Buying New Windows

New windows are long-term investments that have a large impact on your home's energy system. Today, there are many new window technologies available that are worth considering. Glazing materials now come with a variety of selective coatings and other features; frames are available in aluminum, wood, vinyl, fiberglass, or combinations of these materials. Each type of glazing material and frame has advantages and disadvantages.

Shopping Tips

• When you're shopping for new windows, look for the National Fenestration Rating Council (NFRC) label; it means the window's performance is certified.
• Remember, the lower the U-value, the better the insulation. In colder climates, a U-value of 0.35 or below is recommended. These windows have at least double glazing and low-e coating.
• In warm climates, where summertime heat gain is the main concern, look for windows with double glazing and spectrally selective coatings that reduce heat gain.
• Select windows with air leakage ratings of 0.3 cubic feet per minute or less.
• In temperate climates with both heating and cooling seasons, select windows with both low U-values and low solar heat gain coefficiency (SHGC) to maximize energy benefits.
• Look for the ENERGY STAR and EnergyGuide labels.

Electrochromic Windows: The Latest Technology in Home Energy Conservation

Currently, PATH and the U.S. Department of Energy (DOE) are jointly researching the benefits of electrochromic (EC) windows. EC windows are "smart" windows in which an electrical signal changes the light transmittance, transparency, or shading of the unit. Whether utilizing electrically conductive films or suspended particles, the technology uses an electrical current to transfer ions from one layer to another within the electrochromatic material and cause a change in tinting. A licensed electrician must install the windows because they require an electric source and switch.

EC widows block significant amounts of ultraviolet light and radiant heat. As a result of the decreased heat gain from solar energy, cooling burdens can be significantly lowered during the summer months. These windows can cut energy use in a building by an estimated 50 percent. Additionally, EC windows slow the fading of interior furnishings by reducing their exposure to ultraviolet light.

The glazing is currently poised for commercialization and PATH and DOE are evaluating field studies and market feedback to assess the opportunities, benefits, and commercialization issues related to the use of these windows in new homes. The new EC windows are expected to change the way builders, architects, and engineers design and construct homes in the near future.

Content updated on 8/3/2006