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Window Questions Concluded

Question 11: Can windows keep out UV radiation that fades carpeting, furniture, draperies and upholstery?

Answer: 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. It features a polyvinyl butyral inner layer and a low-emissivity coating that filters more than 99 percent of UV radiation that fades interior furnishings.

Question 12: How often should residential windows be replaced?

Answer: Homeowners with windows over 25 years old should consider replacing them, both to gain the best energy efficiencies and to protect the envelope of the house. A home is an ideal candidate for a window replacement if its windows are sealed or painted shut or has drafts that come through the windows.

Question 13: What are egress requirements?

Answer: Egress requirements indicate a minimum opening size that certain windows must meet. These requirements tend to vary from region to region, so please contact your local building code official for egress requirements in your area.

Question 14: What is ENERGY STAR?

Answer: ENERGY STAR is a joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy helping us all save money and protect the environment through energy efficient products and practices. Results are already adding up. Americans, with the help of ENERGY STAR, saved id greenhouse gas emissions equivalent to those from 27 million cars — all while saving $16 billion on their utility bills.

Question 15: What is an ENERGY STAR qualified window?

Answer: ENERGY STAR labeled windows meet a stringent energy efficiency specification set by the Department of Energy and have been tested and certified by the National Fenestration Rating Council (NFRC). NFRC is an independent, third-path certification agency that assigns specific energy efficiency measures such as U-factor and Solar Heat Gain Coefficient to the complete window system, not simply the glass. ENERGY STAR qualified windows may have two or more panes of glass, warm-edge spacers between the window panes, improved framing materials, and Low-E coating(s) which are microscopically thin coatings that help keep heat inside during the winter and outside during the summer.

Question 16: What is Solar Heat Gain Coefficient?

Answer: The Solar Heat Gain Coefficient (or SHGC) refers to a window’s ability to transmit solar radiation. The SHGC ranges from 0-1. A value of 0 indicates that window functions like a wall, essentially preventing any solar energy from entering the building. A value of 1 indicates that the window functions like an opening, allowing all solar energy in. In cold climates, a high SHGC can lower heating costs by using passive solar heating. In warm climates, a low SHGC is desired to keep unwanted heat out and reduce cooling costs.

Question 17: What are R-Values and U-Values?

Answer: R-value is the resistance a material has to heat flow. The higher the R-value, the greater the resistance. U-value is the amount of heat transferred through material. The lower the U-value, the slower the rate of heat flow and the better the insulating quality. When shopping for windows or doors, look for higher R-values and lower U-values for the most energy-efficient products possible.

Question 18: How does insulating glass improve the quality of windows and doors?

Answer: Insulating glass improves the quality of windows and doors by:

Improving the performance of the U- and R-values of your new windows and doors. Reducing condensation. Helping keep the heat in and cold out during winter. Helping keep the heat out and the cold in during summer

Brett Roth 10/11/2009

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