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Conducting An Energy Audit
Published: January 19, 1997

UNLIKE space shuttles and Mason jars, houses are not meant to be airtight. Some houses, however, are better than others at letting outside air in. And what may be good in moderation turns to bad when what is leaking into your house is a lot of cold winter air.

Rather than just bundling up and bearing it, however, homeowners can use winter's onslaught to their advantage: There is no better time than now to conduct a home energy audit.

''In all likelihood, any house built more than 15 years ago and never upgraded could benefit from an energy audit,'' said Alex Wilson, editor and publisher of Environmental Building News, a trade journal in Brattleboro, Vt.

An energy audit, Mr. Wilson said, is used to determine the efficiency of a home's heating system and to pinpoint where energy is being lost.

Professional energy auditors, Mr. Wilson said, will typically use special tools -- like infrared cameras, smoke pencils and blower doors -- to prepare a highly detailed assessment of problems and recommended solutions.

John Lyon, the owner of Energy Services Group, a diagnostic and consulting company in Frazer, Pa., said that when he conducts a home energy audit he gives the house an infrared scan.

An infrared scanner, Mr. Lyon said, like an infrared camera, will display differences in temperature when pointed at a surface. Accordingly, he said, an infrared scan conducted from inside the house will reveal not only the areas of cold air infiltration, but areas of walls and floors that are warmer or colder than adjoining areas.

''We can see heat ducts, water pipes, even the studs in the wall,'' Mr. Lyon said, adding that the infrared scan will also reveal areas of inadequate or nonexistent insulation.

After the scan, he said, he will then conduct a pressurization test using a blower door -- a fan with expandable sides and top that allow it to fit snugly in a doorway -- to draw air out of the house.

''When we suck air out of a house, the outside air comes in through all the points of leakage,'' Mr. Lyon said, explaining that while the outside air is coming in, another infrared scan is taken to determine where the house is leaking -- thereby allowing the homeowner to take action later to plug the leaks with caulking or insulation.

In houses with hot-air heating systems, Mr. Lyon said, an energy auditor should also perform a duct-flow analysis test to assess the integrity of the ductwork in the home.

In such a test, he said, the air blowing out of the system through delivery vents is measured and compared with the amount of air going back into the system through return vents. Since it is more efficient to have previously heated air reheated, Mr. Lyon said, the closer the two numbers are, the better.

''You want the system to be as tight as possible,'' he said. ''So if you're delivering 1,000 cubic feet of air per minute into the house, and only 300 feet per minute is going back into the system, then the system's getting air from somewhere else.'' That ''somewhere else,'' Mr. Lyon said, is typically from unheated areas of the house -- like the basement or attic.

To pinpoint where air is leaking into the system, he said, an auditor will use a smoke pencil -- a pencil-shaped device that emits white smoke to search for points in the system where the smoke is either sucked in or puffed away -- an indication of a leak that can then be sealed.

Most homeowners, of course, don't have access to infrared scanners, blower doors or smoke pencils. They can, however, conduct their own mini-pressurization test by closing all doors and windows and turning on ventilation fans in kitchens and bathrooms. They can then use an incense stick to smoke out areas of air infiltration around windows, doors, baseboards, electrical outlets and at seams in ductwork.

Homeowners can also conduct their own energy audit by calculating the total efficiency of their house and its heating system.

''It's easiest when you heat with fuel oil because in most cases, oil is only used for heat,'' said Mr. Wilson of Environmental Building News. In some houses, he said, the oil-fired furnace is also used to heat household hot water, making an assessment of heating costs alone difficult. Houses that use gas or electricity for heat, he said, pose even greater problems because those energy sources are typically used for other purposes -- such as cooking and running household appliances.

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