Abstract View
Does Residential HVAC Filtration Work?
TIANYUAN LI, Masih Alavy, Zhang Yizhi, Jeffrey Siegel, University of Toronto
Abstract Number: 486
Working Group: Indoor Aerosols
Abstract
Residential filtration performance is understudied when compared to filtration in commercial buildings. There are substantial reasons to expect varied performance including predominantly recirculating systems that do not introduce ventilation air, low runtimes, the application of standardized laboratory tests to non-standardized residential systems, and the importance of dynamic source processes, among others. We measured particle concentrations, filter efficiency, and HVAC system-related parameters in 20 homes in Toronto, Canada in this year-long investigation. Over the course of the year, each home received four types of filters (MERV 8 uncharged media; MERV 8, 11, and MERV 14 electret media) for three months each and installed in a random order in each home. Major findings from the investigation include in-situ filtration efficiency varied widely between homes such that the difference between homes for the same filter was generally larger than the difference between filters with different nominal efficiencies. In most homes, the in-situ efficiency was smaller than the lab-tested efficiency largely due to bypass and face velocity differences. On average, the in-situ efficiency of the electret filters was smaller at the end of a three-month deployment than when new and the MERV 8 uncharged media was unchanged. Filter effectiveness showed similar large variations as in-situ efficiency. Filter pressure drop was very similar (and not significantly different) for all four types of filters, likely owing to differences in filter design as well as face velocity and air bypass interactions with filter flow resistance. Continuous hourly 0.5 – 2.5 µm particle number concentrations as measured with a low-cost optical monitor showed no discernable impact of different filters in these homes, likely due to low median runtimes (9.6%) across the investigation. This suggests that filters have to be selected and used well to have a meaningful impact on residential particle concentrations.