Sustainable Campus

Princeton's Sustainability Action Plan, first adopted in 2008 and expanded in 2019, challenged and focused Facilities in our sustainability efforts. Departments across Facilities contribute significantly to Princeton's sustainability efforts across all elements of stewarding our campus. Before we design a building we discuss the Sustainability Charrette to determine specific sustainability goals for the location. We're investing in sustainable energy systems and building improvements for a campus-wide transition from fossil fuels. In our daily practices we continually balance maintaining a beautiful, comfortable campus with respecting and protecting the environment.  

Building a Sustainable Campus

The sustainable technologies highlighted below feature prominently in our 2026 Capital Plan projects and our net-zero by 2046 goal. 

In 2022, Princeton University entered an unprecedented period of construction as 2026 Capital Plan projects began. In managing the campus infrastructure, we also recognized an opportunity to affect positive and significant change by converting from steam to hot water with geo-exchange technology and thermal distribution.


Converting the campus to a district-scale hot water system, with heat supplied by large central heat pumps coupled with geo-exchange, will dramatically reduce campus carbon emissions. Check out our new What is Geo-Exchange? flyer to understand how geo-exchange works.

Healthy Habitat

Recognizing the value of healthy habitats for human well-being and biodiversity, Princeton takes a campus-wide ecosystem approach to landscape management.

High Performance Exteriors

Super-insulated and airtight building envelopes reduce the energy needed to heat and cool spaces year-round. Other benefits include higher acoustical performance, improved thermal comfort for building occupants, and operational savings.

Layered Land Use

Considering one piece of land as having the potential to be used on three levels -- below ground, ground level, and above structures -- maximizes its efficiency. 

Mass Timber

Using mass timber helps to reduce embodied carbon in our built environment. 

Passive Design

New campus construction has a reduced carbon footprint thanks to an integrative design process that supports passive design principles, including building orientation, climate control, insulation, and ventilation.

Stormwater Management

Green roofs, porous pavement, and bioretention technologies improve surface water quality. Enhanced storm water management reduces runoff of rainwater and restores streams corridors by employing solutions that allow for subsurface storage and infiltration where building footprints will not allow local solutions.

Water Re-Use

To reduce water usage, condensate water from HVAC cooling equipment and rooftop rainwater are collected and used to flush toilets in many buildings.

Powering a Sustainable Campus

Princeton University pledged  to reach net-zero campus carbon emissions without the use of offsets by its 300th anniversary in 2046.

Princeton’s steam system began operation in the 1860s. We estimate that at least 30% of the heat made in the cogeneration plant is lost in the ground due to aging pipes and inefficient technology. We were faced with the decision to replace the steam lines and continue with inefficient technology, or install something new and more efficient. We embraced this once-in-a-generation opportunity to lay the foundation needed to achieve net-zero greenhouse gas emissions by investing in transformational infrastructure upgrades. 

When planning for these upgrades, a core principle was to assess options for their repeatability and scalability beyond the campus. It was important to many within the University, across our community of staff, faculty, students, alumni, and neighbors, that the Princeton campus could be used as a test bed for the kind of wholesale transition to sustainable practices and infrastructure that is critically needed at the national and global level. 

Path to Net-Zero

Princeton's infrastructure upgrades include campus-wide projects that work together to transform the way we power campus. Like most institutions, Princeton historically has relied upon energy sources — primarily steam heat and electricity — that are powered by burning fossil fuels. The University is moving toward a system that will employ a combination of combustion-free technologies to optimize and reduce overall energy usage and eliminate carbon emissions. A critical part of our plan to reach net-zero emissions by 2046 is to transition from steam to a new hot-water energy system driven by electric heat pumps, thermal storage and geo-exchange — becoming one of the first sites in the nation to combine these technologies at this scale. The system will be powered by renewable energy sources, including solar.

These six Path to Net-Zero projects will enable Princeton to convert from steam to hot water, increase our efficiencies and decrease our carbon footprint and reliance on fossil fuels (follow the links to find more information about each project on the Facilities website):

  1. New energy facilities, TIGER & CUB, based on heat pumps
  2. Geo-exchange bore fields
  3. Thermal distribution piping campus wide
  4. Building heating and cooling system conversions
  5. Solar expansion 
  6. Energy conservation Initiatives

A Glimpse of How it Works

The schematic and descriptions below offer a glimpse of how the system will work in our new Meadows Neighborhood, located off Washington Road in West Windsor. This brand new neighborhood provided a rare occurrence on our historic campus, a blank slate with an opportunity to build contemporary, highly-efficient systems from the beginning.

illustration of how new infrastructure will work in meadows neighborhood
  1. Campus buildings: During summer months, heat is removed from campus buildings and transferred to water circulating in a closed-loop system of pipes. The heated water returns to CUB, where it is then directed into the geo-exchange bores and stored in the rock beneath the surface. In winter, the heat is pulled out of the ground and returned to CUB and campus buildings via the same system.
  2. Low-temperature heating and chilled water distribution lines: Distribution pipes carry chilled water (at 40 degrees Fahrenheit) for cooling spaces and heated water (at 120 degrees Fahrenheit) for heat and hot water from CUB to campus buildings. They also send heat from campus buildings to CUB, where it is directed into the geo-exchange piping and stored in the geo-exchange field in the summer.
  3. CUB/heat recovery chiller facility: The main facility controlling the energy needs for the Meadows Campus, CUB, is being built to achieve LEED certification from the U.S. Green Building Council, with a system of passive ventilation and cooling for the equipment it will contain. It will house heat recovery chillers, machines that capture heat generated during the process of chilling water.
  4. Geo-exchange piping: Geo-exchange piping will send heated water from CUB (either harvested from campus buildings that are being cooled or captured by the heat recovery chillers) to be stored in the geo-exchange field. At times when heat is needed for campus, it will transport the energy back from the geo-exchange field to CUB before being transferred out to campus buildings.
  5. Geo-exchange field: Geo-exchange bores, holes dug 600 feet deep on the new campus (and 850 feet on Princeton’s existing campus), will contain piping that recirculates water in the ground, transferring heat energy to the rock beneath the surface via conduction. The rock is heated to 90 degrees, energy that is stored there until it is needed in the winter.
  6. Thermal energy storage tanks: Thermal energy storage tanks will store heated and chilled water that are produced at optimal times for the lowest cost and greatest energy efficiency. That water can then be drawn down and supplied to the campus during periods of high demand.
  7. Backup hybrid coolers: In the summer, when the geo-exchange field is warm and unable to absorb additional waste heat from the cooling process efficiently, the backup hybrid coolers will reject waste heat into the atmosphere. The coolers can operate in dry or wet/hybrid mode. In dry mode, cool air is blown across the warm water coils, like a typical car radiator. When more heat needs to be rejected, the coolers can operate in wet/hybrid mode, where water is sprayed and evaporated to pre-cool the air, prior to blowing over the coils. The pre-cooled air will absorb more waste heat from the coil before being rejecting into the atmosphere.
  8. Electrical yard: The main electrical feed for the new area of campus enters at the electrical yard, where it is distributed to buildings and facilities, running primarily on renewable energy including Princeton’s own solar panels. A generator will be installed there, keeping CUB up and running in the event of a power outage.

The time is now 
Going deep: Princeton lays the foundation for a 'net-zero' campus

Maintaining a Sustainable Campus

Our commitment to sustainability continues well after we open new buildings and involves all aspects of supporting our beautiful campus.

Waste Reduction


The campus bio digester, called Sustainable Composting Research at Princeton (S.C.R.A.P.) Lab, encourages resource reuse by recycling nutrients back into the environment through the conversion of food waste into a soil amendment for campus greens.

Greening Move Out

Every spring, the EcoReps Move Out team partners with local charities and organizations to donate any used or unwanted items from campus dorms. As students move out, we have tented donation stations across campus. Donated dorm items are recycled through the EcoReps Move In Resale, Goodwill, Gradbag, and Arm In Arm.

Recycled Paper Products

Using recycled paper products for printing, toilet paper and paper towels was an easy switch for us, and encourages sustainability in the supply chain and procurement of purchased goods and services. 


Help us make recycling a success on campus by recycling properly and avoiding contamination. Visit our Recycling Guidelines for more information.

Recycling 95% of Construction Materials

When challenged, Facilities found ways to actually meet (and exceed) a 95% minimum requirement to recycle all demolition and recycling debris for all major building projects and renovations post abatement.

Resource Recovery Program

The Resource Recovery program serves as an important function to help us conserve University resources, support sustainability efforts, and safely dispose of electronics and other items. 

Smaller Waste Carts

We removed the huge dumpsters from behind our campus buildings and now drive small carts to transport campus waste. This switch helped reduce gasoline, beautify campus, and over time may help quantify waste coming from different parts of campus. 


Blue Cleaning

Specific blue cleaning equipment turns ordinary tap water into electrically activated water (EAW), resulting in a multipurpose cleaning solution, eliminating the need for traditional cleaners.

Green Cleaning

When blue cleaning is not appropriate, the next best option is green, and we are purchasing more Green Seal Certifed chemical cleaners and soaps each year.

Greenhouses & Nursery

Princeton is one of a handful of non-agricultural universities to have its own greenhouses and nursery, thanks to Beatrix Farrand's vision in 1935.

Integrated Pest Management

We use a system called integrated pest management (IPM), which examines comprehensive information on the life cycle of pests and their interaction with the environment.


We recycle nearly 100% of our vegetative products (leaves, trees, excavated soils) making mulch, compost and soil that is returned to campus. 

Organic Fertilizers

We are experimenting with organic fertilizers and compost teas as effective alternatives to chemical fertilizers.