Is Geothermal Installation Cost-Effective?

Whether you’re heating or cooling with home geothermal, the system is basically free once installed, apart from the electricity to run the pump.

  • Excavator at a home construction site
    Make sure geothermal installation is right for you and your home by determining what the annual return would be on this renewable energy investment.
    Photo by Fotolia/Shime
  • Green Is Good Book Cover
    In “Green Is Good,” author Brian F. Keane uses real-life stories to demonstrate how you too can benefit from adopting renewable energy in your home.
    Cover courtesy Lyons Press

  • Excavator at a home construction site
  • Green Is Good Book Cover

Renewable energy used to be prohibitively expensive, but times have changed, and energy guru Brian F. Keane demonstrates just how affordable it can be now. In Green Is Good (Lyons Press, 2013) Keane takes you through the cost-benefit trade-offs of new technologies — like geothermal energy and introduces you to revolutionary products on the horizon. In this excerpt from chapter 3, “Going Green at Home,” learn about one energy pioneer’s experience with geothermal installation, and how the annual return could likely make sense for you too.

You can purchase this book from the MOTHER EARTH NEWS store: Green Is Good.

Home Geothermal Energy

Shack had been paying about $4,000 a year for heating oil just to keep the relatively few rooms he used in winter at a barely tolerable sixty degrees. Even that he supplemented with electric baseboard and oil-filled electric radiators. The entire tab probably came closer to $5,000 per winter, and that setup did nothing for him come summertime.

Shack also had plenty of what makes geothermal installation practical: land. But not just any land, land that’s easy to work with a backhoe. A house Shack’s size at his latitude (about the 38th parallel) might require a quarter mile of trenching about four to six feet deep. Into that trench goes plastic pipe, generally made of high density polyethylene because it’s very durable and porous enough to allow heat to pass through its walls. Fluid — either water or some sort of anti-freeze solution — then circulates through the pipe maze by a ground-source heat pump to take advantage of the natural ground temperature at that depth, about sixty degrees. In summer, the circulation carries heat and, indirectly, humidity from the house into the ground. In winter, the reverse takes place: the circulating fluid picks up the ground heat and carries it into the house, where a typical forced-air heating system distributes it.

Ground temperature obviously varies depending on whether you live in Death Valley or next to Glacier National Park in Montana, but the principle behind home geothermal is applicable anywhere. It’s just a matter of taking advantage of what’s already in the ground, waiting to be used. If you’re not convinced, think of a cave. In the summer, the interior of a cave is almost always cooler than the air outside. And in the winter, caves are almost always warmer than outside. Like geothermal houses, caves are warmed and cooled by the ground that surrounds them.

Whether you’re heating or cooling with home geothermal, the system is basically free once installed, apart from the electricity to run the pump. In fact, studies show that about 70 percent of the energy expended in geothermal is renewable. As a bonus, you can also add to the system a “desuperheater,” which uses the summer heat it draws out of the house to warm household water for free and, in winter, provides about half the energy for the same purpose.

2/22/2021 6:48:41 AM

I'm thinking of building underground. Once the hole is dug would it be feasible to lay geothermal pipes, back fill some, and pour the slab over that?

4/11/2014 7:35:16 PM

Can you use an old well to run vertical pipe in?



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