Suite-level air tightness and compartmentalization in multi-unit residential buildings: How do we achieve our intended goals?

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Control of inter-zonal air flow in multi-unit residential buildings (MURBs) is currently regulated by ASHRAE 62.2: Ventilation and Acceptable Indoor Air Quality in Residential Buildings, which specifies a maximum whole-suite air leakage rate, normalized by surface area. Despite the fact that the compartmentalization requirement has been in effect since 2013, few studies have explicitly examined the feasibility of the requirement in concrete MURBs. This paper presents results from recent inter-zonal air leakage testing completed in 12 newly constructed MURBs located in southern Ontario, Canada (N = 175). Normalized air leakage under an induced pressure difference of 50Pa (q50) ranged between 0.16 and 2.51 L/s/m2 (0.03 and 0.49cfm/ft2) of total suite surface area with a mean equal to 0.49 L/s/m2 (0.10cfm/ft2), well below ASHRAE 62.2's limit of 1.52 L/s/m2 (0.30 cfm/ft2). However, guarded blower door testing in concrete MURBs revealed large disparities between the various suite boundary types, suggesting that the whole-suite air leakage rate may not provide sufficient information about partition-based air tightness to identify potential performance issues. While guarded blower door testing provides more useful air tightness data, it is very labour-intensive and time-consuming. Completing the test prior to general occupancy improved testing efficiency slightly; however, new logistical concerns arose when testing on an active construction site. Lessons learned and recommendations for future testing efforts are discussed.