVAC system was last operated.
In an effort to understand why the radon levels remain at 4 pCi/L or greater, two additional Pylon
AB5 continuous radon monitors with PRD-1 passive cells were placed outside the building in the
sheltered workshop area on the North side of the building. One of the monitors was located at
ground level and the other approximately 8 feet off the ground. The locations were open and
sheltered only from rain. The results are shown in Figures 24 through 27 where the building average
radon levels (excluding Audiology) are plotted along with the levels measured outside the building.
Also shown in these figures are the OA flowrates and the average (5 day) ground level radon value.
Over the 4 week period the ground level radon averaged 4.1 pCi/L with a weekly high of 5.3 pCi/L
(4/30-5/7) and a weekly low of 2.8 pCi/L (4/16-4/23). Some summary statistics of the data taken
over these 4 weeks are shown in Table 5. These results were of obvious concern since, if the radon
source strength is sufficiently high, the indoor levels can never be reduced below the average ground
level outdoor levels.
74
-------
TABLE 5. COMPARISON OF RADON LEVELS INSIDE
AND OUTSIDE THE LLC BUILDING OVER THE PERIOD
APRTL 16, 1993 TO MAY 12, 1993
Ground Level
(pCi/L)
8' Above Ground
(pCi/L)
Building Avg.
(pCi/L)
Average Level
4.06
1.21
9.46
Highest Level
16.35
9.00
24.14
Lowest Level
0.31
0.08
2.99
Standard Dev.
3.36
0.93
4.36
l hc main reasons for the persistently higher radon levels in the Audiology room were thought to be
due to the isolation of the room combined with a major entry path such as an open (or extremely
leaky) expansion joint located under the room.
Results of the 1993 study were modeled using FSEC 3.0 (Gu 96). While they were able to
reproduce some features of the data, certain aspects were difficult to fit from the information
provided. The observed drop in indoor radon concentration was slower than predicted from the
measured air flowratcs. The limiting concentrations of about 4 pCi/L were difficult to explain
without a significant radon source; moreover, since the building was apparently pressurized, the
source would appear to be diffusive transport or radon in outdoor air above levels reasonably
expected for either contribution.
7.4 1994 PHASE II STUDY
In order to address some of the uncertainties in the 1993 results, permission was obtained for a series
of follow-up tests at the LLC. These tests occurred during April and May 1994. and involved further
measurements by Southern Research and by James Cummings and coworkers from FSEC. This
study involved two phases: a series of intensive characterization measurements by FSEC during
March 29-April 1, followed by a 2 month set of continuous measurements by Southern Research
which replicated some of the measurements performed in the 1993 study. The objective of these
studies was to address some of the following unresolved questions:
75
-------
• What exactly was the pressure balance in the LLC? Under what conditions was the building
pressurized? To what infiltration flowrates do these pressure differences correspond?
• What is the source of the residual radon during daytime operation? Is it outdoor air? Locally
depressurized areas? Failures in the foundation barrier?
The results of these experiments are presented in sections 7.4.1 and 7.4.2. The experimental study
by FSEC was reported with their further modeling results in "Analysis of Polk Life and Learning
Center (PLLC)" (Gu 94). The results in section 7.4.1 are reproduced, in part, from that report.
7.4.1 FSEC Study of HVAC System
7.4.1.1 Building Airtightness T ests
Blower door tests were done to characterize the building airtightness. A total of four blower doors
were used to depressurize the building to as much as -59 pascals (Figure 28). Two were located in
the north entrance, and one each was located in east and north classroom exterior doors. The
building airtightness, as a whole, is 18,047 CFM50 with an airtightness curve of Q = 1621.2 (DP)0 62.
The ACH50 is 4.9 (that is, the air exchange rate of the building when it is depressurized to -50
pascals). This indicates that the LLC is tighter than the average non-residential building.
7.4.1.2 Tracer Gas Infiltration Tests
Infiltration tests using tracer gas decay were done to characterize the infiltration/ventilation rate of
the building under various HVAC conditions. [The length of each test is indicated in brackets.]
1) When the air handler was set to VAV max (maximum flowrate) and OA (outdoor air) was set
at maximum, the building ventilation rate was 0.856 ach (air changes per hour), or 3132 elm.
[77 minutes]
2) When the air handler was set to VAV min (minimum flowrate) and the OA was still at full open,
the ventilation rate was 0.498 ach, or 1822 cfm. [60 minutes]
3) When the air handler was again set to VAV max but the OA was set to "750" cfm , ventilation
dropped to 0.340 ach. or 1244 cfm. [71 minutes]
4) When the air handler and exhaust fans were turned off (passive building), the ventilation rate
dropped to 0.080 ach, or 293 cfm, during an overnight period when there were very light winds.
[ 13 hours]
76
-------
[^uiUing /\jr>ligfilness
Building Descrintlon
Floor Area [sqflj
16700
13.1
219529
20
0.7
23930
Ave Building Height [ft]
Building Volume
Max Building Height [ft]
Height Factor
Surface Area
80
Inside Temp
80
Outside Temp
1.000
Air Density Factor
.
mvm
Wind .Shielding
28.6
"N"
(¦)v«, mi(i)
Blower Door Data
Door Location
Ironl door
Building
Preaa
59.3
51
39.4
BD Id. «
Fan
Press
109.1
S2.5
3512
Pan
Conflq
Fan
Flow
4990
3788
BD Id. ft
Fan
Crcii
120
75
121.8
fronl door
3510
Fan
Confln
Fan
Flow
_5604
4330
5511
BD Id. *
Fan
Press
114
118
124
north classroom
3511
Fan
Confln
Fan
Flow
_5099
5143
5316
BD Id. #
Fan
Pre* a
J 03
108
110
east classroom
100
Fan
Conflfl
"Fin"
Flow
4608
46?4
4781
Sum
Flowa
20301
1T942
15587
Temp.
Comp.
_203O1
17942
15587
Calc
(Jin
2004?
18269
15584
35
73.9
4304
128
5358
110
4781
14423
14423
14487
24
40.4
3193
S3
4611
70
3807
11811
11811
11483
17.5
27.5
2640
55
3559
51
3255
S452
9452
945]
Calculation*
0.62
1621.18
0.9972
n
C
r
1B047
2346.2
6696
1968.1
3808
10798
0.07
.CFM60
.FLA
.CFM10
.EqLA
.CFM4
,.ELA
.C/SurfaceAre*
4.9
0.17
632
4.5
1050
1281
1.1
...ACH50
...acli (ACII50/NJ
...cim (eatlmated)
...SLA
...cfm nsetled for 15cfm/person
...icfm @ 0.35 ach
...CFM50 / sqfl
Notes:
Passive building, all exhausts covered and outside air closed.
Bunding AMIghmttt
29000
_20000
£ 15000
| 10000
sooo
0
10 JO 30 40 50
Praiiura Difference [Pa|
[ » Mwiind ¦ C*fcuW»d]
60
M .!»*•
Figure 28 Blower door test results on Life and Learning Center using four blower doors.
Airtightness is 18,047 CFM50 and 4.9 ACH50 (Gu94).
-------
Figure 29 shows tracer gas decay over a 13 hour period when all mechanical systems were turned
off. It also shows the increase in interior radon levels from about 2 to 10 pCi/L over the same
period.
7.4.1.3 HVAC System Assessment: Air Flowrates
FSEC measured air flowrates of the air distribution system using tracer gas injection (nitrous oxide)
and sampling with a Miran 101 gas analyzer. The following flowrates were obtained by FSEC staff
(measurements made by Phoenix Test and Balance are also indicated):
TABLE 6. SUPPLY AIRFLOWS AT LLC
Air Handler
Flow
VAV max, OA @3000
7350 cfm
VAV min, OA @3000
5250 cfm
VAV max, OA @3000
(Phoenix)
7047 cfm
Supply Trunk Ducts
(tracer injection; VAV max)
Flow
larger trunk
4822 cfm
smaller trunk
2744 cfm
total
7566 cfm
Outdoor air flows were measured under various VAV settings and outdoor air damper settings.
Outdoor air flow does not vary significantly between VAV max and VAV min, because OA is forced
into the building (into the outdoor air duct) by a large fan.
Outdoor air flow does change significantly with various OA damper settings. Note that, when the
air handler flow is at VAV max and OA is at full open ("3000"), 35% of the total system air flow
is from outdoors. When the air handler is at VAV min and OA is at full open ("3000"), 48% of the
total system air flow is from outdoors. This amount of outdoor air represents significantly more
ventilation than would normally be required for a building with this occupancy; and therefore, it
significantly increases cooling loads and indoor humidity.
78
-------
3-29 TO 3-30
ach = 0.080
1900
ii in i in in hi ii i in Minimum ii i it i mi mii inn i nun trf
0800
TIME
N20 —RADON
Figure 29. Infiltration rate of the building with all mechanical air moving systems turned off is 0.08 ach. Radon levels
increase from about 2 pCi/L to about 10 pCi/L during this 13 hour period (Gu94).
-------
TABLE 7. OUTDOOR AIRFLOWS AT LLC
Outdoor Air
VAV max (cfm)
VAV min (cfm)
@3000
2550
2500
@3000 (Phoenix)
3072 (+20.5%)
@2250
2520
2400
@2250 (Phoenix)
2249 (-10.8%)
@1200
1990
1950
@1200 (Phoenix)
1200 (-39.7%)
@750
1400
1400
@750 (Phoenix)
750 (-46.4%)
Exhaust fans are all controlled by manual switches. The bathroom exhausts are tied into the light
switch, so they operate whenever the light is on. Since the exhaust fans are manually controlled, we
have no indication, based on our testing, of how much exhaust air occurs in this building under
typical operation.
FSEC measured the following airflows at the indoor grills using a Shortridge flow hood. They did
not measure any of the exhaust discharges at the roof level, so we do not have any indication of
possible exhaust duct leaks.
TABLE 8. EXHAUST AIRFLOWS AT LLC
Exhaust Fans
Flow
all operating
2649 cfm
as operated night 3/31
2174 cfm
80
-------
7.4.1.4 Airtightness of the Mechanical Room and Ceiling Return Plenum
In order to properly model air flows and pressure differentials in various building zones/cavities, it
is essential to know the airtightness of those spaces. FSEC had already done airtightness tests on
the entire building, but they needed to characterize the airtightness of the mechanical room and
return plenum.
An airtightness test was done on the mechanical room. Two blower doors were installed in the
exterior door of the mechanical room, and the space was depressurized to a range of pressures from
-60 to -10 pascals. CFMSO^, for the mechanical room was 4783. This represents its leakiness to
"the universe." The test was repeated with the building depressurized to the same extent as the
mechanical room, to yield the leakiness of the mechanical room to outdoors only. CFM50Oul was
only 633, indicating that 87% of the zone leakiness was to the building and only 13% was to the
outdoors.
An airtightness test was done to characterize the airtightness of the ceiling return plenum. This test
was done by installing two blower doors in the building exterior door and two in the mechanical
room exterior door. Ceiling tiles were removed from the ceiling of the mechanical room to make
the ceiling plenum and the mechanical room one zone. Then a multi-point blower door test was
done with each zone depressurized to the same extent. We checked that each zone was at identical
pressure by measuring AP between the two zones with a micromanometer having resolution to 0.1
pascal.
The results of the blower door tests are shown in Figure 30. The ceiling return plenum has a CFM50
of 8867 while the downstairs space has a CFM50 of 9688. Since we know that the mechanical room
by itself has a CFM50 of 633 to outdoors, we then can calculate that the plenum by itself is CFM50
= 8234. Therefore, we find that the return plenum has 44% of the entire building leak area to the
outdoors. It is truly amazing that a building cavity that is so leaky is used as a portion of the air
distribution system. It is interesting to note that the sum of the two CFM50 (ceiling plenum and
downstairs) is 18,555. or very nearly identical to the entire building blower door test result of 18.047
CFM50 that was done on the previous day.
7.4.1.5 Pressure Differentials
Operation of the air handler is expected to pressurize the building because of outdoor air (following
pressures are with exhaust fans ofl). Note that all pressures are "with respect to" outdoors (wrt
outdoors) unless otherwise specified. At VAV max and full OA, the building was found to be about
+2.2 pascals (wrt outdoors). At VAV min and "750" OA, the building was measured at about +0.9
pascal. Pressure in the ceiling return plenum typically runs about 0.6 pascal less than in the occupied
space. Thus, in all cases the plenum was at positive pressure with respect to outdoors. The range
of pressures produced by the operation of the air handler and OA blowers is presented in Table 9.
81
-------
oo
K>
5
o
LL
10000
9000
8000
7000
6000
5000
4000
0
Building Airtightness
Conditioned space vs Attic space
10 20 30 40
Pressure Difference [Pa]
50
Conditioned Space Attic Space
Figure 30. Airtightness curves for the Conditioned Space and the Attic return Plenum space (including the mechanical
room). Building leakiness is approximately evenly split between the conditioned space and the attic plenum (Gu94).
-------
TABLE 9. BUILDING AND CEILING PLENUM PRESSURES (EXHAUST
FANS OFF)
VAV OA Setting
Zone Setting
Plenum Pressure
(Pa)
Pressure (Pa)
MAX
3000
+2.2
+1.8
MAX
2250
+2.0
+1.2
MAX
1200
+1.0
+0.5
MAX
750
+1.3
+0.8
MIN
3000
+1.7
+1.5
MIN
2250
+0.9
+0.6
MIN
1200
NA
NA
MIN
750
+0.9
+0.2
Zones of buildings can sometimes experience serious pressure imbalances, related to poorly designed
return air, or operation of exhaust equipment within closed zones. Therefore, FSEC measured
pressure differences in various zones of the building with interior doors closed.
Pressure differentials resulting from closing of interior doors were found to be small. With VAV
max, pressures across closed doors ranged primarily from 0.2 to 0.4 pascal. This is very small
compared to most commercial buildings. The small pressure imbalances were attributed to the
ceiling return plenum. Since it can draw evenly from all rooms, there is little potential for
imbalance.
However, when exhaust fans were also turned on, significant pressure differences were noted. For
example, the janitor's room near the front door goes to -17.3 pascals when the exhaust fan (513 cfm)
is turned on (door closed) and the classroom area across the hall from the janitor's room goes to -8.0
pascals when six exhaust fans (763 cfm) are operated (door closed).
The mechanical room was found to be depressurized relative the rest of the building. This indicates
that return leaks are greater than supply leaks in the mechanical room, which is typical of both
commercial and residential buildings.
83
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• While the building was running at about +2.0 pascals with VAV max and full OA, the
mechanical room averaged 0.0 pascal.
• Cutting OA back to the "750" setting reduced building pressure to about +1.2 pascals and
mechanical room pressure dropped as well to about -1.5 pascals.
• It appeared then that the mechanical room runs typically about 2 pascals negative compared
to the rest of the building.
7.4.2 Continuous Measurements
Continuous measurements by Southern Research Insitute replicated some of the conditions studied
in 1993 and during the FSEC 1994 study. Significant changes included the following:
• Three outdoor air radon monitors were installed to investigate the distribution and time
variability of outdoor radon.
• Since the indoor radon was known to be well-mixed outside the audiologv room, only one
indoor radon monitor (in the Cafeteria) was used. An additional monitor was installed in the
mechanical room.
• In order to investigate the significance of the load-bearing block walls as an entry route, a
pumped radon monitor was used to sample the air within one section of the block wall
cavity. Another pumped radon monitor was used to sample subslab radon concentrations.
• Pressure differentials (with respect to the Cafeteria) were monitored in the following zones:
the mechanical room, outdoors, subslab. and the block wall section.
• SFe was continuously injected into the Cafeteria (and generally found to be uniformly
distributed in the building).
• In addition to operation of the HVAC during several week-long periods at each of the OA
damper positions used previously, several periods of depressurization (using the exhaust
fans) were scheduled on weekends. One period of pressurization (with the HV AC off) was
performed using a blower door. Out of deference to the energy management concerns of the
school district, the customary setback schedule (8 hr on/16 hr off, 5 days/week) was used in
the 1994 study.
Some results of the outdoor radon experiment are illustrated in Figure 31. The monitor sampling
at ground level (3 inches) failed early in the study and was removed. The other monitors (at 4 ft and
on the roof level at the OA intake) continued to operate throughout the study period. Both monitors
showed low values during the day (typically <0.5 pCi/L) followed by peaks of 2-6 pCi/L or higher
at night, when turbulent mixing is low. The roof level monitor peaked at a higher value than the
lower monitor, which was not expected. The possibility exists, however, that these levels may in
84
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fact be partly caused by radon leaving the building during the periods when the OA fan is off. In
order to check for other artifacts, a charcoal filter was placed alternately in front of the inlet to each
monitor. As seen in Figure 31, the measured radon in each monitor dropped to background levels
during the period that the filter was installed. An inadvertent leak to the mechanical room
demonstrated that the monitor used for 4 ft measurements responded normally to indoor levels.
Continuous data during 5 weeks of the 1994 study are summarized in Figures 32-46. Figures 32-36
illustrate pressure differences monitored during the experimental periods. Figure 32 covers
depressurization experiments during the evening of April 14 and 15, and the blower door
pressurization experiments of April 16-18. Figures 33-36 cover week-long periods of normal
operation with the OA damper set at positions corresponding to nominal flowrates of 3000, 750.
2250. and 1250 cfm, respectively. Also included are depressurization experiments (using some or
all exhaust fans) on 4/24-5, 5/8-9, 5/14, 5/15, and 5/23.
Examination of Figures 32-36 confirms some trends seen by FSEC in their short-term study, and
suggest further insights into the normal operating state of the building. First, the cafeteria runs at
positive pressure with respect to outdoors when the air handler is operating. The mean
pressurization varies from about 0.3 Pa at 750 cfm nominal OA to about 1 Pa at 3000 cfm nominal
OA. During weekdays, this pressure differential undergoes dramatic fluctuations. These may partly
be due to changes in the building load (VAV operation), or in the OA fan operation, as they are not
present during periods with the HVAC off, even when the building is mechanically pressurized or
depressurized. However, since these fluctuations are also characteristic of occupied periods (note
that they are greatly reduced on the weekend of 5/14-15), they may result from occupant activity (i.e.,
opening doors or windows).
During HVAC off periods, the cafeteria-outdoor pressure drops to low values, and a slight
depressurization is observed on many nights. This depressurization is most likely explained by the
observation that a few exhaust fans were often left in operation after the staff left at the end of the
day. These unmonitored changes in building operation were unfortunate, since they leave some
uncertainty as to the exact operating mode of the building.
As noted by FSEC, the mechanical room is depressurized relative to the cafeteria by 1.5-2.0 Pa when
the air handler is operating. This difference is greater than the pressurization of the cafeteria, so the
mechanical room is negative with respect to the outdoors for all but brief portions of the normally
occupied periods. Pressures in the other zones monitored (subslab block, walk and mechanical room
during periods without air handler operation) track the cafeteria pressure, but tend to be slightly
lower in magnitude during mechanical pressurization or depressurization.
Figures 37-46 illustrate radon levels during the four operating conditions and the
pressurization/depressurization experiments. Figures 37-41 contain radon concentrations
85
-------
14
Charcoal Filter Inline
Roof CRM
! 4* CRM
Leak to inside
Mi
04/02 04/04 04/06 04/08 04/10 04/12 04/14
OA Roof
Figure 31. Outdoor air radon levels during the LLC radon experiments at three locations: roof level
at the OA intake, 4 feet above the ground, and at ground level (3 inches). A charcoal
filtler was placed at the inlet to the 4 foot CRM for 2 days and then removed and placed
at the inlet of the roof CRM for 2 days.
86
-------
ts
Q.
cc
(2)
• - *
CL
¦D
-3-
04/13 04/15 04/17 04/19 04/21
04/14 04/16 04/18 04/20 04/22
Outdoors Subslab Bk Wall ~~ Mech Rm
Figure 32. Differential pressure of LLC zones to cafeteria during the period 4/13-
4/22/94.
87
-------
(d
CL
m
CD
H-
C0
O
t
£
CL
¦o
is
-3-
04/25
04/29
04/23
04/27
04/24 04/26 04/28 04/30
Outdoors Subslab Bk Wall ——- Msch Rm
Figure 33. Differentia] pressure of LLC zones to cafeteria during the period 4/23-
4/30/94.
88
-------
tc
CL
.......
Cl
"O
05/03
05/05
05/07
05/09
05/04 05/06 05/08 05/10
Outdoors Subslab Bk Wal1 Mech Rm
Figure 34. Differential pressure of LLC zones to cafeteria during the period 5/3-
5/10/94.
89
-------
d
Q_
05/17
05/09 05/11
05/15
05/13
05/10 05/12 05/14 05/16
Outdoors Subslab Bk Wall Mech Rm
Figure 35. Differential pressure of LLC zones to cafeteria during the period 5/9-
5/17/94.
90
-------
05/21
05/23
05/25
05/27
05/22
05/24
05/26
05/28
¦Outdoors
Subslab
Bk Wall
Mech Rm
Figure 36. Differential pressure of LLC zones to cafeteria during the period 5/21-
5/28/94.
91
-------
o
a
c
o
"D
cc
CC
!i
:
04/13 04/15 04/17 04/19 04/21
04/14 04/16 04/18 04/20 04/22
Rn Cafe
Gas 1
Mech Rm
Figure 37. Radon in cafeteria and mechanical room during the period 4/13-4/22/94.
Also plotted is SF6 concentration in cafeteria.
92
-------
o
D.
c
o
u
-------
o
a
c
o
"O
EC
05/03 05/05 05/07 05/09
05/04 05/06 05/08 05/10
Gas 1
Rn
Cafe
Rn
Mech Rtn
Figure 39. Radon in cafeteria and mechanical room during the period 5/3-5/10/94.
Also plotted is SF6 concentration in cafeteria.
94
-------
en
OC
05/09 05/11 05/13 05/15 05/17
05/10 05/12 05/14 ' 05/16
o
Cm*
o
o
o
Gas 1
Rn Cafe
~ Rn
'Mech Rm
Figure 40. Radon in cafeteria and mechanical room during the period 5/9-5/17/94.
Also plotted is SF6 concentration in cafeteria.
95
-------
I
05/21 05/23 05/25 05/27
05/22 05/24 05/26 05/28
m
3
o
c
o
o
O
H
Gas 1
Rn Cafe
Rn
Mech Rm
Figure 41. Radon in cafeteria and mechanical room during the period 5/21-5/28/94.
Also plotted is SF6 concentration in cafeteria.
96
-------
o
o.
c
o
T3
a
cc
1200
1000
-800
-600 =
400
200
04/13 04/15 04/17 04/19 04/21
04/14 04/16 04/18 04/20 04/22
Bk Wall
OA Roof
Rn Cafe
Figure 42. Radon concentrations in block wall section and outdoor air at roof level
during the period 4/13-4/22/94.
97
-------
o
a.
c
o
*D
ec
CC
I., • i
1200
-1000
800
o
Q.
c
CC
-600 =
5
o
_o
CD
h400
-200
04/23 04/25 04/27 04/29
04/24 04/26 04/28 04/30
Bk Wall OA Roof Rn Cafe
Figure 43. Radon concentrations in block wall section and outdoor air at roof level
during the period 4/23-4/30/94.
98
-------
o
D.
c
o
u
CO
cc
10
1200
-1000
800
¦600
400
200
O
Q.
C
CC
15
"o
o
CQ
05/03 05/05 05/07 05/09
05/04 05/06 05/08 05/10
Bk Wall — - OA Roof Rn cafe
Figure 44. Radon concentrations in block wall section and outdoor air at roof level
during the period 5/3-5/10/94.
99
-------
o
a
c
o
¦U
CO
if i—
•i5 » «»> »
• »5 *
! •• •
1200
riooo
800
600
400
200
o
c
CE
15
Js;
o
o
DQ
05/09 05/11 05/13 05/15 05/17
05/10 05/12 05/14 05/16
Bk Wall OA Roof Rn cafe
Figure 45. Radon concentrations in block wall section and outdoor air at roof level
during the period 5/9-5/17/94.
100
-------
o
Q.
c
o
~u
as
DC
Tsl"S!
1200
1000
r800 o
a.
c
600 =
cc
S! 11400
200
o
_o
CD
05/21 05/23 05/25 05/27
05/22 05/24 05/26 05/28
Bk Wall - OA Roof Rn cafe
Figure 46. Radon concentrations in block wall section and outdoor air at roof level
during the period 5/21-5/28/94.
101
-------
in the cafeteria for each period. The three data sets show similar time trends, as would be expected.,
with a few significant differences. First, the radon concentrations in the mechanical room are
consistently higher than in the cafeteria under all HVAC and mechanical ventilation conditions,
although the differences grow smaller for periods of mechanical dcprcssurization or of low OA
damper setting. Since interzone ventilation rates between the two zones arc expected to be high, and
inleakagc of outdoor air is expected to be much higher into the mechanical room as compared to the
cafeteria, the higher concentration suggests a significantly higher radon entry rate into the mechanical
room. This is not surprising in light of the pressure measurements showing the mechanical room
to be the most highly depressurized portion of the building.
A second observation is that the ratio of indoor radon to SF6 tracer is significantly higher in the
daytime (with HVAC in operation) and during depressurization, indicating higher radon entry rates
during those periods. (Since the ventilation rate is also increased, these periods tend to be periods
of lower radon concentrations.) The increased entry rate when the air handler is turned on also helps
explain the slower rate of fall of radon concentration than would be expected from the air change
rate. Indeed, the SF6 tracer gas does drop much more rapidly to its limiting daytime value. The
slower decay time of the radon is partially explained by the larger measurement time constant of the
radon monitors due to decay times of the radon progeny, but is also an indication of the change in
entry rate as the HVAC cycles between normal and setback operation.
One portion of the added radon source becomes more clear in view of Figures 42-46. in which the
concentrations of radon in the outdoor air and block wall cavity are plotted with the cafeteria
concentrations during the study period. The outdoor air contribution is seen to be minimal, since the
outdoor air concentration is at background levels during the day when the building ventilation rate
is significant. In the early morning hours when the outdoor radon concentration is highest, the
indoor concentrations are several times higher; furthermore, the infiltration rate is quite low at these
times. The one period when the outdoor air radon may be a factor is the pressurization period of
April 16-18, in which the indoor radon levels are low and track the daily pattern of the radon in the
outdoor air.
In contrast, the block wall radon concentrations suggest this to be a major pathway for radon entry.
During periods of air handler operation, the block wall radon rapidly rises to levels of 600-1000
pCi/L, then drops back to lower levels during the evening setback period. Inspection of Figures 32-
36 indicates that, while the block wall pressure at the section tested is generally positive with respect
to outdoors during HVAC on periods, it is generally negative with respect to both the subslab test
point and the cafeteria. As hypothesized by FSEC, this depressurization may be due to coupling with
the plenum, and would suggest some path for transport of radon into the return air system.
The pressure coupling would explain the rapid influx of soil gas into the block wall cores as the air
handler activates in the morning, as is clearly seen in Figures 43 and 44. The rapid drop in block
wall radon as the air handler goes off in the afternoon can be attributed to the relief of this driving
pressure gradient combined with transport of the accumulated radon back into the soil or, more
probably, into the building. The likelihood that the block walls provide a major entry path has been
discussed before, since the cores of these walls penetrate the slab to the block courses in direct
102
-------
contact with the soil. Since the pores of the block are highly permeable, a low resistance pathway-
exists directly from the soil to indoors.
Two cautions must be observed regarding any quantitative interpretations from these results,
however. The block wall section tested was a 4 foot wide interior wall segment bordering the
cafeteria and Room 109. Horizontal communication within the wall segment will presumably be
limited by the reinforced filled core sections specified every 4 feet in this building. There are
exhaust fans in Room 109, which may enhance entry in this section over walls adjacent to rooms
with no mechanical exhausts. On the other hand, entry into the walls of the mechanical room might
easily be much higher, and could represent the major source of radon entry into the building. In any
event, the results of the present study clearly indicate that the wall construction detail used in the
LLC is highly vulnerable to radon entry, and alternatives must be provided for a radon-resistant
building standard.
103
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SECTION 8
QUALITY ASSURANCE
In 1993, the EPA approved a Quality Assurance (QA) Project Plan (QAPP) (#93012) for the
"Study of Radon Entry and Control in Large Foot-Print Structures" to develop suitable diagnostic
and mitigation techniques for existing large buildings in Florida. It was under this QAPP that the
1993 parametric study was conducted. In early 1994, the EPA approved a similar QAPP
(#94036) for this and other Large Building 1994 Demonstrations that was used to guide the
collection and analysis of the 1994 Phase II study. The radon measurements were made according
to procedures found in the EPA's "Indoor Radon and Radon Decay Product Measurement Device
Protocols" (EPA 92). The differential pressure measurements were made using MODUS
Instruments, Inc. pressure transducers according to their operating instructions.
8.1 DATA QUALITY OBJECTIVES AND ACHIEVEMENTS
The primary objective of this project was to determine the effect of the HVAC systems of large
buildings in influencing the transport, entry, and reduction of indoor radon in the buildings. The
1993 parametric study showed that in two buildings the HVAC system assisted in lowering the
radon concentrations by inducing enhanced ventilation rates in the building and that the rate of
their decline and the limiting radon concentrations depend on the OA gas flow rate. The peak
radon concentrations reached in the second building (LLC) (just before the HVAC system was
activated) depend somewhat on the amount of OA introduced during the previous HVAC
operation cycle and on the length of time that had transpired since the HVAC system was last
operated. However, two questions remained unresolved: why the radon concentrations in one
room did not follow those of the rest of this building and why the minimum concentrations
achieved were so high. Therefore, the 1994 Phase II study was implemented at LLC. Its
objectives were to address questions not satisfactorily answered by the first study. These
included: the pressure balance in the building; the conditions under which it was pressurized;
the flow rates to which those conditions correspond; and the source of the residual radon
concentrations below which it seemed impossible to reduce the indoor levels with the HVAC
system (outdoor air, locally depressurized areas, or failures in the foundation barrier). The
occupied portion of the building was found to be pressurized whenever the HVAC system was
operated and neutral to slightly depressurized when it was not. However, the mechanical room
was usually depressurized with respect to the outdoors when the building was occupied and the
radon concentrations are consistently higher there, suggesting a significantly higher radon entry
rate into the mechanical room. Although the outdoor air averages a higher than expected radon
concentration, it does not account for the high indoor radon concentrations. High block wall
concentrations suggest that they may be major pathways for radon entry.
8.2 DATA QUALITY INDICATORS
The data quality indicator (DQI) goals for precision, accuracy, and completeness are described in
the QAPPs (#93012 and #94036) of 1993 and 1994, respectively. The precision goals for radon
104
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concentrations of 4 pCi/L or greater are given in terms of a coefficient of variation (CV) or
relative standard deviation and are the 10% levels listed as achievable in the EPA's protocols.
The precision goal for differential pressure of 25% CV was set higher because many of the
measurements are expected to be in the range of ± 1 Pa, and this level of precision will be quite
adequate in this range of measurements. The accuracy goal for radon concentrations was the
criterion for a pass in the EPA's Radon Proficiency Program (RPP), ±25% bias for concentrations
above 4 pCi/L. This bias was also considered adequate for the differential pressure
measurements. The target completeness goal was 90% for each measurement parameter.
8.2.1 Continuous Radon Monitors
8.2.1.1 Precision
As part of Southern Research Institute's ongoing QA/QC program, and before any continuous
radon measurements were started in the LLC building in December 1992, six of the CRMs were
placed in two locations and measured the radon concentration there simultaneously for about 2
days. [The remaining monitors (most belonging to the EPA) were treated similarly, with equally
successful results, but the actual data were not provided.] Several times during the
measurements, two or more monitors were collocated and measured radon concentrations in the
same location over the same time intervals. Once again after the study's conclusion the monitors
were again placed in the same locations and set to measure the indoor radon concentrations there.
The resulting measurements from each of these replications are given in Table 10. The DQI goal
TABLE 10. RESULTS FROM REPLICATE PLACEMENT OF CRMS
Time Period
CRM
CV
1
2
3
4
5
6
165
172
11/25-11/26/91
5.8
5.8
5.1
7%
11/25-11/26/91
18.7
18.5
18.5
1%
04/14-04/15/93
16.5
16.3
16.1
15.2
17.8
17.0
5%
03/02-03/04/94
18.5
17.1
16.5
19.1
18.9
17.6
17.2
16.2
6%
04/11-05/03/94
12.8
13.4
3%
06/14-06/16/95
9.3
9.9
10.0
9.8
9.3
9.2
4%
06/16-06/19/95
9.3
9.8
3%
for the precision of the CRMs was a CV of 10% for radon concentrations greater than 4 pCi/L.
The CVs listed in Table 10 range from 1 to 7%, all less than this DQI goal. Therefore, the
precision of the CRMs was considered quite acceptable.
105
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8.2.1.2 Accuracy
During the last calibration check in the EPA radon chambers at the National Air and Radiation
Environmental Laboratory (NAREL) in Montgomery, Alabama, prior to the commencement of
measurements in 1992, a calibration factor (CF) was calculated for the six CRMs that used alpha
scintillation for radon measurement. The two ionization chamber (IC) CRMs were sent to the
manufacturer for calibration checks. Twice during the study, the six scintillation monitors were
returned to NAREL for subsequent calibration checks, during the second of which the two IC
monitors were also calibrated. After the study was over, the eight CRMs were returned to
NAREL for a final calibration check. The measurements of the radon in the NAREL chambers
were calculated for each monitor as would have been done in the field.
After the exposures, NAREL sent the actual chamber concentrations so that the relative errors
(REs) and the new CFs of the monitors could be calculated. The RE is the difference between the
measured value and the actual concentration divided by the actual concentration, given as a
percentage. The DQI goal for accuracy (or bias) was ±25% RE for concentrations greater than 4
pCi/L. Table 11 lists the results of the bias determinations made for the CRMs based on these
calibration checks. The mean absolute relative error (MARE) (the mean of the absolute values of
TABLE 11. RESULTS OF THE BIAS DETERMINATIONS FOR THE CRMS
CRM
CF-92
RE-93
CF-93
RE-94
CF-94
RE-95
1
1.204
- 1%
1.194
1%
1.208
1%
0
1.193
- 2%
1.174
- 7%
1.098
7%
3
1.111
- 3%
1.080
-10%
0.972
8%
4
1.162
- 8%
1.066
5%
1.114
7%
5
1.082
7%
1.160
3%
1.197
1%
6
1.174
2%
1.268
- 4%
1.222
-1%
165
0.295
- 6%
0.278
- 6%
0.234
7%
172
0.281
-12%
0.249
-13%
0.230
3%
MARE
4%
6%
4%
each of the individual REs) of each set of calibration measurements is also given in the table.
Each of the individual REs and the MAREs were well within the target bias of ±25%; therefore,
the accuracies of the CRMs were considered quite adequate. Even though the QAPP did not
include ambient or sub-slab concentrations as critical measurements, the pumped (quasi-
continuous) mode of making these measurements employed in this study was tested at the
NAREL. A CRM was set up in this mode and sampled the air from one of the chambers for 5
days. The RE of these measurements was found to be about 1%. Other measures that were
106
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routinely taken to ensure that the bias of the measurements was kept to a minimum included
measuring the background of each CRM before it was deployed in a different location.
8.2.1.3 Completeness
Of the roughly 42,100 half hourly indoor radon concentrations measured with the six CRMs over
this study, 38,700 of these were considered valid measurements. This represents a completeness
rate of 91.9%, greater than the DQI goal of 90%. The goal was not met for every experimental
subset of the data, however. Due to monitor failures during the Case Study at the FCN. 74.2%
CRM data capture was achieved from the four monitors in that set. Likewise, one of the three
outdoor radon monitors described in Section 7.4.2 failed early, and a second developed a leak to
indoors. These failures resulted in a 57% data capture for this segment and difficulty in extending
conclusions to the spatial distribution of outdoor radon near the LLC. The indoor radon
measurements for the 1993 and 1994 LLC tests achieved data completeness of 95.6% and
99.9%, respectively.
8.2.2 Integrative Radon Monitors
The integrative radon monitors used in this study were electret ion chambers (EICs).
8.2.2.1 Precision
Duplicate EICs were placed for 189 of the 190 integrative radon measurements made during this
study. Of these, 162 (86%) had CVs of less than the 10% DQI goal. Twenty of the 27
measurements that had greater CVs measured indoor concentrations of less than 4 pCi/L and had
standard deviations (STDs) of 0.4 pCi/L or less; so these were also considered to have met the
DQI goal (total of 95%). Six of the seven remaining duplicate pairs had one of the EICs with a
greater than normal voltage drop, which indicated that it was touched, had dust neutralize some
of its charge, or for some other reason had lost excess voltage, l'he remaining EIC had a lower
than expected voltage drop, for which there was no obvious reason, unless one of the building
occupants had closed or covered it for some period of time. The average CV for those
measurements greater than 4 pCi/L (including two with high CVs) was less than 5%, and the
average STD for those duplicate pairs that averaged less than 4 pCi/L (including five high ones)
was less than 0.4 pCi/L. This level of precision was considered quite adequate for the EIC
measurements.
8.2.2.2 Accuracy
Several steps in our standard operating procedures for making EIC measurements are included to
ensure that the bias of those measurements is minimal. Before reading any of the electrets on the
surface voltage meter on a given day, an uncharged cap is usually placed over the sensor. Never
did the voltage differ from zero by more than 2 V, which was considered acceptable. Reference
electrets are normally read at least once each week that any measurements are made. Never was
there greater than 2 V difference in the reading of a reference electret from its previous reading or
greater than a 4 V change within a month. This was considered to indicate sufficient electrets
reader stability.
Periodically, control electrets are placed in EIC chambers, and they are treated exactly like the
107
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measurement electrets. except that the chamber lids are not opened. Eight times during the study
control electrets were so placed. Three of these showed no change in the voltages; one had a 1 V
change; and two each had 2 and 3 V changes. These were considered acceptable voltage drops
because of the handling to which these devices were subjected. The initial and final electret
readings are made at as close to the same temperatures as possible. When the electrets are read,
they are placed as nearly as possible in the same orientation for each reading. Each electret is
read in the same manner, with repeated openings of the voltmeter shutter until a stable voltage is
read on two consecutive openings.
A selected number of EICs were sent to the U.S. EPA NAREL in Montgomery, Alabama, for
exposure for at least 2 days in a 13.5 pCi/L chamber in 1991 before the first of the measurements
reported in this study and in a 16.6 pCi/L chamber in 1993 after the last of this study's
measurements. There, procedures identical to those employed in the field were followed to make
measurements of the chamber concentration. During the 1991 exposures, five control and two
reference electrets were read. Two dropped 2 V, one dropped 1 V, two remained the same, and
one each read 1 and 2 V higher. Thirty-three of the readings were performed with both our and
NAREL's readers, and the EPA reader averaged 0.8 V higher. All of these checks were within
acceptable ranges. Table 12 lists the results of these calibration checks of the exposed EICs. They
all measured low, probably because 2 days is the minimum exposure time recommended for
these devices, but all were within the ±25% DQI goal (the largest RE was -16%). Therefore, the
accuracy for the EICs was considered adequate for this study. (The CVs for these measurements
were 2 and 4%.)
8.2.2.3 Completeness
Of the 379 EICs used for measurements during this study, only seven produced questionable
results that were not used, for a 98% completion rate, easily exceeding the 90% DQI goal.
Therefore, the completeness of these measurements was considered quite adequate.
8.2.3 Radon Grab Samples
8.2.3.1 Precision
During this study, 40 grab samples were taken, 30 of which had duplicate samples made. Of
these duplicate samples, 25 (83%) had CVs less than the DQI target of 10%. The five duplicate
measurements that exceeded the 10% DQI goal were made with sequential rather than
simultaneous samples, which could have easily allowed fresh air to infiltrate and dilute the
duplicate sample. Therefore, this procedural inconsistency was corrected in later samples. Even
with the five duplicates whose CVs exceeded the 10% DQI goal, the average CV for these 30
duplicate samples was less than the 10% goal. Therefore, the precision of the radon grab samples
was considered adequate.
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TABLE 12. RESULTS OF TIIE EIC CALIBRATION CHECK
Electret
Chamber
1991 Radon
1991 RE
1993 Radon
1993 RE
1
12.6
- 7%
14.4
-14%
2
12.1
-10%
15.9
- 4%
3
13.0
- 4%
15.8
- 5%
4
12.8
- 5%
14.6
-12%
5
12.6
- 6%
14.9
-11%
6
12.9
- 4%
14.8
-11%
7
12.9
- 4%
14.0
-16%
8
12.8
- 5%
15.0
-10%
9
13.0
- 3%
14.7
-12%
10
12.8
- 5%
15.8
- 5%
11
12.7
- 6%
*
*
Mean/MARE
12.7
6%
15.0
10%
* No data
8.2.3.2 Accuracy
In late November 1991 before any of the grab samples were taken for this study, and again in
April 1993 after the grab sampling was completed, most of the grab cells were taken to the
NAREL in Montgomery, Alabama, for checks of their calibration. (Such calibration checks were
usually performed annually, but NAREL could not schedule us before April 1993.) Air from one
of the environmental control chambers was sampled by each of the cells. They were returned to
Southern Research Institute (SRI), Birmingham, AL. where they were counted at least twice.
The average detected concentrations were calculated for each cell using the most recently
determined calibration factor (CF) for that cell. Later NAREL sent the actual concentrations that
were maintained in the chambers at the time of sampling. The relative error (RE), expressed as a
percent, was calculated. Then new CPs were calculated for each of the cells based on the actual
chamber concentrations, "fable 13 lists the calibration results for these two sets of calibration
checks. As was the case with the CRMs, the measure that is used to compare the REs is the
MARE. The individual REs for the various cells ranged from -22 to 20%, with MAREs for both
calibration runs of 9%. All of these error measures were within the DQI goal of ±25%; so the
bias of the grab samples was considered acceptable.
Before a cell was used in the field, a background count was generally made and recorded to
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TABLE 13. CALIBRATION RESULTS FOR THE GRAB CELLS FROM 1991 AND 1993
Cell Number
RE 1991
CF 1991
RE 1993
CF 1993
EPA 1.1
-13%
0.607
2%
0.616
EPA 1.2
2%
0.686
-9%
0.625
EPA 1.3
-12%
0.615
14%
0.784
EPA 1.4
14%
0.796
12%
0.889
EPA 1.5
-15%
0.593
2%
0.606
EPA 2.1
-9%
0.616
EPA 2.2
- 7%
0.654
9%
0.749
EPA 2.3
-14%
0.602
2%
0.612
EPA 2.4
2%
0.701
3%
0.713
EPA 2.5
- 8%
0.644
19%
0.818
SRI 283
14%
0.795
12%
0.889
SRI 291
- 4%
0.672
- 3%
0.649
SRI 292
17%
0.818
- 5%
0.779
SRI 293
- 5%
0.663
-1%
0.655
SRI 294
- 2%
0.690
-5%
0.653
SRI 295
13%
0.794
10%
0.872
SRI 296
10%
0.766
12%
0.858
SRI 297
- 1%
0.694
8%
0.750
SRI 300
1%
0.705
19%
0.838
SRI 301
-12%
0.614
19%
0.824
SRI 495
- 7%
1.203
14%
1.422
SRI 500
-22%
1.009
12%
1.399
SRI 501
-16%
1.087
20%
1.494
SRI 567
- 7%
1.206
- 3%
1.168
MARE
9%
9%
110
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ensure that the cell was relatively "clean." After a sample was collected and counted, the cell
was flushed with clean ambient air and allowed to "relax" to allow the residual decay products to
decay away before another background check was made. With the relatively high radon
concentrations sampled in this study when taking soil and sub-slab samples, the cells were
subjected to large potentials for increased backgrounds.
8.2.3.3 Completeness
Of the 70 individual grab samples taken over this study, 65 produced valid measurements, for a
93% completion rate, exceeding the 90% DQI goal for this measure of data quality.
8*2A Differential Pressure Measurements
As described in Section 5, continuous differential pressure measurements were made with the
Modus pressure transducers in the EPA or Southern Research data logging stations.
Confirmation measurements were taken using digital micromanometers. Due to concerns
regarding possible zero drift, the 1993 pressure data from both the FCN and the LLC were not
used for this study, and are considered questionable. The data reported in Section 7.4 were taken
using instruments with automatic zero reference, and are considered reliable. For 5 minutes at
the beginning of each half hour's measurements the pressure signal sent to the transducers was of
zero pressure drop between the ports, and these readings were recorded by the data logger. The
calculations of the measured pressures each half hour were made with this zero correction.
8.2.4.1 Precision
Before the pressure transducers were placed in the FCN and the LLC, another EPA contractor
(Acurex) checked their precision, and found it to be acceptable. Unfortunately, these data were
not supplied to us, and are not considered relevant in this study since measurements with these
instruments were not used. After the Southern data station was removed from the LLC, the
transducers were used to measure seven known pressures that spanned their ranges. CVs of 21,
21, 10, 18, and 12% were calculated from the higher absolute pressures (5 to 25 Pa). The
measurements of pressures closest to zero had standard deviations of 1 to 2 Pa. These measures
of precision (except for measurements close to zero) were all within the 25% DQI goal;
therefore, the precision of these monitors was considered acceptable.
8.2.4.2 Accuracy
Digital micromanometers, which were routinely sent back to the manufacturer for their
calibrations to be certified with the National Institute of Standards and Technology (NIST)
traceable test equipment, were used to check the calibrations of the pressure transducers. In late
1992, before the LLC measurements were begun, all three micromanometers were so certified. In
late 1993 and again in late 1994 and early 1995 after the building measurements were completed,
the instruments were sent back to have their calibrations certified again. All three instruments
were checked over 6 to 10 pressure ranges, and at no pressure did any of the three devices have a
RE outside the ±6% range.
As mentioned above, Acurex calibrated the pressure transducers before placing them in the LLC,
but those data were not provided to us. After the building measurements began, the Southern
111
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Research pressure transducers used were calibrated with a micromanometer, using seven
pressures that spanned their ranges. These measurements were made with the data acquisition
system configured exactly as it was installed in the building; so that any bias introduced by a
component of the system would be corrected by the calibration procedure. As the transducers
were exposed to the known pressures, they sent to the data logger corresponding DC voltages,
which were recorded and stored. Regressions were run over the pressure range measured,
yielding slopes of pascals/volts and intercepts of calculated pressures in pascals.
8.2.4.3 Completeness
As described above, pressure data from both the 1993 field studies were discarded as
questionable, leaving the 90% completeness DQI goal unmet for these tests. Of the 13.645 half
hourly differential pressure measurements with the five Southern Research transducers reported
in Section 7.4 for the 1994 LLC study, 13,573 are considered valid. This represents a
completeness rate of 99.5% for this subset of the study.
8.3 DATA REVIEWS
Before the study, all of the radon and pressure measuring equipment was calibrated as described
above. Generally QA personnel not directly involved with the actual field measurements checked
the calibration of the equipment. Some of the CRMs and most of die pressure transducers came
from the EPA, and one of their contractors performed the calibrations. The remaining CRMs, the
EICs, the radon grab cells, and the micromanometers used to perform the pressure checks
belonged to Southern. The calibration of these radon measuring devices was checked at the
EPA's NAREL in Montgomery, Alabama, by SRI technicians and/or scientists. The calibration
of the micromanometers was certified by the manufacturer. The results of all the calibration
checks were reviewed by the project manager and the principal investigator and passed to the on-
site project coordinator for use in the field. This individual kept detailed project logs, copies of
which were sent to SRI at least monthly. There they were reviewed by both the manager and
investigator for completeness. At least twice during the project, SRI personnel from Birmingham
visited the NAREL to review the data setup and collection.
8.4 IDENTIFICATION OF CORRECTIVE ACTIONS
The data from the data logger were retrieved within the next working day of any changes to the
system to ensure that their collection was complete and accurate as planned. If any data appeared
to be faulty or missing, the system was checked immediately. For instance, if no data appeared in
the output where some was expected, then the wiring and connections were inspected. If
unreasonable data were detected, then sampling lines were checked for blockage, crimping, or
leaks. Once the data retrieval appeared to be complete, then downloads were conducted
approximately weekly, and another thorough review of the collected data was performed to
ensure that the measurement and collection systems were operating as planned. Because both
study buildings were occupied most of the time the measurements were being made, there were
numerous potential interferences with consistent and continuous data collection. Moreover,
frequent thunder storms and severe weather caused power fluctuations. Generally the system
was inspected as soon as possible after each such event occurred.
112
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SECTION 9
REFERENCES
ASH 89 ASHRAE, Ventilation for Acceptable Indoor Air Quality. Atlanta, GA: The American
Society for Heating, Refrigerating and Air-Conditioning Engineers, Inc., Standard
ANSI/ASHRAE 62-1989, 1989.
ASH 92 ASHRAE, Thermal Environmental Conditions for Human Occupancy. Atlanta, GA:
The American Society of Heating, Refrigerating and Air-Conditioning Engineers. Inc.,
Standard ANSI/ASHRAE 55-1992, 1992.
AST87 ASTM, Standard Test Method for Determining Air Leakage Rate by Fan Pressurization.
Philadelphia, PA: American Society for Testing and Materials, Designation E779-87,
1987.
Axl 90 Axley, J., Element Assembly Techniques and Indoor Air Quality Analysis. In: IA l90:
The Fifth International Conference on Indoor Air Quality and Climate, Toronto, July 29
- August 13, 1990, Vol., 4, pp. 115-120.
EPA 92 U. S. Environmental Protection Agency, Indoor Radon and Radon Decay Product
Measurement Device Protocols, Washington, DC: U. S. Environmental Protection
Agency report EPA-402-R-92-004 (NTIS PB92-206176), July 1992.
FAC94 State of Florida, Florida Administrative Code Chapter 6A-2, Education Facilities,
Tallahassee, FL, 1994.
Feu 90 Fcustel, H.E., The COMIS Air Flow Model: A Tool for Multizone Applications. In
IA'90: The Fifth International Conference on Indoor Air Quality and Climate, Toronto,
July 29-August 13,1990, Vol. 4, pp. 121 -126.
FSE 92 FSEC, Florida Software for Enervironment Computation - User's Manual, Version 3.0.
Cape Canaveral, FL: Florida Solar Energy Center report FSEC-GP-47-92, 1992.
Gu 94 Gu, L., Anello, M.T., Cummings, J., and Swami, M.V., Analysis of The Polk Life and
Learning Center (PLLC), Cape Canaveral, FL: Florida Solar Energy Center Report
FSEC-CR-739-94, October 1994.
Gu96 Gu, L., Swami, M.V., and Vasanth, V., Large Building HVAC Simulation, Research
Triangle Park, NC: U. S. Environmental Protection Agency report EPA-600/R-96-116
(NTIS PB97-104715), September 1996.
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Nag 87 Nada. N.L., Koontz, M.D., Fortmann, R. C., Schoenborn, W.A., and Mehegan, L.L.,
Florida Statewide Radiation Study, Germantown, MD: Geomet Technologies Inc.
Report IF-1808, 1987.
Sau 93 Saum, D.W., Case Studies of Radon Reduction Research in Maryland, New Jersey, and
Virginia Schools, Research Triangle Park, NC: U. S. Environmental Protection Agency
report EPA-600/R-93-211 (NTIS PB94-117363), November 1993.
114
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TECHNICAL REPORT OATA
(Please read Intl/juetions on the reverse before complet
1. REPORT NO. 2.
EPA-600/R-97~064a
3.
4. TITLE AND SUBTITLE
Radon Diagnostic Measurement Guidance for Large
Buildings; Volume 1. Technical Report
5. ncponr date
July IS 9 7
G. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Marc Y. Menetrez and Russell N. Kulp
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING OROANIZATION NAME AND ADDRESS
See Block 12
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-1)2-0062, W. A. 2/049
(SoRI)
12. SPONSORING AGENCY NAME AND ADORESS
EPA, Office of Research and Development
Air Pollution Prevention and Control Division
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final; 4/93 - 11/95
14. SPONSORING AGENCY CODE
EPA/600/13
16. supplementary notes APPCD project officer is March Y. Menetrez, Mail Drop 54, 919/
541-7981. Volume 2 contains appendices.
16. abstract rep0r£ discusses the development of radon diagnostic procedures and
mitigation strategies applicable to a variety of large non-residential buildings com-
monly found in Florida. The investigations document and evaluate the nature of radon
occurrence and entry mechanisms for radon, the effects of heating, ventilation, and
air-conditioning (HVAC) system configuration and operation on radon entry and dilu-
tion, and the significance of occupancy patterns, building height, and other building
construction features. A primary focus of the project was the effect of the HVAC
systems of a large building on the transport, entry and (hopefully) the minimization
of indoor radon in the building. Two buildings were investigated, both of which
showed an inverse relationship between dedicated ventilation air and indoor radon
concentrations, as was expected. Both also showed signs of unusual HVAC design,
operation, and maintenance that presumably adversely affected indoor radon and
other indoor air quality (IAQ) variables. The second building showed clear indications
of foundation design elements that contributed to radon entry. Among recommenda-
tions relevant to building standards that can be concluded from the project is that
design and construction should concentrate on elimination of major soil gas pathways
such as hollow walls and unsealed utility penetrations.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATi Field/Group
Pollution
Radon
Measurement
Air Conditioning
Buildings
Pollution Control
Stationary Sources
Indoor Air Quality
13 B
07B
14 G
13 A
13 M
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
128
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (3-73)
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