Understanding The Information on a Window/Door Sticker
Here is a brief explanation of what all those numbers and codes mean on the NFRC sticker that is on new windows & doors.
![NFRC Label](https://nextdoorandwindow.com/wp-content/uploads/2015/11/nfrc-label-compressor.jpg)
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![U Factor Picture](https://nextdoorandwindow.com/wp-content/uploads/2015/11/u-factor-picture-compressor.jpg)
U-Factor
The rate of heat loss is indicated in terms of the U-Factor. The lower the U-Factor, the better the window insulates. Energy Star approved windows and doors must have a U-Factor that is 0.32 or lower.
Five Important Variables in Every Insulated Glass Unit
Air Leakage
Heat loss and gain can occur by air leaking through cracks in a window. The air leakage rating {AL} is the equivalent cubic feet of air passing through a square foot of window area. The lower the AL, the less air will pass through cracks in the window. Select windows with an AL of 0.30 or less.
![](https://nextdoorandwindow.com/wp-content/uploads/2015/11/air-infiltration-picture-compressor1.jpg)
![Solar Heat Gain Picture](https://nextdoorandwindow.com/wp-content/uploads/2015/11/solar-heat-gain-picture-compressor.jpg)
Solar Heat Gain CoEfficient
The SHGC is the fraction of incident solar radiation admitted through a window, both directly transmitted and absorbed and subsequently released inward. SHGC is expressed as a number between 0 and 1. The lower a window’s solar heat gain coefficient, the less solar heat it transmits.
Condensation Resistance
Condensation resistance {CR} measures how well a window resists the formation of condensation on the inside surface. CR is expressed as a number between 1 and 100. The higher the number, the better a product is able to resist condensation.
Visible Transmittance
Visible transmittance {CT} indicates the amount of visible light transmitted through the window. VT varies between 0 and 1. The higher the VT, the more light is transmitted. A high VT is desirable to maximize daylight.