How to Make Existing Windows Energy-Efficient

Hang thermal curtains and close them to help keep out the cold of winter and the heat of summer, especially on windows that face south and are exposed to direct sun. Other helpful window treatments are cellular window blinds, insulation shutters and solar screens.

Seal your windows with caulk to help stop air leaks around the edges and window. Remove old caulk with caulk solvent (follow the manufacturer's instructions) and a putty knife before applying new caulk to all window joints in the window frame, as well as between the window frame and the wall behind it.

Apply weather stripping to seal the area between the window sash and the frame. This will also help prevent air leaks.

Plant trees that lose their leaves each year near enough to your home so that they provide shade near your windows in the summer and allow light to come through in the winter. However, don't plant them so close that their roots will threaten integrity of your foundation. Discuss your plans with a professional at a local nursery to choose the right deciduous trees for your yard, and call 811 a few days before digging to ensure you don't damage buried lines, pipes and cables.

Hang awnings outside your windows to help reduce the temperature around them by up to 15 degrees Fahrenheit. This is especially helpful on south-facing windows, as it protects them from the glaring sun. Work with a professional at a home store who can help you choose an awning that compliments the style of your house and correctly fits your windows.