Articles -> Energy Savings -> Geo-Thermal Heating

Home Heating Gets Down and Dirty
by Eric Englund

Just when you thought the only choices for heating your home were electricity and gas, a hot new option has been unearthed—and you might really dig it!

Geothermal heating systems use the earth's natural heat to control the temperature of a home or business. The process involves burying pipe or coils in your yard, filling them with liquid, letting the earth heat the liquid, and then bringing the warmth from that liquid into your home.

Not unlike the operating principle behind a refrigerator, the geothermal method exchanges heat for cold and cold for heat. In fact, during the summer, it essentially turns your house into a giant refrigerator.

The concept may date back to cave dwellers, who realized that the earth was able to moderate temperatures—keeping people warm in winter and cool in summer. The idea of burying pipe to gather heat energy surfaced in the 1940s. The technology has been used for nearly 30 years in the western U.S. and has recently become adaptable to areas with harsh winter weather.

The two most common types of geothermal heating systems are closed-loop and open-loop.

The closed-loop option uses a continuous length of buried plastic pipe as a heat exchanger. The pipe is connected to an indoor heat pump to form a sealed, underground loop through which an antifreeze solution is circulated.

The electrically powered geothermal heat pump moves heat energy from one place to another. In winter, the heat pump removes heat energy stored in the earth and transfers it into your home or business. In summer, the process is reversed, and indoor heat is extracted from your home and transferred into the earth.

Geothermal heat pumps are more than three times as economical as the most efficient fossil-fuel furnace. Instead of burning a combustible fuel to produce heat, they simply move heat that already exists. By doing that, they provide three units of energy for every one unit used to power the heat pump!

The open-loop method consumes water from a well. Groundwater is pumped into the heat-pump unit, where heat is extracted; then the water is disposed of in an appropriate manner. No pollutants are returned to the groundwater.

Since groundwater has a relatively constant temperature year-round, it is an excellent heat source. The water must be high-quality and free of excessive minerals, particles or organic matter, in order to prevent clogging the heat pump.

Both of these systems require three basic components. A heat pump goes inside your home, usually in the basement, garage or crawlspace.

A liquid heat-exchanging medium is a second important part. Third, an air-delivery system (ductwork) is needed.

What about costs? The installation price of a geothermal system will be higher than for conventional heating. However, sometimes a local electric company will offer to subsidize the installation to some degree.

Heating bills should show a substantial cost savings during winter months—anywhere from 20 to 70 percent! Summer savings will be less impressive, since electricity use is similar to that of an air conditioner. Some sources claim summer savings of up to 25 percent.

Maintenance costs are lower than with traditional systems, since plastic pipe lasts 50–75 years. The closed-loop version requires less maintenance than the open-loop system, because it is sealed and pressurized, eliminating the possible buildup of minerals or iron deposits.

The overall financial picture makes geothermal heating an excellent option for new homes. In recent years, due to new heat pump designs and improved pipe materials, the geothermal system has become the most efficient heating and cooling system available.

The system can pay for itself in five years. The jury is still out on whether geothermal heating is a good choice for existing homes, since there may be substantial costs involved in switching heating systems.

But wait! There's still more good news! Here's the dirt: Geothermal heating systems can also heat water for your home, saving you up to 50 percent on your water-heating bill, by preheating tank water. Also, there is no visible or noisy outdoor equipment and there are no fumes or burning fossil fuels. Geothermal heating is remarkably clean, because it runs exclusively on electricity. Plus, the pipes and trenches have no adverse effect on your landscaping, other than the fact that you will have to replace some grass.

Other points to keep in mind: Installation is easy, but call a contractor to do the work.

Also, check with local authorities regarding laws that may apply, especially if you use the open-loop system, where water (albeit pure) is returned to a well or a stream. If you don't have a lot of yard space (at least 20 ft. by 80 ft.) for digging horizontal trenches, vertical digging is another option; however, the latter may involve a 40 percent higher installation cost.

Maybe this all sounds too technical. But geothermal heating offers personal advantages as well. Your home will maintain an even, comfortable temperature. You may also experience better health, since the indoor air will be cleaner—free from such airborne pollutants as carbon monoxide and sulfur. The possibility of toxic poisoning from fire or carbon monoxide will also be greatly reduced, since there is no burning going on.

If you suffer from asthma, you could see a marked improvement. With geothermal heating, the home is airtight, reducing asthma induced by breathing mold. In a conventionally heated home, mold—which can bring on asthma in children—is produced when the home's heat meets cold air that is trapped in the outside walls. Over the last 20 years, cases of asthma in children have increased by nearly 70 percent. This is almost entirely attributable to conventional home-heating systems. Why aren't homes airtight now, to reduce mold? They can't be. If combustion-heated homes were completely sealed, the buildup of pollutants would make people ill.

Geothermal heating may be more expensive to install, and it uses electricity to run its components; but indoor air free from toxins and mold may sway your decision. And don't forget the lower winter heating bills, the reduced costs to provide hot water, the even temperature and the noiseless operation. And how about the advantage of cooling your home with the same system, so you don't need an air conditioner?

Congratulations! You may have found a heating system you can really warm up to.

Graphics courtesy of Geothermal Heat Pump Consortium, Inc.

Sources: Econar  Energy Systems Corporation; The Electric Heating Institute of Indiana; Maritime Geothermal Ltd.; Minnegasco Northern States Power Company; Shoreview/Arden Hills (Minn.) Bulletin, April 9, 1997.