For decades, Macalester College has heated its entire campus with a central natural gas boiler system. That infrastructure served the college well, but when Macalester committed to full campus decarbonization by 2050, it became clear that the boiler network would need to give way to something fundamentally different.
The catalyst for change is a new five-story residence hall and welcome center rising at the corner of Grand Avenue and Macalester Street in St. Paul. The building will house 224 students, create a public plaza, and include a ground-floor welcome center designed to serve as the college’s primary arrival point. Scheduled to open in August 2027, it will be the first building on campus served by geothermal heating and cooling, and is being built specifically with future expansion in mind.
The project reflects Macalester’s broader campus plan. The geothermal plant being constructed to serve the new building is sized to eventually support all campus buildings north of Grand Avenue, allowing additional facilities to connect to the system over time and continue reducing the college’s dependence on fossil fuels.
Macalester’s 60-acre urban campus presents a challenge that has historically made geothermal energy impractical for many dense institutions: there simply is not enough land to support a traditional closed-loop system. A conventional ground-source heat pump installation capable of serving a building of this scale would require hundreds of borings and tens of thousands of square feet of land that the college does not have.
Darcy’s groundwater-enabled approach solves that problem. Four wells, each drilled to approximately 400 feet, access an aquifer where groundwater maintains a consistent temperature of around 52 degrees year-round. Sealed heat exchangers move thermal energy between that groundwater and the building’s heating and cooling systems, delivering 422 tons of cooling capacity and 3,112 MBH of heating from a wellfield that occupies just a few square feet above ground.
The system is also designed as a thermal energy network from the start. When the college eventually connects additional buildings north of Grand Avenue, waste heat from one building can be transferred to another rather than released into the environment, delivering a significant efficiency advantage that compounds as the network grows. The project includes rooftop solar panels and a high-performance building envelope, integrating geothermal into a comprehensive clean energy strategy rather than treating it as a standalone upgrade.
Construction on the residence hall began in 2026, with the geothermal plant located in the basement of the new building. The system is designed around Darcy’s compact aquifer technology, which was developed from research at the University of Minnesota and has since been deployed across commercial, institutional, and public-sector projects throughout the Midwest and beyond.
The building also features hybrid cross-laminated timber and stick-frame construction to reduce embodied carbon, native plantings, and a green roof terrace. These factors combine to make it one of the most comprehensively sustainable new buildings on any Minnesota college campus.
The Macalester project is significant beyond the campus itself. Urban college campuses across the country face the same challenge Macalester has confronted: how to decarbonize aging thermal infrastructure on constrained land, without displacing the outdoor spaces and historic character that define campus life.
By demonstrating that a high-capacity groundwater geothermal system can be installed and expanded in a dense urban setting — and that it can serve as the foundation for a campus-wide thermal energy network — Macalester and Darcy are providing a replicable model that other institutions can learn from and build on.
In early 2025, the University of Minnesota opened the Offsite Collections Facility (OCF) on its St. Paul campus, providing a purpose-built structure designed to house millions of library volumes and archives in a secure, stable, and efficient environment. The facility addressed the longstanding challenge of how to preserve and provide access to the university’s vast collections without consuming valuable space in campus libraries.
Since February 2025, five full-time library staff and 20–25 student employees have operated the facility, moving more than 3.5 million volumes into carefully organized high-density storage. Each item is housed in a size-sorted tray and scanned into a shared Big Ten library system, ensuring every inch of space is optimized and every item remains retrievable. A reading room is planned to eventually allow visitors to access collections by appointment, expanding public engagement with university archives and special collections.
Sustainability at the University of Minnesota is not a project-by-project decision. All new buildings follow the Minnesota B3 Guidelines, an adaptation of LEED, ensuring every project meets a consistent standard for environmental performance. According to Shane Stennes, the University’s Chief Sustainability Officer, sustainability is a foregone conclusion, and efficiency is not an afterthought but a design foundation.
The University’s 2023 Climate Action Plan sets a clear path toward decarbonization, including reducing heating and cooling-related carbon emissions by 20% by 2033 and achieving full decarbonization by 2045. These goals are directly embedded in how the university approaches new infrastructure like the OCF.
There is also a deeper connection between this project and Darcy specifically. Darcy’s core groundwater geothermal technology originated from research conducted at the University in the early 2010s by our Chief Science Officer Jimmy Randolph and Chief Geologist Scott Alexander. The OCF is the first University-built project to utilize that technology, representing a full-circle moment from academic research to real-world institutional application.
The design and construction team, led by Trevor Dickie, Scott McCord, and Nicholai Fugate, evaluated a range of systems for heating and cooling, including air-cooled chillers, boilers, and source heat pumps. Two requirements narrowed the field considerably: the OCF’s unique storage environment demanded exceptional temperature stability to protect sensitive collections, and the university’s sustainability mandate required maximum efficiency within a minimal footprint.
Initial site constraints made geothermal seem like a long shot. Traditional closed-loop systems often require hundreds of borings to achieve the needed capacity. Darcy’s groundwater-enabled approach delivered commensurate capacity with just three 12-inch-diameter wells. The simplified design met capacity requirements and improved energy efficiency, even as the building’s total energy use was set to double with the addition of high-density storage operations.
Dickie described the process as an integrated design journey that balanced innovation, practicality, and long-term value.
Construction began in April 2023 and wrapped up by February 2025, with geothermal drilling completed in fall 2023. The geothermal system uses a four-part water circuit with variable speed control, ensuring optimal temperature regulation across the facility’s demanding storage environment. By integrating geothermal energy with efficient building envelopes and low-temperature hot-water loops, the project team achieved both reliability and performance within a smaller mechanical plant footprint.
For the University, the OCF was an opportunity to test, measure, and refine sustainable design practices at scale. From mechanical engineering to library operations, collaboration across disciplines was central to the project’s success.
“You have to figure out how you can use less, then find efficient systems that can do the job,” said Dickie. Long-term lifecycle savings ultimately made geothermal the compelling choice. “The dollar always wins, but when you start to see and quantify the savings, it changes how you think.”
The University of Minnesota views the OCF geothermal installation as a pilot for future opportunities. Geothermal is now firmly part of the University’s toolbox for sustainable infrastructure, with each new project evaluated on its own site conditions, financial case, and operational needs. The success of the OCF demonstrates that groundwater geothermal can perform even where space is limited and demands are high.
As the facility continues to fill with history of the university’s collections, the geothermal system quietly ensures that knowledge is preserved efficiently and responsibly for generations to come.
The urban Louisville renovation project aimed to demonstrate that sustainability and financial logic go hand-in-hand. The goals included demonstrating the potential for geothermal in an urban area, improving energy efficiency and showing that innovative new technologies can be built in tight urban areas. It also focuses on energy efficiency and a reduced total cost of ownership through the application of groundbreaking HVAC technology.
Design of the water wells for this project needed considerable investigation and collaboration. A variance for the onsite backup energy system was required, while the aesthetics and landscape design is meant to provide a serene environment for workers. Balancing well placement for a beautiful campus while allowing for future O&M requirements took ongoing discussion and planning from the architects, K. Norman Berry Associates, and their partners.
Mobilization on this project is planned for 2026. It is a 3-well, 338-ton groundwater geothermal system supporting the research mission of the Envirome Institute by providing sustainable, high-efficiency thermal management. The system serves as a live demonstration of environmental stewardship and incorporates the institutional values of the organization in how they transform their facilities and prepare to futureproof their operations.
The project stands out for its ability to deliver superior energy performance on restricted sites. By choosing Darcy for the Envirome Institute in Louisville, KY, stakeholders secured a high-efficiency geothermal solution that provides lasting value and supports future growth.
