What to Know About Geothermal Heating and Cooling

Geothermal heating and cooling blends ancient practices with modern technology. But is this environmentally friendly solution right for your home?

Increasingly popular with homeowners, geothermal heating and cooling systems deliver environmentally friendly performance at a fraction of traditional HVAC operating costs. Whether you’re planning a new build or upgrading an existing HVAC unit, it’s worth your time to take a look at your geothermal options.

How Does it Work?

Geothermal cooling systems work much like a traditional heat pump. But instead of drawing on the ambient air temperature, they use the constant temperatures below ground to shed excess heat or cold from your home. Geothermal systems pump a liquid (usually a water/antifreeze mixture, but it can be groundwater) through a loop of underground pipes. During the summer this liquid channels heat from your home, dispersing it underground. In the winter, that process is reversed.

For a great visual demonstration, check out the Department of Energy’s Geothermal 101 video.

Secondary Benefits

In addition to less fossil fuel consumption and drastically reduced heating and cooling costs, geothermal systems can help run your home’s water heater. Using a “desuperheater” (which we promise is a real word), the system transfers excess heat from the geothermal compressor to your water heater tank. You’ll still need a supplemental heat source, especially in a large household, but it will make a significant difference in your energy consumption.

Geothermal heating and cooling is also surprisingly quiet. While most geothermal units use a fan to circulate conditioned air, the sound of a firing furnace or condenser spinning up is a thing of the past. On average, an indoor geothermal unit makes about as much noise as a refrigerator.

New Build vs. Retrofit

Far and away the biggest challenge of installing a geothermal heating and cooling system is sinking the coils. This is why geothermal units are most commonly installed when building a new home, as much of the lot is already torn up. That’s not to say that they can’t be installed as a retrofit — there are a number of possible coil layouts, and there’s one to fit almost any lot configuration — but accommodations must be made to avoid damaging existing structures. And you’ll need to budget for landscaping repairs.

Dollars and Sense

For many, the decision to invest in a geothermal heating and cooling system boils down to balancing upfront cost and total savings. Factors to consider include your local climate (a home in San Diego won’t see the same savings as one in Tuscon) and the soil makeup of your property. The latter can be tricky, since it affects installation cost and the efficiency of the unit. You may consider drilling for soil samples on your own or with a professional.

For most homeowners with a high-efficiency furnace, it’s unlikely switching to geothermal will make sense on a purely dollar/cost basis. But if you have an aging unit on its last legs, it may be worth checking into geothermal for your next HVAC upgrade.

Dan Stout
Ohio-based freelance writer and author Dan Stout is a former residential remodeler, commercial site supervisor and maintenance manager. He’s worked on nearly all aspects of building and DIY including project planning and permitting, plumbing, basic electric, drywall, carpentry, tiling, painting and more. He also publishes noir fantasy thrillers, including The Carter Series, from Penguin imprint DAW Books.