If your home has single-pane windows, as almost half of U.S. homes do, consider replacing them. New double-pane windows with high-performance glass are available on the market. In colder climates, select windows that are gas filled with low-emissivity (low-e) coatings on the glass to reduce heat loss. In warmer climates, select windows with spectrally selective coatings to reduce heat gain. If you decide not to replace your windows, there are other ways to improve their performance. In cold climates, close your curtains and shades at night, and open them during the day. Installing storm windows can also reduce your heat loss, by up to 50%. In warm climates, install white window coverings to reflect heat away from the house, and close south- and west-facing curtains during the day.