What makes a window or door energy efficient?

Numerous factors, including how the frame and sash are engineered and built, the type of glass used (single-, double- or triple-pane), the weatherstripping, the type of low-emissivity coating on the glass and the presence of argon or krypton gas.

What is ENERGY STAR® and what does it have to do with windows and doors?

ENERGY STAR is a U.S. government program administered by the Department of Energy and the Environmental Protection Agency with the cooperation of manufacturers that is designed to reduce the consumption of fossil fuels through the education of consumers. Windows and doors can only carry the ENERGY STAR label if they are tested by an independent laboratory through the NFRC program and meet specific, predetermined U-value ratings. By selecting ENERGY STAR products, you can reduce your energy costs and help make the environment cleaner.

What is an R-value and how important is it in selecting windows?

Although the U-value is actually the important number in evaluating windows and doors, most people are more familiar with the related concept of R-value (or R-factor). The R-factor of a window is the measure of its resistance to the transfer of heat flow. The higher its R-value, the greater its insulating ability.

What is a U-Factor and how does it relate to ENERGY STAR?

U-Factor (or U-Value) is the measure of the rate of heat loss through a material, the lower the U-Factor, the less heat that is escaping. To be eligible for the ENERGY STAR, products must be rated, certified, and labeled for both U-Factor and Solar Heat Gain Coefficient (SHGC) in accordance with the procedures of the National Fenestration Rating Council (NFRC) at levels which meet specific ENERGY STAR qualification criteria one or more climate zones.

Visit https://www.energystar.gov/products/building_products/residential_windows_doors_and_skylights to learn more.

What is LowE and, how important is it to have it on your windows or doors?

Low-E stands for low emissivity and is a microscopic, metallic coating applied to a surface of glass that reflects and re-radiates heat energy either into or out of a home thus saving heating and cooling costs. Windows with "clear" glass are the least efficient, while windows with LowE are much more thermally effective. The best performing windows are those using LowE/Argon glazing.   In addition to energy savings, LowE also effectively reduces the amount of transmitted ultraviolet light which can damage carpets, fabrics, and drapes.   Argon gas is much heavier than air, making it more difficult for warm or cold air to pass through. Theses glazing choices will meet or exceed most local building code requirements and provide ENERGY STAR® qualified performance.

Where do I go to buy an efficient window?

Before you buy a window, we recommend that you do your research and then shop around.  Educate yourself about what kind of window is right for your needs. Learn about the NFRC and ENERGY STAR® labels and why they are important. Visit retailers or distributors. Look for the product you want within your price range. Ask questions of the sales staff and let them tell you about the energy efficiency features of the products. Remember to 1) look for the ENERGY STAR®, 2) look for the NFRC label, 3) select a product that is right for your climate and your budget.

Installation is a very important part of the window buying process.  If you have a contractor whom you trust, ask for a detailed description of the installation process. Make sure your contractor knows as much about ENERGY STAR® products and NFRC labeling as you do.

Why is weatherstripping important?

Weatherstripping provides the barrier against air and water in windows and doors and is the only element of operating windows or doors that make them reasonably air tight. High-quality weatherstripping that's applied and compressed properly improves the insulating performance of windows.

What are the different types of weatherstripping, and what benefits do each have?

Although there are many different types of weatherstripping, they basically fall into one of three categories - woven piles, flaps, and hollow or foam bulbs. Which is best depends on the window style, design and application. Windows and doors that are expertly engineered are designed with weatherstripping that creates the tightest possible seal and holds up to time and heavy use.

Can windows and doors reduce outside noise?

All windows and doors reduce noise to some degree. The best solution, however, is to use a laminated, insulating glass in windows and doors which can significantly improve sound deadening over other glass types.

Can windows keep out UV radiation that fades carpeting, furniture, draperies and upholstery?

Using a low-emissivity glass in your new windows or doors will filter more than 50 percent of the damaging UV light. The absolute most effective glass for this purpose, however, is laminated insulating glass which features a polyvinyl butyral inner layer and a low-emissivity coating that filters more than 99 percent of UV radiation that fades interior furnishings.