Airtightness of Swedish residences.

Pressurization, or depressurization, of buildings is a tool to assess the airtightness of building envelopes. A common working pressure is 50 Pa, and the airtightness is expressed in terms of the number of air changes per hour at 50 Pa. To compare buildings of different size a more efficient measure is to define a nondimensional leakage area. We suggest a method to define and calculate the relative leakage area from pressurization data. The method corrects for calibration errors and the effects of aeromotive and buoyancy forces. It is demonstrated that the pressurization can be carried out at pressures much lower than 50 Pa, it is sufficient to apply pressures In the range from 10 to 20 Pa. Phe lekage areas predicted agree well with those predicted from tracer gas measurements of the air change rate. The method has been used to calculate relative leakage areas of 300 Swedish dwellings. A comparison is made of the airtightness of residences of different age.