By Jay Fox

Carleton College is located in Northfield, a small city amid the eastern prairies of Minnesota that sits about 40 miles south of Minneapolis and St. Paul. The school is regularly ranked among the top liberal arts schools in the nation and enrolls around 2,000 students. While its campus features numerous Collegiate Gothic buildings dating back to the nineteenth and early twentieth centuries, many new buildings have embraced a more contemporary aesthetic.

The most recently constructed student residences have also been built with efficiency and sustainability in mind. Eight townhouses were completed in 2024 as part of Phase I of the school’s Student Life and Housing Plan. Phase 2 saw the completion of three more townhouses that were completed in summer 2025. All eleven townhouses were designed to meet Phius CORE 2021 standards. The eight townhouses built during Phase I have already received final certification, and the three built during Phase II are expected to receive final certification soon.

Additionally, a 20,000-square-foot Student Health and Counseling Center was built as part of Phase II but was not designed to Passive House standards.

Building on a Climate Action Plan

Carleton’s decision to build the new townhouses to Phius standards is in keeping with the school’s 2011 Climate Action Plan, which has guided Carleton’s efforts to reduce campus-wide greenhouse gas emissions. Instead of business-as-usual, the plan was designed to bring net campus-wide emissions down to zero by 2050 through a combination of emissions reductions and carbon offsets.

In 2024, Carleton released the Sustainable Futures Framework, which updates the original Climate Action Plan to better align with the college’s evolving priorities on climate issues. The Framework calls for continuing Carleton’s leadership in emissions reductions on campus and collaboration on and beyond campus to accelerate climate action, according to the school’s website. “Our goals and actions are designed to build upon the success of Carleton’s 2011 Climate Action Plan, while deepening and expanding our work to support the integration of sustainability, climate action, and environmental justice into our curriculum,” it reads.

Concerns about climate change and Carleton’s desire to take a leadership role on the issue of sustainability certainly influenced the school’s decision to aim for net-zero back in 2011, but it also made financial sense when compared to the business-as-usual model. Two factors vital factors affecting cost were increasing volatility in energy prices and the belief that lawmakers would enact more rigorous carbon regulations. While the latter now seems unlikely anytime soon, at least at the federal level, the former was prescient: electricity prices throughout the country have been rising steadily and are expected to continue rising for the foreseeable future. Consequently, producing more electricity onsite and reducing primary energy use makes good financial sense, as Carleton (like most educational institutions) will maintain ownership over the buildings and facilities on their campus for decades to come.

Since enacting the plan, the school has transitioned from a district steam heating system to a district low temperature hot water heating system. The system, which was completed in 2021, partially relies on a geo-exchange system that is paired with heat pumps. The school now uses 1/3 of the natural gas it once did to operate the new system and hopes to expand the geothermal heat recovery system to further reduce reliance on natural gas. Systems upgrades have also included a new Building Automation System that is being installed campus-wide to ensure buildings are heated and cooled more efficiently.

The school has also reduced reliance on the regional grid by investing in wind and solar systems that feed directly into the campus grid. Currently, the school receives approximately 40% of its electricity from two wind turbines (1.65 MW and 1.6 MW), as well as 300 kW from local photovoltaic systems.

Applying Passive Principles

The 2011 Climate Action Plan also recommended designing new buildings to energy efficiency standards that go beyond LEED Silver certification to reduce EUI, though they did not explicitly specify Passive House certification. Independent of the Climate Action Plan, the college also hoped to create more living options for students and set a goal of making 20% of residences townhouse-style residences.

When it came to be time to build more student housing, the administration selected the design team and then issued a separate request for proposal (RFP) for a Construction Manager at Risk (CMR) in June 2022. Townhouses-style residences were a given, but there was no clear demand for Passive House design certification.

“The RFP for the CMR named several options for sustainable design certification, including Phius, as well as likely sustainable strategies that would be employed,” according to Carleton Associate Vice President of Facilities and Capital Planning Linda Weingarten.

“The college required the design team to use our district heating and cooling system,” Weingarten added. The school also required the new structures’ total energy use to not exceed that of the buildings to be replaced. This was a challenge because “the new buildings are about three times the square footage of the original buildings.” Passive House's rigorous performance standards allowed the team to meet this requirement.

Despite lingering questions about costs, the students appreciate the new townhouses, according to Weingarten. “Carleton students in general appreciate the college’s commitment to sustainability and many see these townhomes as a tangible result of that commitment.”