AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Measuring Penetration Factors of Fine and Ultrafine Particles in Single Family Homes before and after Weatherization Retrofits
HAORAN ZHAO, Brent Stephens, Illinois Institute of Technology
Abstract Number: 218 Working Group: Indoor Aerosols
Abstract Human exposure to particles of outdoor origin is highly dependent on their infiltration into buildings, which also depends on the nature of leakage pathways in the building envelope. Weatherization retrofits, which typically include efforts to air-seal and insulate building envelopes, are increasingly being applied in homes to improve energy efficiency. Because these retrofits will affect the nature of air infiltration pathways, they may also impact the ability of outdoor particles to penetrate indoors. Here we report preliminary results of the application of a recently developed test method to measure envelope penetration factors for ultrafine particles (UFPs) and fine particles (PM2.5) in seven single family houses in and around Chicago before and after their weatherization retrofits were applied. The test procedure involves the following steps to yield estimates of both penetration factors (P) and deposition loss rate coefficients (k) from the same short-term test: (1) introduce outdoor particles through temporary increases in natural ventilation to elevate indoor particle concentrations, (2) measure the subsequent decay of indoor particles during a ~1 hour indoor-only measurement period, and (3) alternately measure indoor and outdoor particle concentrations during normal infiltration conditions over a period of ~3-4 hours. An automatic switching system was used with a TSI NanoScan SMPS and Optical Particle Sizer in all homes. The data were aggregated to provide estimates of P and k for integral measures of UFPs and PM2.5 mass (assuming spherical shape and unit density). Preliminary results demonstrate that mean(±S.D.) estimates of P for UFPs and PM2.5 across 14 tests from 7 houses were 0.70±0.16 and 0.78±0.22, respectively, ranging from 0.46 to 0.88 and 0.64 to 0.94. Results from blower door tests show the weatherization retrofits improved the air tightness of these houses by as little as ~0% to as much as ~46%, and the changes in particle penetration factors ranged from a decrease of ~17% to an increase of ~32%. No obvious correlations were found between the retrofits and the changes in envelope penetration factors. Data continue to be collected, with the goal of measuring in a total of 30 homes.