Every year following reunions and commencement activities the campus performs its annual one-day steam shutdown. This shutdown is integral for Facilities Operations teams to perform maintenance on the district steam system to ensure it continues to run smoothly. 

“Every mechanical system requires maintenance,” describes Dave Weis, who started as Campus Plant Director at the beginning of 2025. “We have several pieces of steam-producing equipment in the plant, but there is only one set of pipes delivering steam to the campus and when the pipes are carrying steam, some maintenance and repair activities become too complicated or too dangerous to perform. Shutting down the system for a day provides an opportunity to safely do that work. A lot of planning and coordination helps keep the duration to a minimum.” 

Energy is something most of us take for granted throughout our daily lives on campus, but Weis is living and breathing Princeton’s dynamic geo-exchange system every day. As the overseer of all campus plant operations, he has a unique advantage when it comes to Princeton’s energy usage and commitment to sustainability. “Because we are electrifying our thermal energy system, and we’re getting greener and cleaner, I would suggest that everybody be conservation-minded and be a bit more energy-conscious. Every little bit that we can do reduces the demand on our energy systems and reduces our energy consumption and carbon emission.”

Dave’s history with Princeton began at the start of the campus’s thermal energy operations in 2004. “Part of my experience prior to joining Princeton was working here as a contractor. I had the opportunity to work on many of the systems in the Energy Plant, so I became familiar with the concept of thermal storage and how we support Princeton’s mission.”

The thermal energy system has a variety of equipment to ensure that the University always has what Weis calls “a readily available source of energy,” and it helps the campus save money during peak electrical usage times. This concept, which is a key part of campus energy operations, is “economic dispatching.” 

“Economic dispatching helps us decide what equipment to run and how to best utilize thermal storage.  Our thermal system allows us to run electric chillers, which consume considerable amounts of electricity, at night and in the early morning hours, when the cost of electricity is low,” he explains. “Then that thermal energy is available for us at the peak of the day when electricity is high. Smaller motors are needed to pump the water, and that takes stress off the electrical grid.”

That said, the key word Weis stresses when it comes to Princeton’s overarching energy operations approach is reliability. “We are serving a campus community and critical research with specific thermal energy needs. Economic dispatching helps us manage the cost of providing that energy without compromising reliability.”

Looking towards the future, Weis is excited about how the campus’s gradual conversion to a hot water-powered system will help with meeting the space heating and domestic water needs on campus. “One of the next challenges we need to solve is called ‘process steam,’” he says. “We’re looking at how to produce steam with electricity, taking that same reliability approach.” The electrified steam would serve laboratory and research activities, like sterilizing instruments, which require temperatures much higher than the new hot water system could provide. 

Weis is proud to talk about Princeton’s energy system and commitment to sustainability while giving tours of the campus plant. “I’ve had the opportunity to hold several tours of the TIGER facility with faculty, students, our peers in higher education, and those in the industry who are all interested in energy conservation and innovative technologies. That’s my opportunity to share what TIGER and the campus is all about.” 

Interested in learning more about Princeton’s sustainable campus, energy transition and campus energy efficiency? Check out this animated video overview of the TIGER Facility and geo-exchange system here.