At present, the use of the geothermal heat pump (GHP) in cooling and heating systems is considered by experts as very energy-efficient, cost-effective, and environment-friendly among others. This assessment is certified by the U.S. Environmental Protection Agency (EPA).
Sometimes referred to as GeoExchange by experts, these pumps give their systems very prominent efficiency ratings that can go as high as 300% to 600% on the coldest nights during winter. (Air source heat pumps register 175% to 250% efficiency ratings.)
Based on the principle that heat flows from higher to lower temperatures, the pump is tailor-fit to any of the three systems of heat transference. These are conduction (molecule to molecule), convection (air currents), and radiation (electromagnetic). Heat transfer is done through heat exchangers.
A geothermal heat pump, however, can do more. It can transfer heat from a cool space to a warm space, which is against the natural flow direction of heat. This is an added extra to their regular function of enhancing the natural heat flow from a warm area to a cold area.
Basically, the geothermal heat pump is a system where a refrigerant is pumped through a vapor-compression refrigeration cycle that moves heat. (Heat pumps are definitely more efficient at heating than heaters powered by pure electricity, even when they are extracting heat from the cold winter air.)
In contrast with other heat pumps that collect heat from outside air, the geothermal heat pump uses the main underground earth as its heat source.Since underground temperatures are relatively constant and stable compared to those of the air, the system is more energy efficient.
Furthermore, heat sourcing from the ground is not affected by seasonal variations of temperatures, even in extreme weather conditions. Ground temperatures are warmer and cooler than air during winter and summer respectively.
Accordingly, the pump extracts heat from the ground during winter for use in aboveground heating in buildings and houses. Conversely, it transfers the heat back into the ground during summer when cooling buildings and homes.
The geothermal heat pump is used on four basic types of ground loop heating systems – horizontal, vertical, pond/lake, and open loop. Each type is dependent on the climate, soil, and land area where they are used.
Except for the open loop, all the others are closed loop systems. The pump transports an antifreeze solution across the loop buried underground (or submerged in water). This transfers the heat from the source to where it is needed. (Open loop systems are used only where there is adequate supply of water.)
Savings and other benefits
Air conditioners, oil furnaces, and other electrically powered heating systems generally release greenhouse gases into the atmosphere. A system that uses a geothermal heat pump releases less polluting gases.
Savings-wise, energy consumption is reduced up to 44% side by side with air source heat pumps. This goes up to 72% reduction compared with those using electrical heating devices.