INDOOR AIR QUALITY LARGE BUILDING CHARACTERIZATION

PROJECT PLANNING

by: Marc Y. Menetrez, and Russell N. Kulp
U, S. Environmental Protection Agency '

Office of Research and Development
National Risk Management Research Laboratory
Research Triangle Park, NC 27711

Bobby Pyle, Ashley Williamson, and Susan McDonough
Southern Research Institute	. .

P.O. Box 55305
Birmingham, AL 35255-5305

Abstract

Three buildings were characterized in this project by examining radon concentrations and
indoor air quality (IAQ) levels as affected by building ventilation dynamics. IAQ data collection
stations (IAQDS) for monitoring and data logging, remote switches (pressure and sail switches), and
a weather station were installed. Measurements of indoor radon, carbon dioxide (C02), particle
concentrations, temperature, humidity, pressure differentials, ambient and sub-slab radon
concentrations, and outdoor air (OA) intake flow rates were collected.

The OA intake Mas adjusted when possible, and fan cycles were controlled while tracer gas
measurements were taken in all zones and IAQDS data were collected. Ventilation, infiltration,
mixing rates, radon entry, pressure/temperature convective driving forces, C02 generation/decay
rates, and IAQ levels were established for baseline and OA-adjusted conditions. These dynamic
interacting processes characterize the behavior of these and similar large buildings. Techniques to
vary OA and pressure differential, and to track IAQ were incorporated into the experimental plan
and are discussed with the project rationale.

Introduction

This paper describes a research study undertaken in support of the Florida Standard for
Radon Resistant Construction in Large Footprint Structures (funded by the U.S. Environmental
Protection Agency and the Florida Department of Community Affairs) The project entails an
extensive characterization and parametric assessment study of large buildings with the purpose of
assessing the impact of radon entry on design, construction, and operating features of the building,
particularly, the mechanical subsystems 23,4.

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As part of the study, the response of the structure to a range of heating, ventilating, and air-
conditioning (HVAC) operating conditions was continuously monitored with the purpose of
determining the optimum HVAC conditions to reduce indoor radon within the envelope of
acceptable operation as regards to energy, comfort, and IAQ impacts on the structure.

Three Florida buildings were studied. This paper is limited to describing the project planning
aspects of a completed research project. Other aspects of the project will be dealt with separately.
An example building for the purpose of discussion is the Polk County Administration Building
located in Bartow, Florida, a publicly owned building constructed in 1988. The building has 14,000
m2 (149,000 ft2) of floor space distributed over five floors, and has a permanent occupancy of
roughly 300 county employees and elected officials. HVAC needs are met by 11 air handlers (3 on
the first floor and 2 on each of the other four floors). The building is equipped with a variable air
volume (VAV) distribution system with plenum return, and each air handler is supplied by a separate
outdoor air (OA) intake.

Study Objectives

The building was selected for this study as best representing the research needs identified as
being important to the development of a definable construction standard for this class of structure.
The study has five main objectives:

1. Determine the effect of HVAC operating cycles (including OA level and exhaust ventilation)
on radon-relevant parameters of the structure. These parameters include building pressure,
ventilation rate, radon concentration, and radon entry rate (assuming a well-mixed building). The
results were determined in the course of the parametric study in which I1VAC parameters such as
ventilation air were systematically varied.

2- Evaluate the effect of a large slab on the driving pressure which promotes radon entry. In the
course of the study, we will monitor subslab pressure variations with position and HVAC status.
(Two superimposed effects were expected, one dependent on position and the time derivative of the
barometric pressure and the other dependent on the HVAC cycle and possibly outdoor temperature.)

3.	Assess the effect of ground floor interzonal pressure balance on radon entry. Supply or
return imbalances between zones and the relative areas of negative pressure are effecting points of
radon entry. Increased attention is given to ground floor ventilation rates, pressure differential, radon
concentrations and entry compared to zones above the ground floor.

4.	Monitor the transport of air (and radon) between zones and floors. Building air change rates,
OA intake rates, building mass-balance, and pressure imbalances were studied. Ground floor tracer
gas injection, coupled with monitoring the buildup on adjacent floors can identify transport
mechanisms and their effect in spreading radon.

5.	Assess the effect of building features/faults on response variables. Some of the features and
assessment strategies to be used are; elevators (monitor shaft bottom for radon and estimate flow
induced by car movement to evaluate a semi-quantitative estimate of radon pumping); stairwells
(determine concrete wall isolation of radon entry by monitoring radon as source); atrium (determine
inter-zonal effect on radon transport); ground floor mechanical rooms (assess as entry locations by
monitoring pressure differential and radon); and visible slab penetrations (seal and assess effect
using local or whole building measurements).

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Measurements

The IAQ investigation of the Polk County Administration Building involved a series of
manual measurements and the use of measurement instrumentation operating continuously and
downloading automatically. Manual measurements were taken as part of both an initial intensive
testing phase and a weekly testing series to evaluate HVAC and building performance. For
continuous measurements, 13 IAQDS were used, with internal and remote input sensors. Each
IAQDS stores information in an internal microprocessor and transmits this information by modem.
In addition to the IAQDS, air exchange rates, weather station data, and ambient radon measurements
were recorded.

The IAQDS measurements included indoor radon concentrations, differential pressures, room
temperatures, relative humidities, and carbon dioxide concentrations in several zones. In addition,
percentage operation cycle times for selected air handlers, exhaust fans, and elevators are obtained
via switches; duct air temperature and relative humidity in selected air handlers were monitored; and
a particle counter in a single first floor zone was monitored to provide indicative measurement of
indoor particulate levels. The 13 IAQDS were distributed two per floor on the top four floors, with
five stations distributed in several zones on the first floor.

Building Selection and Plan Development

A building was located which was found to contain elevated radon concentrations (in the
4-15 pCi/L range). A draft study proposal was presented to the building owners, and approval was
obtained. Plans to the building were obtained and used to guide selection of measurements. Walk-
through visits were conducted to confirm locations of continuous samplers, phone and electrical
connection availability, and to obtain a survey of pressure differences between zones of the structure.
Monitoring equipment was obtained, calibrated, and prepared for installation5,6.

A)	Installation of Continuous Monitoring Systems

A team installed 13 IAQDS sensors and associated interconnecting wires and tubes. A
weather station was installed and monitored by a Campbell 21X data logger. Building features were
inspected and modifications made to some measurement locations in response to on-site conditions.
Several deficiencies in the HVAC installation and operation were noted and reported to the Facilities
Management Staff. The most significant of these included: significant supply duct leakage in the
fifth floor attic; and a total lack of ventilation (outdoor) air into both second floor air handlers due
to obstruction of OA intakes by building framing after installation. Inadequate ventilation into first
floor air handlers due to insufficient OA supplies was reported and, for the purpose of this study,
temporarily increased. Permanent improvements to OA supplies are planned.

B)	Characterization of HVAC Systems

In addition to the design survey and survey pressure measurements performed, a certified
HVAC test and balance (TAB) company was contracted to verify and spot-check data from earlier
balance reports of the system. These measurements include: 1) Monitoring of total flow and trunk
line supply flow rates from all air handlers at full open VAV conditions; 2) Measurement of supply
and OA flow rate at each air handler at four demand OA flow conditions (60, 70, 85, and 100% of

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capacity) by use of four positions of all operable OA dampers (foil open, closed, and 50 and 75%,
respectively); and 3) Measurement of exhaust fan flow rates.

C)	Installation of Tracer Gas System

Sample lines and a computerized sample injection and gas chromatograph electron capture
detector system were installed, checked, and left in continuous operation. The injection cycle (using
sulfur hexafluoride, SF^) was set at 1 injection per day due to observed decay rates. In addition, SF6
was injected into OA intakes to measure OA intake rates, and into specific zones to identify inter-
zonal transport and mixing.

D)	Operating Cycles

1: Baseline

With all systems operational, a week of data in the "as found" condition was obtained,
downloaded, and analyzed. Attention was given to the effects of the building setback period.

2: Maximum Outdoor Air

All operable outdoor air dampers were set to their full open position, and a week of data
obtained, downloaded, and analyzed. During this period, the data were surveyed for indications of
cooling system incapacity (including chilled water temperature) to meet the added latent heat load
(inability to maintain set points, or excessive relative humidity in air zones).

3: Minimum Outdoor Air

Operable outdoor air dampers were also set to a condition of low outdoor air consistent with
occupant comfort and IAQ status. The target OA levels were 50% of the baseline outdoor air flow
rates. Outdoor air levels were to be reduced, to a level corresponding to less than 5 cfin (0.00236
m3/s)/person at foil building occupancy. Due to the impact on radon entry and migration, the areas
within the building which were of principal importance were the first floor. The second floor was
next in importance, and the above floors were of minor importance because of their low radon
concentrations. After measurements of OA were made by air flow hood and tracer gas techniques,
the first floor was found to be below the 5 cfm (0.00236 m3/s)/person. This low OA intake was
decreased to near zero flow only for a weekend (no occupancy) measurement period. During
occupied hours the OA intake remained at approximately baseline levels.

4; Altered First Floor Pressure Balance

During this cycle, the pressure imbalance between first floor zones was enhanced by partial
obstruction of dampered return sleeves through fire zone walls in plenums above ceilings.

5: Modified Setback

Depending on observed time-resolved behavior of pressures, temperatures, and relative
humidity during earlier setback periods, an alternate setback cycle was designed and tested. These
components include; 1) One hour (rather than 30 min) setback periods; and 2) Reductions of exhaust
air flow either continuously (by throttling exhaust lines) or intermittently (by cycling fans off with
air handler setback).

6: Sealed Penetrations to Soil

In the initial walk-through, several locations were discovered with significant soil gas
pathways (i.e., several holes greater than 1 in.2 [6.45 cm2] in area). Some of these penetrations are
in mechanical rooms or other similarly vulnerable locations. At the beginning of this test period,

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major penetrations were sealed with a suitable polymeric compound. Mechanical rooms were
monitored for radon concentrations.

Conclusion

The continuous and manual measurements continued for a period of 3 months to accomplish the
project objectives. This presentation of objectives and methods of accomplishing those objectives
was part of an on-going research project. This paper addresses describing the project planning of
a study to characterize large buildings, and presented one example building for the purpose of
determining the optimum HVAC conditions to reduce indoor radon within the envelope of
acceptable operation as regards to energy, comfort, and IAQ impacts on the structure.

References

1)	Pugh, T.D.; Interim Radon-Resistant Construction Guidelines for Use in Florida - 1989,
EPA-660/8-90-062 (NTIS PB90-265349), pp. 1-12, August 1990.

2)	ASHRAE Standard 62-1989. Ventilation for Acceptab le Indoor A ir Quality. The American
Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. Atlanta, GA, 1989.

3)	Leovic, K.W., Craig, A. B., Saum, D.W.; Radon Mitigation in Schools - Part 1. American
Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Journal, Vol.
32, No. 1, pp. 40-45, January 1990.

4)	Leovic, K.W.; Summary of EPA's Radon Reduction Research in Schools During 1989-90,
EPA-600/8-90-072 (NTIS PB91-102038), pp. 3-77, October 1990.

5)	ASHRAE 1989 Handbook. Fundamentals, The American Society of Heating, Refrigerating
and Air-Conditioning Engineers, Inc. Atlanta, GA, 1989.

6)	Parker, J.D.; HVAC Systems in the Current Stock of U. S, K-12 Schools, EPA-600/R-92-125
(NTIS PB92-218338), pp. 2-44, July 1992.

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PB98-1

111111

1. REPORT NO. 2.

EPA fiOO/A-QR/ORl

lilt !Bill 11 111

.4 V18 4

4. TITLE AND SUBTITLE

Indoor Air Quality Large Building Characterization
Project Planning

S. REPORT DATE

6. PERFORMING ORGANIZATION CODE

7. authoris) m.Menetrez andR.Kulp (EPA); and B. Pyle*
A. Williamson, and S. McDonough (SoRI)

8. PERFORMING ORGANIZATION REPORT NO.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

Southern Research Institute
P.O. Box 55305
Birmingham, -Alabama 35255

10. PROGRAM ELEMENT NO.

11. CONTRACT/GRANT NO.

68-D2-0062

12. SPONSORING AGENCY NAME AND ADDRESS

EPA, Office of Research and Development
Air Pollution Prevention and Control Division
Research Triangle Park, NC 27711

13. TYPE OF REPORT AND PERIOD COVERED

Published paper; 9/92-5/97

14. SPONSORING AGENCY CODE

EPA/600/13

15, supplementary NOTES APPCD project 0fficer is Marc Y, Menetrez, Mail Drop 54, 919/
541-7981. Engineering Solutions to IAQ Problems, RTP, NC, 7/21-23/97.

16< ABSTRACT pr*t i * ¦ ¦* < » ¦ . >

The paper discusses planning for a project involving the characterisation
of indoor air quality (IAQ) in a large building. Three buildings were characterized in
this project by examining radon concentrations and IAQ levels as affected by building
ventilation dynamics. IAQ data collection stations (IAQDS) for monitoring and data
logging, remote switches (pressure and sail switches), and a weather station were in-
stalled, Measurements of indoor radon, carbon dioxide (C02), particle concentra-
tions, temperature, humidity, pressure differentials, ambient and sub-slab radon
concentrations, and outdoor air (OA) intake flow rates were collected. The OA intake
was adjusted when possible, and fan cycles were controlled while tracer gas measure-
ments were taken in all zones and IAQDS data were collected. Ventilation, infiltra-
tion, mixing rates, radon entry, pressure/temperature convective driving forces,
C02 generation/decay rates, and IAQ levels were established for baseline and OA-
adjusted conditions. These dynamic interacting processes characterize the behavior
of these and similar large buildings. Techniques to vary OA and pressure differential
and to track IAQ were incorporated into the experimental plan and are discussed with
the project rationale.

17. KEY WORDS AND DOCUMENT ANALYSIS

a. DESCRIPTORS

b. IDENTIFIERS/OPEN ENDED TERMS

c. cosati Field/Group

Pollution Carbon Dioxide

Buildings Particles

Radon

Ventilation

Dynamics

Measurement

Pollution Control
Stationary Sources
Indoor Air Quality (IAQ)
Particulate

13 B
13 M
07B
13 A
20K

18. DISTRIBUTION STATEMENT

Release to Public

19. SECURITY CLASS (This Report)

Unclassified

21. NO. OF PAGES

5

20. SECURITY CLASS (This page)

Unclassified

22. PRICE

EPA Form 2220-1 (9-73)

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