As you may have noticed, replacement windows in Lakewood, CA have a label that gives an energy performance rating. The National Fenestration Rating Council (NFRC) is an independent contractor that provides these labels so you can compare products and make an informed decision. But how do you know what window is right for your climate if you don’t understand what these ratings mean? That is why we are here. This is everything you need to know about reading NFRC labels and which ratings are best for Lakewood, CA windows.   


This rating is the inverse of the R-value and shows how well the window prevents non-solar heat gain. Ratings go from 0.20 to 1.20, and lower ratings mean the window is a better insulator. In Southern California this rating is fairly important, but not as important as it would be in places with higher heating bills.   

Solar Heat Gain Coefficient (SHGC) 

This rating is a little more important for the area. These values show how well your windows reduce solar radiation and keep it from entering your home. Again, the lower the number, the better your window will insulate against solar heat. You want to find a rating of 0.25 or less if you really want to help reduce your summer cooling costs.   

Air Leakage (AL) 

This shows the amount of heat lost or gained through the cracks in the frame and window assembly. The measurements are in cubic feet per square foot and often fall between 0.1 and 0.3. No window or door will be 100% air tight. That said, windows with lower numbers will seal the cool air in and keep the hot air out. Unfortunately this rating is not required, and as a result, some manufacturers will not post it on their labels.   

Visible Transmittance (VT) 

This does not have as much to do with energy savings as it does with just the amount of light coming in through your windows. Ratings go from 0.3 to 0.7. If you are a fan of daylighting, then you want a higher VT rating. If you want to keep the light muted so you can watch television without a glare or be awakened by early morning light, then you want a lower VT.   

Condensation Resistance 

This is another rating not required, but that can still tell you something about your Lakewood, CA windows. It shows how well your window resists condensation forming on the interior surfaces of the glass. Here a higher rating is actually better, with values between 0 and 100.   


That said, just because a window meets building standards for the California Energy Commission does not make it a great window. This is why some labels also feature some certifications at the bottom like Hallmark Certified, Energy Star, or the Window and Door Manufacturers Association (WDMA). These show that other entities give these products a stamp of approval that goes above industry standards.   

Want to browse some products and test your NFRC label knowledge? Come visit us at Seaport Windows and Doors. You can call to set up a free consultation 714-220-3939 or just come by 4201 Katella Ave., Los Alamitos, CA 90720. We can hook you up with the best Lakewood, CA windows