Building Science Attic Fans

Using a fan to blow hot air out of the attic doesn t address the radiant heat flow from the roof to the attic floor.

Building science attic fans.

In westfield mass who helped write the new code language. This american designed fan is designed to reduce attic temperatures and remove destructive moisture thus making your home more comfortable and reducing the load on your hvac system and lowering your electricity bills. Trying to solve the heat gain problem in your attic by using a fan is like lying out at the beach with a fan blowing over you and thinking you re not going to get a sunburn. Unlike a ventilation fan a whole house fan an attic mounted fan that exhausts air from a home at night is designed to cool a house that is to lower the indoor temperature.

Most moisture gets into an attic via air movement not by diffusing through materials we want to keep the living space and the nonhabitable attic space at the same moisture conditions says armin rudd of building science corp. The amount of attic cavity ventilation is specified by numerous ratios of free vent area to insulated ceiling area ranging from 1 150 to 1 600 depending on which building code is consulted the 1 300 ratio being the most common. Using fans to ventilate your attic violates the fundamentals of building science. A powered attic ventilator has a different purpose.

Attic hatches got their name because they were hatches. However as a very old builder 70 years i have known cases where roof mounted attic fans have helped tremendously where the roof is a full hip and the ratio of ridge vents to soffit vents was way out of whack. Even solar attic fans can cause problems. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.

I am trying very hard to simply accept the science from an expert in this case. Attic air conditioner and furnace standard vented combustion gas furnace with a single stage air conditioner located in a south texas attic. The remington solar ventilation attic fan is completely the remington solar ventilation attic fan is completely powered by free solar energy. Much of that heat then conducts downward and finds its way into the house.

Don t let your attic suck power attic ventilators are a bad idea. Sometimes just a piece of plywood covered a hole hidden in a closet. It is designed to lower the temperature of an attic by exhausting air from the attic and replacing attic air.