TECHNOLOGY BASICS: What are Window Retrofit Films?

Window films are one of the lowest cost options for improving the energy and comfort performance of windows. They can be used to reduce glare for building occupants as well as reduce cooling and/or heating energy use.

Window films consist of one or more polymer layers, sometimes encasing other materials, that are mounted on the interior or exterior surface of the window glass using a transparent adhesive. These films modify the way windows behave with regards to light and heat, generally reducing light/heat that is admitted through the window and into or out of the building. Interior-mounted films are the most common in energy-efficiency applications.

A wide variety of film products are commercially available from several major manufacturers. Films focused on improving the comfort and energy performance of windows are usually transparent and have a clear appearance. Once the installation and drying processes are successfully completed, the presence of a film is usually not noticeable to the casual observer and requires closer inspection to be detected.

Available film products also include films with patterns – e.g., for decorative purposes – or with some level of impact resistance, preventing shattering of glass.