In the outdoor airflow formula, what is the unit of the resulting airflow?

• A. Cubic feet per minute (CFM)
• B. Cubic meters per hour (m3/h)
• C. Liters per second (L/s)
• D. Gallons per minute (GPM)

Answer: (B)

Airflow rate is a measure of how much air volume passes a point in a given amount of time. When you use the outdoor-air calculation in SI units, you typically multiply a room's volume (in cubic meters) by a rate per hour, so the result is in cubic meters per hour. That makes the unit consistent with the time basis of the calculation, and it’s a common, practical unit for ventilation design.

The other units either come from different measurement systems or represent per-second rates, which isn’t the standard form for this particular formula. CFM is feet-based and used in US customary units, L/s is per second, and GPM is gallons per minute (often used for liquids). In this context, the SI-based formula yields cubic meters per hour.