Energy-efficient windows on the south wall of a home provide free (passive) solar space heating innovation. South-facing windows can provide much of the heat needed during cold weather, and when used in conjunction with an insulated slab foundation, concrete floor, or other ‘thermal mass’ indoors, much of that heat can be stored for release after the sun goes down.

It is important that all windows in the home be energy efficient with little heat loss through the glazing and frame. It is also important that an overhang shade south-facing windows during summer.