How To Choose Windows With The Right Energy-efficiency Ratings For You
If you can feel the cold of winter through your windows
, or have to close the drapes or blinds to stop the room overheating when the sun shines, you could be wasting a lot of money on heating and cooling air that simply goes straight out through your windows.
Save Money with Energy-Efficient Windows
Installing energy-efficient windows can reduce the amount of energy you use, which in turn reduces carbon emissions. Energy-efficient windows are green windows.
How to Identify Energy Ratings
The ENERGY STAR rating is the most important aspect to get correct if you want green windows in your home. The ENERGY STAR rating you need depends on the climate in which you live. ENERGY STAR certification means that the windows meet the energy code requirements for your locality. The U.S. Department of Energy reports that ENERGY STAR helped to save $6 billion, and preserve enough energy to power 10 million homes and avoid the equivalent greenhouse emissions from 12 million cars last year.
The National Fenestration Rating Council (NFRC) label on your windows gives you all the information you need about the window's energy properties and confirms the window's compliance with the energy code.
Look at the Solar Heat Gain Coefficient (SHGC) and U-factor of the windows. The SHGC figure on the NFRC label relates to the amount of solar radiation transmitted through the window. A lower figure means less solar heat is transmitted. The U-factor relates to the rate of heat loss. Again, a lower U-value means a greater insulation value. Green windows have the appropriate SHGC and U-factor for your climate.
The NFRC label also gives a figure for Visible Transmittance (VT), Air Leakage (AL) and Condensation Resistance (CR). The VT figure indicates the amount of visible light transmitted through your windows. The AL figure relates to the cubic feet of air that passes through each square foot of window. The CR figure has to do with how resistant to condensation the window is: a higher number indicates better window condensation resistance.
The Efficient Windows Collaborative provides fact sheets to help you select green windows appropriate for your state.