What Makes a Window ENERGY STAR® Certified? An Overview for Fort Worth Area Residents

Window Fort Worth TXWhile researching the window replacement options for your home in or near Fort Worth, you may have come across the term ENERGY STAR®. This is a government-backed certification for energy efficiency that can be found not just on energy-saving windows but a plethora of both consumer and commercial products – from home appliances and electronics to office equipment and HVAC equipment.

Just what does it mean, specifically, for a window to be ENERGY STAR® certified? It essentially boils down to a window’s ability to either meet or exceed minimum federal requirements for energy efficiency. The five performance criteria are as follows:


Also called the U-value or thermal transmittance, the U-Factor of a window is a measure of how well it insulates. The lower the U-Factor, the better.


SHGC is simply a measure of how well a window blocks heat caused by sunlight. Similar to the U-Factor, the lower the SHGC, the better.


We all know that windows let in light. That is, after all, one of their primary purposes. Visible transmittance, or VT, is a measure of how much light a window lets through.


This is a metric of how moisture-resistant a window is. The higher the CR factor, the less moisture buildup a window allows.


AL measures the rate at which air infiltrates through a window’s joints. The lower the AL value, the less air leakage there is.

For more information, contact Gulf Coast Windows – the ENERGY STAR® certified window installer of choice for countless homeowners in the Fort Worth area. We also install doors, siding, and more.