Schedule a Free Consultation

A Quick Guide to Understanding ENERGY STAR® and NFRC Ratings

When in the market for new windows, don’t just settle for any kind of windows. Make sure you get the most of your investment by looking for two things: the ENERGY STAR® and National Fenestration Rating Council® labels.


An ENERGY STAR label is present whenever a window has been tested and passed specific standards for energy performance. For instance, our windows are made of Fibrex® frames and High Performance™ Low E4® glass. These materials can help your home retain cold air during summer and warm air in winter. These properties have earned us the ENERGY STAR seal year after year.

What Is NFRC?

Their website describes the NFRC as a third-party non-profit organization that sponsors certified rating and labeling to help consumers compare the performance of windows, doors and skylights. Like ENERGY STAR, this label offers a seal of approval for energy-efficient windows.

What Do These Performance Ratings Mean?

These ratings have five categories, namely the following: the U-Factor, Solar Heat Gain Coefficient (SHGC), Air Leakage (AL), Visible Transmittance (VT) and Condensation Resistance. The U-Factor tells you how well a window insulates while the SHGC indicates how well it blocks the heat. AL measures the amount of air passing through the window. The lower the value, the fewer air leaks. VT, on the other hand, measures the amount of light that your window allows into your home. Condensation Resistance indicates how a window counterattacks water accumulation.

Renewal by Andersen® of San Francisco hopes that this information will be helpful the next time you get new windows. If you need more information, give us a call at (510) 263-3210, or fill out our contact form. One of our experts will be ready to assist you or give you a FREE in-home consultation at your convenient schedule. We serve San Francisco and surrounding areas.


"I wished to have this done long time ago, had I known the benefits of these products provided by Renewal by Andersen"

June 26

View All Reviews