Don’t let precious heated or cooled air escape through cracks. Caulk and weather-strip to reduce air leakage. Professional auditors use a device called a smoke pencil to locate leaks, but you can get similar results with an incense stick. On a windy day, hold the lit stick next to your windows, doors, plumbing fixtures, electrical outlets, ceiling fixtures and attic areas, anywhere there is a possible path to the outside. Changes in the smoke column mean cold air can enter and heat can escape. Reducing these drafts can decrease your annual energy cost by as much as 30%.