Although geothermal heating and cooling systems don't generate electricity, they do help reduce the need to use electricity, natural gas, or heating oil to heat or cool a building. GeoExchange systems use the constant temperature below the earth's surface to help the heating and cooling process, a process that is considerably more efficient than systems that use outside air as a heat source or sink.
Think about it: On a cold winter day (30 °F), standard heating systems (such as a heatpump) need to heat cold outdoor air by 40 °F or more before it is used to warm a building. On a hot summer day (95 °F), air conditioners need to cool the air considerably before it is circulated. Geothermal systems, on the other hand, raise (in winter) or lower (in summer) the temperature of the air or water used to heat or cool a building to approximately 55 °F (the temperature below the earth's surface). This reduces the amount of energy needed to bring indoor temperatures to a comfortable level.
Overall, geothermal systems save users 30 to 60 percent in energy costs compared to conventional heating or cooling systems. They often pay for themselves in 5 to 10 years.
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Is a GeoExchange System Right for Me?
Geothermal systems aren't obtrusive, so they can be great options for buildings where aesthetics are a concern or where zoning regulations prohibit installing other renewable energy systems. (However, is necessary to drill wells or trenches to lay the geo-energy exchange loop, so some there is some outdoor disurbance during installation.) Also, geothermal systems require only limited maintenance, and they are quieter and last longer than air-source heat pumps. The system life is often rated at 25 years; the ground loops are good for at least 50 years.
Geothermal systems can be designed in a variety of ways to meet your needs and can often be integrated with existing equipment. The design and size of a geothermal system directly affect its cost, so it's necessary to seek the advice of a qualified designer or installer to estimate the cost and savings potential of installing a system.
Residential Geothermal Systems
The diagrams above show the pattern of heat exchange in a residential geothermal system in both heating (left) and cooling (right) modes. Click on either image to see a larger image. Source: GeoExchange.org
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Selecting and Finding a Service and Product Provider
When shopping for a geothermal system installer, always check for relevant licenses, request references and a list of itemized costs, and get multiple quotes. Additional qualifications to inquire about include the International Geothermal Heatpump Association (IGSHPA) accredation. The following sites include lists of qualitifed providers:
Additional Resources and Incentives for Geothermal Technologies
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