Air Leakage

Uncontrolled and/or unintended airflow through a building enclosure or between units of occupancy. Leakage from indoors to outdoors is known as exfiltration and leakage from outdoors to indoors is known as infiltration. Air leakage can cause indoor air quality problems, condensation, excess energy use, comfort complaints, and smoke transport.

Related resource: Air Leaks—How They Waste Energy and Rot Houses, RR-0303: Ventilation and Air Leakage