A building’s windows can be a major source of heat loss in winter and unwanted heat gain in summer. But window technology has advanced significantly in recent years allowing consumers to save more money through reduced heating and cooling costs. In selecting new windows for a building, it’s important to consider the type of windows needed by prioritizing features such daylighting, solar heating, shading, ventilation and aesthetic value.
Urban Edge Guidelines
- Select an ENERGY STAR qualified window. Be sure to specify the climate zone. In the Northern Climate zones, ENERGY STAR qualified windows have the following characteristics:
- Low E-glass
- Wood, vinyl, fiberglass or composite frame materials. For Vinyl or fiberglass windows, be sure to get an insulated frame.
- Gas fill of Argon, Krypton, or other inert gas
- Look for efficient window properties on the National Fenestration Rating Council (NFRC) label. Use the NFRC label to compare ENERGY STAR products. For Northern Climates, be sure windows meet the ENERGY STAR Guidelines below *.
- U-factor: U<=0.35; if air conditioning loads are minimal, U-factors of .40 are also energy efficient if the SHGC is >=.50
- Solar Heat Gain Coefficient (SHGC)—To reduce heating, select the highest SHGC available, usually .30-.60 for colder climates.
- For cooling concerns, select windows with an SHGC of .55 or less
- Visible Transmittance -Select windows with a higher VT to maximize daylight and view
- Air Leakage -Select windows with an AL of .30 or less. Casement or awning windows due to gasketing and mechanical closing mechanisms have much lower air leakage rates than hung windows. Single hung have less than half the leakage of double hung windows.
Click here for more information on energy performance ratings in windows.
Spotlight on Urban Edge
Egleston Crossing uses double-glazed, low-e, argon-filled vinyl windows with a U-factor of .30.
Options and Criteria Review
There are several window components to consider in selecting an energy efficient window:
Energy Efficient Window Costs
ENERGY STAR windows are approximately 5 to 15 percent higher than the market standard, but the extra initial costs are easily regained when energy savings are considered. According to ENERGY STAR, selecting ENERGY STAR windows over the typical double-paned, clear-glass windows saves $65 a year (2006 dollars) in New England.