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Campus Energy


The University is committed to measurable greenhouse gas reduction through local verifiable action and no purchase of offsets. Princeton's goal is to reduce direct emissions to 1990 levels by 2020, even while expanding building square footage.

Goal, Strategy & Progress

Goal: Reduce greenhouse gas emissions to 1990 levels (95,000 metric tons) by 2020. This reduction is some 17,000 metric tons less than the current amount, assuming no campus growth. When campus growth is taken into consideration, the amount of CO2 reduction needed increases to an estimated 55,000 metric tons.

Strategy: Develop and implement the University's Energy Master Plan.

Progress (Overall):

  • In 2008, the University established an Energy Master Plan to allow Princeton to approach its 2020 reduction goal while expanding square footage. The plan calls for investing $45 million between 2009 and 2017 in energy-savings projects in order to achieve $8.5 million in annual savings. In 2010-11, the University spent about $477,500, resulting in savings of about 1,000 metric tons of COand $193,000 in energy costs. Since the master plan was established, the University has invested $5.3 million in energy-savings projects, resulting in annual savings of about $1.7 million in energy costs and 10,000 metric tons of CO2
  • Campus CO2 emissions have declined by approximately 2.6 percent since fiscal year 2008, even with the addition of more than 560,000 square feet to the University's physical plant in the same time period (Figure 1). In the past fiscal year, emissions deviated from the reduction trend slightly, rising by 1.5 percent, to approximately 111,700 metric tons.* The increase is likely due to bringing the new Frick Chemistry Laboratory on line, while the old building, which will be converted to a less energy-intensive nonlaboratory building, was still on line, as well as a significant increase in campus heating and cooling demands due to more extreme weather (more cold or hot weather for longer than average periods of time) over the past year. 
  • Due to conservation efforts, electricity usage by the campus increased only by 3.9 percent from fiscal year 2008 to fiscal year 2011, even with the addition of Whitman College, Sherrerd Hall, Lewis Library, Roberts Stadium, the Fields Center and the Frick Chemistry Laboratory.
  • An additional 5 percent (equal to more than 3,000 metric tons of CO2) of the University's operational strategies for reducing greenhouse gas emissions were determined this past year, bringing the total of known strategies needed to achieve its 2020 goal to 84 percent. At the outset of the Sustainability Plan in 2008, the University had identified only 70 percent of the strategies needed to reach the goal. To date, the University has achieved 28 percent of the strategies necessary to reach the goal (Table 1).

*NOTE: Due to a refinement of the emissions data analysis by the utility from which Princeton purchases some of its electricity, fiscal year 2009 CO2 emissions have been determined to be lower than previously reported. The decrease in emissions from fiscal year 2008 to 2009 was approximately 3.6 percent versus the less than 1 percent previously reported. Fiscal year 2010 CO2 emissions have also been determined to be lower, making the decrease in emissions from fiscal year 2008 to 2010 approximately 4 percent versus 2.5 percent.

Figure 1: Campus Growth and Greenhouse Gas Emissions History
Between 2008 to 2011, campus emissions have declined by 2.6 percent, despite a corresponding expansion of more than 560,000 square feet. Reaching the Sustainability Plan goal without additional square footage expansion will require reducing direct emissions by some 17,000 metric tons over the next 10 years.

Table 1: Strategies to Reach 2020 Greenhouse Gas Reduction Goal

Reduction Strategies Goal
(Metric Tons)
Actual Completed
(Metric Tons)

Percent Completed
Biodiesel 4,773 - 0%
Automated Building Optimization 2,771 282 10%
Demand Controlled Ventilation 1,230 117 10%
Distribution System Improvements 4,608 4,792 104%
Grid CO2 Reductions 5,000 - 0%
Ground Source Heat Pumps 5,035 - 0%
Heat Recovery 353 252 71%
Improve Plant Efficiency 4,920 4,535 92%
Increase Plant Runtime 2,800 - 0%
Jadwin Hall HVAC Renewal 1,969 2,588* 131%
Lighting Improvements 5,320 722 14%
Low Flow Fixtures 810 810 100%
Other Building Retrofit HVAC Renewals 2,363 471 20%
Solar Collector Field N/A 3,091 0%
Undetermined 10,468 1,237 12%
Total 55,511 15,806 28%


Progress (Detailed):

Renewable Energy

  • The University will begin installation of a 5.2-megawatt solar collector field in the fall of 2011 on 27 acres it owns in West Windsor Township. The system, comprising 16,500 photovoltaic panels, is expected to generate 8 million kWh per year — enough to power the equivalent of 700 homes, or enough to meet 5.5 percent of the total annual campus electrical needs while avoiding about 3,000 metric tons of CO2 per year. Notably, no CO2 emissions reductions will be claimed until the system is paid for (by 2020), and generated Solar Renewable Energy Credits (SRECs) are "retired" (no longer sold).

Existing Building Energy Conservation Projects

  • A control system optimization technology was put into place in Robertson Hall, maximizing the academic building’s energy efficiency. Similar technologies are planned for more than 40 existing buildings on campus.
  • Energy audits were completed on 30 of the top 50 energy-consuming buildings. A total of 290 energy-efficiency projects have been identified; they are expected to result in more than 20,000 tons of CO2 reductions once implemented, with a simple payback period of about five years.
  • Of approximately 300 energy meters scheduled to be installed in the top 60 energy-consuming buildings on campus, 35 electrical meters, two chilled water meters and four steam meters have been installed to date.

Lighting Upgrades

  • New fluorescent fixtures with built-in occupancy sensors were installed in the cogeneration plant; these are estimated to reduce energy consumption by 340,000 kWh per year, or 112 metric tons of CO2.
  • LED lighting has been installed in the theater and dance studios and around the east building entrance of New South, the small conference room of the MacMillan Building, and the food servery at the Center for Jewish Life. LED task lighting will also be used in Frick Chemistry Laboratory offices.
  • LED lighting has been approved for installation in the main Dillon Gym as well as the two multipurpose rooms; it is expected to result in approximate savings of 43,000 kWh and 16 metric tons of CO2 per year.

Heating, Ventilation and Air-Conditioning (HVAC) Replacement

  • HVAC system upgrades to reduce air changes were made in two large research laboratories (Thomas and Icahn) using advanced air sensor control.

Distribution System Improvements

  • The University worked with the New Jersey Board of Public Utilities to modify existing regulations to allow Princeton to distribute efficient cogeneration power to remote parts of campus using the utility grid.
  • More than 290 steam traps — some of the 10,000 devices in the University’s distribution system that hold steam vapor into the pipe while letting water drain out — were replaced in the last fiscal year, resulting in expected savings of nearly 800 metric tons of CO2 emissions annually.

Plant Efficiency Improvement

  • A grant of $500,000 from the New Jersey Clean Energy Smart Start Program was applied to a heat recovery project in the cogeneration plant, which is expected to result in an annual savings of 4,700 metric tons of CO2 emissions.


  • During the 2011 fiscal year, the Office of Information Technology (OIT) "virtualized" 110 physical servers, bringing the total to more than 380, or nearly 65 percent of servers, that have been virtualized since 2007, saving more than 1.9 million kWh annually, or 737 metric tons of CO2.
  • OIT also installed desktop power management software for 2,500 computers this past year. The automated shutdown at night and on weekends has achieved an annual savings of 1.6 million kWh, or 620 metric tons of CO2.

What's Next

Short Term

  • Complete construction of a 5.2-megawatt solar collector field.
  • Upgrade lighting in at least 12 buildings during fiscal year 2012, including Dillon Gym.
  • Audit the remaining 20 of the top 50 energy-consuming buildings.
  • Complete installation of approximately 150 (out of 300) energy meters in top 60 energy-consuming buildings
  • Begin installation of control system optimization technologies in more than 40 buildings across campus.
  • Increase server virtualization target to 75 percent.
  • Migrate servers and storage from less-efficient data center rooms to the new High-Performance Computing Research Center.
  • Investigate the feasibility of additional desktop energy-savings (e.g., expanding the number of desktop computers using power management software).

Long Term

  • Identify the remaining, currently unknown, 16 percent of the operational strategies needed to achieve the 2020 greenhouse gas reduction goal.
  • Complete energy audits in the top 50 energy-consuming buildings and implementation of identified energy-efficiency projects.
  • Implement HVAC system upgrades in Thomas Laboratory, and HVAC and lighting system upgrades in Icahn Laboratory.
  • Complete installation of control system optimization technologies in more than 40 buildings across campus.
  • Continue to install motion sensors integrated with lighting, room heating and cooling systems.
  • Continue installation of more than 600 steam traps as well as adding heating and cooling piping insulation.
  • Expand LED lighting as improved aesthetic, cost-effective options become available; standardize LED task lighting where feasible.
  • Continue to pursue, as financially feasible, the use of biodiesel in the cogeneration plant. (Princeton acquired the first permit in the state to burn biodiesel in stationary boilers, and the first permit in the world to burn biodiesel in an LM1600 gas turbine engine.) 
  • Optimize plant operations and utility distribution to reduce energy use. 
  • Investigate the feasibility of local offshore wind power as part of the University's renewable energy portfolio.
Solar Field

"The Princeton engineering team is clearly expert at cost-benefit analysis, having designed and implemented the most innovative and cost-effective energy plant of any university we've seen. The solar project met all of Princeton’s tough criteria and should prove to be a crowning jewel.”
—Tom Leyden, former managing director, SunPower Corp.,
the global solar technology company that will design and build the 5.3-megawatt solar collector field the University is installing on land it owns in West Windsor (Photo by Tom Grimes Photography for SunPower)


Investing in Energy

To finance the solar collector field, the University is using a distinctive business model for this application that will pay for the project's lease through incentives and by initially selling solar renewable energy credits associated with the project. During the eight-year lease, Princeton will sell the Solar Renewable Energy Certificates (SRECs) produced by the project to a utility that then will be allowed to claim all environmental benefits. Many states, including New Jersey, require utilities to provide a percentage of their electricity sales from solar generation. Rather than building their own solar plants to meet these targets, suppliers can buy SRECs to achieve compliance with the state's renewable portfolio requirements.

The University will sell the SRECs associated with the system to help pay the lease. However, Princeton will not claim any environmental benefits, such as carbon emissions reduction, until the University stops selling the SRECs and begins "retiring" them, which is expected to occur in 2020. Retiring the SRECs in 2020 would mean that the University would, from that point on, prevent the emission of approximately 3,090 metric tons of carbon dioxide per year — 6 percent of the reduction goal.


Why No Offsets?

Princeton believes in verifiable, long-term solutions to reducing reliance on fossil fuels and has committed to reducing its primary emissions to the fullest extent possible without the purchase of market offsets.


EPA award

In fall 2010, Princeton was awarded a U.S. Environmental Protection Agency CHP Greenhouse Gas Reduction Partnership Certificate in recognition of the University's most recent highly efficient enhancements to its cogeneration systems. The first CHP award was received in 2007 for the University's original system. CHP stands for combined heat and power — also known as cogeneration — an efficient, clean and reliable approach to generating power and thermal energy from a single fuel source.