Geothermal: Digging Deep for Efficient Energy

The Commonwealth Building in Portland, OR was the first commercial building to install a geothermal system. Geothermal's general reliability has contributed to its installation in facilities across the country. PHOTO COURTESY OF UNICO PROPERTIES

Types of Geothermal Heat Pumps

Based on your location and building’s property, you will need a specific type of geothermal heat pump system. They are classified into three main categories:

Closed-loop systems typically circulate an antifreeze solution through a closed loop often made of plastic tubing that is buried underground or submerged in water. The system exchanges heat between the heat pump’s refrigerant and the antifreeze solution in the closed loop. Loops can be oriented horizontally, vertically, or in a pond or lake, but vertical is most commonly used in commercial buildings, schools and other larger facilities because it can be implemented in locations with land area restraints.

Open-loop systems use well or surface body water as the conduit for heat exchange to circulate through the system. Once the water is cycled through the system, the water returns to the ground through the well, a recharge well or surface discharge. Open-loop systems only work where there is a ready supply of clean water and the system meets groundwater discharge codes and regulations.

Hybrid systems will use multiple geothermal resources or a geothermal resource with outdoor air through the use of a cooling tower, for example. These systems are most effective when a building needs more cooling power than heating.


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