A pulse pressurization technique to measure the airtightness of the building envelope is developed. The governing equations are introduced and the procedure for deriving airtightness parameters from the pressure decay curve is shown. Pulse pressurization is supplied using a high-pressure air tank. The pressure decay after pulse pressurization is measured provides the air leakage equation for a test house.
The National Building Code of Canada (NBC) requires that an "effective" air barrier system be incorporated within the building envelope. Although the NBC addresses the performance characteristics to be considered to demonstrate that an effective air barrier system has been achieved, the NBC does not prescribe any specific test protocols with acceptance criteria to verify compliance of proprietary air barrier systems.
A building's envelope is the product of the choice of framing materials and quality of craftsmanship. Exposed to weather, it may 1101 provide the same airtight conditions in which its insulation material had been tested. Air permeable insulation offers little resistance to pressure driven, or convective, heat loss. Air impermeable insulators can additionally reduce convective, as well as conductive, heat loss by being sprayed into and sealing up sources of infiltration normally addressed by caulks and sealants.