 They sure can. Obviously, during the hot summer months, shades, blinds, drapes, closing the window, keeping as much solar exposure out of the home will help keep the living space that much cooler. And again, not forceful ACs or central ACs to work that much harder to keep the living space cool. Conversely, there are shades that you can use during the winter months that if you have drafty windows, obviously, if you have a drafty window, you can keep the living space cool.