How Energy Efficient Windows Work

Windows bring in light and provide style to your home. More importantly, they play a major role in energy efficiency. There have been many improvements in the engineering of windows over the years. It may be economically beneficial for you to replace your windows if your utility bills are high. Watch this video to learn how energy efficient windows work.

A primary factor in a window’s energy efficiency is its U-Factor, which measures the overall ability to resist heat. The lower the U-Factor, the higher the energy efficiency. Like a drinking glass, heat easily escapes through a single-paned window. Double-paned windows, however, have a 1/2″ to 3/4″ air space between the panes which greatly reduces the heat flow; air flow can be reduced even more by adding argon, carbon dioxide or krypton into the space. Another contributing factor is the frame’s heat conductivity. Most new frames constructed from aluminum, vinyl or wood are engineered for efficiency.

Low-emittance or low-e coatings also help in reducing heat flow. Low-e coatings are microscopically thin metal or metallic oxide layers deposited on a window. Coating a glass surface with a low-emittance material and facing that coating into the gap between the glass layers lowers the total heat flow through the window. Low-E coatings are transparent to visible light. Different types of these coatings have been designed to allow for high, moderate or low solar gain.

If you are in the market for energy efficient windows, start by looking for windows with Energy Star approval. The Energy Star program was created by the U.S. Department of Energy and the U.S. Environmental Protection Agency with the goal of promoting energy efficient product choices. Americans have been able to save up to 30% on their energy bills by installing Energy Star approved products. Quality windows will have this rating; if not, they should be avoided. The majority of well-known window manufacturers advertise this rating, such as Jeld-Wen and Milgard.