Window film is only for single pane glass.

Energy Products Distribution

False! Window film is not just for single pane glass. While double pane glass has a significantly lower U value than single pane glass, thus reducing heat loss in the winter months, it still has a SHGC that is somewhat similar to single pane glass. Therefore, window film can increase the energy performance of double pane glass. Additionally, some window films not only reduce a window’s SHGC, but also its U value. These insulating types of film are appropriate for any window, whether single or double pane, that needs a lower U value.