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Geoexchange Helps You Bury Your Energy Costs

Geoexchange taps into the earth to help lower home heating and cooling bills.
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My basement den is often my favorite room in the house. It's cool enough during the dog days of summer that I can actually feel the temperature drop as I walk down the stairs from the ground floor. Yet during the winter it's still temperate enough to feel cozy.

This is the working theory behind


heating and cooling systems. They're also sometimes called ground-source heat pumps.

The idea is that regardless of whether you live in a cooler or warmer area, the air underground remains a relatively steady temperature -- 45-50 degrees in the northern U.S. and 50-70 degrees down south, according to

. If you can push this ambient temperature up into your home, you can reduce or even eliminate the need to use air conditioning or fossil-fuel-based heat.

These days, that can translate into major savings -- and a good conscience for reducing greenhouse gases from burning fuels and using an alternative to drawing electricity from a power plant.

I'm no engineer, so if you want the technical specs for how it works, check out


very good explanation or


layman's discussion of it.

Basically, a contractor you hire digs several holes in the ground -- 100 feet or so down -- for pipes and then installs an electric pump that pushes air or water down to be warmed during the winter or cooled during the summer.

It sounds exotic, but it's an option that's becoming more common in both new and existing homes. They're used in all 50 states, according to

National Renewable Energy Laboratory

. The Energy Information Administration reports that sales of these pumps were up 33% in 2006 from a year earlier.

These systems aren't cheap to install. The

Department of Energy estimates

$2,500 per ton of capacity, or about $7,500 for the typical house. But in a study of Louisiana army housing where the pumps were installed, the DOE reports that they "reduced summer peak electric demand by 43 percent, and reduced electricity consumption by 33 percent, while eliminating natural-gas consumption altogether."

The DOE estimates that in homes that use these systems for both heating and cooling, energy savings are typically about 30% and can be as high as 40%. Most estimates have them paying for themselves in five years or so, but you'll have to do your own math to figure out how quickly it will pay off for you at current energy prices.

If you're interested in the long-term savings but lukewarm on the short-term cash outlay, take a look at the

Dsire website

. In a well-meaning but arcane and hard-to-follow way, it keeps track of the incentives and rebates available locally for investing in renewable resources and energy-saving upgrades. It can also tell you where to find loans to pay for these improvements.

In addition to the utility savings,


points out that they are also quieter and need less maintenance than conventional HVAC systems -- and they reduce humidity, too.

So if you have the resources and want to save on electricity and fuel, geoexchange systems are worth considering -- or you can just hang out in your basement year-round.

Eileen P. Gunn writes about the business of life and is the author of "Your Career Is An Extreme Sport." You can learn more about her at

her Web site.