Radon Mitigation using Ventilation Assessment Tool

Group 9William Allred

Joshua ChastainDaniel DiazRyan Nester

12/02/08 Group 9 – Department of Health

Introduction

Natural decay of uranium in soil

Responsible for over 20,000 deaths each year

EPA recommends to test for high levels

12/02/08 Group 9 – Department of Health

Introduction

Radon found in high-rise buildings

Florida standards on amount of air ventilation

Radon mitigation ventilation assessment tool for Florida Department of Health

12/02/08 Group 9 – Department of Health

The Design Concept

Assessment tool: Spreadsheet Input: Radon level and leakage

characteristics of the structure Output: Amount of air ventilation

needed to reduce the radon to a safe level

Assist in the diagnosis of the appropriate ventilation system required

12/02/08 Group 9 – Department of Health

The Design Concept

Microsoft Excel Data Validation & Formulas

12/02/08 Group 9 – Department of Health

Dillution Equation

DtV

Q

lnCi

Cf

V Volume of Room

Q Flow Rate from Ventilation Equation

DtTime for Dillution

CiInitial Concentration

CfFinal Concnetration

Initial Calculations

Ventilation Equation

Q C Pn

C Cwindows Cdoors Cwalls

n .5 Assuming A Fully Turbulent Flow

P Pressure Difference from Inside to Outside

Q Desired Volumetric Flow Rate

12/02/08 Group 9 – Department of Health

Contaminant Equations

ρi is the density in zone iVi is the Volume of the zone iCi is the concentration of the contaminant in zone I

is the contaminant mass flow rate from zone j to i (in) is the filter efficiency (not applicable)

(mass of contaminant a in c.v. i at time t+Δt ) =(mass contaminant a in c.v. i at time t) +

Δt × (rate gain of contaminant a – rate loss of contaminant a)

General Form of Equation

12/02/08 Group 9 – Department of Health

Contaminant Equations

ρj is the density of the air in zone jCj is the concentration of the contaminant in zone jGi is the generation rate of the contaminant in zone i

is the generation of a species from chemical reaction (not applicable) is the contaminant mass flow rate from i to j (out)

is the removal coefficient (not applicable)

12/02/08 Group 9 – Department of Health

CONTAM – Model 1

Supply Duct40 cfm

Return Duct35 cfm

Contaminant SourcePressure Driven

Gen. Rate 100 pCi/s

Double HungWindow

0.424 cfm

WindowFrames0.288 cfm

Door Frames0.051 cfm

Double DoorWeather-stripped

3.9 cfmZone DefinitionArea 100 m2

Volume 300 m3

Initial Concentration20 pCi/L

Pressure Difference

Air Flow

Constant PressureDifference 0.666 Pa

Ambient Zone20 deg C

1 atm

Air Handling Unit

12/02/08 Group 9 – Department of Health

CONTAM – Model 1

12/02/08 Group 9 – Department of Health

CONTAM – Model 2

Apt 1 Zone DefinitionArea: 1000 ft2

Volume: 8000 ft3

Apt 2 Zone DefinitionArea: 1000 ft2

Volume: 8000 ft3

Pressure Difference

Air Flow

Pressure Difference

Air Flow

Pressure Difference

Air FlowDouble Hung WindowNot Weather-stripped

0.968 cfm Contaminant SourcePressure Driven

20 pCi/sAir Handling

Unit

Air HandlingUnit

Supply Duct50 cfm

Supply Duct50 cfm

Return Duct40 cfm

Return Duct40 cfm

Double Hung WindowNot Weather-stripped

0.968 cfm

Contaminant SourcePressure Driven

20 pCi/s

Double DoorNot Weather-stripped

8.06 cfm

Single DoorNot Weather-stripped

4.03 cfm

Single DoorNot Weather-stripped

4.03 cfmHallway

Apt 1

Apt 2

12/02/08 Group 9 – Department of Health

CONTAM – Model 2

12/02/08 Group 9 – Department of Health

Summary

Attempts to gain access to conduct on-site testing have still been denied

Currently seeking other suitable locations CONTAM modeling assisted in understanding

contaminant behavior and leakage rates Modeling also assisted in understanding dominating

parameters Determined applicable equations for spreadsheet Results from spreadsheet will be used to assist in the

diagnosis of the mitigation system appropriate for the particular unit.

12/02/08 Group 9 – Department of Health

Future Plans

Continue modeling with CONTAM Continue modifying and formulating

spreadsheet Use results from spreadsheet to determine if

efficiency requirements are met Continue attempts to conduct on-site testing Potential cost analysis, none thus far

12/02/08 Group 9 – Department of Health

References

Design of Fluid Thermal SystemsWilliam S. Janna

NIST Multizone Modeling Website (CONTAM)http://www.bfrl.nist.gov/IAQanalysis/index.htm

Walton, George. “CONTAM 2.4 User Guide and Program Documentation.” http://www.bfrl.nist.gov/IAQanalysis/docs/

NISTIR_7251c.pdf

12/02/08 Group 9 – Department of Health

Acknowledgment

Special thanks to Florida Department of Health

Clark Eldredge Jorge Laguna

FAMU Director of Building Sciences Thomas Pugh

Faculty Advisor Juan Ordoñez