Evaluating your home's energy efficiency

Leaks through small cracks around windows and doors are responsible for 30 to 40 percent of the heat that leaks out of your house. Before you tackle more extensive—and more expensive— insulating jobs, track down and fix these smaller problems. Companies will do this for you using infrared detectors and other sophisticated equipment, but while they may do a slightly more dramatic job, you’ll be able to figure out on your own where the problems are.

Start outside by looking at places where two different materials meet: walls meeting windows, water spigots, pipes, or phone lines. These are the areas where leaks occur. Try slipping a sheet of paper between the two surfaces, or look for light leaking through. Either indicates a space. Check for rattling—a window or door that rattles in its frame is loose, and loose equals leakage. Finally, do what’s called a depressurization test. Wait for a cool, windy day and close up the house as tightly as you can. Turn on any fans, such as bath or kitchen vents, that move air outdoors. Check for leaks with a smoking match or burning incense stick as described below. Once you’ve checked 10 or 20 windows, it can be difficult to remember which of them needed to be fixed. Mark any leaks as soon as you find them, using a piece of red tape. It’s guaranteed to nag you into fixing the problem.

TOOLS: Thermometer, incense sticks, paper

CHECK FOR LEAKS AROUND WINDOWS AND DOORS on a cool, windy day. Close and lock all the windows and doors, and turn off the furnace. To help encourage leaks, turn on all the fans, such as those in bathrooms or cooking hoods. Move a smoking incense stick around the doors and windows. If the smoke flutters, you have a leak.

TO LOCATE THE LIKELY SOURCE OF A LEAK, look at existing weather stripping and caulking. Look for signs of deterioration, such as crumbling foam or rubber; hardening of flexible products, such as felt or foam rubber; or damaged or torn metal stripping. Replace the products as needed. Most weather stripping products will last only a few years, so expect this to be a seasonal chore. When caulking, instead of filling the gap, apply the caulk so that it spans the gap and grabs onto the adjoining surfaces.

LOOK FOR CONDENSATION, FROST, OR ICE BUILDUP ON THE INSIDE SURFACES OF INTERIOR WINDOW SASHES. Such conditions indicate that you need storm windows or that air is leaking around the ones you have. Also check for condensation, frost, or ice buildup on storm windows. This indicates that warm, moist air is escaping and that the seal between the interior window and the storm window needs attention.

EVEN IF THE WINDOW IS WELL-SEALED, AIR CAN LEAK AROUND AND THROUGH AN AIR-CONDITIONER. Put foam air-conditioner weather stripping around the edges of the air-conditioner, and put a vinyl fabric cover over the outside of the air-conditioner at the first sign of cold weather.

MEASURE THE TEMPERATURE IN DIFFERENT PARTS OF A ROOM. Differences of more than 1 or 2 degrees indicate that the room is poorly sealed or that air movement inside the house is poor. Update weather stripping around doors and windows, then measure temperatures again. If the differences still exist, you may have an airflow problem with your heating system. Often, your public utility company will provide information about airflow problems and how to correct them.

A SURPRISING AMOUNT OF COLD AIR SEEPS IN AROUND OUTLETS AND SWITCHES. Seal the leaks by slipping an inexpensive foam gasket between the faceplate and the electrical connection.

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