﻿Exterior window film reduces solar gain
Exterior window films from 3M are applied to the outside of the window and claimed to block up to 77% of solar energy to reduce solar gain. Applying these films externally to double or triple glazing greatly reduces the risk of breakage from thermal stress.
These films transmit up to 90% of visible light to preserve interior and exterior views. There is no change to the exterior appearance of the building such as darkening of windows or mirror effect.