Replacing Window Glass With True Energy-Efficient Models
December 15, 2009
U-factor. SHGC. VT. Know any of these acronyms? What about the terms air infiltration or condensation resistance? If not, you need to shore-up on your window glass ratings before your energy bills break the bank. After all, the summer months are the perfect time to replace older windows with newer models.
If you aren't sure how to replace window glass with energy-efficient models, you're not alone. The terms can be a bit confusing if you don't know what they mean. However, ignorance can be costly in the long run--particularly with respect to heating and cooling costs. According to the Green Energy Consultancy, 20 percent of your home's heat is lost through the window. What's more, treatments such as double-glazing can cut the heat loss by up to 50 percent. Here's more on window glass ratings.
The Rating Game: Why Window Glass Ratings Matter
In an effort to establish a fair, accurate and credible rating system for window performance, the National Fenestration Rating Council created a series of testing procedures required for manufacturers. To meet the guidelines of the Energy Policy Act of 1992 and certain federal government program requirements, companies must list window glass ratings with respect to such qualities as U-factor, Solar Heat Gain Coefficient, Visible Transmittance, Air Infiltration and Condensation Resistance.
The ratings are typically adjusted according to climate zones to take into account geographic variables. Window glass ratings work in coordination to improve the overall energy-efficiency of homes and offices.
How to Replace Window Glass with Energy-efficient Models
Perhaps the surest way to know is to look for the ENERGY STAR insignia on any potential window glass purchases. This seal of approval means that the particular model you're considering meets industry guidelines for energy-efficiency and eco-friendliness. If a window product is truly ENERGY STAR-compliant, you'll notice the designation on all selling materials.