In 1993 the National Fenestrating Rating Council began rating window performance to allow for comparison and evaluation of windows. The lower the u-factor the better the overall insulating value of the window. A cooler, well-ventilated attic will reduce cooling costs. Some are wind powered, others are electronic and feature either manual or automatic thermostat controls. Turbine attic fans are mounted on top of the roofs and are powered by the wind.
Installation requires cutting a hole in the roof.
Gable power attic fans are mounted to an attic gable. These types of fans are typically activated by a thermostatic control. Attic roof ventilators are powered by electricity and are thermostatically controlled. Installation of these vents require cutting a hole in the roof to allow for mounting. Determining the proper type of attic fan is a function of the availability of electricity and the existence, location and size of vent gables.