Geothermal Systems explained
Geothermal systems harness the earth’s natural heat and coolness to regulate a building’s temperature.
The temperature of the ground below the frost line remains at a relatively constant 10˚C-12˚C year-round. This enables geothermal systems to extract and store heat energy in the earth. Geothermal systems are often called geoexchange systems because they are highly efficient at transferring heat in and out of buildings. This is also to distinguish them from high-temperature geothermal systems that generate steam to produce electricity.
Geoexchange systems for buildings consist of three components: a ground source heat pump (indoors), a heating and cooling distribution system, and a ground loop heat exchanger (outdoors). Ground loops are filled with a water-antifreeze mixture which is circulated to enable heat exchange with the ground. In winter, heat is extracted from the ground and, as warmed fluid, is circulated from the ground loop to the heat pump. The heat pump pressurizes the fluid, heating it further, and moves it across a heat exchanger. This transfers heat into the building’s distribution system, usually a blower, which pushes an air stream through the HVAC ductwork, in the same way as a conventional forced air furnace does.
To provide air conditioning during summer, the geoexchange system is reversed. So rather than adding heat to the air stream, the heat pump draws it out of the building, back to the ground loop. The warmed fluid then exchanges its heat with the cooler earth, with that heat remaining underground until needed again in cooler weather, when the system is reversed.
Most geoexchange systems operate at 300% efficiency, meaning that three units of heat energy can be stored and retrieved from the ground for every unit of electrical energy required to drive the heat pump. The U.S. Department of Energy has stated that "no active technology for heating and cooling is more efficient than the geothermal heat pump."
Potentia installs complete geothermal systems that reduce a building owner’s reliance on fossil fuels while also reducing greenhouse gas emissions.
