NFRC label from a Pella sliding window

Demystifying Window Labels

If you’ve started to shop for windows, you’ve likely encountered a scary sight. No, it’s not the price tag (but we will talk dollars and cents in a future post). We’re talking about the window label.

You may have heard it described as the NFRC label. NFRC stands for National Fenestration Rating Council® (what a mouthful, huh?). This independent, nonprofit organization rates and certifies windows and doors according to strict requirements.

The NFRC doesn’t recommend which windows to buy. Instead, it helps you do an apples-to-apples comparison of different brands and styles.

At first glance, though, the NFRC label can be a bit intimidating. We’ll help you decode it.

The NFRC’s ratings measure:

  • U-Factor. This tells you how well the window insulates. The lower the U-Factor, the more energy efficient the window.
  • Solar heat gain coefficient. This measures how effective the window is at blocking the sun’s radiant heat. The lower the solar heat gain coefficient, the less solar heat the window allows into your home.
  • Visible transmittance. This quantifies how much light the windows allow into your home. Windows use various degrees of tinting to control energy efficiency and solar heat gain. The lower this number, the more tinting you’ll notice.

The NFRC label may also include the ENERGY STAR logo. If it does, the window meets the ENERGY STAR certification in the region of the country indicated on the map.

Using the label ratings

A Pella Windows NFRC label
A Pella Windows NFRC label

What should you aim for in terms of rating ranges for your windows? That depends in large part on where you live.

The glass choice for a window that’s efficient in Miami, for instance, would actually cost a person in Maine more money and the home would be less uncomfortable — and vise versa. Your local window expert can help you determine which rating levels are appropriate for your area and your needs.

Evaluating windows based on NFRC ratings will help you shorten your list of manufacturers. Your next step, then, is to decide between wood, fiberglass or vinyl windows. We’ll share tips for making that decision in a future post.

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