What are the Criteria for Energy Star Windows?

From on September 29, 2009 in Window Replacement

What does the Energy Star badge mean and why is it so important? In short, Energy Star is a government-regulated standard for energy efficient products. Purchase one of these certified products, and you’ll save an average of 20 to 30% on energy costs. This is especially crucial for your windows, given that the energy needed to offset heat losses and gains through windows accounts for one-fourth of your total energy bill. In other words, upgrade to airtight windows and shave up to 25% off your heating & cooling bill.

To earn Energy Star Certification, the window replacement must meet specific guidelines for heat loss, known as the U-Factor in cooler climates and Solar Heat Gain Coefficient (SHGC) in our warmest climates. The U-Factor measures how well the window prevents heat from escaping. This measurement generally falls between 0.20 and 1.20, with the lower number being the most efficient. SHGC measures how solar heat is blocked as it passes through the window. It’s expressed as a numerical value between 0 and 1, with the lower number again being the most energy efficient.

Criteria for Energy Star residential windows, doors and skylights are divided into four U.S. climate zones. So, the criteria for Miami would be quite different from that of Minneapolis.

We’ll walk you through this. Consult the charts below to check your climate zone:

energy-star-remodel-guide.jpgENERGY STAR Qualified Windows, Doors and Skylights Eligibility

Let’s say you live in California. You fall under the South/Central climate zone. Therefore, any window with a U-Factor and SHGC of 0.40 or below meets the Energy Star requirements for your state.


Manufacturers will most likely display their Energy Star badge with pride, seeing as they’ve gone to great lengths to earn it. And their hard work translates to dollars in your pocket, a smaller carbon footprint and drastically improved climate control in your home.