National WAP Evaluation: Radon Paul Francisco University of Illinois at Urbana-Champaign
IAQ Study One of many studies in the National WAP Evaluation Conducted in 2010-2011 Several contaminants assessed Temperature/Relative Humidity Mold/Moisture Carbon Monoxide Formaldehyde (25% of homes) RADON
Sampled Geographic Areas ~ 500 homes from 77 agencies in 35 States; high radon areas oversampled
Sampling Design Groups of 8 homes within an agency’s territory 5 treatment 3 control All homes tested about 3-6 weeks before and after weatherization of treatment homes Samplers deployed within a 3-day period 5-7 day tests
Radon Sampling – Instrumentation Used diffusion barrier charcoal canisters provided by EPA – Las Vegas lab Analysis done by EPA Las Vegas lab 1 of 16 canisters received duplicate 1 of 16 canisters received blank
Radon Sampling – Location Every first floor Every basement and crawl space No samplers below manufactured homes Followed standard placement rules
Analysis “Difference-of-differences” Pre-post change for treatment Pre-post change for control Difference of these changes Evaluated many explanatory factors, e.g. Outdoor temperature Air change rate (blower door and modeled natural airflow) Precipitation Ventilation Etc.
RESULTS
Radon Results (Arithmetic Means) N Change (Post – Pre), pCi/L Treatment Group Control Group Net (Treatment – Control) Overall all cases 447 +0.14 ±0.13 -0.29 ±0.18 +0.44 preWX radon <10 pCi/L 438 +0.11 ±0.12 -0.16 +0.28 ±0.14 EPA radon zone High (Zone 1) 234 +0.29 -0.50 ±0.33 +0.79 ±0.31 Moderate (Zone 2) 170 +0.10 ±0.26 -0.11 ±0.25 +0.23 ±0.28 Low (Zone 3) 43 -0.10 +0.01 ±0.20
Significant factors All cases included: Estimated change in natural infiltration rate Change in outdoor temperature Change in fraction of days with rain Addition of mechanical ventilation Replacement of heating system with sealed combustion Remove cases with changes greater than 3x (n=8):
FOLLOW-UP NATIONAL WAP STUDY: ADDED EXHAUST VENTILATION per ASHRAE 62.2
Study Design Selected 18 homes with levels between 4 and 8 pCi/l Add exhaust ventilation per ASHRAE 62.2-2010 Controls performed “on-off” operation of fan in 1-week increments Look at changes from week-to-week
Sample Home Exhibiting Reductions in Radon When Ventilation is On
Overall results
HISTORY CONTEXT
Timeline SWS specify expected outcomes from various retrofit actions. 2010 2011 2012 2013 IAQ Study in Heating Climates Follow-up on Exhaust Ventilation IAQ Results Made Available to WAP Standard Work Specifications (SWS) Development Initiated WPN 11-6 Implemented ASHRAE 62.2 Enacted by WAP SWS Complete and Workforce Guidelines Published WAP Implements Quality Work Plan EPA HIEP Available to Public SWS specify expected outcomes from various retrofit actions. Includes ventilation / health & safety WPN 11-6: Health & Safety guidance for WAP. Includes precautions regarding radon EPA recognizes “do no harm” principle
QUESTIONS? Paul Francisco pwf@illinois.edu