Detecting Drafts With an Energy Audit

By: Eileen McCluskey, This Old House magazine (Page 1 of 5)

one man holding camera and other marking lines for insulation

Photo: Russell Kaye

Energy expert Bruce Torrey uses an infrared camera to spot temperature changes inside walls, directing This Old House general contractor Tom Silva as he marks the places where he'll need to beef up insulation.

Photo: Russell Kaye

A smoke stick demonstrates how air leaks through a vulnerable door

Photo: Russell Kaye

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

Photo: Russell Kaye

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.

Photo: Russell Kaye

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.

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Bruce Torrey held up a chunk of fiberglass insulation that he'd just ripped from a crawl space off the third floor of Madeline Krauss and Paul Friedberg's soon-to-be-renovated Shingle-style home. Turning it over, he showed Maddy the dirty black streaks that coated its edge. "Wow, what is that?" she asked with concern. "Was there a fire?"

Thankfully, the house—the site of This Old House TV's 2007 project house—hadn't been damaged by flames. But the ugly smudges were a warning that the three-story house could still burn its new owners—with outsized heating and cooling bills. The marks were soot streaks, caused by drafts whipping against the fiberglass insulation, which collected the dirt particles from the air. Finding such drafts is part of Torrey's job as senior building investigator for Building Diagnostics, the Cape Cod–based company the couple hired to conduct an energy audit on their house before construction began so they could learn where they needed to tighten up.

Leaks and drafts that let heat escape in the winter and trickle in during the summer aren't easily detected, because they're usually the result of problems behind walls or in other hard-to-reach places. "Heat loss and drafts are by their nature invisible," says Torrey, who worked with TOH general contractor Tom Silva to identify problems in the 1897 house. Together, they ran a diagnostic energy audit, which relies on a combination of sophisticated equipment and good old-fashioned detective work. For a cost of about $400, such an audit provides homeowners with a written report detailing a home's problem areas and laying out cost-effective solutions.