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Understanding the NFRC Energy Performance Label

The National Fenestration Rating Council (NFRC) label will help you choose the best and most energy-efficient replacement windows for your home. This label indicates a product’s energy efficiency through different performance ratings. Since the NFRC independently tests each product, you can rely on their findings. Here’s how to understand the NFRC label:

Air Leakage

All windows allow a certain amount of air into and out of your home. The more air that escapes from your home, the harder your HVAC has to work to maintain your desired indoor temperature. The air leakage rating ranges from 0.1 to 0.3, and a low number means a lower level of air leakage.

Solar Heat Gain Coefficient (SHGC)

The SHGC rating measures the solar heat gain that gets through your windows. In a window that’s not energy-efficient, the sun’s heat can penetrate through your glass and raise your indoor temperature. This rating ranges from 0 to 1, and low numbers are better. Picture windows, sliding windows and other window types with low SHGC numbers are excellent at reflecting the heat. They can improve your home’s energy efficiency, particularly during warm months.


The U-Factor measures the ability of your replacement window to keep indoor heat from escaping. This rating ranges from 0.20 to 1.20, and windows with a low U-Factor value are better at preventing heat loss. Different windows have different U-Factor and SHGC values, so you’ll need to take your local climate into account when choosing which rating to prioritize.

Visible Transmittance

The Visible Transmittance rating measures how much visible light is admitted through the window glass. Some replacement windows are heavily tinted to improve energy efficiency, so this rating will help you find windows that strike a balance between energy efficiency and ability to let in sunlight. This rating ranges from 0 to 1, and, unlike the other ratings, a higher number is better.

Renewal by Andersen® of Austin provides some of the most energy-efficient replacement custom windows and doors on the market. We designed our windows to maximize energy performance. That’s why all our window frames are made of our exclusive Fibrex® material and all our windows come standard with our High Performance™ Low-E4® glass. We serve many areas including Georgetown, TX. Call us at (866) 842-3370 to learn more about our services and products or to request a free consultation.


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