Airflow into, out of, and within buildings affects building durability, occupant comfort, indoor air quality, and, importantly, energy consumption. Modelling results estimate that approximately 16% of heating and cooling for office buildings in the United States, and 24% of multi-unit residential building energy consumption, is attributable to infiltration (VanBronkhorst, Persily & Emmerich, 1995; CMHC, 2007).

Despite the significant impact of air leakage on building energy consumption, relevant building codes and standards provide limited guidance with respect to the construction of these systems, and also with respect to accurate modelling for energy calculations. The two energy standards referenced by the National Building Code of Canada (NBC) 2010, National Energy Code of Canada for Buildings (NECB) 2011 and ASHRAE-90.1 2010, both indicate that a continuous air barrier is required, but do not provide a quantified performance requirement, nor do they require verification of performance by testing. This study works to provide the necessary technical background to support potential implementation of airtightness performance requirements in the NECB and also to provide comment on the air leakage rate currently prescribed in Part 8 of the NECB for energy modelling.

Prepared by RDH for the National Research Council of Canada.

RDH Building Science