Committees Agree on Definition of Attic; No Decision on Proposed Data Center Ban
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Report on the joint public hearing of the Planning Board and Community Resources Committee, Nov. 12, 2026
The meeting was held on Zoom and was recorded.
Present
Planning Board: Doug Marshall (chair), Angus McLeod, Jerah Smith, Roy Johnson, and Jesse Mager. Absent: Bruce Coldham. CRC: Councilors Pam Rooney (chair, District 4), Andy Churchill (District 2), Jennifer Taub (District 4), and Mandi Jo Hanneke and Ellisha Walker (at large). Staff: Jeff Bagg (director of planning and economic development), Walker Powell (planner), Rob Morra (building commissioner), Athena O’Keeffe (council clerk), and Pam Field Sadler (Planning Department assistant). Twenty attendees on Zoom.
At their Nov. 12 public hearing, the Planning Board and the Community Resources Committee (CRC) voted unanimously to recommend that the Town Council adopt zoning bylaw amendments for protected-use accessory dwelling units (ADUs). The amendments clarify the definition of gross floor area (GFA) for a protected-use ADU, which is limited to 900 square feet or half the GFA of the principal dwelling, whichever is smaller.
Questions remain about how to define a data center, so the two bodies continued the hearing on a proposed data center ban to Jan. 6. A separate proposal for a 24-month moratorium on data centers is on the agenda for the council’s Nov. 16 meeting.
Revised ADU Regulations Forwarded to Town Council
After the Oct. 22 public hearing on revising the town’s ADU bylaw, the Planning Department drafted a memo that addressed concerns raised at the hearing and proposed alternative wording, particularly for the definitions of “attic” and GFA.
Planning and Economic Development Director Jeff Bagg said that because Amherst’s Zoning Bylaw does not define “attic,” confusion has arisen over how top-floor living space should be counted in the GFA calculation (Section 5.0112). The proposed addition to the definitions in Article 12 of the bylaw states, “An attic shall be any space above the ceiling of the uppermost story or half-story, or any space behind a wall at the eaves of a roof that is unable to be utilized as habitable space in accordance with the Massachusetts Building Code.”
Bagg said that because the state Executive Office of Housing and Livable Communities (EOHLC) is updating some of its ADU regulations, the town’s bylaw could simply defer to the state guidelines. But given the controversy over ADUs in town, he said he felt it was best to spell out what is appropriate for Amherst. He said he wasn’t sure whether the state would accept Amherst’s interpretation, but he believes it aligns with the state’s thinking. The town attorney has reviewed the proposed changes.
In a recent decision, EOHLC also named several other exclusions from the GFA calculation: breezeways, common areas, and enclosed porches. The Planning Department memo included definitions of all three terms.
The definitions of breezeways and enclosed porches are straightforward, but Councilor Mandi Jo Hanneke raised concerns about the definition of common areas. Rather than “spaces in a building with two or more dwelling units that are not exclusively available to one occupant,” she suggested defining them as spaces not exclusively available to the occupants of one unit. Others present agreed to the change.
Building Commissioner Rob Morra clarified that in a multifamily dwelling, the GFA of the principal dwelling is the total GFA of all its units, and the associated ADU cannot exceed 50% of that total. Where a lot has more than one principal dwelling, the one with the largest GFA is used to determine the maximum size of a protected-use ADU.
Members suggested and accepted minor changes to Sections 6.180, 6.181, and 6.182. The last of these defines “half-story,” a term not used in most zoning bylaws. Amherst’s bylaw includes it because some zoning districts limit building heights to 2½ stories, and the term allows a small third story.
During public comment, John Kuhn said much of the confusion over protected-use ADUs arose because Amherst’s Zoning Bylaw did not define “attic” and the state does not use the term “half-story.” He said the proposed amendments should resolve those issues.
Although she voted to recommend the revisions, Hanneke said she believes protected-use ADUs larger than 900 square feet should be allowed. She acknowledged, however, that making that change now would “not be good legislative practice,” because it would require a separate discussion and hearing.
No Conclusions Reached on Proposed Data Center Ban
Town Councilor Amber Cano-Martin, the primary sponsor of the proposed ban, said she knew a moratorium proposal was coming before the council. She said she still supports a ban because “we know some of the dangers of data centers. They use a ton of electricity, they use a ton of water, they cause air pollution. They cause noise pollution. And right now, big tech is trying to build as many as possible.”
Cano-Martin acknowledged that data centers have to go somewhere, but she said, “We don’t have the land for it. We certainly don’t have the water for it. Any land that we have, we’re looking to develop more housing, not data centers. So why would we spend time and energy and money on looking into this while we have a moratorium, when what we know is that we don’t want to have data centers to begin with?”
As an alternative to a complete ban, Cano-Martin suggested Amherst could sort data centers into tiers by energy use, and possibly allow small centers in town. Mansfield, MA, has taken that approach and allows small data centers.
Confusion remained about how to handle the competing proposals for a ban and a moratorium. The moratorium will likely also go before the Planning Board and CRC on Nov. 16. Council Clerk Athena O’Keeffe said the council could table the ban until it votes on the moratorium. If the ban were defeated, it could not be proposed again for at least two years.
The moratorium’s three sponsors, Councilors Andy Churchill, Lynn Griesemer, and Cathy Schoen, are also among the nine councilors sponsoring the proposed ban.
Strong Public Support for Data Center Ban
Eleven residents spoke in favor of the ban. Josna Rege asked where a data center could be located without harming residents’ quality of life. She cited Wrentham, which enacted a ban after considering a moratorium, and noted that Westfield recently stopped a 150-acre data center project. She also mentioned the town of Sutton, which has proposed a campus of up to 10 data centers, each 250,000 square feet, drawing 900 megawatts of electricity when fully completed in 2033. She said she worries that a buyer of the Hampshire College campus might want to build a data center there.
Allegra Clark said forests, farmland, and recreational and open spaces are vital to community health and that “unsustainable patterns of human development are the No. 1 driver of habitat loss and ecosystem destruction.” She called for sustainable development with walkable neighborhoods and locally grown food and asked whether a data center fits that vision.
Ashwin Ravikumar, an assistant professor of environmental studies at Amherst College, said, “I don’t think I need to tell you all about how bad AI data centers and this massive boom of data centers are for the environment and climate change.” He urged Amherst to take the lead and apply the precautionary principle. “We should not wait around for studies and for loopholes to be exploited by companies. We should instead shift the burden of proof that these should not be banned to this sector,” he said. He added that Massachusetts communities are especially vulnerable because, under Chapter 40A of the Massachusetts General Laws, a facility that was legally built cannot be removed or made illegal through later local zoning changes.
Rachel Hall and Esther Azar agreed with earlier speakers. Hall said she was shocked that the ban was even being questioned. Azar said, “The only reason we are discussing a moratorium is that someone wants to do a study to see if our lives are less valuable than the money we might get from it.”
Angelica Bernal, a climate scholar at the University of Massachusetts Amherst, warned about the environmental cost of data centers and the accumulation of corporate wealth by the four biggest tech companies. She urged Amherst to lead the way by banning data centers.
Leyla Moushabeck noted that enough councilors had sponsored the proposed ban to pass it, although three of the nine sponsors are also sponsoring the moratorium. She said Amherst lacks the infrastructure to support a data center and, given the town’s known budget needs, asked, “Why spend time and money studying the hypothetical impact of a hypothetical data center that nobody wants?”
George Utting said he cannot imagine there is enough public support for a data center in Amherst.
Arlie Gould said a moratorium would leave the town open and vulnerable to people coming in and exploiting it.
Ellen Guidera said an AI data center does not align with the community’s values.
Darcy Dumont said, “I am horrified at the thought of Amherst getting a data center. I’ve seen lots of situations where staff has spent a lot of time researching some topic that could have been eliminated at the outset.”
Group Decides It Needs More Time to Weigh a Ban Versus a Moratorium
Hanneke noted that data center rules are also changing at the state level. On the day of the meeting, the Massachusetts Municipal Association held a webinar on the subject that defined a hyperscale data center as one using more than 30 megawatts. The 1-megawatt centers that the proposed ban would allow are considered micro data centers. She pointed to on-site data centers that serve governments, banks, schools, and hospitals and said the town needs to consider what kinds of data centers it wants to ban. She proposed keeping the hearing open at least another month to discuss the options a moratorium or a ban would offer and to consider a tiered ban that would prohibit hyperscale centers. Churchill, who also attended the webinar, stressed the need to ban harmful data centers “without sweeping up the smaller things in the same net.”
Cano-Martin said she thought the ban’s sponsors would be open to a tiered ban like Mansfield’s, and she agreed that smaller computing centers should be allowed. Everyone agreed that hyperscale data centers should not be allowed.
Planning Board member Angus McLeod noted that under an executive order Gov. Maura Healey signed in September, state agencies cannot issue permits for a data center with peak demand above 25 megawatts unless the developer has a community benefits agreement with the host community. He said he was unhappy with the wording of the proposed amendment and wanted to revise it to more precisely target what the town actually opposes.
Planning Board members Roy Johnson and Jesse Mager said that even smaller data centers would not be acceptable in most parts of Amherst. Mager said a 1-megawatt data center would occupy about 5,000 square feet, roughly the size of a large garage, and he would not want one next to his house.
Bagg said the state is working on model bylaws, so Amherst could get far along with its own bylaw changes based on Mansfield’s and then have to recalibrate when the state issues new regulations. He said a ban and a moratorium would both take staff time, and he reminded attendees that the Planning Department is handling several larger initiatives.
Planning Board member Jerah Smith asked why a ban was urgent. Cano-Martin replied that Hampshire College would be the most likely site for a large data center and that the town needs to make clear that a data center is not an acceptable use of that land.
After being told by Hanneke that no new data center proposals can be approved while the hearing remains open, members of the CRC and Planning Board agreed to continue the hearing to Jan. 6. Hanneke noted that the sponsors could revise their proposed ban to target data centers of certain sizes, as long as they met in groups of six or fewer to avoid violating the state Open Meeting Law.