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ENERGY STAR®, NFRC® and Their Differences

When you’re looking for a new window replacement, you may have noticed two certain labels in some products. One is the ENERGY STAR® label, and the other is the white National Fenestration Rating Council® (NFRC) label. These two labels should always be present if you’re looking for good and reliable energy-efficient windows. You may not know it, but both serve different purposes in ensuring energy-efficiency in window products.

How Do They Differ? 

When you see the ENERGY STAR label in a window, it means it has met the strict energy efficiency criteria set by the U.S. government. However, they still need to be tested and certified by a different organization, such as the NFRC, for its actual energy performance. They’re recognized by the industry as the certifying body for windows and some glass doors, and they’re responsible for the rating, certification and labeling of the product, which consumers look for when they compare the energy performance of windows and doors.

Keep in mind that the NFRC is not responsible for setting the minimum performance standards or mandate performance levels, which means you won’t find any “good” or “bad” ratings from their label. ENERGY STAR already helps identify NFRC-certified products with its energy performance.

How the Labels Work Side by Side

The NFRC label can be found on all ENERGY STAR-certified windows and doors, and they’re usually listed with five measurements. These can help you choose which window replacement you need for your home since the labels give you an idea on how much a certain window performs in a given application. Here’s what you’ll find in the labels.

  • U-Factor 

Range: 0.20 to 1.20

This measures the rate of heat transfer and tells you how well the window insulates. The lower the number, the better an insulator the window or door is.

  • Solar Heat Gain Coefficient (SHGC)

Range: 0 to 1

This measures the fraction of solar energy transmitted and tells you how well the product blocks heat caused by the sunlight. The lower the number, the less solar radiation and heat the window or door allows inside.

  • Visible Transmittance (VT)

Range: 0 to 1

This applies to windows and patio doors. VT is the amount of light a window allows to pass through into your home. Lower number means the room will be dimmer; a higher number means the room will be brighter. Check the VT numbers if you’re looking to reduce glare in a room or fill it with natural light, but be warned that a very low VT may mean you have to use artificial lighting even during the day.

  • Air Leakage (AL)

Range: N/A (but 0.3 is the standard building code)

This measures how much air passes through the product’s joints. The lower the number, the more airtight the window or door. Keep in mind that ENERGY STAR standards don’t really consider air leakage because it’s difficult to measure accurately and can change over time as the frame materials expand, contract, or warp in place.

  • Condensation Resistance

Range: 1 to 100

This measures how well a given window or door resists moisture buildup. The lower the number, the more condensation the window or door allows to build up. Just remember that ENERGY STAR-rated windows tend to resist condensation well so this number won’t likely affect your purchase decision.

When it comes to excellent and reliable windows replacement, we have you covered. Call Renewal by Andersen® of San Francisco today at (510) 263-3210, or you can reach us online by filling out our contact form. We serve San Francisco and nearby areas.


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