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Doors & Windows

Understanding the Window or Door Energy Label

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Have you ever gone window-shopping? I don’t mean when you are at the mall looking for clothes or shoes, I mean real windows!  When It’s time to replace a window or door, the one thing that most people see but don’t give it a second glance, is that label on the glass. What is that label and what does it mean?


The label shows the Energy Performance Ratings of that product and that it has been certified by the National Fenestration Rating Council. The NFRC is a nonprofit organization that empowers consumers who are in the market for energy efficient windows, doors, and skylights. When you see the NFRC label on these products, this is your promise that it is going to perform the way it is advertised.


You are probably asking yourself, what exactly is Fenestration? Well, fenestration refers to an opening in a wall, such as a window, a door or a skylight—it’s based on the Latin word for window—“Fenestra”.


Now back to window labels 101. The two most important numbers on this label are the U-Factor and the Solar Heat Gain Coefficient (SHGC). 

U-Factor: The U-Factor indicates how well a product prevents heat from escaping a building or home. The lower the U-factor, the better a product is at keeping heat inside. U-factor is particularly important during the winter heating season in colder climates. U-factor ratings generally fall between 0.20 and 1.20.

Solar Heat Gain Coefficient: (SHGC) measures how much heat from the sun is blocked. SHGC is expressed as a number between zero and one. The lower the SHGC, the more a product is blocking solar heat gain. Blocking solar heat gain is particularly important during the summer cooling season.


If you are remodeling and you are replacing windows and/or doors, most if not all towns, villages and cities will want you to replace them with Energy Star compliant products, see you building department for details. Therefore, understanding this label will help you save money and save energy for years to come. 


If you need more information, check out these links below:

Why NFRC uses U-factors for windows

Everything you wanted to know about the NFRC, but were afraid to ask

NFRC Assists You in Making Energy Efficient Window Choices







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Posted 2014-05-15T18:23:12+0000  by Angelo_HD_CHI Angelo_HD_CHI