Air leakage is the unplanned, unpredictable and unintentional airflow across the building enclosure. This makes air flow control important for several reasons: to avoid air transported moisture and moisture damage, to reduce energy losses and to ensure occupant comfort and health.
The renewed emphasis on energy conservation in building codes has led to increased awareness of the importance of controlling air leakage of buildings. One of the most effective ways to conserve energy is to provide an airtight building envelope.
With changing energy code requirements, as represented in ASHRAE 90.1 or California’s Title 24, designers, engineers and contractors are facing practical challenges trying to meet these higher standards. One approach that is prescribed is the use of continuous insulation on the outside of building framing.
As building materials and methods become better at sealing air leaks, the question arises, “How tight is too tight?” In terms of energy efficiency, one cannot build too tightly. Reducing air leakage is critical to lowering heating and cooling energy consumption.