Everything you wanted to know about geothermal heating and cooling but were afraid to ask (or feared you wouldn’t understand)!

The geothermal heat pump (GHP), also known as the ground source heat pump, is a highly efficient renewable energy technology that is gaining wide acceptance for both residential and commercial buildings. It is used for space heating and cooling.

The technology relies on the fact that beneath the surface, the Earth’s temperature remains relatively constant throughout the year; warmer than the air above during the winter and cooler in the summer. A geothermal heat pump takes advantage of this by transferring heat stored in the earth or ground water into a building during the winter, and reversing the process in the summer. The ground, in other words, acts as a heat source in the winter and a heat absorber, or sink, in the summer.

Geothermal systems tap the Earth’s energy through a series of pipes buried in the ground near the building to be conditioned. These “loops” can be buried either vertically or horizontally. They circulate water that absorbs heat from, or relinquishes heat to, the surrounding soil, depending on whether the building is being heated or cooled.

For our new residence hall, we drilled a total of 28 wells (vertical loops) 430 feet deep. Each will be connected to the building through a series of horizontal pipes approximately 4-6 feet below the surface. During the winter, a geothermal heat pump will remove the heat from the fluid in these loops, concentrate it, and transfer it to the building. During the summer, the system will remove the heat from the building and transfer it to the ground.

The biggest benefit of geothermal heat pumps is that they use 25-50 percent less electricity than conventional heating and cooling systems—up to 72 percent less, according to EPA estimates. GHPs also improve humidity control by maintaining about 50 percent relative indoor humidity, making them very effective in humid areas.

Geothermal heat pumps are also effective at reducing another form of pollution–noise pollution. GHPs have no outside condensing units (think of an air conditioning unit sticking out of a window), so there’s no noise outside the building. And a GHP system is so quiet inside a building that users do not know it is operating.

As a final benefit, because the hardware requires less space than that needed by conventional HVAC systems, the equipment rooms can be greatly scaled down in size, freeing space for productive use. GHP systems also provide excellent “zone” space conditioning, allowing different parts of the building to be heated or cooled to different temperatures.