Air Barrier Testing Considerations in Your Design
Designers should be thinking about air barrier system testing in the design phase to ensure that the barrier can be installed correctly. Contractors need to follow installation procedures and guidelines to make sure that the system works as intended. However, because air barriers are crucial, whole-building systems, air tightness testing is normally required to prove that the enclosure is sound. It can also be used to find problems with existing buildings.
To test an air barrier system, air leakage is tested and measured either throughout the building or through a representative section of the building.
In residential buildings, the ‘blower door’ test is standard. Using a blower door, which functions like a fan (but a very powerful one), the leakage rate of the building can be measured. In large commercial buildings, multiple blower doors can be used, or the building’s HVAC system.
The point is to measure the airflow and the change in pressure in order to determine how much air equivalent to the house’s volume will leak over a standardized time, at a standardized pressure. The German PassivHaus program requires leakage rates of .6 [email protected], which is very low. Most newly-constructed residential buildings have a leak rate of 4 [email protected] or less. Older buildings can have a rate of 8 to 12 [email protected]! High rates of air exchange lead to energy inefficiency because energy moves through the wall with the air. Residents of older buildings should be encouraged to do an energy audit and perhaps hire someone to fix the leaks.
This testing is very important for new buildings to make sure they are performing up to standard and that there are no problems with the air barrier system. Exterior air barrier systems have the advantage of being testable early in the building process because of their placement relative to the rest of the wall’s layers. You can learn more here.
A fan (more powerful than a box fan) could be used in a pinch to detect air leaks, although it cannot provide measurements.