is a machine used to measure the airtightness of buildings. It can also be used to measure airflow between building zones, to test ductwork airtightness and to help physically locate air leakage sites in the building envelope.
There are three primary components to a BlowerDoor:
(1) a calibrated, variable-speed fan, capable of inducing a range of airflows sufficient to pressurize and depressurize a variety of building sizes,
(2) a pressure measurement instrument, called a manometer, to simultaneously measure the pressure differential induced across the face of the fan and across the building envelope, as a result of fan airflow, and
(3) a mounting system, used to mount the fan in a building opening, such as a door or a window.
A variety of BlowerDoor airtightness metrics can be produced using the combination of building-to-outside pressure and fan airflow measurements. These metrics differ in their measurement methods, calculation and uses.
BlowerDoor tests are used by building researchers, weatherization crews, home performance contractors and others in efforts to assess
- the construction quality of the building envelope,
- locate air leakage pathways usually with a smoke machine,
- assess how much ventilation is supplied by the air leakage,
- assess the energy losses resulting from that air leakage,
- determine if the building is too tight or too loose,
- determine if the building needs mechanical ventilation and to assess compliance with building performance standards.