Click this link to watch a few short videos on energy use in an existing home.

Windows

A typical wall construction using 2 inch by 6 inch studs and insulated with fiberglass batts will have an R-value of 19. The best, most efficient, windows will have R-values closer to an R-6 or lower. As a result windows can be areas for greater heat loss than walls. This video will cover some of the energy basics of windows.