Geothermal Energy

a	Classroom Temp °C	°C
b	Returning Geothermal Liquid Temp °C	°C
c	Bottom Geothermal Liquid Temp °C	°C
d	Ground Source Supply to School °C	°C
e	Ground Source Return From School °C	°C
f	Ground Source Supply from Ground Water °C	°C
g	Heat Pump 1-4 Supply Temp °C	°C
h	Heat Pump 1-4 Return Temp °C	°C

A geothermal heating and cooling system uses the near constant ground temperatures in the earth's upper layer as a thermal energy storage bank where energy can either be extracted or added as needed. There are three main components of a geothermal heating and cooling system: the ground heat exchanger (GHE), the heat pump, and the building distribution system.

The GHE works as a heat source by releasing energy stored within the earth during system heating operation, and conversely as a heat sink to store energy back into the earth during the system cooling operation. One type of GHE commonly used is a closed loop piping arrangement. A closed loop system uses a system of continuous underground piping where both ends are connected to the heat pump. Water or a mixture of water and an environmentally friendly anti-freeze is used as the heat transfer fluid and is circulated through the piping to transfer heat between the heat pump and the earth

The heat pump is a machine which operates on electricity and is located within the building. It uses a compressor and refrigerant circuit to extract heat or to reject heat back to the GHE supplied water in conjunction with the mode of operation. Depending on the type of heat pump, either heating or cooling air, or hot or chilled water can be made to be used for space conditioning within the building. Heat pumps are also beneficial due to the fact that their energy efficiency ratings can be in the area of 400%; that means for every unit of energy input to the machine, the resulting output is four times greater.

The distribution system in the building can consist of air ducts or hydronic (fluid based) terminal components such as radiant floor tubing to provide comfort control to the building.

How it is used in the school:

A geothermal heating and cooling system at the school is made up of a GHE, water source heat pumps, and various hydronic heating and cooling components. The GHE consists of 28 individual vertical ground boreholes each 113 m (370 ft) deep with a 31 mm high density polyethylene (HDPE) tubing loop, and packed with a grout mixture. The individual borehole loops are piped together with eight common pipes and then run into the building to the second floor mechanical room. The GHE is not visible because it is in the ground under the school playground, however the piping into the building can be seen through the viewing window located in the central stairwell. Water-to-water source heat pumps located in both 2^nd floor mechanical rooms use the GHE water to make either hot water in the winter or chilled (cold) water in the summer that is circulated throughout the building. Installed hydronic equipment includes infloor heating and cooling tubing in classrooms and the gymnasium, cabinet unit heaters in the stairwells, and heating and cooling coils in the air handling units.