Use Windows to Beat the Heat

Windows bring views, comfort, ventilation, and energy efficiency to a home. Windows also bring large solar heat gains and kick the cooling system into overdrive, not to mention the damaging UV rays that fade furniture, draperies, and rugs. Whether a home is designed to fit your dream site or you are working with a builder to select the best options for a neighborhood home, increased energy efficiency and reduced heating and cooling costs can be achieved by carefully planning window placement.

Protecting against the sun makes big dollar sense. According to the U.S. Department of Energy, an average household spends over 40 percent of its total annual energy budget on heating and cooling costs. In South Florida, consumers may spend that much on cooling costs alone. These costs can be reduced by 15 percent on average just by switching to energy-efficient windows and planning for window placement, shading, and ventilation.

Which Way to Turn

First and foremost, homeowners need to pay attention to which direction their home is facing. The angle of the sun in the summer and the length of direct exposure are extreme on eastern- and westward-facing sides of the home.

California-based energy expert Steve Easley explains how to avoid that beating sun, all while understanding that no one wants a blank wall with no windows. “Orient your glass so that it faces south,” Easley says. “The sun is higher in the summer, so it hits the glass at less of a direct angle. Also avoid large amounts of glazing on the east and west faces where the sun will heat it at a direct angle for long periods of time.”

For a hot-climate home, battling the sun and controlling cooling costs are the critical focus for design and energy calculations. In some areas of the country, design reviews and approvals focus on a building’s ability to control solar heat gain. Progressive review boards want to know the impact of solar heat gain on cooling loads, or how much energy it takes to reduce a home’s temperature. These boards require strategies for reducing heat gain without overly consumptive energy use. Controlling energy use in hot climates means controlling heat gain.

“When we created the Palm Springs EnergyWise House, we designed first for the views,” says Dennis Cunningham, a builder at Palm Springs Modern Homes, “then we did the calculations to see if we could make it work. We were lucky with this project that the views were north-northwest. As a result, we don't get any beating sun.”