This week the windows were installed, and the house is starting to take on more character and definition. We have installed Loewen windows, which earn 3 points in the LEED certification process, due to their exceptional energy efficiency.
According to the EPA, heat loss through windows accounts for 50% of a home's heating and cooling needs. Window technology in Germany and Canada has surpassed that of the U.S. But we are catching up. Jeld-Wen, a company that began in Oregon, produces highly efficient windows that exceed Energy Star requirements.
The performance values to look at in a window are the U-factor and the solar heat gain coefficient (SHGC). The U-factor is a measure of the thermal resistance to heat flow of the overall window. The lower the U-factor, the greater the resistance to heat flow.
The SHGC is a way of expressing the amount of solar heat entering through the window. The lower the SHGC, the less solar energy entering through the window. In some cases, a higher SHGC is desirable, for example, for passive solar home design. In any case, the selection of window should meet or exceed Energy Star specifications.