This is an overview on how energy efficient windows work. Information is provided about how they can help save money on heating and cooling costs.
Up until the 1980's, most windows were made of a single pane of glass with the option of adding storm windows for extra protection. On average, these windows are ten times less energy efficient than the walls surrounding them.
One way that your heating or cooling is lost through windows is conduction. Conduction is the transfer of energy from one source to another. An example of this would be touching an ice cube with your bare finger. When you touch the cube it feels cold to you. Heat from your finger is transferred to the cube, causing the temperature of the ice to rise and the ice to melt. On the flip side of that, the ice is conducting cold to your finger, thus bringing down the temperature of your finger. In much the same way, the air surrounding the windowpane loses and gains heat. Your furnace or air conditioner must work harder to keep the temperature steady, thus, higher heating and cooling bills.
Upkeep is another problem with older windows. Many houses shift over time, causing the seals to weaken around the windows and frames. If wood frames are not properly maintained, cracks occur and air from outside can seep into your home.
Energy efficient windows were created to combat these problems. Most newer windows have two panes of glass, with a small air pocket between them. This air acts as an insulator, much like the insulation in your walls. Some manufacturers insert gases that have low conducting properties such as argon or krypton. For maximum insulation, the space should be larger than a half inch but no greater than an inch wide.
Special glazes have been produced that help keep the heated or air-conditioned air in your home. The trick was to produce something that allowed natural light to come through while stopping energy leakage. One type of glazed glass is classified as "low emissive glass". This glass is treated with a glaze that prevents heat loss by 40 to 70 percent while letting 100 percent of the natural light from outside to come through.
Another type of glazed glass is "reflective glass". This type of glass is coated with a reflective film that reduces the solar energy absorbed by the windows. This is most helpful in warmer climates where most homes need to be air-conditioned on a year round basis.
Another way to improve efficiency is to have the right type of window frame material. Cracks and gaps in window frames can account for up to 50 percent of your energy loss. The three basic types of materials used in window framing are aluminum, wood and vinyl.
Aluminum frames are considered the most resilient in build and offer the most variety for design purposes. However aluminum tends to be highly conductive and is prone to condensation problems.
Wood frames require more upkeep than aluminum and vinyl. They are more apt to crack, break, or shift. Wood is also most prone to damage from the elements such as rain, snow, and ice.
Vinyl frames are made from polyvinyl chloride, better known as PVC. These are considered the best type of frame for energy efficient windows. Vinyl frames conduct very little heat as compared to the other types of frames. They are highly versatile and require very little maintenance. The only draw back of vinyl is that they are not quite as strong as wood or metal frames. For larger windows, they have to be reinforced with metal supports.
Energy efficient windows also add to the value of your home. They look great and come in many varieties. If you call or visit your local home improvement store, they can help you decide which type is best for your needs.
