Hybrid geothermal system considerations

Install a hybrid geothermal heat pump system and reduce the cost of implementing geothermal heating and cooling on your building project. A hybrid system reduces the peak capacity of your ground loop, letting you install a smaller, less expensive ground heat exchanger.


The Energy Center of Wisconsin with assistance from the University of Wisconsin Solar Energy Laboratory collected a year of operating data on three working hybrid system installations to analyze the economic and environmental impact of the hybrid approach and to compare it to other HVAC system designs. This data was used to investigate what contributes to an effective hybrid design and to validate energy models of these systems.

The study was funded by the United States Department of Energy, Alliant Energy, and Madison Gas and Electric. As a result of this project the Energy Center developed documents and tools for HVAC system designers to use, including a freeware version of their model, to assess the benefits of applying the geothermal hybrid approach on building projects. 

Free software models hybrid geothermal systems

A new tool developed by the Energy Center and UW Solar Energy Lab fills a gap for engineers and designers by modeling hybrid systems that can lower the up-front costs of geothermal. The free modeling tool can be used for the following:

  • Determine how much money a building owner can save by choosing a hybrid geothermal system.
  • Select optimal sizes for the equipment in a hybrid system.
  • Compare different hybrid geothermal approaches in terms of energy and economics for a given building project.
  • Analyze the effects of different control strategies for your geothermal or hybrid system.

- Edited by Chris Vavra, Consulting-Specifying Engineer, www.csemag.com 

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