How does Geothermal Cooling Work?

Jason C. Chavis

Geothermal cooling is a process by which shallow ground is utilized within a system to regulate temperature. The upper 10 feet of the earth's surface holds a stable temperature between 50° to 61°F (10° to 16°C). This stable temperature is harnessed, using a geothermal device, to draw heat energy out of a system and thus transfer the cool temperatures into a warmer area.

Man with hands on his hips
Man with hands on his hips

Surface temperature has almost no effect on the ground underneath the frost line. Using this knowledge, a pump can be placed under the ground, in an area such as a basement, that effectively pulls the cool sustaining temperature from the ground. This device is connected to a loop of copper tubing or high-density polyethylene, which is literally buried underneath the earth's surface. This loop contains a refrigerant that is pumped through the tubing, exchanging the warm energy in the building with cooler energy in the ground and acting almost like a heat sink. This process is known as direct exchange and is very effective at keeping a location at a stable cool temperature.

Geothermal cooling uses two different methods to implement the cooling process: water-to-air systems or water-to-water systems. Water-to-air systems replace central air conditioning systems by using a liquid coolant to transfer the energy into the air that can then be blown throughout a structure. Water-to-water systems use a large system of liquid spread throughout the building that is cooled, keeping the area at a stable temperature. The water-to-water system has the bonus of working very effectively at heating as well.

The U.S. Department of Energy estimates that approximately 50,000 geothermal cooling devices are installed in homes and businesses each year. The cost per ton of capacity averages $2,500 US Dollars (USD). A three-ton appliance is needed for the average home. The energy savings equates to the device paying for itself in approximately five to ten years. The components inside the geothermal cooling pump last for roughly 25 years, while the copper or polyethylene loop placed in the ground has a lifespan of 50 years.

The main advantage of using geothermal cooling is that it does not use fuel or chemicals to regulate the temperature. Central air conditioning devices use materials that can be harmful to the environment. They also create carbon emissions that pollute the atmosphere. With the average home producing 5,550 tons of emissions each year according to the U.S. Energy Information Administration, geothermal cooling is a viable option to cut greenhouse gas emissions while maintaining a comfortable home environment.

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Discussion Comments


Does anyone know the difference in price between a geothermal heating and cooling system that uses a deep well versus systems that use coils that loop under your yard or a small pond? I live in a rural area, and I was just wondering what the difference in installed costs would be. Thanks to anyone who can help me out.


@ Babalaas- The benefits of a geothermal cooling and heating system are even better when factors like cost tax incentives and energy savings are considered. The cost to install a new traditional HVAC system in a 2500 sq. ft. home is about $4500. The tax credit for installing a residential geothermal cooling system is an uncapped 30%. If the system costs $7500 to install, the cost after tax credit will be $5250. You could probably save anywhere from $500 to $1000 on energy every year, so the geothermal system would cost less after the first or second year. Geothermal systems are also much less maintenance then a traditional HVAC system, so you will save on those costs as well.


Wow, what a great article. This article really gave a lot of information about geothermal heating and cooling. I was completely unaware of this type of heating and cooling system until I saw a show on the planet green network about a couple who installed a geothermal well in their Chicago duplex. The article did a great job explaining the costs, the life expectancy of the system, the ROI, and the size system needed for the average home. Thanks wiseGEEK!

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