1.6.3 Ground and Water Source
Take advantage of the thermal stability of the earth (50°F (10°C) at 5 to 10 feet underground, year-round) to function as a heat source in the winter and a heat sink in the summer, reducing electricity demand for heating and cooling.
System of 5/8” PE or PB tubes and heat exchangers. Most common are closed-loop horizontal and closed-loop vertical systems. Using a body of water as the heat source/sink is very effective, but seldom available as an option. Open-loop systems are less common than closed-loop systems due to performance problems (if detritus gets into the heat pump) and risk of contaminating the water source or, in the case of well water, inadequately recharging the aquifer.
Either air or a nontoxic antifreeze-water mix is circulated through buried polyethylene or polybutylene piping. This water is then pumped through one of two heat exchangers in the heat pump. When used in the heating mode, this circulating water is pumped through the cold heat exchanger, where its heat is absorbed by evaporation of the refrigerant. The refrigerant is then pumped to the warm heat exchanger, where the refrigerant is condensed, releasing heat in the process. This sequence is reversed for operation in the cooling mode. (Source: www.eere.energy.gov)
A study by the U.S. Environmental Protection Agency found that ground-source heat pumps are as much as 72 percent more efficient than electric heating and air conditioning systems.
Free heating and cooling reduces energy costs. Usable floor area or building height increases due to elimination of cooling towers. Simple technology reduces maintenance and repair cost. Very quiet. (Ground-source and water-source heat pumps work the same way, except that the heat source/sink is the ground, groundwater, or a body of surface water, such as a lake).
Soils testing is required to verify and confirm the adequacy of ground conditions. Ground-source heat pumps make the most sense in mixed climates with significant heating and cooling loads because the high-cost heat pump replaces both the heating and air-conditioning system. Plan the site work and project scheduling carefully so that the ground loop can be installed with minimum site disturbance or in an area that will be covered by a parking lot or landscape.
1.7.10 Radiant Cooling