Detecting Drafts With an Energy Audit

A smoke stick demonstrates how air leaks through a vulnerable door

Homeowner Madeline Krauss examines a piece of fiberglass batting as Torrey explains that the smudges are caused by dust and dirt filtered from air that passed over the insulation in a leaky top-floor knee wall

To start his energy audit, Torrey replaced a porch door with a blower fan so he could lower the air pressure in the house and force outside air to be pulled in through uninsulated spots. Then he used an infrared camera to see where air from the hot outdoors was infiltrating the cool house.

These infrared camera images, taken in winter, show black marks where there are cold air pockets—the result of slipped or missing insulation along the top of the wall (a) or around an exterior door. An exterior door (b), like a window, is vulnerable to cold drafts. Improperly sealed light fixtures (c) or plumbing pipes can leak heated air in winter.