Building heating systems are being converted from steam to hot water heating. The system is run through existing and new Energy Facilities, where geo-exchange technology is used to maximize efficiencies. This massive conversion will reduce total energy consumption, life-cycle costs and carbon emissions as part of the effort to move Princeton University to carbon neutrality by 2046. 

Over 180 buildings require work to convert their existing mechanical systems to accept hot water. We will build new hot water systems while parallel existing steam equipment continues to provide seamless building operation. Some buildings may require temporary infrastructure to maintain operation of existing systems. Converting every existing campus building to hot water heating will be done in phases and will take many years to accomplish. 

Building Conversion Phases

Over the next 20 years, every existing building on campus will be retrofitted to work with the new hot water and geo-exchange system. The building conversions will be done in phases, combining small groups of buildings located near one another. Some buildings and dorms use steam for radiators, domestic hot water heating and for re-heating lab spaces. Each building requires a unique conversion plan and includes new equipment for heating, domestic hot water, preheat and reheat coils. 

All recent and current construction projects were designed with hot water systems and therefore do not require conversions, such as New College West and Yeh College. As the new Meadows Neighborhood buildings come online, their heating, cooling and energy will come from the new CUB facility. As other neighborhood buildings come online, such as the Frist Health Center, ES & SEAS, and the new Princeton University Art Museum, their heating, cooling and energy will come from the new TIGER facility. 

5x More Efficient

The improvement of the new heating and cooling system is phenomenal. Under the old steam heating system, when we input one unit of energy, we could only move three-quarters of a unit of energy to a campus building. Using hot water, heat pumps and geo-exchange, when we input one unit of energy, we can move four units of energy to a campus building. 

The new system is expected to be over five times more efficient.

Buildings on Hot Water

The following building conversions were completed in 2024 and connected to TIGER (as of May, 2024):

• Bloomberg
• Butler College
• Center for Jewish LIfe
• Caldwell Field House
• DeNunzio Pool
• Jadwin Gym
• Prospect House
• Icahn Laboratory
• Neuroscience Institute
• Peretsman-Scully Hall
• Thomas Laboratory

The following construction projects were built with hot water heating and are connected to TIGER or CUB:

• Meadows Neighborhood buildings
• New College West
• Yeh College

Path to Net-Zero

Check out the other projects that will enable us to begin converting from steam to hot water, conserve energy, increase our efficiencies, and decrease our carbon footprint and reliance on fossil fuels:

1. New Energy Facilities based on heat pumps (TIGER & CUB)
2. Geo-Exchange bore fields
3. Thermal distribution piping campus-wide
4. Building heating & cooling system conversions
5. Solar Expansion 
6. Energy Conservation Initiatives