Geothermal Conversion

In its 2011 Climate Action Plan, Carleton College pledged to become carbon-free by 2050. Salas O’Brien worked with Carleton to develop its 2016 utility master plan to chart a multi-year, multi-phase course for doing so. Since then, Carleton has become the first college campus to transition off steam entirely and the first college campus to install a district energy-scale geothermal system.

The new system of borefields located throughout the campus, capable of supporting simultaneous heating and cooling, enabled the transition to a 120°F heating hot water system. Peak heating and cooling demand can be met with supplemental new high-efficiency gas-fired boilers and the existing chiller. This comprehensive utility project is housed in a new primary-source energy station incorporated as the sub-basement of Carleton’s new science building.

Completion Year


Construction Cost

$42 million


2.5 million square feet
30 buildings

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.
Steve PoskanzerFormer Carleton President