You can choose window treatments for windows or coverings not only for decoration but also for saving energy. Some carefully selected window treatments can reduce heat loss in the winter and heat gain in the summer. Window treatments, however, aren’t effective at reducing air leakage or infiltration. You need to caulk and weather-strip around windows to reduce air leakage. Window awnings can reduce solar heat gain in the summer by up to 65% on south-facing windows and 77% on west-facing windows. You can use an awning to shade one window or have an awning custom-made to shade the entire side of your house.
Window treatments for windows like blinds vertical or horizontal slat-type are more effective at reducing summer heat gain than winter heat loss. Because of the numerous openings between the slats, it’s difficult to control heat loss through interior window blinds, but the slats offer flexibility in the summer. Unlike shades, you can adjust the slats to control light and ventilation. Exterior roller blinds are usually made of wood, steel, aluminum, or vinyl. They’re mounted above the window, and side channels guide them as they’re lowered and raised. When you lower these blinds completely, their slats meet and provide shade. If partially raised, the blinds allow some air and daylight to enter through windows.
A drapery’s ability to reduce heat loss and gain depends on several factors, including fabric type closed or open weave and color. With such a wide variety of draperies available, it’s difficult to generalize about their energy performance. Draperies also stay cooler in the summer than some other window treatments because their pleats and folds lose heat through convection. To reduce heat exchange or convection, draperies should be hung as close to windows as possible. Also let them fall onto a windowsill or floor. Two draperies hung together will create a tighter air space than just one drapery. One advantage is that the room-side drapery will maintain around the same temperature as the interior space.