U.S. Department of Energy - Energy Efficiency and Renewable Energy
Building Technologies Office – High Performance Windows Volume Purchase
Low-E Storm Windows
Low-E coating on the glass reflect heat back into the room during the winter months.
Storm windows can reduce heat loss through the windows by 25% to 50%, and low-E storm windows save even more energy. They not only have the benefits of regular storm windows, providing an additional insulating barrier and reducing infiltration, but the low-E coatings (microscopically thin coatings applied to the window glass) help keep heat inside during the winter and outside during the summer.
Chicago low-E Storm Window Study
HUD's PATH program, along with the DOE and industry partners, sponsored a field evaluation to investigate the performance of low-E storm windows. The local weatherization agency in Chicago identified 6 older homes with single pane windows to use in the study.
- Energy usage measured in the winter of 2005-2006.
- Monitoring began with single pane windows in late October 2005
- Low-E storm windows were added in January 2006
- Monitoring continued through March 2006
Conclusions from Chicago Study
- Clear glass storm windows reduced the whole house heating load by 13% with a 10 year simple payback.
- Low-E storm windows reduced heating load by 20% with less than a 5 year simple payback.
- Reduction in summertime cooling requirements may also provide additional energy savings.