What is The NFRC Label?
The purpose of the NFRC Label is to be able to compare all windows on an even playing field. This sticker will show you how the window preforms in several categories relating to the windows energy efficiency. These numbers are taken directly from the laboratory performance tests on the windows frame, glass, and spacers that separate the individual glass panels.
U-Factor is the resistance to heat flow. It measures the insulating preperties of the entire window. The lower the U-Factor, the more money you'll save on your energy bill.
Visible Light Transmittance (VT) measures the amount of visible light that is able to come through the glass. A dark, tinted window would have a low visible light transmittance number and the majority of people are looking for a high number to let in the most natural light.
Solar Heat Gain Co-Efficient (SHGC) measures how much infrared light gets through the glass. A single pane window would have a high SHGC and therefore let the suns rays heat up your home. On the other hand, a window with a low solor heat gain would keep the heat of the sun out and your house cool. Usually more important in warmer climate areas.
Air Leakage (AL) measures the rate at which air passes through joints in the window. AL is measured in cubic feet of air passing through one square foot of window area per minute. The lower the AL value, the less air leakage. Most industry standards and building codes require an AL of 0.3 cf·m/ft².
Condensation Resistance measures how well the window resists water build-up. Condensation Resistance is scored on a scale from 0 to 100. The higher the condensation resistance factor, the less build-up the window allows.