How to Stop Heat Transfer Through Windows

Clean the window thoroughly inside and out, using window cleaner and clean cloths. Both sides must be cleaned completely to ensure no dirt particles are on the pane so the film can bond to the glass.

Measure the windowpane with a yardstick. Roll out the window film on a table and use scissors to cut it to overlap the pane by a few inches on each side.

Ask someone to hold the film close to the window. Liberally spray the window pane with the film installation solution that came with the window film, then peel the backing from the window film and spray the adhesive side of the film.

Press the window film against the wet glass pane and rub from the center out to the edges of the pane with the palms of your hands, forcing air bubbles out of the film.

Squeegee the window film after pressing out the largest air bubbles with your palms. Start at the top of the glass pane in the center and squeegee to the edge, then squeegee from the center top to the opposite edge.

Continue to squeegee from the center out to the sides, going from the top of the window to the bottom. Squeegee out all air pockets, but leave tiny water beads to evaporate from the sun.

Place the yardstick against the edge of the windowpane and cut down the yardstick into the window film with a utility knife. This will leave about a 1/16-inch gap between the edges of the film and window frame, allowing the film to expand with heat during the summer.