The Fires Underneath Pforzheimer House

We set out to uncover and understand the system that keeps Harvard running — from heating and cooling to electricity. A deeply complex system emerged — one at once modern and old-fashioned — and one that will have to change as climate change accelerates.



September 23, 8 p.m.: That’s when we hear it.

It’s among the first chilly days of fall — the sweaters we lugged to Cambridge weeks ago are ready to be used. A sense of summer’s conclusion lingers in the brisk air.

Suddenly, inside our Cabot House bedrooms on either side of the Radcliffe Quadrangle’s lawn, a hissing, clanking noise kicks in.

Twenty feet below Pforzheimer House, a fire dashes violently through the center of a menacing, truck-sized heap of metal and pipes known as a Kewanee Classic III Scotch Boiler, a trusty, decades-old machine. The boiler pumps out steam, which races down hallways, slithers under floorboards, and weaves through bedrooms, where it reaches our radiators. There, it heats the metal up before condensing into water and rushing back toward the boiler.


The boiler room tucked below Pfoho’s Moors Hall is but a small part of the behemoth energy operation that makes life at the University possible.


All told, Harvard owns and operates two power plants: the new Allston District Energy Facility, a key part of the University’s expansion in the area, and the Blackstone Steam Plant, which heats roughly 80 percent of campus and co-generates electricity. Harvard also operates its own electric microgrid, with a capacity and peak energy demand enough to power about 40,000 homes.

But for students like us, this vital operation of heating and cooling our campus, including the workers that run it, is often hidden from view: in basement boiler rooms, power plants, and the mythic network of tunnels.

We set out to uncover and understand the system that keeps Harvard running — from heating and cooling to electricity. From tours of the infrastructure, conversations with facilities workers and administrators, and many, many emails, a portrait of a deeply complex system emerged — one at once modern and old-fashioned. It’s also a system that will have to change if the University is to meet its ambitious climate goals: fossil fuel neutral by 2026, and fossil fuel-free by 2050.

Though Harvard has decreased greenhouse gas emissions by about 29 percent over the last 16 years, its carbon footprint remains gargantuan: the University emitted the equivalent of 200,000 metric tons of carbon dioxide in 2021, according to data released by the Office of Sustainability — roughly 14,000 times the average American’s annual carbon footprint.

The University faces a steep challenge, because reaching its goals depends not only on increasing energy efficiency and remaking campus infrastructure, but also on the makeup of the larger Massachusetts grid, which does not share its fossil fuel-free goal.

As the 1.7 trillion tons of carbon dioxide emissions sitting in the atmosphere — more than a quarter of them from the United States — dramatically, painfully remake our world, Harvard’s institutional position as a global leader on climate change, both in decarbonization goals as well as its research and education, will only become more important.

As climate change accelerates, the University must grapple with difficult questions: Are the administration’s ambitious climate goals the right way for Harvard to lead? And is it even within the University’s control to meet them?

The first place we look for answers to these questions is the basement of Pfoho.

'The Keeper'

On a crisp September afternoon, we follow John P. Sabbio, a maintenance operator for the University’s Campus Services, down a narrow corridor under Moors Hall.

Ducking under a low ceiling, Sabbio leads us down a rickety metal staircase. At the bottom, the rough concrete walls give way to a hot labyrinth of rusty metal and dirty concrete. Pipes intersect, twist, and snake in and out of view; brightly colored “danger,” “warning,” and “caution” signs stick out. At the core of the maze are three boilers, each about 12 feet tall.


In a gruff, Boston accent, Sabbio explains how the boiler system works, going through each component in quick succession.


What looks to us like an incomprehensible maze is second nature to Sabbio, who has been an employee of the University for 37 years. Sabbio began his career in Heating, Ventilation, and Air Conditioning as a Machinist’s Mate on the USS Dwight D. Eisenhower, a nuclear-powered aircraft carrier.

Only one boiler is in use on this day. Another is undergoing its annual inspection and retooling, so we can look inside — it’s studded with cylindrical holes about two inches across, which fill with water that’s converted into steam, Sabbio tells us.

He points us to the glass end of a thin metal tube that sticks out from the center heating cylinder, through which we can see the single fire that ultimately provides heat to the Quad. He explains that the fire only turns on periodically, when the pressure within the pipes drops and the temperature of the steam falls below 212 degrees.


Sabbio counts down. “Fifteen seconds,” he says. We wait. “Three, two, one, right now!” A series of bright yellow and red hues spurt into view. The steam and pressure within the pipes rise, and after a while, the fire kicks back off.


Standing beside the noisy boiler, he explains his role. “I babysit it, I watch it, I’m the keeper.” In a system as high-pressure as this, though, babysitting is often a dangerous task, as a burn mark on his right hand attests.

Under Sabbio’s careful watch, the boiler — and, during the wintertime, sometimes multiple boilers — produces the steam that heats all the buildings in the Quad and powers the HUDS kitchens that serve Pfoho, Cabot, and Currier.

To make sure this essential system runs smoothly, the boilers are monitored in a control center, by a group in the Energy and Facilities Department that Sabbio calls “the brains of the whole place.” If something goes wrong — a busted pipe, or an offline boiler — they call someone like Sabbio to fix the problem.


Although Sabbio’s job is most demanding during the winter, it’s his favorite time of year to be in the boiler room. “On a zero degree day I come down here first because it’s always so hot,” Sabbio says. “You know, when it’s snowing out, it’s awesome. In the summertime, when it’s hot, it’s miserable.”

Sabbio enjoys his job, and recognizes its importance. “I just like heating, you know. I’m an HVAC mechanic,” he says. “I don’t do a lot of cooling. I do a lot of heating.”


Thanks to this system, Quad residents get heat and hot food every day. The Quad’s heating system is separate from the rest of the University, though, a relic from when the buildings still constituted Radcliffe College. To understand what heats the rest of campus, we need to go to the river.

The Beating Heart of Campus

Walk down Memorial Drive to Western Avenue and you’ll find the beating heart of Harvard’s heating system: the Blackstone Steam Plant.

On the day we go to Blackstone, it’s covered in scaffolding for ongoing repairs, but squinting through the black mesh, we can see its red brick and tall, arched windows that span several stories. Two silver towers protrude from the roof.

Harvard has owned Blackstone since 2002, when it acquired the plant from NSTAR utility company for $14.6 million, but the facility has produced steam for Harvard since 1930.

Today, Blackstone provides heat to more than 165 buildings on campus, and also co-generates enough electricity to fulfill roughly a third of Harvard’s electricity demand. The rest of Harvard’s electricity needs are met by a combination of on-campus solar panels, wind power purchases, and the regional grid.


From the outside, Blackstone appears sleepy and peaceful. But inside, it’s home to four natural-gas boilers, a turbine, and a machine that produces heat and power concurrently, surrounded by a maze of silver pipes, chains, and beams.

Unlike the Quad’s system, Blackstone’s boilers bring the steam to much higher pressure – 400 pounds per square inch – meaning that the temperature of the steam is also higher – 450 degrees.

The plant then cools down the piping hot steam — a process it harnesses to produce additional electricity. The steam rushes through a turbine, turning fans that then capture that energy as electricity, spitting out up to 5 megawatts, enough to simultaneously charge 1 million phones.

More electricity is also generated in Blackstone through a unit that creates heat and power at the same time, generating up to 7.5 megawatts of electricity — another 1.5 million phones.

The newly-cooled steam then exits Blackstone and enters a network of tunnels. The tunnels are a source of legend at Harvard, inspiring countless stories. A Nazi spy escaped an FBI agent through them, one story goes. Alabama governor George C. Wallace, fleeing protestors for his pro-segregation views in 1968, escaped through them, goes another. Nowadays, whispers of secret late-night rendezvous spread through campus.


Though these legends are most of what students hear about the steam tunnels, they also serve a vital function. Built in the early 20th century as Harvard transitioned from having individual boilers for each building to using Blackstone as a centralized hub, today they facilitate the distribution of heat and hot water across Harvard’s campus.

They heat the Yard, River Houses, Kennedy School, Divinity School, Law School, and lab buildings. They even provide heat to some of Harvard’s Allston campus, bringing steam to the Business School through a tunnel embedded in the hollow Weeks Bridge, so narrow that the rare maintenance worker making the crossing sometimes has to stoop or crawl.

The steam might end up warming a sleeping first year in their Wigglesworth dorm, a mouse in the Biolabs, or a Business School student partying with their friends.

As the only supplier of heat to most of Harvard’s campus, Blackstone is vital for the University’s daily functioning — and the reason we don’t freeze during Boston’s bitterly cold winters. In case of power outages or natural disasters, the University has standby units that are maintained at all times.

Once winter turns to summer, though, the challenge shifts from heating to cooling. Harvard’s chilled water system, which consists of a 13,000-ton plant in the Science Center and a 7,500-ton plant in the Northwest Building, cools 75 buildings across campus. As the chilled water runs through the building, warm air is blown past it and cools down in the process, before reentering the room and cooling it down in turn.

Machinery in the Science Center basement pumps the water up to three towers that protrude from the roof. The Northwest Building also produces some chilled water. Together, the facilities provide cooling power equivalent to installing 6,800 residential air conditioners.


The energy Blackstone produces flows into Harvard’s own microgrid, a complex network of miles of wires and cables that supplies power to over 250 of the school’s buildings. At peak demand, the system uses 40 megawatts, enough to supply 40,000 homes with electricity.

This energy demand does not come equally from all buildings on campus. Labs, despite only making up 22 percent of campus, consume 46 percent of Harvard’s energy due to the energy-intensive devices they include. Residential spaces, by contrast, use 16 percent of Harvard’s energy despite making up 31 percent of its land area.

Since Harvard owns its microgrid, it can control which sources provide the electricity that flows through it.

Blackstone produces up to 12 megawatts. Rooftop solar panels, installed across 31 locations, can provide up to 3 megawatts, depending on the weather. Harvard also buys around 13 megawatts of wind power from the Stetson Wind Il facility, which does not go to powering campus, but rather to offsetting its emissions. What isn’t provided by these sources is taken from the regional grid — which stretches from New York to the Canadian provinces of Ontario and Quebec.


Though some of Harvard’s electricity comes from renewable sources, it is still reliant on fossil fuels. Last year, Blackstone used 13 million therms of natural gas, 330,000 gallons of fuel oil, and 40,000 gallons of waste vegetable oil.

In the regional grid, 10 percent comes from renewable energy, 3 percent from nuclear, and 6 percent from hydro power. As for the rest, 46 percent comes from fossil fuels, while 16 percent is imported, making its breakdown unclear

Harvard’s partial reliance on the fossil fuel-dependent regional grid for electricity — one that might grow should Harvard stop burning fossil fuels to generate power and rely more on electricity — points to the fundamental issues of making a fossil-fuel-free promise in a deeply interlinked energy system.

'Green is the New Crimson'

On an October afternoon in 2008, thousands packed into Tercentenary Theatre — under banners promising that “Green is the New Crimson” — to hear an address from former Vice President Al Gore ’69, a vocal climate activist.

Then-University President Drew G. Faust introduced him: “How we light our classrooms, how we heat our water, how we build and ventilate our laboratories all send powerful signals,” she said.

Gore took the stage. “We have to do something unprecedented in favor of the survival of human civilization,” he said to the cheering crowd.

Criticizing the world’s “absurd overdependence on carbon-based fuels,” Gore emphasized the role higher education could play in combating the climate crisis.

“If we are to accept that goal, we must find ways to make better use of the knowledge produced in universities,” he said, “and supply their best and most recent conclusions as a basis for decision making.”

Gore’s speech capped off a month-long sustainability celebration University-wide, with events that included panels, film screenings, and discussions, and emphasized Harvard’s environmental focus.

As part of the event, Faust officially launched the Office for Sustainability, an expanded version of the former Green Campus Initiative. Its primary task would be implementing the sustainability plan Faust had unveiled that summer — with its ambitious goal of reducing campus emissions 30 percent from a 2006 baseline by 2016.


“We at Harvard must be a model as we demonstrate our commitment to the future,” said Faust at the event. “Every person at Harvard — student, faculty, staff — can contribute to the effort to avert the dire outcomes that scientists are predicting.”

“Green is the New Crimson” — at once a rallying cry and promise — seemed to reach and unify every corner of campus life. Students and professors worked with dining hall staff to create sustainable meals. William James Hall and the Hoffman Labs won “green medals” in a five month-long contest among thirteen FAS buildings to reduce energy usage. (According to a Harvard Gazette article at the time: “The real winner, though: Earth itself.”) And the University administration kicked into gear, working towards a goal it ultimately achieved.

In 2016, Harvard had met its 30 percent goal, with its “absolute” emissions down by 24 percent. Electricity purchases from local renewable sources made up the other 6 percent.

Simply switching to less carbon-intensive fossil fuels — and largely continuing to run systems uninterrupted — accounted for nearly half of the reduction in greenhouse gas emissions. Burning natural gas releases half as much carbon dioxide as coal, and about 30 percent less than oil per unit of energy produced.

Blackstone’s switch to natural gas from oil accounted for 33 percent of the reduction, while another 16 percent came from the regional electric grid’s increased use of natural gas. About a quarter of the reduction came from energy efficiency measures — specifically, those made possible by a $12 million fund through which Energy and Facilities upgraded existing heating, cooling, and lighting systems.

But the coalition that had been so united during the 2008 sustainability celebration didn’t hold together for long.

In 2012, Fossil Fuel Divest Harvard was formed, setting off a tense relationship between student climate activists and administration officials. From a referendum that advocated for divestment from fossil fuels — which earned approval from the undergraduates who voted — to protests and petitions, this new fractured reality came into focus.

In April of 2015, FFDH held “Harvard Heat Week,” a weeklong series of protests and organizing efforts. It culminated in a blockage of Massachusetts Hall, which, in part, focused on blocking President Faust from entering the administrative building.


“The time for dialogue has passed. The time for action is now,” said Divest Harvard co-founder Chloe S. Maxmin ’15 at a teach-in.

Faust was not sympathetic to activist demands, and her rebuke of the Massachusetts Hall blockade was sharp: it “signaled a movement away from the principles of exchange and legitimate free expression,” she told The Crimson at the time.

In September 2021, following nearly a decade of pressure from campus activists, the University announced it would allow its remaining investments in the fossil fuel industry to expire, paving the way for its endowment to eventually divest its holdings from the sector.

In a message to Harvard affiliates announcing the move, Bacow wrote that fossil fuel investments have become imprudent “given the need to decarbonize the economy and our responsibility as fiduciaries to make long-term investment decisions that support our teaching and research mission.” But he has stopped short of using the word “divestment,” and the University has not provided a timeline for the liquidation.

Harvard has also separately pledged to achieve net-zero greenhouse gas emissions in its endowment portfolio by 2050.

In February 2018, Faust set a new, longer-term climate goal: achieving fossil fuel neutrality by 2026, and going fossil fuel-free by 2050. Unlike the 30 percent emissions reduction goal, Harvard’s new goal is much more far-reaching, and means that by 2050, it will have to buy all of its electricity from renewable sources. It also means that the District Energy Facility and University vehicles will need to operate without fossil fuels.

In an emailed statement, Heather A. Henriksen, Harvard’s chief sustainability officer, outlined “four key components” the University must address to deliver on its 2026 and 2050 fossil-fuel promises: “District Energy Systems, its standalone buildings, its purchased energy supply, and its fleet vehicles.”

“To achieve these ambitious goals, all of Harvard’s district energy systems and buildings must be heated, cooled, and powered without the use of fossil fuels, all University vehicles must be 100% electric, and all of Harvard’s purchased electricity must come from renewable sources,” she wrote.

As for just how exactly Harvard plans to decarbonize its power plant — or ensure the Massachusetts grid is clean— the University remains tight-lipped, and a clear path forward remains muddy.

Henriksen was not made available for an interview for this story.

The main administrative unit that oversees Harvard’s current sustainability efforts is the Office for Sustainability. On its website, it lists four goals: teaching and empowering students, implementing research findings on campus, institutionalizing best practices, and spreading them throughout the school and outside of Harvard. It considers Harvard a “living lab,” as it tries to implement different sustainable practices and see what effect they have.

From day to day, the office is responsible for developing sustainability-focused campaigns and initiatives, and providing expertise to Harvard’s schools about their sustainability efforts.

For instance, as part of its pledge to reach zero vehicle emissions, the Sustainability Office helped initiate Harvard’s purchase of four electric shuttles in 2021, and began setting up infrastructure for them to charge.


Another example is the office’s “Green Labs” initiative, which provides strategies and programs to help labs conserve energy and resources. Its Shut the Sash Program, for instance, encourages labs to keep fume hoods, which are energy intensive, closed when they’re not in use. Pizza parties are raffled off to labs that reach their conservation goals, and wine and cheese celebrations are hosted twice a year for labs that consistently meet their goals.

But how will these smaller-scale efforts stack up in the long-term?

Beyond Harvard

It’s a bright afternoon when we take the shuttle across the bridge into Allston. As a soccer field emerges on the right, space opens up, and the Science and Engineering Complex comes into view, a shining monolith with glimmering fish scales which reflect the sun.

But the building’s $1 billion futuristic design is not just an aesthetic choice; it also reflects how Harvard is thinking about preparing for long-term climate impacts.


The fish-scale exterior is designed to reduce the amount of energy needed to power the 544,000-square-foot facility. The angle of the scales in relation to the sun are designed to let light into the building in the winter, warming it, and reflect it during summer, cooling it. Because of these and other innovations, the SEC is LEED Platinum-certified, the highest possible distinction for the prestigious green building certification.

In the basement, giant cisterns are prepared to collect stormwater in the event of catastrophic flooding. Bioswales and retention basins capture rainwater and funnel it into a 78,000-gallon tank to be reused. The complex’s mechanical and electric infrastructure is located above flood levels, insurance against potential catastrophic events.

And the SEC is just one piece of Harvard’s planned expansion into Allston — it’s currently in the midst of building its Enterprise Research Campus, a mixed-use space intended to house everything from labs to retail to residential areas.

To support this expansion, Harvard is building an entirely new energy system, the District Energy Facility. Sitting several hundred feet from the SEC, the DEF promises to provide Harvard’s new Allston campus with the trifecta — heating, cooling, and electricity — but in a much more energy-efficient way.

Outside the glass, exposed to the elements, is a large, 1.3-million-gallon metal tank wrapped in a spiral staircase. It houses chilled water, which is produced when electricity is cheaper and less energy intensive — normally nights and weekends. Heating and electricity are created together in the new plant, and also involve a new, greener system: As the chilled water is produced, the residual heat is used to make heated water and produce electricity. Water is also heated by capturing waste heat from equipment and exhaust.

Though this new heating system is much more energy efficient, it is still powered by natural gas. But according to the Office for Sustainability’s website, the DEF’s “flexible” design will allow it to incorporate lower- or zero-carbon options as technology develops.


Making a real impact on climate change could not be more urgent, especially in the Boston area. The city is particularly vulnerable to sea level rise, with the World Bank ranking Boston as the eighth most vulnerable city globally in 2013. This sea level rise will impact Harvard, which is located right on the banks of the Charles — some experts have even suggested raising some Harvard buildings, like Widener and the River Houses, on stilts.

But as climate change turns up the pressure, it remains unclear exactly how Harvard can reach its goals. The general formula exists: decrease energy demand by increasing energy efficiency, build infrastructure that can run on renewables, and then clean up the energy supply. But the actual steps for executions are anything but clear, and are not laid out explicitly in any of Harvard’s publicly-available documents.

Harvard also faces an essential limitation: Because it uses energy from the regional grid, even if Harvard’s own infrastructure is ultra energy efficient, if the regional grid runs on fossil fuels, it will be difficult to reach its 2050 goal.

Several hurdles exist to decarbonizing the grid. The first is technological — does the needed technology exist, and can it be reasonably implemented?

According to James H. Stock, Vice Provost for Climate and Sustainability, it varies by problem. “To a considerable extent, the technologies we need for electricity are present, with the final 10 percent being not quite clear,” says Stock in an interview. For heating, though, Stock says that more technologies need to be developed.

The existence of the technology is not the only consideration, though — price also matters. Many technologies “don’t really exist at a cost point that is at all reasonable,” Stock says, mentioning that despite Harvard’s $50.9 billion endowment, “everybody's got a budget.”

Ultimately, Stock says cleaning up the grid is not just a question of technology, but a “social project for the entire United States.”

Stock hopes that this will happen soon. “If a national grid becomes fossil fuel free by 2050, we failed — that’s way too late,” he says. “We need to make the grid decarbonize much sooner than that. Harvard will piggyback on that.”

Nevertheless, Stock is “quite confident” that Harvard will reach its 2050 goal, and may even get there before then. “A lot of that depends on how these technologies mature and what is possible,” Stock says, mentioning that many Harvard laboratories are doing research into vital topics that will enable the energy transition right now.


Though Harvard is ultimately just one actor, Stock still hopes it can play an important role in realizing the national decarbonization goal. “It’s a project for the entire country, and we're a microcosm of that,” Stock says. “It’d be great to see Harvard taking the lead. And I expect that we will.”

Whether or not Harvard achieves its goal, Daniel P. Schrag, Professor of Environmental Science and Engineering and Director of the Harvard University Center for the Environment, believes that the University’s own net-zero focus — however well intentioned — fails to address what matters most: global cumulative emissions of greenhouse gasses.

“Should Harvard behave responsibly in terms of its own emissions? Sure, absolutely,” Schrag says. “But I think, frankly, the sustainability effort at Harvard has been too much at the center of the discussion on what Harvard should do.”

Schrag called institutions of all stripes to consider how they might help the world get to net-zero, rather than just themselves.

Where Harvard can ultimately be most influential, Schrag says, is in its educational mission. He called the influence of the University’s combined student body “the big lever that we have.”

“I'd like to see every student at Harvard really be able to think critically about climate change and how to manage it in the future,” he said.

Ian J. Miller, a history professor and the Faculty Dean of Cabot House, echoes Schrag’s sentiment about the importance of Harvard’s educational mission, emphasizing that climate change is a relevant issue across many fields.

“What I find is especially encouraging in the ways that the FAS leadership and the university leadership have defined the problem is that it is clearly understood accurately, as a problem that exceeds any one school or discipline,” Miller says. He adds that climate change is not just something for scientists to address but also economists, public health officials, doctors, and people at the divinity school.

Harvard has “begun to think really creatively, and with appropriate ambition, about how to knit those various factors together, while continuing to sustain the kind of disciplinary excellence that has set Harvard apart in any field,” Miller says.

Stock’s role as the Vice Provost is an important piece in realizing Harvard’s climate education mission. He describes the urgency of his job as twofold: helping faculty “really engage in coming up with practical solutions for these climate problems” and also to educate students. “We need to make sure that we train you properly,” Stock says.

Even if we stopped emitting carbon dioxide now, our climate would continue to change as a result of the carbon dioxide that has already been put into the atmosphere — transformations that will play out over the next hundreds of years.

“We've set in motion something that has very long time scales,” Schrag says. “The reality is that we are going to continue to feel increased impacts of climate change around the world for the next many decades, at least.”

Growing Pains

Back at Cabot, it’s easy to forget about energy, infrastructure, and climate change. We return to our dorms after long days, think about our essays and problem sets, fold our laundry, and talk to our friends. Meanwhile, the same boilers run below Pfoho, keeping our rooms at a stable, comfortable temperature.

When we first started reporting this article, the first person we visited was Mike G. Russell, Cabot’s building manager. Despite his dizzying number of responsibilities — he oversees the custodial staff, keys, swipe access, mail, packages, security, and maintains all of the House spaces — he greeted us with a smile, and welcomed us into his office.

We asked him: what is Cabot doing to be more sustainable?

He told us that Cabot is installing LEDs to replace fluorescent bulbs and switching over to more efficient hot water boilers. Larger changes will come, though, when renovations happen. “We're going to do what we can until we end up getting renewed here at Cabot,” he said.

When that happens, all of Cabot’s buildings will be gutted and then built back up with better insulation and more energy efficient systems, like the other houses that have already been renovated.


For the last four or five years, Sabbio says that he’s been “walking around with a bunch of engineers” trying to calculate and understand “what it would take to rip out those three boilers that were down in that mechanical room I took you to in Moors and replace them with some energy efficient, gas-fired, 90-percent efficient boilers.” That boiler would still run on fossil fuels.

Though change is coming to Cabot and Harvard, it’s hard to imagine what it will be like in 10 years — let alone 50 or 100. What new heating systems will be put in place? Will Harvard hit net zero? If they don’t, will it even matter?

Despite this uncertainty, every day behind the scenes, engineers, facility maintenance operators, building managers and office workers are working and making the decisions about Harvard’s energy infrastructure and role in the climate crisis – decisions that may ultimately create the future we live in.

As Russell puts it: “Nothing happens around here without thinking of energy.”

—Magazine writer Io Y. Gilman can be reached at

—Magazine writer Graham R. Weber can be reached at