According to the U.S. Environmental Protection Agency (EPA) geothermal systems are, "the most energy-efficient, environmentall clean, and cost-effective space conditioning systems available today."  Extremely high levels of efficiency are possible because a geothermal heat pump only uses electricity to move heat, not produce it.  A geothermal unit typically supplies four to five kilwatts of heat for ever kilowatt of electricity used.  Three to four of these kilowatts of heat come directly from the earth itself, and are clean, free and renewable.  Geothermal heat pumps also take advantage of the mild ground temperature for extremely high efficiency cooling.  Most systems also include a hot water generator which diverts a portion of the supplied heat to the domestic water heater.  This provides a substantial portion of a family's hot water needs at a very low cost.  Overall, geothermal technology offers the highest cooling and heating efficiencies of any system available today.