Attic Exhaust Fan Sizing

Proper attic ventilation consists of a balance between air intake at your eaves soffits or fascias and air exhaust at or near your roof ridge.

Attic exhaust fan sizing.

Our installer friendly energy star ventilation solutions help you design beyond code without compromising interior aesthetics. With an attic fan you can cool the attic to the same temperature as it is outside greatly reducing the house from heating as quickly. During the summer an attic can be 40 to 50 hotter than the outside temperature which in turn heats up the house very quickly. To determine what size power vent fan s you need for your attic you first need to know the size of your attic in square feet.

Powered exhaust vents feature an electric or solar powered fan to create an effect similar to that of a turbine view example on amazon. Quietcool attic fans work almost everywhere almost anytime. Those vents would give you 9 square feet of vent area which meets the venting need. Attic fan size cfm 0 7 x sq ft area of the attic formula 1 the size of an attic fan is calculated in terms of cfm.

The result is a cooler attic space with plenty of air exchange. Attic vent fans are designed either to fit over a hole cut in your roof or to mount to the inside of a gable vent. The formula above gives an approximate value of the cfm needed for an attic fan. That translates to one attic vent 3 feet by 3 feet or two attic vents each 1 feet by 1 feet.

A standard powered. Federal housing authority recommends a minimum of at least 1 square foot of attic ventilation evenly split between intake and exhaust for every 300 square feet of attic floor space. Attic fans perform this ventilation by pushing hot air out into the environment while also pulling fresh cool air into the attic. Cfm cubic feet per minute is a measure of the amount of air the fan moves in a minute.