With the blower door test, the air tightness of a building is measured. The leaks in the building are determined by leakage detection and can be corrected by the client later. The blower door test was originally from the United States and has been used in Europe since the early 80s. It is the standard method for testing the airtightness of a building. The blower door test is no longer performed only in the new dwellings, but also includes large buildings such as warehouses, office buildings, cold stores, gyms, or consumer markets to the standard of a construction project.

The objectiv is to save energy long-term, prevent structural damage and of course create an optimum living comfort. Therefore it is necessary to provide a relatively air-tight building envelope. In Germany the DIN 4108, part 7 requireds new buildings to “install an impermeable layer for air over the entire envelope”. Thermal performance of buildings – Determination of air permeability of buildings – Fan pressurization method (ISO 9972:1996, modified); German version EN 13829