As part of the Association of Bowdoin Friends’ community lecture series, Keisha Payson, the director of sustainability, discussed the College’s plan to decarbonize by 2042 in Moulton Main Lounge yesterday. She spoke on what the College has already achieved and on the difficulties that lie ahead.

The College achieved carbon neutrality in 2018, two years ahead of its 2020 goal, and the Office of Sustainability is now focused on becoming fossil-free by 2042.

Heating, Payson said, comprises the largest percentage of Bowdoin’s carbon footprint. Payson said that the biggest priority and challenge in decarbonizing is moving many of Bowdoin’s buildings from a steam heat system, among other fossil-fuel powered systems, to a low-temperature hot water (LTHW) system.

“Basically about 65 percent of our campus is heated with a district steam plant, and that is heated with natural gas,” Payson said in an interview with the Orient. “We hired an engineering firm in 2019 to help us figure out how to get there, and they said, ‘You need to get off steam. That’s old technology. You need to move to LTHW.’”

This switch, Payson said, will involve a temperature switch from 180-degree steam to 130-degree water, which could make the older buildings on campus colder since they are not as well-insulated.

“One of the pieces we need to figure out is how to make these older buildings be able to heat [people] comfortably, if all of a sudden the temperature you’re sending to the building is 130 as opposed to 180,” Payson said during the lecture.

Payson noted that the older buildings on campus are likely to require more major heating renovations in order to properly retrofit the building with equipment that can distribute heat throughout the building at a comfortable temperature.

“We’re going to have to do major renovation work to the mechanical systems to the radiators. So say I have a four-foot-by-four-foot radiator putting out 180-degree temperature, and now I’m gonna make it 130 or 140—I may have to double the size of that radiator,” Payson said during the lecture.

In addition to requiring more extensive renovations, the older buildings on campus will be generally more challenging to renovate as well, Payson said in the interview.

“[We] are trying to figure out how much work we are gonna have to do on all our buildings because the range of their capability is a lot,” Payson said. “It’s a wide range from Massachusetts Hall—which is currently all steam heat, single-pane glass [windows]—to Maine Hall, which was renovated in 2007.”

It will also be an added challenge to preserve the historic character of buildings like Massachusetts Hall, the oldest building at the College, constructed in 1802.

“I don’t know what we’ll do with Massachusetts Hall, but my guess is we would not go in and replace the windows there … because they’re beautiful,” Payson said. “So how can we go about looking at some of our more historic buildings and making sure we’re preserving their historic character but also bringing them into the current age?”

While a steam heat system requires a flame, which is produced by burning natural gas at Bowdoin, releasing carbon into the atmosphere as a result, low-temperature hot water systems can be heated without using fossil fuels since the water isn’t turned into steam.

Payson said one common way of heating LTHW water that Bowdoin is exploring is a geoexchange system, which draws heat for the building from the ground in the winter and transfers heat in the building into the ground in the summer. This makes geoexchange systems more flexible as heat can be drawn upon, pushed out or redistributed as needed

“The beauty of a geoexchange system is that during the shoulder seasons [spring and fall], you can actually share heating and cooling from other parts of campus, and you’re not necessarily relying as much on the ground,” Payson said in the interview. “If you’re getting solar gain on the south side of your building, you can be rejecting that heat into a colder office on the north side of the building.”

In addition to being fueled by clean energy, the LTHW system has other benefits since the system is more stable too, Payson said.

“Some of the benefits of a LTHW system is you have less energy loss in your distribution system [and] less failures throughout your system, so there’s a lot less maintenance involved,” Payson said during the lecture.

This winter, the College will lower the heat in some buildings on campus to test which ones are less efficient.

“This heating season, we’re going to be dialing back the temperatures in some of the buildings that we think can handle it to see how it goes,” Payson said in the interview. “If people start complaining we can always turn it back up again, but it’s gonna give us a sense of where the problem areas are.”

Avril Fessenden, a Brunswick resident who attended the lecture, said she was impressed by the plan.

“It seems to me that Bowdoin is doing a lot, which is great,” Fessenden said. “I’m very interested in climate issues, and I didn’t realize all that Bowdoin was doing.”