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What exactly is air infiltration on windows & why isn’t it reported on the NFRC sticker?

Thanks for this great question. It is easy to get confused about this. Air infiltration is when air flows unintentionally into a house through gaps and cracks in the building envelope. In fact, about 30% of your heat loss may come from gaps and cracks around the windows and doors in your home.

Air infiltration, more commonly referred to as Air Leakage (AL) when it comes to windows and doors, is effected by weather conditions such as wind and temperature. It is a rating that tells you if the window is drafty or not. The Efficient Window Collaborative recommends a rating of 0.30; the lower, the better.

Quite franky, most manufactured windows are designed to meet this standard or better. And that’s why they don’t often include the rating on their NFRC label. It’s optional.

Most manufacturers already participate in the certification program adopted by the American Architectural Manufacturers Association (AAMA), that includes air infiltration, water leakage, structural resistance to pressure (like wind), and even resistance to forced or criminal entry.

ANSI/AAMA 101 window design and performance sticker

A gold  label on the inside jamb of a new or replacement window indicates it passes the AAMA 101 design and performance standard.

80 – 90% of manufacturers easily pass the test and the NFRC suggests that air leakage issues in many windows are the result of improper installation.

You may see mention of leakage and infiltration in marketing literature, but there is not a significant difference among manufactured windows that meet this requirement. Of course every reputable manufacturer should be able to provide these independent test results to you if asked.

If you live in an area prone to weather extremes and wind-driven rain, you may also be interested in reading my post on Design Pressure (DP) ratings, which is included in the ANSI/AAMA test as well.

I hope that helps clear up some of the confusion.

Gerry Rogers About Gerry Rogers

Gerry Rogers is the President of Mr. Rogers Windows

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