Window Air Infiltration Ratings
Our guide to window air infiltration ratings can help you better understand this important term for your home's overall energy efficiency. Air infiltration is often simply abbreviated AI by contractors and industry experts. (Confusing now with artificial intelligence, but that's the window industry for you.) AI is an important term (along with U-factor, SHGC and VT) to help determine a window unit's level of energy efficiency.
Window Air Infiltration Range
Typically, window units are measured and tested for air infiltration by simulating 25 mph winds, which is the equivalent pressure load of 1.56 psf or pounds for square foot. Specifically, AI refers to the amount of air that is able to pass through window unit and will fall somewhere between .30 and 0. Anything from .30 to .15 is pretty horrible, .15 to .10 is decent, and anything below .10 is good.
Excellent window air infiltration ratings range from 0.06 and lower. Not surprisingly, well made vinyl and fiberglass windows will typically have the best AI numbers on the market. So, the top or premium models from Soft-Lite, HiMark and Sunrise Windows should have .05 or lower. Also, upgrades to the glass package or sill reinforcements will help a product lower the AI number.
Sample AI Ratings
The following are sample window air infiltration ratings from popular window manufacturers. Also, check out our Guide To Energy Efficient Windows article to see additional factors that go into making cost effective windows. Finally, quality manufacturers should list their window series AI numbers on their websites. Lastly, the National Fenestration Rating Council is an excellent source for window and door performance data on thousands of products.
Window World 3000 Series » .18
Silverline 9500 Series » .14
Great Lakes Uniframe » .09
Okna EnviroStar Series » .01
