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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 emissions to 1990 levels by 2020 even while expanding building square footage.

Figure 1: Campus Growth and Greenhouse Gas Emissions History

Between 2008 to 2010, campus emissions have declined by 2.5 percent, despite a corresponding expansion of nearly 364,000 square feet. Reaching the Sustainability Plan goal without additional square footage expansion will require reducing direct emissions by more than 18,000 metric tons over the next 10 years.

Table 1: Strategies to Reach 2020 Greenhouse Gas Reduction Goal
Reduction Strategies Goal
(Metric Tons)
(Metric Tons)
Percent Completed
Biodiesel 4,773 - 0%
Automated Building Optimization 2,771 132 5%
Demand Controlled Ventilation 1,230 117 10%
Distribution System Improvements 4,608 4,002 87%
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 5,320 610 11%
Low Flow Fixtures 810 810 100%
Other Building Retrofit HVAC Renewals 2,363 471 20%
Undetermined 13,559 1,237 9%
Total 55,511 14,754 27%

Table 2: Sample of Energy Conservation Projects Implemented in 2009

The examples in the table below of energy conservation projects are related to their strategies in the table above by color and by symbol.

Project First Cost Annual Cost Savings Annual MT CO2 Savings CO2 "tax"* Payback (yrs)**
Steam Traps
Distribution System Improvement
$404,000 $364,000 2,734 $95,190 2.0
Dillon Back Pressure Turbines
Distribution System Improvement
$914,000 $188,000 1,268 $44,000 3.0
Cogen Exhaust Heat Recovery
Plant Efficiency Improvement
$2,700,000 $900,000 4,535 $159,000 2.2
Lighting Projects
Lighting Improvement
$755,628 $152,801 610 $21,333 3.5

MT = metric tons

*CO2 tax = a voluntary “tax” based on average market values used by the Facilities Department when conducting financial cost-benefit analyses to determine whether to undertake more energy-efficient designs and technologies. By applying this “tax,” the University places a monetary value on its environmental impact, which in turn allows the institution to consider some high initial-cost energy-efficient technologies and designs as wise investments in what is likely to be an increasingly carbon-constrained market. The value of this tax was developed as a hybrid of the market value of CO2 certificates in European markets and the anticipated value of CO2 avoidance in the United States if incentives such as cap-and-trade or a carbon tax are implemented. Princeton also consulted faculty members to estimate what the cost of sequestering CO2 would be if such technology becomes available. 

**Payback calculations include any incentive rebates received.

Goal & Progress

Goal: Reduce greenhouse gas emissions to 1990 levels by 2020.


  • Even with square footage expansion, emissions are declining (Figure 1). While the decrease from fiscal year 2008 to fiscal year 2010 has been modest (2.5 percent), it is meaningful, considering that the University added 363,630 square feet to its physical plant during the same time period. The decrease from July 2008 to July 2009 was just under 1 percent. (See update.)
  • Due to conservation efforts, electricity usage by the campus increased only by 3.2 percent from fiscal year 2008 to fiscal year 2010, even with the addition of Whitman College, Sherrerd Hall, Lewis Library, Roberts Stadium, Butler College and the Fields Center.
  • The University established an Energy Master Plan that calls for spending $45 million between 2009 and 2017 on energy-savings projects, including setting benchmarks through an audit of the top 50 energy-consuming buildings on campus, to reduce overall utility usage on campus by at least 25 percent. In 2009-10, the University spent $4.3 million, resulting in savings of 9,000 metric tons of CO2 and $1.5 million in energy costs. The goal is to achieve $8.5 million in annual savings and 65,000 metric tons of annual reductions in CO2 emissions. Reducing emissions by this magnitude will allow Princeton to approach its 2020 reduction goal while expanding square footage.
  • LED lighting, including integrated motion sensors for lighting, heating and cooling systems, was installed above the main stairwell in the Thomas Laboratory lobby, with an estimated energy savings of over 16,000 kWh per year, preventing CO2 emissions equivalent to the energy needed to support one average home for one year.
  • One of the nation's first large academic installations of high-efficiency self-closing fume hoods took place in the Frick Chemistry Laboratory. Research labs on the upper three floors of the building feature 200 of these fume hoods equipped with automatic sash closers that reduce both air supply and exhaust requirements.
  • An additional 9 percent (or more than 1,200 metric tons of CO2) of the University's strategies for reducing greenhouse gas emissions have been determined (30 percent of these strategies were "to be discovered" when the Sustainability Plan was launched in 2008). These include the installation of new network software by the Office of Information Technology (OIT) that allows office computers to "sleep" when not in use, with no loss of backup functions. Through this program, the University has saved about 1,529,000 kWh, or $134,534 annually. Since 2007, OIT also has "virtualized" more than 250, or 40 percent, of servers on campus, saving more than 1,406,000 kWh, or $120,000 annually. Combined, that savings is equivalent to preventing the emissions associated with 11 railcars' worth of coal. To meet the need for increasing power requirements while reducing power consumption, OIT has used virtualization techniques to run multiple operating systems on single servers. In addition, OIT has upgraded to more efficient computer power supplies.
  • Fully implemented for the first time at the 2010 Reunions, 400 90-watt incandescent bulbs were replaced with 23-watt compact fluorescent bulbs, resulting in an estimated 74 percent energy reduction and an estimated 858 kWh and 875 pounds of CO2 savings (see sidebar photo). The associated emissions savings is equivalent to preventing the consumption of 70 gallons of gasoline.

What's Next

Short Term

  • Complete energy audits of the top 50 energy-consuming buildings on campus, as part of the Energy Master Plan, and identify specific strategies for reducing energy usage.
  • Upgrade lighting systems in Dillon and Jadwin gymnasiums.
  • Install advanced sensor technologies to reduce air changes in Thomas and Icahn laboratories.
  • Partner with the New Jersey Board of Public Utilities to distribute power from the cogeneration plant to remote parts of campus.
  • Remove old Frick building from active status as new, more energy-efficient Frick Chemistry Laboratory opens in 2010-11.
  • Replace hundreds of 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.
  • Complete construction of the High-Performance Computing Research Center for computing consolidation in 2011.
  • Install optimization software to monitor building energy performance, and 150 new building energy meters.
  • Reduce energy use of Jadwin Hall by up to 45 percent through efficient design during the current major maintenance renovation.
  • Optimize plant operations and utility distribution to reduce energy use.
  • Encourage departments to transition to server virtualization.

Long Term

  • Use an energy audit to refine the Energy Master Plan, developing specific, quantified strategies for reducing campus energy usage.
  • Identify remaining, currently unknown, 21 percent of the operational strategies needed to achieve the 2020 greenhouse gas reduction goal.
  • Continue to pursue, as feasible, the use of biodiesel in the cogeneration plant. (Princeton acquired the first such permit in the country.)
  • Expand outdoor LED lighting as improved aesthetic options become available.
  • Continue to install motion sensors integrated with lighting, room heating and cooling systems.
  • Investigate the feasibility of local offshore wind power as part of the University's renewable energy portfolio.
  • Replace remaining steam traps and continue to add heating and cooling distribution piping insulation.
  • Complete the installation of new building energy meters, and subsequent energy controls system optimization software.
  • Maximize computer virtualization.

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.

"To address climate change we need to actually reduce emissions of carbon dioxide. Princeton's on-campus efforts result in real reductions. The problem with purchasing offsets is that you're not sure what you're getting. Until offsets are regulated to guarantee that each one purchased actually displaces energy from fossil fuels, we will more reliably achieve reductions in emissions through on-campus action."
—Denise Mauzerall, associate professor of civil and environmental engineering and public and international affairs, Princeton University


Fume hood

One example of cutting-edge efficiency projects in new construction are the self-closing high-efficiency fume hoods installed in the new Frick Chemistry Laboratory.

Awards & Achievements

Princeton was recognized as a "Commercial/Business Leader for Energy Efficiency" in 2010 by the Northeast Energy Efficiency Partnerships. The University was honored for its continued efforts to advance energy efficiency. "Princeton University is a model of sustainability not just for higher education, but for the commercial sector as a whole," said Lee A. Solomon, president of the New Jersey Board of Public Utilities, in a news release about the award.


Figure 2: Princeton Primary Greenhouse Gas Emissions

Princeton University carbon dioxide emissions originate primarily from the central physical plant and purchased electricity. Click to enlarge.

"During my time working at the Office of Sustainability, I developed an inventory of Princeton's greenhouse gas emissions. I learned quite a bit about how the physical plant infrastructure that supports research and residential life at Princeton is operated. Having full access to the data and staff was a really cool opportunity to learn how a complex system works. I learned that sometimes the technical features of the infrastructure preclude benefits from common sense solutions (e.g., reducing heat demand by the end-user may not actually result in energy savings at the plant due to the fixed nature of the distribution network)."
—Mark Smith '09, Ph.D. student in microbiology, Massachusetts Institute of Technology

Reunions CFLs

Crews from the University Electric Shop replaced incandescent bulbs with compact fluorescent bulbs in Reunions event tents, decreasing energy usage by an estimated 74 percent.

"The internship [in the Office of Sustainability] was an excellent experience, learning first-hand the challenges and opportunities of emissions reduction efforts on the local campus level."
—Dennis Markatos-Soriano GS08, executive director, East Coast Greenway Alliance