The Environmental Protection Agency and the U.S. Department of Energy recognize geothermal systems as the most environmentally friendly way to heat and cool a home. The systems move heat from the earth rather than using an energy resource to create heat. Unlike other comfort systems, geothermal systems do not emit carbon dioxide, carbon monoxide or other greenhouse gases. Geothermal systems do not rely on outside air, so the units keep the air inside of buildings cleaner and free from pollens, outdoor pollutants, and other allergens.