Measuring Building Airtightness

The easiest way to measure building airtightness is with a diagnostic tool called a Blower Door. The Blower Door consists of a powerful, calibrated fan that is temporarily sealed into an exterior doorway. The fan blows air out of the house to create a slight pressure difference between inside and outside. This pressure difference forces air through all holes and penetrations in the building envelope. Blower Door tests are typically performed at a pressure difference of 50 Pa (0.2 inches of water column).