Air Leakage Testing
Air leakage is defined as the flow of air through gaps and cracks in the building fabric. Uncontrolled air leakage increases the amount of heat loss as warm air is displaced through the envelope by colder air from outside. Air leakage of warm damp air through the building structure can also lead to condensation within the fabric (interstitial condensation), which reduces insulation performance and causes fabric deterioration.
Air leakage is random, often visibly concealed, uncontrollable and costly. It is not to be confused with ventilation. Ventilation is planned for and controlled by the residents of a home. It is necessary to move air for cooling or to expel moist or stale air.
The energy consumed by dwellings accounts for a large proportion of Canberra’s total energy consumption, and the carbon dioxide emissions which contribute to climate change. Much of this energy is accounted for by heating. Insulation standards for roofs, walls, and floors, plus performance standards for windows, have increased in recent years to improve energy efficiency, however, little attention has been paid to air leakage.
The air leakage rate of a building can be determined by means of a pressure test using a ‘blower door’. During a pressure test the major sources of air leakage are easily detectable by touch and sight (sometimes even sound and smell!). Infrared thermography (use of a thermal camera) helps detect the more subtle or concealed leaks.