User:Shaws NIH/sandbox

Insulating window inserts are products made to be positioned on the house side of an existing window and reduce heat loss through the window.

Rationale
Windows are a major source of heat loss from both residential and commercial buildings. Window heat loss is an especially big problem for two reasons in older buildings for two reasons. First energy conservation was not an important design consideration in older construction. Second, as buildings age, windows often deteriorate and heat loss increases.