Commonwealth-carbon-footprint
Sustainable Commonwealth: The Latest On Our Carbon Footprint

What’s the greenhouse-gas impact of a school that occupies two brownstones? Overall, impressively low, concluded the Environmental Club, led this year by Jay ’24, Anya ’25, and Lillian '25, after calculating Commonwealth’s carbon footprint for the first time. 

As Jay put it, “Commonwealth only uses as much electricity as 2.5 homes because it is the size of 2.5 homes!” Sixty-five square feet per student means a culture of relentlessly optimized space, as anyone who’s spent time in the building knows, with classrooms and offices in constant use. “Only using gas and electricity emissions,” writes Jay, “the school produces around .13 metric tons of CO₂ per student per year.” This figure represents both “scope 1” emissions, those produced directly by Commonwealth, and “scope 2,” those produced by the electricity we purchase. Jay calculates that “Commonwealth produces 6 times less CO₂ from gas, electricity, and other ‘scope 1 and scope 2’ emissions per student than the Boston Public School system.” 

The Environmental Club didn’t stop there but extended its analysis to Scope 3, “emissions up and down the value chain,” which included everything from the paper in school printers to the flights students and staff take for the foreign-language exchanges and trips. That air travel accounts for 57% of the school’s carbon footprint; student commuting accounts for another 27%. During the 2022–2023 year, the club surveyed students and staff on how they get to school, wisely assuming that people don’t do it the same way every day, as reflected here:

On average students commute to school via:

  • Feet 5% of the time
  • Bike 5% of the time
  • Bus 7% of the time
  • Light Rail 37% of the time
  • Commuter Rail 19% of the time
  • Car 27% of the time

On average, faculty and staff commute to school via:

  • Feet 17% of the time
  • Bike 17% of the time
  • Bus 13% of the time
  • Light Rail 23% of the time
  • Commuter Rail 11% of the time
  • Car 19% of the time

The commuting impact is about half a metric ton of CO₂ per person per year, compared with 3.6 metric tons for a typical American driving a midsize car to and from work. The school’s solid waste compares well too, at about eighteen metric tons per year, or twenty-two average Americans’ yearly contribution to municipal solid waste. Another 6.4 metric tons of food that would otherwise contribute to methane emissions is composted.

What’s Next?

Adam Hinterlang, Director of Facilities and Information Systems, said he was “very impressed and heartened” by the data the club gathered, which included “a lot of things I wasn’t factoring in.” In turn, Jay, who worked closely with Adam in putting the report together, says “Mr. Hinterlang has been improving the school a lot” in terms of energy efficiency. 

Building managers like him, Adam says, have to think about cost alongside “other things I really care about. Being responsible citizens is part of the school’s mission.” Both come into play when it comes to Commonwealth’s electricity mix. The school was able to lock in a low rate a few years ago by contracting to buy from a mix of renewable and nonrenewable sources “depending on where the supplier is delivering from.” In principle, the school could switch to 100% renewables, but at a higher cost and only after sifting through a lot of detail. “It’s not designed to be easy to switch,” says Jay. Nonetheless, he concluded that taking that step, along with replacing some gas-powered heating and water-heating units in the Cafegymatorium once they are fully depreciated, could make the school carbon neutral (using Scope 1 and 2) “within years.” 

A Mass Save energy audit every three years, Adam says, also pays off because the state program will cover much of the cost of upgrades and the technology around efficiency changes constantly. After our most recent audit, for instance, “we had some power monitors added to our walk-in freezer and refrigerator units, which will cut down on their power usage by around 40%, since they are no longer running 24/7 but only running to maintain the target temperature.” He also learned about “legacy LED lighting”: older-generation LED bulbs need heat sinks, but the newest ones release so little heat that they don’t. So last spring Adam updated the fluorescent bulbs in the library.

A bigger lift will be new, double-paned windows for the classrooms on the third and fourth floors. “Climate control is one of the most challenging things I have to do,” says Adam, who looks forward to our already-efficient heat pumps becoming more so. Other hopes: air-quality monitors (“More oxygen, more alertness!”) and, looking further ahead, “If there was a way to have a solar array on the roof, I would love it.”

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