Highly insulating triple-pane windows keep a house snug and cozy, but it takes two decades or more for the windows to pay off financially based on utility-bill savings, according to a report by energy efficiency experts at the Department of Energy’s Pacific Northwest National Laboratory.
For this study, the PNNL team studied the effect of replacing aluminum-frame double-pane windows, which are common in homes across the country, with newer, triple-pane windows, also known as highly insulating windows. The team found that the newer windows slash energy use in the home by 12.2 percent. But because of the cost of the highly insulating windows, it would take anywhere from 23 to 55 years for the reduced energy cost to make up for the increased expense.
“A savings of 12 percent on whole-house energy consumption is substantial, especially when you’re talking about changing a relatively small percentage of a home’s envelope,” said Parker, a founder of the Lab Homes project. “But the windows are expensive.” “Comfort is also important,” said Parker. “The windows cut down dramatically on cold air radiating from the windows and they reduce temperature variations in the home, where some areas will be much warmer or cooler than others. They also nearly eliminate the formation of condensation on the inside of the window which can lead to mold growth and unhealthy indoor air. It’s hard to put a dollar value on comfort and health.”