Up to one-third of heating and cooling costs can be lost through inefficient windows, and many utility customers have older less efficient single pane windows in their buildings. Once installed, window film may offer year-round savings of about five to 10 percent of the buildings’ total energy bill. New window films block 40-60 percent of all energy being lost through glass in winter and may cut cooling costs by 30 percent.
Window film, which comes in a variety of shades from visually clear to dark, also prevents most harmful UV rays from penetrating into the home and causing harmful exposure to your skin and interior furnishings. Window film installation costs can range from $3 to $11 per square foot, depending on the type of application and the process can be completed in one or two days.
Here is information on how to determine the performance of window film (pdf)
Window film reflects solar and radiant heat, saving on cooling costs, reducing glare, and protecting from UV damage. Window films may reduce the sun’s solar heat gain coming through glass by up to 85%.
Window film may provides up to 92% insulating power to existing windows, keeping radiant heat inside during colder months and save on heating costs.