Window Of Opportunity
(Energy News - September 2009)
Choose Models That Will Keep Your Energy Bill Down
It's important for windows to look nice, but they also should be energy-efficient. If you are building, adding on or replacing existing windows, be sure to evaluate the options.
Window shopping may seem overwhelming with the many styles offered today. Since efficient windows can cut your energy bills by up to 24%, it's smart to learn about some of the key features, according to the U.S. Environmental Protection Agency.
Energy-efficient windows use several technologies to help reduce heat loss, including:
- Multiple panes. These panes trap a layer of insulating air between the warm air inside and cold air outside.
- Low-emittance coatings. Thin, invisible layers of metal are put down on the window surface to reflect heat back into the building rather than allowing it to escape outside through the glass.
- Spacers. Spacers are strips of material that separate panes of glass. They are made of low heat-conducting material like steel or silicone to minimize condensation around the edge of the glass.
Read The Label
One of the smartest things to do is look for the ENERGYSTAR® label when shopping for windows. This indicates a window meets stringent energy-efficiency specifications set by the U.S. Department of Energy. ENERGYSTAR criteria are based on the performance of the entire window, including framing material, glass and spacers.
The National Fenestration Rating Council (NFRC) also has an energy rating system for windows. NFRC is a third-party certification agency that assigns energy efficiency measures to full window systems.This allows you to compare energy performance between different manufacturers.
Check energy-performance labels on windows for the:
- U-factor, which measures the rate of heat loss. A lower U-factor translates to greater insulating ability and greater energy performance.
- Solar heat gain coefficient (SHGC). The higher the SHGC, the more solar heat is allowed to pass through. This means winter sun can help heat your building.
For More Information
If you have questions about energy-efficient windows, contact Wisconsin Public Service's Business Solutions Center at 877-444-0888, or your account executive.