These pumps are similar to ordinary heat pumps but use the ground instead of outside air to provide heating, air conditioning and, in most cases, hot water. They use the earth’s natural heat for all the heating. Hence, the geothermal heat pumps are among the most efficient and comfortable heating and cooling technologies currently available!
Set by the US Environmental Protection Agency and the Department of Energy, the products from the ENERGY STAR meet strict energy efficiency guidelines.
Via: Energy Star