People ask for Low-E windows, but the term is a bit vague at best. “Low-E” literally means low emissivity, which in turn means a surface that emits low levels of radiant heat. All surfaces reflect, absorb, and transmit heat. So, a Low-E coating reduces the amount of that heat transfer.

Replacement windows have been developed as a labor and cost-cutting alternative. There are two main types of replacement windows: