Aluminum Window Basics
Aluminum windows are made, not surprisingly out of aluminum metal. Most aluminum window frames today are what's called thermally broken, meaning that there is a piece of nonconductive material between the different pieces of aluminum used in the frame. This greatly helps to better the energy efficiency of the windows. Even with this advance, aluminum window frames are still much less energy efficient than other types of window frames such as vinyl and fiberglass.
Aluminum windows are used in most commercial buildings due to their incredible strength. Aluminum windows are some 8x as strong as vinyl windows and 20x as strong as a full wood window. Unfortunately, the frames are very energy inefficient. The poor performance numbers are enough to keep most homeowners with the other frame alternatives. The one exception is very hot climates where aluminums strength and durability is a great option.