Look for ENERGY STAR -certified windows. Established in 1992, ENERGY STAR is a program run by the U.S. Environmental Protection Agency with a mission of providing consumers and businesses with reliable, unbiased information to help them choose products that will lower their energy costs, improve air quality, and protect the climate through reduced greenhouse gas emissions. Windows certified by ENERGY STAR have been confirmed to offer these benefits while contributing to a more comfortable temperature inside your home.
Check ratings on the energy performance label from the National Fenestration Rating Council (NFRC) . While an ENERGY STAR certification indicates that a product is energy-efficient, NFRC ratings can help you compare specific factors that contribute to energy performance across multiple products. These ratings are available for windows, doors, and skylights. Specifically, NFRC ratings examine the following factors:
U-factor - this indicates how well a window insulates by measuring the rate of heat transfer. U-factor values typically range from 0.20 to 1.20, with numbers on the lower end indicating better insulation.
Solar Heat Gain Coefficient (SHGC) - this measures the amount of solar radiation let in through a window and released as heat inside the building. SHGC values range from zero to one, and as with the U-factor, a lower number is better.
Air leakage - this measures how much air will enter a room through the window. According to the NFRC, windows should have an air leakage rating of 0.3 or less; the lower the number, the less drafty your home will be.
Visible transmittance - unlike the other three factors, you should look for a visible transmittance rating on the higher end of the spectrum between zero and one. Visible transmittance measures how well the window will allow natural daylight into your home, which can help reduce your need for artificial lighting.
Opt for dual-strength glass. Modern dual-pane window systems use glass packages that are generally double the thickness of builder-grade products. By combining glass thickness to 1/8- inch or 3/16-inch, these glass systems are stronger and more durable against the weather. By providing better insulation, dual-strength windows can help improve energy efficiency and reduce utility costs. They are also less likely to break than single-strength glass, and can help with soundproofing.
Look for low-emissivity (low-E) coatings. Another important quality of energy-efficient windows is a low-E coating, which is a colorless, microscopically thin, nontoxic metal or metallic oxide coating that reflects out heat and UV rays in the summer while reflecting heat back into the home during the winter. Low-E coatings reduce the window’s U-factor and are available in options for low, moderate, and high solar gain. As an added benefit, low-E coatings help to block harmful UV rays, which can fade the color of your carpets, flooring, drapes, and furnishings. While windows with these coatings tend to cost more upfront, they reduce energy loss by 30 to 50 percent—which means that they will save you money in the long run.
At The Window & Door Store, our window systems feature the latest in energy-saving technology, helping to ensure that your home will feel comfortable and run efficiently year-round.