As residential building codes and energy conservation standards continue to evolve, many are requiring proof of high-quality air sealing. This is done through blower door testing. The building envelope is typically depressurized using a flexible panel with a variable speed fan that’s temporarily installed in the opening of an exterior door. By measuring the speed of this fan, and correlating it to the slight (but measurable) difference in air pressure between the inside and outside of the building, it’s possible to determine the air changes per hour air leakage rate.
A leaky house could test out at 15 to 20 air changes per hour at 50 Pascals (about 0.00725 psi) of air pressure differential. A well-sealed new house could have an air leakage range in the range of 1 to 4 air changes per hour at 50 Pascals pressure difference. A super-tight house, built to current Passive House standards, must not exceed an air leakage rate of 0.7 air changes per hour at the same 50 Pascal pressure difference.