Geothermal heat pumps work on a different principle than ordinary furnace/air conditioning systems, and they require little maintenance or attention from homeowners. Furnaces must create heat by burning a fuel–typically natural gas, propane, or fuel oil. With geothermal systems, there’s no need to create heat, hence no need for chemical combustion. Instead, the Earth’s natural heat is collected in winter through a series of pipes, called a loop, installed below the surface of the ground or submersed in a pond or lake. Fluid circulating in the loop carries this heat to the home. An indoor geothermal system then uses electrically-driven compressors and heat exchangers in a vapor compression cycle–the same principle employed in a refrigerator–to concentrate the Earth’s energy and release it inside the home at a higher temperature. In typical systems, duct fans distribute the heat to various rooms.

In summer, the process is reversed in order to cool the home. Excess heat is drawn from the home, expelled to the loop, and absorbed by the Earth. Geothermal systems provide cooling in the same way that a refrigerator keeps its contents cool–by drawing heat from the interior, not by injecting cold air.

Geothermal systems do the work that ordinarily requires two appliances, a furnace and an air conditioner. They can be located indoors because there’s no need to exchange heat with the outdoor air. They’re so quiet homeowners don’t even realize they’re on. They are also compact. Typically, they are installed in a basement or attic, and some are small enough to fit atop a closet shelf. The indoor location also means the equipment is protected from mechanical breakdowns that could result from exposure to harsh weather.

Geothermal works differently than conventional heat pumps that use the outdoor air as their heat source or heat sink. Geothermal systems don’t have to work as hard (which means they use less energy) because they draw heat from a source whose temperature is moderate. The temperature of the ground or groundwater a few feet beneath the Earth’s surface remains relatively constant throughout the year, even though the outdoor air temperature may fluctuate greatly with the change of seasons. At a depth of approximately six feet, for example, the temperature of soil in most of the world’s regions remains stable between 45 F and 70 F. This is why well water drawn from below ground tastes so cool even on the hottest summer days.

In winter, it’s much easier to capture heat from the soil at a moderate 50 deg F. than from the atmosphere when the air temperature is below zero. This is also why geothermal systems encounter no difficulty blowing comfortably warm air through a home’s ventilation system, even when the outdoor air temperature is extremely cold. Conversely, in summer, the relatively cool ground absorbs a home’s waste heat more readily than the warm outdoor air.


This marvelous technology relies primarily on the Earth’s natural thermal energy, a renewable resource, to heat or cool a house or multi-family dwelling. The only additional energy geoexchange systems require is the small amount of electricity they employ to concentrate what Mother Nature provides and then to circulate high-quality heating and cooling throughout the home.

Geoexchange heating and cooling is cost effective because it uses energy so efficiently. This makes it very environmentally friendly, too. For these reasons, federal agencies like the Environmental Protection Agency and the Department of Energy, as well as state agencies like the California Energy Commission, endorse it.

According to data supplied by the U.S. Department of Energy (DOE) Office of Geothermal Technologies, nearly 40% of all U.S. emissions of carbon dioxide (CO2) are the result of using energy to heat, cool and provide hot water for buildings. This is about the same amount of CO2 contributed by the transportation sector. (source: Environmental and Energy Benefits of Geothermal Heat Pumps)

A typical 3-ton residential geoexchange system produces an average of about one pound less Carbon Dioxide (CO2) per hour of use than a conventional system. To put that in perspective, over an average 20-year lifespan, 100,000 units of nominally sized residential geoexchange systems will reduce greenhouse gas emissions by almost 1.1 million metric tons of carbon equivalents.

That would be the equivalent of converting about 58,700 cars to zero-emission vehicles, or planting more than 120,000 acres of trees.

And the waste heat removed from the home’s interior during the cooling season can be used to provide virtually free hot water-resulting in a total savings in hot water costs of about 30% annually, and lowering emissions even further.
Studies show that approximately 70 percent of the energy used in a geoexchange heating and cooling system is renewable energy from the ground. The remainder is clean, electrical energy which is employed to concentrate heat and transport it from one location to another. In winter, the ground soaks up solar energy and provides a barrier to cold air. In summer, the ground heats up more slowly than the outside air.


Homeowners in virtually every region of the United States are enjoying a high level of comfort and significantly reducing their energy use today with geothermal heating and cooling.

We often find that homeowners initially chose geothermal because of the cost savings, but after experiencing the outstanding comfort afforded by this technology, they often cite comfort as the their favorite aspect of the system.

Those who use geothermal systems give them superior ratings because of their ability to deliver comfortably warm air, even on the coldest winter days, and because of their extraordinarily low operating costs. As an additional benefit, geothermal systems can provide inexpensive hot water, either to supplement or replace entirely the output of a conventional, domestic water heater.

What about radiant heating?

Radiant floor heat is widely recognized as providing the highest comfort level compared to other methods of heat delivery. By nature, radiant floor heating achieves this outstanding comfort due to it’s ability to heat objects such as people and furniture, instead of heating the air in your home like traditional forced air heating systems.

Less draftiness, fewer hot and cold spots, less dust and even temperatures throughout your home are just a few of the benefits of radiant floor heating. But where does the heat come from? It comes from hot water. Traditional radiant floor heating systems utilize a fossil fuel or electric boiler to generate the needed hot water. These boilers can be very costly to operate compared to the efficiency of geothermal.

So let’s clarify. Radiant floor heat is simply a method of heat delivery into your home. We still need an efficient way to generate the hot water. That’s where geothermal comes in.

Geothermal systems produce hot water at an efficiency approaching 400%. By harvesting abundant amounts of heat from your own backyard, geothermal systems are widely recognized as providing the highest efficiency compared to other methods of generating hot water. The best fossil fuel boilers today have efficiency’s below 100%. Most are only 80-90% efficient. That means for every dollar of fuel purchased, 10-20 cents worth is lost up the chimney and wasted.