How to cut air-conditioning costs

Solar screens, or mesh-like window screens, intercept up to 70 percent of solar energy before it gets into the house, Krigger says. Window screens are particularly effective on east- and west-facing windows, according to the U.S. Department of Energy.
Window films are another option. They are transparent, metalized sheets that reflect heat before it can be transmitted through glass.

However, windows must be shut for window films to work, while solar screens do double-duty, keeping sun and insects out even with windows open.