We recently described low-E windows in a previous blog post. They are double-paned windows whose interior panes are sprayed with metals that reflect radiation from the sun. Low-E coatings often display similar performance as high-end ceramic films in total solar energy absorption, which can be dangerous to glass if they are improperly combined. Here’s why.
Double pane windows consist of two single pane windows separated by a sealed space, usually filled with an insulating gas like Argon. This creates a total of 4 glass “surfaces.” Surfaces 1 begins on the interior of the window, surface 2 is the other side of that single pane that faces the outside, surface 3 is the interior surface of the second pane, and surface 4 is the exterior surface of the second pane which faces outside. Low-e coatings are most often applied to surface 2, while traditional window tint is applied to surface 1. That means that all the solar energy absorption is happening on the same pane of glass, which can cause it to break if it gets too hot.
However, if you want the maximum amount of performance out of your windows, there is now a solution to this problem, for there are new window films available now, such as SolarGuard’s Sentinel Plus that are designed to go on the surface 4, that is, the outermost layer of a double pane window. This design disperses the heat absorption between the two panes, rather than concentrating it all on the same one, which removes the danger of breaking one of the panes while allowing the window film and low-E coating to work together in order to maximize performance.