Upgrade the Window, Improve the Efficiency
Upgrade the Window, Improve the Efficiency
Single-pane windows are one of the largest sources of heat loss in winter due to their low insulating ability and high air leakage rates. They're also a major source of unwanted heat gain in the summer. As a result, single-pane windows are significant net energy losers, responsible for 25 to 50 percent of the energy used to heat and cool homes.
Since single-pane windows have become dinosaurs, almost any window will be an improvement.
A safe bet is to select a window with an Energy Star label. The National Fenestration Rating Council (NFRC) energy performance label will also help you compare windows based on five factors:
- U-factor measures how well a product prevents heat from escaping.
- Solar heat gain coefficient (SHGC) measures how well a product blocks heat caused by sunlight.
- Visible transmittance measures how much light comes through a product.
- Air leakage measures how much air will pass through cracks in the window assembly.
- Condensation resistance measures the ability to resist the formation of condensation on the interior surface.
The optimal combination of U-factor and SHGC depends on your climate zone. Products with the Energy Star label will include a map to help you determine the right window for your area.
In storm-prone regions and regions that require protection from flying debris, suggest an upgrade to impact-resistant windows. Impact-resistant assemblies have laminated glass and generally require longer screws (for deeper, more secure penetration) and more screws in more places (for added support). Check your local building code for requirements.
For more information, visit www.toolbase.org, www.energystar.gov and www.nfrc.org.
