PNNL: News – Highly insulating windows are very energy efficient, though expensive

” 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.”
http://www.pnnl.gov/news/release.aspx?id=1026