Going Green with Geothermal

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Geothermal heat pumps (GHPs) are heating/cooling systems that take advantage of stable temperatures within the earth. This provides typical annual energy savings of 30% to 60% compared to conventional systems, which lower greenhouse gas emissions! GHPs can be installed in new and retrofit situations for both residential and commercial applications.

‘The ground heat exchanger in a GHP system is made up of a closed or open loop pipe system. Most common is the closed loop, in which high density polyethylene pipe is buried horizontally at 4-6 feet deep or vertically at 100 to 400 feet deep. These pipes are filled with an environmentally-friendly antifreeze/water solution that acts as a heat exchanger. In the winter, the fluid in the pipes extracts heat from the earth and carries it into the building. In the summer, the system reverses and takes heat from the building and deposits it to the cooler ground.’ (GHPs that are equipped with a device called a “desuperheater” also heat household water — providing free hot water in the summer and cutting water heating costs in half during the winter)!

‘The air delivery ductwork distributes the heated or cooled air through the house’s duct work, just like conventional systems. The box that contains the indoor coil and fan is sometimes called the air handler because it moves house air through the heat pump for heating or cooling. The air handler contains a large blower and a filter just like conventional air conditioners.’

GHPs can be zoned for temperature control in individual rooms or sections of a building, and also work very well to control humidity.

The equipment is smaller than conventional HVAC systems which allows for better use of space or smaller-scaled utility rooms. Since geothermal heat pumps are located in interior rooms, they last much longer (often lasting 20 years or more) than conventional air-source heat pumps. The underground piping lasts for 50 years. They also operate quietly, unlike those noisy conventional compressors located right outside your window!

Look for the Energy Star label when selecting a new GHP which indicates the unit’s efficiency. The most efficient models have a heating COP of 2.8 or greater, and an EER of 13 or greater. The COP is the coefficient of performance, or the ratio of heat provided in Btu per Btu of energy input. The EER indicates the cooling efficiency which is the ratio of the heat removed (in Btu per hour) to the electricity required (in watts) to run the unit.

Special financing or tax incentives for purchasing energy efficient products may be available through federal, state, and local governments; power providers; and banks or mortgage companies that offer energy-efficient mortgage loans for energy-saving home improvements.

Average price for a 3-ton unit (a typical residential size) is roughly $7,500. A system using horizontal ground loops will generally cost less than a system with vertical loops. In comparison, conventional systems would cost about $4,000 with air conditioning. Because of the super energy efficiency, low maintenance, and reduced utility bills of a GHP, payback period is just a few short years.

Since installation of GHPs is not a do-it-yourself project, find a qualified installer by calling your local utility company, the International Ground Source Heat Pump Association, or the Geothermal Heat Pump Consortium for their listing of qualified installers in your area. Installers should be certified and experienced.

Source: The U.S. Dept of Energy

Tag(s): Energy, Greening the Home, Greening the Office, Money Saving, The Great Green Outdoors

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