In HVAC terms, what does 'supply' air refer to?

Supply air refers specifically to the conditioned air that is delivered to a space within a building to maintain desired temperature and humidity levels. In HVAC systems, this air is usually treated or conditioned (heated, cooled, dehumidified, or humidified) before being distributed throughout different areas via ducts and vents. The purpose of supply air is to provide thermal comfort to the occupants and ensure efficient ventilation within the environment.

The other options do not align with the definition of supply air. Exhausted air refers to air being removed from the space, outside air pertains to unconditioned air that may be brought in for ventilation but is not specifically the air being supplied to conditioned spaces, and filtered air describes air that has been cleaned of particulates but does not indicate that it has been conditioned or is being delivered to a space. Thus, the choice representing supply air accurately captures its role in HVAC systems.