Rejecting solar heat at the window means less heat to remove later, which is where the comfort and efficiency argument for film starts. Rooms that used to be unusable by mid-afternoon become easier to keep at an even temperature, and cooling equipment cycles against a smaller load. How much difference you see depends on the film, the glazing, the orientation of the room and how the home is used, so treat it as an improvement to the glass you already have rather than a fixed figure. For Palm City homeowners, film is a much smaller job than replacing windows, though it is not the same thing as new glazing. Identifying the existing glass first matters: double-pane and low-e units need a film specified to suit them, and that is part of the conversation with the dealer before anything is ordered.