Ball State is the home of the country’s largest geothermal system. This week the university began the second and final phase of converting to a geothermal ground-source heat pump system. The project began in 2009 and the first phase was completed earlier this year and now provides heating and cooling to nearly half the campus. Upon completion, the conversion should save Ball State $2 million a year.

The geothermal system is a vertical, closed-loop district system that uses only fresh water. It works by using the heat stored in ground water and thermal masses. A geothermal heat pump uses the Earth as either a heat source, when operating in heating mode, or a heat sink, when operating in cooling mode.

“When costs began to escalate for the installation of a new fossil fuel burning boiler, the university began to evaluate other renewable energy options,” said Jim Lowe, director of engineering, construction and operations. “This led to the decision to convert the campus to a more efficient geothermal-based heating and cooling system.”

Phase 2 includes installation of 780 of the remaining 1,800 boreholes in a field on the south area of campus. Construction will continue throughout 2013-2014 and will include a new District Energy Station South containing two 2,500-ton heat pump chillers and a hot water loop around the south portion of campus. The system will then connect to all buildings on campus — eventually providing heating and cooling to 5.5 million square feet.