Most manufacturers recommend sizing an attic fan at 2 to 3 CFM (cubic feet of air per minute) per square foot of living space.
How do I choose an attic fan?
Attic fans are categorized by CFM (cubic foot per minute), a measure of how much air can be moved per foot, per minute. The size of your attic will determine the CFM required for proper air exhaust. To determine your attic size, multiply the width by the length of the attic floor and multiply the two.Jun 30, 2018
How much attic space do I need for a whole house fan?
Installing and Using a Whole House Fan You'll need 2 to 4 times the normal area of attic vents, or about one square foot of net free area for every 750 cubic feet per minute of fan capacity. The net free area of a vent takes into account the resistance offered by its louvers and insect screens.