Even in regions without large high temperature geothermal resources, a geothermal heat pump can still provide space heating and air conditioning. Like a refrigerator or air conditioner, these systems use a heat pump to force the transfer of heat from the ground to the application. In theory, heat can be extracted from any source, no matter how cold, but a warmer source allows higher efficiency. A ground-source heat pump uses the shallow ground or ground water (typically starting at 10–12 °C, 50–54 °F) as a source of heat, thus taking advantage of its seasonally moderate temperatures.