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A ground source heat pump would generally be used in place of a normal (air-source) air conditioner or heat pump, as a more efficient option. Heating and cooling of homes and industrial buildings is the most common use. The basic idea is that the heat pump uses the ground to extract or store heat, rather than the air. This is often more efficient because the ground temperature in most locations is usually warmer than the air temperature at times when heating is desired (e.g. during the winter) and cooler than the air when cooling is desired (e.g. during the summer).