Many factors determine a window’s energy efficiency. The first is Low-E (Emissivity). It’s a reflective coating on the glass that reflects heat. Low-E works to keep homes comfortable year-round. In the winter, heat is reflected into the room instead of leaking out into the environment. In the summer, the outside coating reflects UV rays out, so that it doesn’t penetrate the glass. Reflecting UV rays also reduces the ability for the sun to fade carpet, furniture, and upholstery.
The next attribute for energy-efficiency is argon gas. It’s an irenic gas and fills the gap between the glass, raising the R-value of the window. R-value is a measurement of insulation. As an example, for insulating a wall, you would choose from R 13, R 15, or R 19, depending on how thick your walls are. Argon adds some insulating feature as well.
Obviously, a window is a big hole in your wall with glass in it, so the more insulating factor or R-value you can get, the more energy efficient it is. Thus, argon increases the R-value and keeps the heat in or out depending on the weather and temperatures outside.
When replacement windows were first on the market, there was often a lot of condensation around the edges of the window. New technology and a better-made window have mostly eliminated this. It reduces the heat transfer, which in turn, cuts down on any condensation around the window.
Another way windows are energy efficient is the use of interlocking meeting rails. It is a feature that locks the window tight and prevents air to pass through. When there are two sashes, there will be an interlocking meeting rail. Weatherstripping is another feature of new replacement windows that delivers the ultimate benefit. Weatherstripping should be placed where this is vinyl to vinyl contact in or other frame material such as wood, fiberglass, or aluminum. The weatherstripping prevents you from being able to see right outside. Weatherstripping helps decrease drafts, especially in colder or windy weather.
As you can see, all these energy-efficient improvements for replacement windows help consumers reduce energy costs. Replacing old windows with ENERGYSTAR® certified windows, the U.S. government’s label for windows meeting certain thresholds lowers household energy bills by an average of 12% nationwide. Lower energy consumption also reduces greenhouse gas emissions from power plants and homes.
If you are considering replacing your windows, be sure to ask about the energy-efficient characteristics of the window so that you make a sound investment.