Windows in your home can be a major factor in heat loss during the winter and heat-gain during the summer. Energy used to heat and cool homes and buildings accounts for one quarter of all energy used for space heating and cooling.

Window frame construction is an important factor, along with the glazing (glass), that contributes to the energy efficiency of the window. Window frame frames come in a variety of materials including aluminum, vinyl, fiberglass and wood. While aluminum frames are strong and are ideal for customization, they are also prone to heat loss and condensation. Most energy efficient windows have wood or vinyl frames that do not conduct heat as easily as aluminum, for instance.

If a window has a high resistance to heat-flow (or a high R-Value), it will lose less heat than a window with a lower R-value. There are a number of factors that affect the R-value of a window. These factors include glazing material, the number of layers of glass, the size of the air space between the layers of glass, the thermal conductivity of the spacer materials and the tightness of installation to prevent air leaks.

Energy Star (a US EPA program) performance requirements for windows are tailored to fit the various energy needs of different areas of the United States. The Energy Star label will identify the rating of the window as well as the region which it is rated for.

Filed under: Energy Efficiency