ENERGY STAR is a joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy helping us all save money and protect the environment through energy efficient products and practices.

For more information, visit the ENERGY STAR website at www.energystar.gov. 

In 2008 alone, Americans like you, with the help of ENERGY STAR, saved enough energy to avoid greenhouse gas emissions equivalent to those from 29 million cars—while saving $19 billion on their utility bills. 

Every ENERGY STAR qualified window is independently certified by the National Fenestration Rating Council, or NFRC, to perform at levels that meet or exceed strict energy efficiency guidelines set by the U.S. Dept. of Energy. Just like the EPA sticker on a new car gives you a car’s fuel economy, or miles per gallon, the NFRC label will help you measure and compare the energy performance of different window brands. ENERGY STAR requirements for windows and doors vary by climate zone. For instance, a window that is energy efficient in Miami, FL will not be the best choice in Anchorage, Alaska. 

The first energy performance rating is the U-Factor. U-Factor measures heat transfer through a window and tells you how well the window insulates. The lower the U-factor, the better the window insulates. During winter months, the lower a windows’ overall U-factor, the less heat you will lose through that window, and the less energy you will use to heat your home.

The second performance rating is Solar Heat Gain Coefficient. This measures how much solar heat is admitted into your home through the window, and tells you how well the window blocks heat caused by sunlight. The lower the SHGC, the better the window is at blocking heat. During summer months, a lower SHGC means less solar radiation is admitted through your windows, keeping your home cooler, and saving you money on running your air conditioner.