Heat pumps are electrical devices that can transfer heat from one environment to the other. The device is used in refrigerators and air-conditioning and has become popular lately in household heating. The pump uses the heat found in the air, ground or underground water to heat water circulating inside the house, warming it or used for consumption. An experiment set up inGermany follows more than a hundred of such systems and compares their performance since 2006.
Utilizing Ambient Heat
Even on very cold nights, the air still contains a lot of energy, in other words, it can be colder. By cooling the air a bit more, the heat pump heat the water used for heating or domestic consumption. Heat pumps consume grid electricity but produce 3-4 times more energy than initially invested in.
As the air temperature drops, the efficiency of the system becomes lower until it's useless at about -5 to -10 degrees Celsius. This drawback of the heat pump called the use of ground or underground water as a heat source. The ground, in a depth of more than two meters has a relatively stable temperature which the system can use more efficiently. The ground heat pump is sometimes reffered to as geothermal heat pump.
The Heat Pumps Efficiency was Measured
The Fraunhofer Institute for Solar Energy Systems, which performs research on technology supposed to supply energy efficiency, has set up a platform for inspecting the performances of air, ground and underwater heat pumps. In 2006 it set up a system that constitutively monitors 70 heat pumps in single family homes. Another 40 devices were added to the experiment afterwards. The goal of this experiment was to test whether or not heat pumps can be utilized to answer the heating needs of an average household.
After a year and a half of measuring the conclusions were clear. The heat pumps did their work properly and saved 66%-73% of the energy used for heating. The average ratio between the energy consumed by the pump to the energy it produced ranged between 3.7 in the ground based system to 3 in the air based system. The underground water based heat pump gave a coefficient of 3.5.
The research, which its final results should be published at the end of 2010, reached the conclusion that the technology of heat pumps is mature enough to support the needs of an average home. The technology performed well throughout the winter and a backup system was rarely activated. The technology is by far the most efficient heating method and can reduce more than two thirds of the energy consumed for household heating.
More information can be found at the Fraunhofer ISE website
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