Replace existing windows
From a comfort perspective, it’s hard to overstate the importance of well-functioning windows.
About one-third of a window’s performance comes from its glazingWhen referring to windows or doors, the transparent or translucent layer that transmits light. High-performance glazing may include multiple layers of glass or plastic, low-e coatings, and low-conductivity gas fill., one-third from its frame, and one-third from the spacer system between the glass panes.
In order to make an informed choice, arm yourself with some facts. The National FenestrationTechnically, any transparent or translucent material plus any sash, frame, mullion, or divider attached to it, including windows, skylights, glass doors, and curtain walls. Rating Council (NFRC) rates windows according to three primary categories: The first is U-factorMeasure of the heat conducted through a given product or material—the number of British thermal units (Btus) of heat that move through a square foot of the material in one hour for every 1 degree Fahrenheit difference in temperature across the material (Btu/ft2°F hr). U-factor is the inverse of R-value. , the amount of heat that a material conducts; the second is the solar heat gain coefficient(SHGC) The fraction of solar gain admitted through a window, expressed as a number between 0 and 1. (SHGCSolar heat gain coefficient. The fraction of solar gain admitted through a window, expressed as a number between 0 and 1.), a measure of how much of the sun’s heat energy is transmitted through the glass; the third, visual transmittance (VT), is the percentage of visible light transmitted through the glass.
The guidance offered by the Efficient Windows Collaborative is thorough and accurate. Use the reference below to access their information and selection tools.
Learn more in the Green Building Encyclopedia
Windows, Glass, Ratings, and Installation
Further Resources
Efficient Windows Collaborative
Profiled in our Product Guide
