Carleton College


Campus Utility Master Plan and Geothermal Conversion


Mechanical & Electrical


Northfield, Minnesota




$42 million


2.5 million square feet
(30 buildings)

Reducing Carbon Footprint through Geothermal Conversion

In its 2011 Climate Action Plan, Carleton College pledged to become a carbon-free campus by 2050. It is the first college campus to completely transition off steam and the first college campus to install a district-energy scale geothermal system. Our team worked with the campus to develop its 2016 utility master plan, which assessed the existing systems and made recommendations for new technologies to help the college reach its long-term goal of carbon neutrality. These recommendations are being implemented in a multi-year, multi-phased campus conversion project.

Our designs replace the existing gas-fired boilers and high-pressure steam distribution piping with a 120-degree heating hot water system, served by a new geothermal system comprised of a water-to-water heat pump and a series of geothermal bore fields located throughout campus. The new geothermal system is capable of providing simultaneous heating and cooling and is sized to meet the campus’ continuous heating and cooling demand. New high-efficiency gas-fired boilers will address the peak heating demand, and the existing chiller will remain in service to address the peak cooling demands.

By summer 2020, after one year of operation with only half of the system online, Carleton’s natural gas consumption decreased by over 40 percent, and total campus energy use (gas and electricity) decreased by nearly 30 percent. After the project’s completion, Carleton’s geothermal system will serve 70 percent of Carleton’s annual heating and cooling needs.

I’m excited and proud of how our bold conversion to low-temp hot water energy generation on campus is considerably reducing Carleton’s carbon footprint. I’m grateful to all those whose careful planning, creative thinking and hard work helped us achieve this new mode of operation.

Former Carleton President Steve Poskanzer