Geothermal Heating and Cooling: An Overview

The earth absorbs and stores vast amounts of energy from the sun. Due to this stored energy, the ground only a few meters below the surface holds a fairly constant temperature of 12 C (54 F) all year long. Geothermal heating and cooling systems rely on this constant temperature to heat and cool a home or other structure, and to heat water.

Rather than creating energy by burning a fossil-fuel source, geothermal systems transfer existing heat from one location to another through circulating fluid ? most often water mixed with an antifreeze solution. The fluid circulates through pipes in the home and also down underground, absorbing and releasing heat as it moves. Where heat is absorbed and where it is released depends on whether cooling or heating is needed.

A vapor-compression heat pump transfers heat between the building and the fluid; a pipe system, or “earth connection,” transfers heat between the fluid and the earth; and a distribution system delivers warm or cool air throughout the home.

During the cooling process, the fluid absorbs heat from the air in the home. It then cycles through the underground pipes where it releases the heat into the earth, which acts like a heat sink. The now-cooled fluid circulates back through the system, and cooler air is distributed through ductwork in the home. The fluid cycles around once again, absorbing more heat from the air.

To heat an air space, the process is effectively reversed. The fluid circulating underground now absorbs heat from the earth, which becomes the energy source. As the fluid travels back through the system, it’s compressed to increase the temperature further. The heat is extracted, and warm air is delivered through the home’s ductwork.

It’s also possible to have a “desuperheater” in the geothermal system to collect excess heat from the fluid during both the cooling and heating sequences; the collected energy is then used to heat water. It can supply as much as 50 percent of the hot-water needs for a home or business, with an associated reduction in cost.

Geothermal systems deliver energy with an efficiency rating of around 400 percent, far surpassing many conventional energy systems. Additionally, geothermal systems don’t emit greenhouse gases. They use modest amounts of electricity to operate the components, but are considered the most environmentally friendly ways to heat and cool a home or business – with the lowest possible operating costs.

Related pages: Geothermal Heating Systems