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What Metrics To Use When Assessing Your Window’s Performance

When shopping around for new windows, it’s important to arm yourself with as much information as you can to ensure you make the most informed decisions. And we don’t just mean about the latest architectural styles and trends, but also about how well a window performs. This is where ratings from The National Fenestration Rating Council (NFRC) come in.

Window's Performance

NFRC Ratings

The NFRC is an independent, nonprofit organization that establishes objective energy-efficiency ratings for windows, doors and skylights. These ratings help consumers compare products side by side with each other so homeowners can get the best windows that are suited to their needs. Keep in mind that a low or high rating for each criterion doesn’t always mean it’s better or worse for your home – that depends on where you live.

  • U-Factor – This rating measures the amount of heat inside your home that can escape through a window. It is the top-left number on all NFRC labels and typically ranges from 0.10 to 2.00. A lower number means less heat loss.
  • Solar Heat Gain Coefficient – This measures the amount of solar heat from the sun that can enter your windows. It is the top right number in all NFRC labels with a rating range of 0.00 to 1.00. A lower number means less heat gain.
  • Visible Transmittance – This measures the amount of light that can enter your home. This rating is found on the middle or bottom of an NFRC label and is represented by a number between 0.00 to 1.00. A higher number means more natural light.
  • Air Leakage – This measures the volume of air that can infiltrate your home through a window. Its rating range is represented by a value that is less than or greater than 0.3. A lower number means less air leakage. This is an optional rating.
  • Condensation Resistance – This rating measures a window’s ability to prevent interior moisture. Its rating is represented by a value between 1 to 100. A higher rating means less condensation. This too is an optional rating. 

Having trouble deciding which windows are for you? Then give Renewal by Andersen® of Long Island a call at (855) 728-1756 or fill out our contact form and we’ll guide you through the entire window selection and installation process. 


"I was very impressed with Renewal by Andersen. They showed up in time and we received several follow up phone calls as the installation was being done as well as the sales representative stopping by to check in on the installation. The delivery/ installer was very professional. I would highly recommend Renewal By Andersen."

February, 18

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