Air leakage testing is the measurement of the amount of air movement between the inside and outside of a building, also referred to as measuring the air permeability or airtightness of a building. It is important as excessive air movement can cause additional heat loss and energy consumption, while sufficient fresh air supply is required to provide a healthy internal environment.
Air movement to and from a building occurs in two forms. Through deliberate ventilation, such as the supply of air through a mechanical system or a controlled opening. Or infiltration, which is unintentional air movement through cracks and gaps in the building fabric.