Solar control window film is a thin film applied to existing glass that reduces the amount of solar energy entering the building. It reduces solar heat gain and glare, and Solar Gard’s architectural films block more than 99 percent of ultraviolet light. It goes on the glass you already have, with no window replacement.
How much heat a film rejects depends on the film and the glass. On 1/4 inch clear glass, Solar Gard lists total solar energy rejected at 53 percent for Ecolux 70, a light, low-reflective interior film, and 77 percent for Silver AG 25 Low-E, a darker, reflective interior film. Exterior films can go higher: Sentinel Plus Silver 20 OSW lists 82 percent.
Films balance heat rejection, daylight and reflectivity in different ways. Some reject a good share of solar heat while keeping most of the daylight; darker or more reflective films fit where more glare reduction or a different exterior look is wanted. These are published ratings for the film on a given glass, not a prediction of how much a building’s energy bills will drop.
Solar control film mainly addresses summer heat and glare. If heat loss through the glass in winter is also a concern, Low-E window film works in both seasons.

