Finding your home's drafts
Is your home drafty? Though some drafts may be caused by gaps in your home's exterior air barrier that allow cold outdoor air to enter your home, many apparent drafts are not caused by air leaks at all.
Air leakage that allows outdoor air into your home can increase heating and cooling expense by 10 to 30 percent. The heated or cooled air in your home will easily travel through cracks that are hidden behind trim, under carpet, or around light fixtures. But these tiny openings don't tend to add up to much real heat loss. It's the big holes around chimneys, wires, and plumbing fixtures that sap your home's energy efficiency, and the average home has lots of them.
Take a bright light into your attic, basement, or crawl space, and follow the paths of these utilities where they pass through walls, ceilings, and floors. Use foam sealant, sheet metal, or caulking to seal large openings that allow air to pass into hidden cavities. You'll save energy in both summer and winter by sealing these large air leaks.
Windows may seem drafty, but they don't usually leak that much air. What happens instead is that the cold window glass cools the air right next to the window. This cold, dense air then sinks to the floor, and flows out across the room. Warm air flows in at the top of the window to replace the cold air, and a circular pattern of airflow is established in the room. It's tempting to blame all the small cracks around your windows, doors, and baseboards for these drafts, but caulking them up usually doesn't save much energy. What is the solution to most cold window problems? Install heavy curtains, or install storm windows if your windows only have a single pane of glass.
You can save a lot of energy and be more comfortable if you seal up your home's drafts. But don't worry about the little stuff until you've found and sealed all the large hidden openings in your home's air barrier.
Source: Saturn Resource Management