• Ground Source Heat Pump

  • Ground source heat pumps use the Earth’s energy storage capability to heat and cool buildings and to provide hot water. The earth is a huge energy storage device that absorbs a significant amount of the sun’s energy. As a result, in Connecticut, the average temperature of the earth is approximately 50 degrees, year round. During the heating season, the system uses a conventional vapor compression heat pump to extract the latent heat stored in the earth’s surface. In summer, the process reverses and the unit is used for air cooling with the earth becoming a heat sink.

    Heat exchanger designs include closed loop systems which use either horizontal or vertical heat exchangers made of high density polyethylene pipe. These systems usually circulate water to the heat pump with a biodegradable anti freeze added. Another type of heat exchanger is called an open loop system which draws ground or surface water through the heat pump and returns it back to the source unaltered except for a small temperature change. The vertical closed loop system is the most common type of heat exchanger used in Connecticut.

    Ground source heat pumps offer a proven technology that is one of the most environmentally clean and most efficient of any space-conditioning system available. Since the heat pump extracts heat from the relatively constant temperature of the earth, it is able to operate at high levels of efficiency. In comparison, air-source heat pumps extract latent heat from ambient air and must work against very large swings in temperature, experiencing a significant loss of efficiency when outside temperatures drop below 40 degrees. Ground source heat pumps are generally 2.5-to-4.0 times more efficient than resistance heating and water heating alone, and have no combustion or indoor air pollutants. The EPA found that even after accounting for all the losses in electricity generation at power plants, ground source heat pumps were much more efficient than competing fuel technologies. They are an average of 48% more efficient that the best gas furnaces and over 75% more efficient than oil furnaces.

    Green Energy Systems has found that although the cost of a ground source heat pump system is higher than a conventional heating and cooling system, the return on the incremental investment, after factoring in tax credits and rebates, is generally very high – making the system worthy of careful consideration.