Sustainable energy

We work aggressively to reduce greenhouse gas emissions to 1990 levels by 2020 by designing, operating and maintaining energy systems that help the University achieve our Sustainability Plan goals. Here's how we do it:

Energy Sources

Cogeneration Plant

Producing electricity, steam and chilled water to heat, power and cool campus is what the Princeton cogeneration (cogen) plant does every day. In addition to providing electricity, heat and cooling to most buildings on campus, the plant serves as a laboratory for learning about energy efficiency and water conservation.


Importing energy in the form of natural gas and diesel fuel provides other options for powering our campus. Plant engineers monitor our energy usage and outside energy prices in real time, and seamlessly provide the most cost effective energy to campus. 

Public Utilities

We are both a customer and a supplier to our local utility company. Our Cogen Plant engineers monitor campus power usage and outside energy prices in real time, and seamlessly switch between buying energy when at a lower cost than producing it, or selling energy back when prices are high. Our plant also supplies "grid services" such as voltage and frequency adjustment, providing revenues to offset our electricity costs.

Solar Energy

Sunshine on 16,528 photovoltaic panels located on 27 acres south of the lake delivered to campus via a 13KV power cable = energy we don’t have to produce or purchase. Even on a cloudy day, our solar field can produce enough electricity to power 7,800 laptops. Peak output of the system can reach 4.5 megawatts and produces between 5% and 6% of the university’s total annual electric use. 

Greenhouse gas reduction

Campus Energy Group

Our Engineering and Campus Energy group contributes to and helps drive significant progress toward reducing our campus greenhouse gas emissions. The University is on track to reduce CO2 emissions to 1990 levels (95,000 metric tons) by 2020. The University has accomplished this through investments in energy upgrades, renewable energy resources, and an award-winning cogeneration energy plant. 

Energy conservation initiatives

Targeting our heat to 68 degrees in the winter and our cooling to 78 degrees in the summer conserves our energy while also maintaining comfort. 

Energy Master Plan

Since the University’s Energy Master Plan was established in 2008, annual energy savings of approximately $5.7 million and annual CO2 reductions of more than 25,000 metric tons have been realized or identified for implementation.


Replacing and recycling 200,000 lamps with LEDs will save approximately 14 million kilowatt hours, 9,690 metric tons of net CO2 and realize an annual energy cost savings of $1.2million. The campus-wide LED installation is expected to be completed by January 2018.

Sustainable Building Systems

Incorporating sustainable systems into our new and existing buildings, such as adding geoexchange heating and cooling systems and installing temperature sensors to monitor and control mechanical, heating and cooling systems, contributes significantly to reducing energy demands and greenhouse emissions.


Future Planning

Running a campus community is a 24/7 job, and we are planning for future emergencies to ensure we are ready when the next storm hits our area.


Generating and distributing power locally, with a microgrid, provides a reliable and cost effective electricity system. When Hurricane Sandy hit New Jersey in October 2012, Princeton’s Cogeneration Plant microgrid was able to generate power for campus, while also maintaining steam and chilled water. The University served as a place of refuge while neighboring towns remained without power for days. We also have two founding chairs of the Microgrid Resources Coalition right here on campus.