Worn and torn weatherstripping around doors and windows creates drafts and lets in cold air. Seven to 12 percent of a home's heat loss occurs around windows and doors, which often prompts homeowners to turn up their furnace to keep comfy. Even if they don't turn it up, they're losing warm air, causing the furnace to work harder. "Weatherstripping around doors, and caulking around doors and windows, can cut down on drafts," says Jeff Rogers, president of the Energy Audit Institute, an energy audit training and certification company in Springfield, N.J.
Some weatherstripping needs to be replaced every few years because of wear. Replacing it is typically as simple as pulling off the old and tacking on the new.