Fan Size/Air Changes Per Hour

Have you ever been in a stuffy room and felt really uncomfortable? Exhaust fans provide the appropriate amount of air changes to ensure the comfort, and at times, the safety of a room’s inhabitants.

Most commercial and residential spaces require 6-8 changes per hour. Designated smoking areas and restrooms often require 12 air changes per hour. For battery rooms where hydrogen may be present, 12 air changes are required according to the International Standard: 1332 Battery Room.

Choose to solve for either fan displacement (CFM) or air changes per hour using this tool. If you are solving for fan displacement, a recommended minimum filter area is also provided.

Solving for

Results
Room Volume (ft^3)
Air Change (per hour)
Minimum Filter Surface Area (sq. ft.)
FILTER IS SIZED TO ENSURE FLOW RATE ACROSS THE FILTER IS NO MORE THAN 200 CFM PER SQUARE FOOT OF FILTER AREA