Differentiating SHGC and U-Value in Windows

Some replacement windows are more energy-efficient than others. One way to determine this is to check their energy performance ratings, which can be found on the black-and-white National Fenestration Rating Council (NFRC) label on the front of the window. You’ll find that it has values for SHGC, or solar heat gain coefficient, and U-value.

Differentiating SHGC and U-Value

Both ratings point to the windows’ ability to manage heat transfer. The similarities, however, end there. Here’s what you need to know about the SHGC and U-value of windows, and their differences.

Definition of SHGC and U-Value

The solar heat gain coefficient (SHGC) measures how much solar heat gets inside when it hits the window. It’s expressed as a value between zero and one, with one being the maximum level of solar transmission. The U-value, meanwhile, measures how well your windows prevent heat from escaping your home. The lower the number, the less energy can escape to the outside environment.

Their Main Difference

The main differences between SHGC and U-value are heat loss and heat gain. SHGC measures how much of the sun’s energy is let into your living space, while U-value focuses on how well windows resist energy transfer.

In southern regions, the amount of natural light entering the home must be controlled. Since the summer months can get hotter in this part of the United States, windows with lower SHGC and U-value ratings are recommended to minimize indoor cooling requirements. Homes situated in areas experiencing extreme winters, however, will need windows with high SHGC and U-value ratings to maximize the sun’s heat during mornings and retain it until the evening.

The Best Window Ratings in Houston, TX

ENERGY STAR® designated climate zones for homeowners to determine whether the windows they intend to purchase are suitable for their location. Houston, TX, is situated in the Southern Climate Zone, and ENERGY STAR-qualified window products in this zone must have a U-value of 0.40 or less, and SHGC rating of 0.25 or less.

Renewal by Andersen of Houston remains the go-to choice for exceptional window replacement services in Harris County and beyond. Call us at (281) 547-6177, or fill out this contact form to get an estimate.