Technical note: Airtightness of older-generation energy-efficient houses in Saskatoon

Abstract

The aim of this study was to collect long-term in-service energy efficiency data from older-generation energy-efficient houses built in Canada in the past decades. Six houses with highly insulated building envelope assemblies built (or retrofitted) from 1979 to 1992 in the Saskatoon area were inspected during March 2012. As typical energy-efficient houses for this area, all were built with double 2 × 4 stud walls with the gap between walls ranging from 4 to about 12 in and with nominal wall insulation varying from RSI * 6.34 (R* 36) to RSI 10.57 (R 60). The roof insulation ranged from RSI 10.57 (R 60) to RSI 14.09 (R 80). The below-grade walls were also well insulated, and these were mainly permanent wood foundations. Polyethylene was used as a combined air barrier and vapour barrier for the building envelopes. The major results included the following: the airtightness values based on blower-door tests ranged from 0.78 to 2.55 air changes per hour at 50 Pa measured under normal operation conditions, with four houses below 1.50 air changes per hour at 50 Pa after 20–30 years. The No. 2 house had an original airtightness of 0.29 air changes per hour at 50 Pa and 0.22 air changes per hour when the windows were sealed with masking tape after the energy retrofit in 1982. The airtightness was measured to be 1.23 air changes per hour at 50 Pa in this survey after the owner installed new windows without properly sealing the interior air barrier. The No. 4 house had an airtightness of 0.78 air changes per hour, while the original airtightness test was 0.47 air changes per hour when the house was built over 20 years ago. All the six houses had EnerGuide Rating System of over 80, and one had a remarkable EnerGuide Rating System of 87. Windows and ventilation air were identified to be the largest heat loss components, followed by basement and exterior walls.