How are ventilation rates generally expressed?

Ventilation rates are most commonly expressed in cubic feet per minute (CFM). This measurement indicates the amount of air that is being moved in a space per minute, which is crucial for assessing how effectively a ventilation system is providing fresh air and removing contaminants. CFM is a standard unit in the HVAC industry, allowing for easy comparison and calculation of air exchange rates in various environments such as residential, commercial, and industrial facilities.

While other units, such as liters per minute or cubic meters per hour, can be used in particular contexts, CFM remains the most utilized metric in North America for ventilation assessment. The measurement in gallons per hour is typically not relevant for air movement, making it unsuitable for expressing ventilation rates. Thus, cubic feet per minute is the preferred expression for evaluating and ensuring adequate air quality in indoor environments.