What is an ENERGY STAR qualified window?
ENERGY STAR labeled windows meet a stringent energy efficiency specification set by the Department of Energy and have been tested and certified by the National Fenestration Rating Council (NFRC). NFRC is an independent, third-parth certification agency that assigns specific energy efficiency measures such as U-factor and Solar Heat Gain Coefficient to the complete window system, not simply the glass. ENERGY STAR qualified windows may have two or more panes of glass, warm-edge spacers between the window panes, improved framing materials, and Low-E coating(s) which are microscopically thin coatings that help keep heat inside during the winter and outside during the summer.
