NPR Story
3:26 pm
Wed December 4, 2013

The Cost Of Energy Efficient Windows

RICHLAND, Wash. -- If you’re looking to keep out the winter cold, triple-paned windows will do the trick. But Northwest researchers have found have found it can take decades before savings from these highly insulated windows pay you back.

Researchers are using two identical homes to test some of the latest advances in energy efficient appliances, heating and cooling systems, and most recently, windows.

One home was retrofitted with triple-paned, extra-insulated windows. The other has typical aluminum-framed windows found in most Northwestern homes.

Researchers at Pacific Northwest National Laboratory found the energy-efficient windows cut your home’s energy use by about 12.2 percent throughout the year.

The lab’s Graham Parker said the windows are expensive and could take 23 to 55 years to start paying you back.

“Windows are not one of the more cost-effective retrofits that you can do to a building, unless, of course, your windows are broken, or they’re letting a lot of air leakage through around the window frame,” Parker said.

The researchers found that the windows saved more energy in the summer than in the winter, 18.4 percent and 11.6 percent, respectively.

"We were a little bit surprised," Parker said. "I think the biggest reason is the highly insulating windows have what we call low emissivity coating, or low-e coating. That tends to block a lot of the radiation coming from the sun in the summertime."

Parker said the triple-paned windows can make homes more comfortable by reducing that drafty, cold feeling that's common near older windows.

They can also prevent condensation, which would in turn reduce mold.

"That's really an issue from a health perspective," Parker said. "Moisture and condensate creates mold; mold growth creates spores, which can create health problems in a lot of homes."

Parker said the most cost-efficient time to install the triple-paned windows is when you’re building a new home.

Sarah Widder, a research engineer with the lab, said the energy reductions from triple-paned windows is important.

"We shouldn't forget that triple-pane windows reduce energy usage, which helps the environment and reduces the impact of our energy use on the climate," she said in a news release.

Researchers are working to reduce the cost of the triple-paned windows.

Copyright 2013 ERTHFX. To see more, visit .