Ground-Source Heat Pumps
Ground-source heat pumps (GSHPs) are well-established systems that can economically heat and cool buildings in most locations. They are in use on campuses throughout the United States because these facilities have buildings with long or year-round cooling requirements and heating loads. GSHPs take advantage of moderate soil temperatures available year-round a short distance underground.
The following links go to sections that describe how GSHPs may fit into your climate action plans.
GSHPs operate for many years. These systems use equipment that is the same as or similar to conventional district heating and cooling systems that most campus maintenance staffs are familiar with.
Campus Ground-Source Heat Pump Options
There are two ways campuses use GSHPs.
Individual buildings: A GSHP should be considered for a new or retrofit building that relies primarily on electric power for heating and cooling. The U.S. Department of Energy (DOE) publishes a fact sheet that helps federal facilities managers evaluate individual buildings for GSHP installations titled Preliminary Screening for Project Feasibility and Applications for Geothermal Heat Pump Retrofits.
District heating and cooling systems: In the future, larger GSHP systems will provide heating and cooling for entire campuses through district heating and cooling systems. Notwithstanding that most GSHP systems currently operate at temperatures suitable for heating and cooling a single building, larger GSHP systems are appearing throughout the world and in the United States (see example project from Ball State University below). Heated water is hotter and chilled water is usually cooler—called temperature delta—for distribution in district heating and cooling systems that serve multiple buildings.
Considerations for Campus GHSP Installations
- Are soil conditions suitable?
- Are heating and cooling needs large?
- Are fuel costs high?
- Is the necessary land available?
Research campuses should consider the following before undertaking an assessment or GSHP installation.
Suitable Soil Conditions
The geotechnical conditions and hydrology of the soil must be evaluated for heat transfer at a specific site before a GSHP system is considered. Usually, an installer will drill an exploratory well before estimating the cost to drill a large number of wells for a GHSP field.
Significant Heating and Cooling Needs
GSHP systems are relatively expensive to install and are most likely to be cost effective with a combination of high winter heating loads and summer cooling loads. This reduces the payback time for the initial investment.
High Fuel Cost
Ground-source heating and cooling are more likely to be cost effective where fuel and electricity costs are relatively high. This is usually the case where inexpensive natural gas is not available and electricity is used for heating and cooling.
GSHP systems may require significant open space for wells or ground loops. The land can be used for parking or open space use after the system is installed, but installation may take some time.
Leading Example: Richard Stockton College GSHP Project
Richard Stockton College in Pomona, New Jersey, successfully installed GSHP systems for heating and cooling. The Stockton College system has been operating since 1994 and has served as a model for many others. The original 1,470-ton cooling system (which was later expanded) was projected to cost $1.2 million more than a conventional boiler and chiller. (The college received utility rebates that offset initial costs.) The college expected to recoup this initial cost through energy savings in less than four years. Today, the college uses this system to teach design professionals about GSHP technologies.
Additional examples of research campus GSHP projects include:
The Lewis Center at Oberlin College: Uses 240-foot-deep vertical loops beneath a garden.
Ball State University: Is in the process of converting its central heating and cooling system to one of the largest GSHP systems in the United States.
Fort Polk: Fort Polk, Louisiana retrofitted 4,003 conventional residential HVAC systems with closed loop, vertical-borehole ground-heat exchange systems in cooperation with an energy service company in one of the largest ground source heat pump projects ever undertaken.
In this section you will find links to technology basics and industry information.
The Geo-Heat Center at Oregon Institute of Technology: This resource center provides information about all forms of geothermal heating.
GeoExchange: This industry resource provides information about GSHPs.