Assess windows as a whole for energy efficiency
"I recently moved to a home where the front windows face southwest. There are no shade trees in the front yard, so I'm expecting the front rooms to get hot this summer. I plan on replacing the glass but I'm getting conflicting advice. Should I get low-E glass and rely on it to block infrared heat waves, or get clear glass and have an infrared-reflective film applied? Which will give me the best results" – Angie's List member Roger Linville
"If you want to improve overall energy efficiency, replace the windows," says Duane Aldridge, a manager at highly rated Energy Pro Windows in Belton, Mo. "It's the whole window system that makes it more energy efficient," Aldridge says.
For new windows, look for two key performance ratings: the U-factor and the solar heat gain coefficient. The U-factor expresses a window's overall energy efficiency; the solar heat gain coefficient defines how much solar energy a window transmits.
Both should be at or below 0.30, as a lower number indicates better performance. Aldridge says new windows start at $400 each and may also qualify for a federal tax credit of up to 30 percent of a certified product's cost up to $1,500, not including labor or installation. Visit energystar.gov for more information.
"Solar film could be a less costly option," says Peyton Gambrell, president of highly rated Sustainable Solutions, an Overland Park, Kan., energy efficiency auditing firm.
"To just block solar heat gain, window film is more cost effective," Gambrell says. "A good film costs about $7 to $9 a square foot." However, installing the reflective film won't address an inefficient window frame.
Both new energy-efficient windows and solar reflective film may qualify for a federal tax credit of up to 30 percent of a certified product's cost up to $1,500, not including labor or installation costs. Visit energystar.gov for more information.
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