Today’s window are available in a wide range of materials. Glazing choices affect how much light they let in, how much of the sun’s heat they allow in interior spaces, and how well they prevent the flow of heat.
Windows are among the most complex building components in a house, and for several hundred dollars or more a piece. Among the most expensive.
Window frames do more than hold the glass in place and allow the window to open and close. They are an important part of a window’s overall thermal performance, and the type of frame helps dictate how much maintenance the window will need over its lifetime. Frame materials, include wood, fiberglass, vinyl, aluminum, and both vinyl and aluminum clad substrates.
In addition to the important architectural contribution they make, windows have far-reaching energy consequences.
As the thermal performance of the frame and glazing improves, so does the performance of the spacer, with thermal effects that can extend out up to more than 2 inches into the glazing. And spacer performance is important in controlling condensation as well. Look to all elements of a window for high performance.
In the recent decades, window manufacturers have begun using more rot-resistant materials, including aluminum, vinyl, pultruded fiberglass. Or some combination of these materials. Fiberglass and aluminum are likely to be the most durable choices. From an energy perspective, fiberglass is far preferable to aluminum.
Aluminum windows are highly conductive; since they don’t insulate as well as vinyl, wood o fiberglass frames, they are rarely appropriate for an energy efficient house. Foam-filled fiberglass frames perform better than other materials. Foam-filled vinyl frames are a closed second, followed by woods frames. Some manufactures offer composite frames made from a variety of materials; if these include a thermal break, they can perform well.