I hate to throw another monkey wrench into the home-buying process, but I'm beginning to see considerable wisdom in having an energy audit performed as part of the home-inspection process.

I know what you are saying, listing agent or seller of home. It's bad enough that the market seems to be slowing, and now here comes Heavens suggesting we add another potential slowness and doubt on the transaction.

My reason is simple: With the cost of energy rising so rapidly, buyers already stretched to the edge by home prices should have a good idea what it costs to heat and cool that house every year before they buy, as well as how much it might set them back to make the changes needed for more efficient energy consumption.

What is an energy audit? Well, if you have a degree in electrical engineering from MIT, you can use one of the energy-auditing tools available on the Internet.

If you are math or even computer challenged, you may need to hire a professional for $200 to $300 to do it for you. Check the website of the National Association of Energy Service Companies for a list of home energy auditors in your area.

This is not a job for a home inspector, who is, for want of a better description, a generalist. A home inspector can tell you if your windows have problems, but he or she doesn't usually have the technology to tell you where the warm air is leaving the house and how to stop it.

By the way, stopping it requires more than just throwing insulation at the problem. It requires something call air sealing -- that is, closing all the gaps that precious heat will find to get out of the house.

Here's how an energy audit is performed:

A blower door is a fan mounted into an exterior door frame. The fan pulls air out of the house, lowering the air pressure inside. The higher outside air pressure then flows in through all unsealed cracks and openings.

Thermography, or infrared scanning, measures surface temperatures -- the light in the heat spectrum -- with video and still cameras that record the temperature variations of the building's skin. The tests are designed to check for air leaks and to determine where insulation should be installed, or whether the insulation already there has been put in improperly.

The air leaks are usually found around utility or plumbing chaseways -- the openings that plumbers and electricians cut to run pipes and wires from the top to the bottom of the house, as well as around chimneys and heating and air conditioning ducts.

Some of the gaps are small and can be filled with insulating foam or caulk. Some must first be filled with, say, a plastic trash bag filled with insulation to fill up the hole and then with foam to seal it.

You can fold a piece of kraft-faced (paper) insulating, squeeze it in the space, and then use foam to fill it in.

If your house is not insulated, see whether insulation would help cut the heat loss. If it has insulation, it might not be enough to meet federal recommendations. For example, if you have less than 11 to 12 inches of attic insulation, you probably need more.

Because heat is a form of energy, it always seeks a cooler area, flowing out of the house in winter and into the house in summer. Insulation reduces the heat flow, and, when used properly, it results in less energy used for heating and cooling.

How well insulation resists heat flow is its R value. Standard fiberglass insulation is rated at R-3.5 per inch. R-11, recommended for exterior walls, is about 3.5 inches. R-38, used for ceilings below ventilated attics, is about 13 inches thick.

The first inch offers the most resistance to heat escape; each consecutive inch offers slightly less.

R-values are cumulative, so there is no need to remove what's already there. By layering two different batts together, you get the combined R-value of both batts. For example, two layers of R-19 batts will give you a total of R-38.

If you have forced-air heat, change the filters regularly for more efficient operation, not just once in the fall and once in the spring.

Lighting accounts for 10 percent of your electricity bill. Check the wattage of your light bulbs and see whether you can use 60 watts instead of 100 watts in the lamps and fixtures.

There are other inexpensive ways to cut costs.

Every time you increase the temperature on the thermostat by 1 degree, you add 3 percent to your fuel bill. If you are chilly, put on a sweater.

If your furnace does not have a built-in humidifier, use a portable unit in frequently occupied areas such as the bedroom and living room. The additional moisture will increase the heat index inside your home, making 68 degrees feel more like 76.

And open up the shades and curtains on sunny days to let the heat in. Do the reverse in the summer.

Knowing the energy-efficiency of the house you are buying before you buy may not deter you from buying it, but it certainly will help you become aware of the costs awaiting you after you move in.