Radon Mitigation using Ventilation Assessment Tool

Group 9William Allred

Joshua ChastainDaniel DiazRyan Nester

04/07/09 Group 9 – Department of Health

Introduction

Naturally occurring radioactive gas

Colorless, tasteless, odorless

Found all over the World

Kills over 20,000 people each year (EPA)

04/07/09 Group 9 – Department of Health

Introduction – What is the Problem?

High rise residential buildings also have Radon problems

Limited on mitigation techniques

Ventilation applicable to dilute Radon

Need methods to estimate airflow for dilution

04/07/09 Group 9 – Department of Health

Project Scope

Develop a spreadsheet tool to evaluate the parameters necessary for successful mitigation of a single unit within a multi-family structure using ventilation techniques.

Current radon level Target radon level Characteristics of unit Volume of unit

Natural leakage to outside Ventilation rate required to reach target

04/07/09 Group 9 – Department of HealthGroup 9 – Department of HealthGroup 9 – Department of Health

The Design Concept

City State Weather FactorPensacola FL 0.76Apalachicola FL 0.63Daytona FL 0.73Jacksonville FL 0.77Miami FL 0.69Orlando FL 0.73Tallahassee FL 0.63Tampa FL 0.75

Major Cities

04/07/09 Group 9 – Department of Health

Design Concept – How it Works

Equations / Theories

Where: ELA = Equivalent Leakage Area As = Floor Area W = Weather Factor V = Volume of unit ACH = Estimated Annual Infiltration Rate Co = Initial Concentration of Radon G = Generation rate of Radon

ACH 1000ELA

As W G Co V ACH

04/07/09 Group 9 – Department of HealthGroup 9 – Department of Health

Contaminant Equations

- Mass of Radon in zone i after a given time

- Initial mass of Radon in zone i

- Mass flow rate of Radon into zone i

- Generation rate of Radon in zone i

- Mass flow rate of Radon out of zone i

Dilution Equation

04/07/09 Group 9 – Department of Health

Spreadsheet Demonstration

04/07/09 Group 9 – Department of Health

On-site Testing – Miami, FL

Blower Door Fan Tests

Leakages found from Pressurization and Depressurization tests

Smoke Sticks for airflow direction

Unexpected leakage sources

04/07/09 Group 9 – Department of Health

Spreadsheet Results – Loft 2

ELA 5.16%ACH 7.65%CFM 4.91%

Percent Difference

Floor Area (ft2) 654Ceiling Height (ft) 10

Volume of Unit (ft3) 6540Weather factor 0.69

Initial Rn Concentration (pCi/L) 2.4Target Rn Concentration (pCi/L) 1.3

Time Step (s) 60Density of Air (lb/ft3) 0.075

Ambient Rn Concentration (pCi/L) 0.400Correction Factor 1

Rn Generation Rate (pCi/s) 19.388Equivalent Leakage Area (in2) 21.434

Natural Ventilation (cfm) 17.117Initial Air Changes per Hour 0.157Total Required Flow (cfm) 45.636

Additional Required Flow (cfm) 28.519New Air Changes per Hour 0.419

Inputs

Default Constants

Outputs

04/07/09 Group 9 – Department of Health

Spreadsheet Results – Park Place by the Bay

ELA 3.80%ACH 2.31%CFM 3.83%

Percent Difference

Floor Area (ft2) 875Ceiling Height (ft) 8

Volume of Unit (ft3) 7000Weather factor 0.69

Initial Rn Concentration (pCi/L) 2.4Target Rn Concentration (pCi/L) 1.3

Time Step (s) 60Density of Air (lb/ft3) 0.075

Ambient Rn Concentration (pCi/L) 0.400Correction Factor 1

Rn Generation Rate (pCi/s) 16.776Equivalent Leakage Area (in2) 23.184

Natural Ventilation (cfm) 14.811Initial Air Changes per Hour 0.127Total Required Flow (cfm) 39.521

Additional Required Flow (cfm) 24.709New Air Changes per Hour 0.339

Inputs

Default Constants

Outputs

04/07/09 Group 9 – Department of Health

Spreadsheet Results – Key Biscayne

Floor Area (ft2) 1251

Ceiling Height (ft) 8Volume of Unit (ft3) 10008

Weather factor 0.69Initial Rn Concentration (pCi/L) 1.2Target Rn Concentration (pCi/L) 1.3

Time Step (s) 60Density of Air (lb/ft3) 0.075

Ambient Rn Concentration (pCi/L) 0.400Correction Factor 1

Rn Generation Rate (pCi/s) 24.705Equivalent Leakage Area (in2) 68.283

Natural Ventilation (cfm) 43.623Initial Air Changes per Hour 0.262Total Required Flow (cfm) 58.162

Additional Required Flow (cfm) 14.538New Air Changes per Hour 0.349

Inputs

Default Constants

Outputs

ELA 11.44%ACH 12.67%CFM 11.52%

Percent Difference

04/07/09 Group 9 – Department of Health

Cost Analysis

Standard 136-1993 $25.00

Rental Car $171.44

Hotel Rooms $356.12

Gas $107.50

Parking $10.30

Total $670.36

04/07/09 Group 9 – Department of Health

Conclusion

Accuracy depends on construction methods Other sources of error include unknown

leakage values, data libraries, and blower door extrapolations

Spreadsheet gives a reasonable approximation of airflow required for mitigation

Serves as a foundation for future development in high-rise residential Radon mitigation

04/07/09 Group 9 – Department of Health

Future Improvements

Test wide variety of units Test after mitigation Implement correction factor More weather data Consider indoor leakages More libraries

04/07/09 Group 9 – Department of Health

Acknowledgment

Special thanks to Florida Department of Health

Clark Eldredge Jorge Laguna

FAMU Institute of Building Sciences Director Thomas Pugh

Faculty Advisor Juan Ordoñez

Homeowners Garmin Ranck Daniel Montesinos Nicholas Landera

04/07/09 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

Minneapolis Blower Door Operations ManualThe Energy Conservatory

Walton, George. “CONTAM 2.4 User Guide and Program Documentation.” http://www.bfrl.nist.gov/IAQanalysis/docs/NISTIR_7251c.pdf