What is the term for the air that is intentionally removed from a building?

The term that refers to the air that is intentionally removed from a building is exfiltration. Exfiltration describes the process where air, often stale or contaminated, is intentionally vented or drawn out from an indoor environment. This is typically done to improve indoor air quality or manage ventilation effectively, ensuring that fresh air is circulated while removing unwanted air that may carry pollutants or humidity.

In contrast, infiltration involves unintentional air leakage into a building from the outside, often due to differences in pressure. Diffusion refers to the natural movement of air molecules from areas of high concentration to low concentration and is not specific to mechanical processes in buildings. Recirculation pertains to the process where air is cycled through a system without being replaced with new outdoor air, which does not involve the direct removal of air. This makes exfiltration the appropriate term for the intentional removal of air from buildings.