What does the blower door test measure?

The blower door test specifically measures air infiltration at an elevated test pressure. This testing procedure involves using a specialized fan mounted in the door frame of a building to create a pressure difference between the inside of the building and the outside environment. By doing this, it allows for the quantification of how much air leaks into and out of the building through cracks and other openings.

This measurement is crucial because excessive air infiltration can lead to increased heating and cooling costs, reduced comfort, and potential moisture issues within the building envelope. During the test, the fan maintains a constant pressure level, typically around 50 pascals, and the volume of air that needs to be moved to maintain that pressure is then recorded.

The other options, such as temperature differential, volume of air movement, and ventilation effectiveness, are related concepts but do not specifically define what the blower door test measures. Temperature differential might relate to overall energy efficiency but isn't a direct measurement from this test. Volume of air movement can refer to airflow rates under different conditions but isn't the primary focus of the blower door test. Ventilation effectiveness is more about how well the designed ventilation system is operating rather than measuring leaks in the building envelope.