SLA stands for specific leakage area and is a method of describing how much air enters or escapes from a building (building air infiltration). The lower the number the tighter (less leaky) a building is. Air leakage is important as the air escaping from the building represents energy loss.

Buildings with high SLAs are drafty, uncomfortable, and hard to heat and cool. Conversely, a building with too low of an SLA can experience problems with moisture, and mold and have overall poor indoor air quality.

Use Efficiency First California’s SLA Calculator to calculate CFM50 for any area of conditioned floor space.