Enviro 101 - Geothermal Heating and Cooling




Illustration by Alec Bec

Geothermal heating and cooling technology has been around for decades, but not many people use it—compared to a conventional heat pump, it’s expensive to install. But if you’re building a new house, installing a geothermal system will only cost a few thousand dollars more than a conventional system and can pay off big through reduced energy and upkeep costs.
Here’s how it works:
A liquid, usually treated water or an antifreeze mixture, is pumped through a series of pipes (1) installed (either in a vertical or horizontal position) in the ground. When the liquid reaches a compressor (2), it will either be warmer or cooler than the air outside, depending on the time of year. It is pumped into a heat exchanger that transfers the temperature of the liquid to the air, which is then blown through vents (3) in the home. How does this reduce energy costs? Unlike air, soil doesn’t experience dramatic swings in temperature—it averages about 55 degrees year-round in seasonal regions in the U.S. (warmer in southern climates and cooler in northern climates). So when the temperature outside is 30 degrees, it’s much more efficient for your compressor to extract heat from the ground than from the air. And because the process heats your home during the winter and cools it during the summer, a geothermal system can replace both heating systems and air conditioners (it can be outfitted to heat water as well).

The technology works best in areas with pronounced seasonal high and low temperatures and good soil for heat transfer. And because the compressor is located indoors, it won’t be as susceptible to exposure damage as conventional central air units, which need to be replaced every 10 to 15 years.

Issue 25



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