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The Metrics Used to Assess Whole-window Performance

Purchasing windows, whether it’s for a house you’re building from the ground up or as replacements for your old ones, should never be taken lightly. You’ll want to take a bit of time to do your research, so you end up with something that’s not just beautiful but energy efficient as well. That’s where the National Fenestration Rating Council (NFRC) comes in. The NFRC has established energy-efficiency ratings for doors, skylights and, of course, windows to help consumers compare products and make the most informed decisions.

Whole-window Performance

NFRC Ratings

  • U-Factor. This rating measures the amount of heat inside your home that can escape through a window. It is measured by a number between 0.10 and 2.00. A lower number means less heat loss.
  • Solar Heat Gain Coefficient (SHGC). This rating measures the amount of solar heat from the sun that can enter your home through a window. It is represented by a number between 0.00 and 1.00. A lower number means less heat gain.
  • Visible Transmittance. As the name suggests, this rating measures the amount of solar light that can enter your home through a window. It is represented by a number between 0.00 and 1.00. A lower number means more natural light. 
  • Air Leakage. This rating measures the volume of air that can enter your home through a window. It is represented by a number that is less than or greater than 0.3. A lower number means less air leakage. Note: This rating is not mandatory.
  • Condensation Resistance. Finally, this rating measures a window’s ability to prevent moisture buildup in the interior of a window. It is represented by a number between 1 and 100. A higher rating means less condensation. Note: This, too, is not mandatory.

Getting new windows doesn’t have to be overwhelming. All you really need is a trusted partner like State Roofing that can walk you through the entire process. To schedule your free appointment, simply give us a call at (360) 794-7164 or fill out our contact form and one of our experts will be happy to assist you.

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