Air leaks drain more than a quarter of home heating energy, experts say

The fixes target a structural weakness common to most U.S. housing stock: gaps and cracks around doors, windows, electrical outlets and recessed ceiling lights allow warm air to escape continuously, forcing heating systems to compensate and driving up utility bills.

The Environmental Protection Agency estimates that air leakage accounts for more than a quarter of the energy used to heat or cool a typical American home — a hidden drain that energy experts say can be meaningfully reduced without expensive whole-house insulation or ductwork replacement.

“It’ll lower your utility bills, it’ll make your home more comfortable and reduce your energy use,” said Johanna Neumann, senior director with the advocacy organization Environment America.

Finding the leaks

Neumann said the first step is locating where air escapes. On a windy day with all windows and doors closed, a lit candle or burning incense can reveal problem spots: a flickering flame or smoke that bends toward a surface indicates a draft. Homeowners willing to spend $100 to $200 or more can use thermal cameras, which show temperature differences across walls and frames.

Neumann said it is best to search for leaks on a cold or very hot day, when the temperature outside differs from the inside by at least 15 degrees Fahrenheit (8 degrees Celsius).

Windows

Matt Lanteigne, a DIY home construction expert, recommends putty or sealant for cracks along window edges and trim, along with indoor window insulator kits — both typically less than $20. The kits include a plastic film spread over the window and secured at the edges with double-sided tape; a blow dryer tightens the seal.

“They’re really easy to install, and they’re not permanent, as long as you’re careful taking the tape off after the winter,” Lanteigne said.

Eric George, an energy auditor and contractor with Home Comfort Advisors, said window trim is a frequent culprit because painters often skip caulking the top and bottom edges, where the gaps are not visible. Different putties work with drywall, plaster, concrete and metal, and George said homeowners should match the product to the surface.

Doors and outlets

Door sweeps — strips of metal, rubber or plastic affixed to the bottom of an exterior door — typically cost less than $20 and block the gap at the threshold. Felt or rubber weatherstripping, which typically costs less than $10 per 10 feet (3 meters), seals the gap along the top and sides of the door frame.

“You just go around and you tack it or glue it to the inside of the door jamb where the draft is. And it should fit pretty snugly,” Neumann said.

Indoor electrical outlets can leak because they are often left unsealed when cut into drywall or plaster. Cold air in the wall cavity flows through the opening. Foam outlet sealers — small rectangular sheets installed under the outlet cover plate — cost less than $10 for a multipack and require only a screwdriver to install. In attics and basements, caulk guns or spray foam can seal gaps where electric wires and pipes pass through walls, ceilings and floors.

Recessed lights and attic access

George said recessed ceiling light fixtures are among the most consequential sources of air loss in many homes.

“Most of the air in your house leaks out of the top of the house. And as that air leaks out the top the house, it draws air in through the bottom of the house,” George said.

Many recessed fixtures were designed for incandescent bulbs that ran hot, leaving extra holes to allow heat to dissipate. Those holes become air passages in an era of cooler-running LED lights.

“There’s people that have 20, 30, 50 recessed lights in their houses and it basically turns their house into Swiss cheese. I mean, there’s just tons of air leaking out,” he said.

Hardware stores carry retrofit kits costing between $5 and $30 that address the problem. George said the process involves switching off the breaker, removing the old bulb, caulking the gap between the fixture and the drywall, and sealing the holes in the can with metal tape before installing an LED adapter. He said the work can typically be done without an electrician.

Vents for dryers, bath fans and kitchen hoods often allow outdoor air to flow back inside when not in use. Backdraft dampers — cylinder-shaped add-ons with metal or rubber valves that allow air to flow out but not in — typically cost between $10 and $50 each. For attic entrances and pull-down staircases, George recommends foam boards to cover the openings and weatherstripping along the edges to stop warm air from escaping through the ceiling.