The rate at which outdoor air replaces indoor air within a given space or room.

The rate at which outdoor air replaces indoor air within a given space or room.

• A. Ventilation Rate
• B. Outdoor Air Change Rate
• C. Air Exchange Rate
• D. Infiltration Rate

Answer: (C)

The main idea here is the air exchange rate, which measures how quickly outdoor air replaces the air inside a space. It’s typically expressed as air changes per hour (ACH) and is calculated by dividing the outdoor air flow rate by the room’s volume (Q/V). This concept captures the actual rate at which the room’s air is refreshed by outdoor air, not just how much outdoor air is supplied (that would be the ventilation rate) or how much air leaks in uncontrollably (infiltration). Infiltration is outside-controlled air entering through leaks, which isn’t the deliberate replacement the term air exchange rate describes. So, the best term for the rate at which outdoor air replaces indoor air is the air exchange rate.

The main idea here is the air exchange rate, which measures how quickly outdoor air replaces the air inside a space. It’s typically expressed as air changes per hour (ACH) and is calculated by dividing the outdoor air flow rate by the room’s volume (Q/V). This concept captures the actual rate at which the room’s air is refreshed by outdoor air, not just how much outdoor air is supplied (that would be the ventilation rate) or how much air leaks in uncontrollably (infiltration). Infiltration is outside-controlled air entering through leaks, which isn’t the deliberate replacement the term air exchange rate describes. So, the best term for the rate at which outdoor air replaces indoor air is the air exchange rate.