The earth has a constant temperature, and this is the basis of all geothermal heating and air conditioning systems. By drilling down to a place where the earth’s temperature is constant, energy can be extracted from the earth itself using a rather simple and easily-obtainable heat exchanger, which is not much different from a the guts of a standard air conditioner.

There are many advantages to a geothermal system. For one, the primary source of energy – the earth itself – is constant and free. A small amount of electricity is used to run the system, but far less electricity than is needed for a conventional heating or air conditioning system, so there is a savings on utility bills and your home has less of a carbon footprint. Green is good.

Installing a geothermal system is not easy or cheap – although, on the plus side, geothermal heating and air conditioning works equally well in both hot as well as cold climates. The reason? Because basically the earth is the same temperature a hundred feet down, regardless of surface conditions.

But let’s get back to costs. A brand new geothermal system will run – typically – around $42,000. The government will rebate approximately 30% of the cost as a tax credit, leaving the homeowner with a bill of just under $30,000. The primary cost of a thermal system is for excavating several thousand feet of looped holes plus the cost of pipe to go into those holes. Once the system is set up, it should run for close to 20 years with only minimal maintenance.

$30,000 sounds like a lot – and in one sense it is. But consider that if a homeowner were to install a conventional whole-house heating and air conditioning system the cost could be upwards of $20,000. Next consider the typical savings in utility costs with a geothermal system. The cost of electricity for heating and cooling a home drops to virtually zero with a geothermal system, and that negligible cost continues for at least 20 years, while the cost of gas and electricity will undoubtedly continue to rise.

The company a homeowner chooses to install a geothermal system can make a great deal of difference. Unfortunately, even though geothermal systems have been around for many years (more than one million systems are in operation worldwide) not all companies installing those systems are created equal.

Check around, ask questions. Find other homeowners who have had these systems installed and ask them how well they like their system and ask them which company did their installation.

Is geothermal worth the costs and the time and trouble for installation? That depends entirely on the homeowner and the land. When it comes to new construction, geothermal may very well be an excellent choice, especially considering the government’s generous rebate program (which lasts until at least 2016). Is geothermal a good choice for an existing home? That depends.

If a new integrated heating and air conditioning system is needed anyway, then geothermal should be on the table. Geothermal will cost more initially, but could save a considerable amount of electricity and/or natural gas in the long run – and geothermal, once set up, is one of the greenest forms of energy on the planet.