Benefits: Save on Heating and Cooling Equipment

Efficient windows save money in multiple ways, including lowering a house’s reliance on heating and cooling systems, such as furnaces, heat pumps, air conditioners, and fans. Owners can buy smaller and less-expensive machinery if they select efficient windows before calculating heating and cooling needs. In a cold climate such as Minneapolis, efficient windows can reduce heating and cooling requirements for a typical house by about 33 percent. In a hot climate such as Phoenix, efficient windows can have an even bigger impact, lowering the required cooling capacity by up to 50 percent.

Use the Window Selection Tool to find the windows that would be most efficient for your house. Windows rated by NFRC have a label that rates their efficiency, and selecting windows that also have an ENERGY STAR® label can ensure energy efficiency, especially those with an ENERGY STAR® Most Efficient label. Learn more about NFRC’s ratings and the Energy Star certification in the Measuring Performance section of this site.

Note: The peak system sizing figures shown were generated from simulation results using RESFEN provided by Lawrence Berkeley National Laboratory ( Results assume a typical new construction 2600 sq ft house with 15% window-to-floor area distributed equally on all four sides. U-factor and SHGC are for the total window including frame. Conversion between air conditioner electric load and system sizing assumes an 11.2 EER.