Geothermal Heat Pump Technology
A geothermal heat pump (GHP) system consists of one or more water-to-air heat pump units inside the building, which are connected by a common water distribution loop to an earth-coupled heat exchanger (or "ground loop") outside the building. A typical system arrangement for a school or other institutional or commercial building is shown below.
The building interior heat pump units typically range in capacity from 1 to 10 tons *, but some unitary equipment is available in capacities up to 50 tons. In a school situation, an interior heat pump may condition one large space such as a gym, cafeteria, or auditorium, or it may condition a “zone” of individual classrooms.
Since each room or zone of rooms has its own dedicated heat pump unit, it is possible for building occupants to adjust the thermostat setting of each different space as appropriate to its activity or location. For example, a GHP system can maintain a lower temperature in a gym full of highly active students while at the same time maintaining a warmer temperature for students seated in a darkened auditorium.
Before considering this and other advantages of GHP systems for schools, it will be helpful to read through this section of the Web site to learn exactly how geothermal heat pumps work. Since seasonal variations in underground temperature strongly influence the selected configuration and design of the earth-coupled heat exchanger, the page on soil thermal properties should be read before reading the page on ground loops. The last page in this section explains the mechanics of heat pumps, and how these units interact with the ground loop to provide space heating and cooling, as well as domestic water heating.