Evaluating Window Insulation
CCHRC evaluated eight types of common window insulation methods, including interior and exterior types of moveable insulation. Windows are an expensive part of the building envelope to replace, so people in cold climates often resort to cheaper methods, such as shutters or curtains, to reduce heat loss. Others may already have high performance windows, but want to reduce heat loss further on cold winter nights.
To help guide these decisions, CCHRC conducted a study of common window insulation methods and compared them in terms of effectiveness, affordability, ease of installation, durability, and functionality. Researchers studied a variety of methods and windows in volunteers' homes to understand how the methods work in real-life situations. CCHRC also modeled the retrofit window treatments to help explain more generally how they can help homeowners.
This report also offers simple background information that will help explain terminology, like U-value, which measures the ability of the entire window (including glass and framing) in resisting the movement of heat.
The chart below compares various window insulation methods on the six factors we looked at.