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 first select efficient windows and then calculate 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 need in some cases by almost 50%.

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.