Why stopping drafts under your door won’t save much money

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caulking drafty windows

There’s a nip in the air. And whether you live in a brownstone in the city or a big spread in the suburbs, you don’t want the chill to come in with you — or your home’s warmed air to leak out — when you settle in for the night.

Air leaks are uncomfortable, maybe even irritating, and they also cost you money. According to the Environmental Protection Agency’s Energy Star program, you can save as much as 10 percent on your total energy bills (20 percent of your heating and cooling costs) each year by properly sealing and insulating your home. Here is some advice on how to get started.

Know common sources of air leaks

If you’ve lived in your house for a while, you probably know where some air leaks are, simply because you’ve felt them. And while you might think windows and doors are the biggest culprits, Energy Star says your most significant air leaks likely come from other sources hidden away in the basement and attic of your home:

  • Knee walls (side walls that supports attic rafters)
  • Attic hatch/opening
  • Wiring holes (cable TV, electrical outlets, phone lines)
  • Plumbing vents
  • Recessed lights
  • Furnace flues or ducts
  • Basement rim joists (where the foundation meets the wood framing)

Identify your home’s drafts

DO YOUR OWN INSPECTION. You’ll need to identify these less-obvious air leaks to make a impact on your energy bills. Energy Star says you can do that yourself, with a careful visual inspection inside and out: Look for gaps and cracks at the common points of air leakage (e.g., knee walls, dryer vents, outdoor faucets, attic hatches, sill plates) and pay close attention to the building envelope — the outer walls, doors and other openings of your home. Take notes of any cracks, gaps or other openings, so you can return and air-seal them later.

You can also perform a simple test to supplement your visual inspection. Energy Star outlines various methods, but offers the following steps for performing a DIY smoke test:

  • Pick a cool and windy day, and turn off all appliances or stoves that create air disturbances.
  • Shut all windows, doors and fireplace flues.
  • Carefully light a stick of incense and hold it near any potential points of air leakage (see the common points of air leakage list above).

If the smoke begins moving unsteadily back and forth, or if it’s sucked out of the room or blown into it, you have an air leak.

GET A PROFESSIONAL INSPECTION. Of course, you can also hire a professional to identify air leaks by performing a home energy audit. Typically, the process includes a blower door test, where a powerful fan is mounted to the frame of an exterior door. The fan pulls air out of the house, lowering the pressure inside, and allows the higher outside air pressure to flow in through cracks and other openings (the pros typically use something called a smoke pencil, similar to the DIY smoke test outlined above, to spot the culprits; a blower door test not only locates air leaks but can also assess the overall air tightness of your home).

Some energy companies and local and state governments offer free energy assessments and recommendations to make your home more energy efficient, so if that’s something you’re interested in, contact your local energy supplier or state public services.

Gather your materials

Now that you’ve found your home’s air leaks, it’s important to get familiar with the tools of the trade. Caulk and spray foam are designed to seal up stationary materials and fixtures like window frames (Energy Star recommends using caulk on holes 1/2 inch or less and spray foam on holes 1/2 inch to three inches). Weatherstripping is meant for items that move, like doors and operable windows (between the frames and sashes). You might also need a few specialty materials, like high-temperature caulk, metal flashing and reflective foils, depending on the project.

One important thing to note: Air sealing can inadvertently cause a different problem, trapping indoor pollutants like radon or carbon monoxide and creating an unsafe situation inside your home. Energy Star says you should consider bringing in a professional to test for radon and to check whether heating appliances are sending out potentially harmful gases — both before and after doing any air sealing; he may recommend ventilation fans to maintain safe air quality in your home.

Prioritize your projects; attics first, then basements

So, where to begin? Energy Star recommends prioritizing projects based on the biggest opportunity for comfort and savings.

ATTICS. At the top of the list is your attic. Don’t worry about finding all the little gaps and cracks, the program says; focus on sealing up the largest holes first, because that’s where you’ll realize the biggest energy savings.

An attic air sealing project might include creating pouches of fiberglass insulation to plug open stud cavities and gaps behind knee walls; using reflective foil to cover soffits; and fitting aluminum flashing on the openings surrounding furnace and water heater flues.

BASEMENTS AND CRAWL SPACES. From there, your next biggest savings come from tackling the basement and crawlspace, where sealing air leaks can prevent cold floors and reduce drafts from below.

A basement air sealing project might include using spray foam or caulk to seal cracks and openings in the basement walls, ceiling or floor; along the gap between the sill plate and the foundation; at the bottom and top of each rim joist (where cement walls meet the wood frame) at each end of the house; and the openings for gas, water and electrical lines, ducts and wiring that pass to the outside (like your dryer vent). Larger holes might need pieces of insulation to cover them.

DOORS, WINDOWS, AND WALLS. Though leaks in doors and windows probably result in your most noticeable drafts, sealing them has the least impact on your energy use, Energy Star says. But, because these areas area readily accessible and the solutions tend to be simple, they offer an opportunity for a simple do-it-yourself job that will likely result in minimizing obvious uncomfortable drafts.

A door or window air sealing project might include rolling self-adhesive weather stripping (felt, vinyl, rubber or silicone) down the side of a window; installing a door sweep to seal the gap between the bottom of the door and the threshold; applying plastic over windows; and fitting inexpensive foam gaskets (found at most hardware stores) behind electrical outlets on perimeter walls.

Whether you do these draft-stopping projects on your own or hire a pro, once you’re done, don’t forget to sit back and enjoy that extra warm feeling that only comes from saving on your energy bills.


 

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