GREENFIELD — One hundred and ten residents have signed a petition calling for the city to better regulate its accessory dwelling unit (ADU) ordinance in the wake of a new state law.

The proposed amendment, which was submitted to the City Clerk’s Office on Monday morning in the form of a petition, sets a minimum lot size of half an acre on ADU developments, and requires parcels that seek to add an ADU to consist of at least 50% open space. It also requires that ADUs meet setback requirements in its host parcel’s zoning district and prohibits the use of ADUs for short-term rentals such as Airbnbs.

The petition was drafted by local housing advocates Al Norman, Joan Marie Jackson and Mitchell Speight.

Although the state’s Affordable Homes Act, which Gov. Maura Healey signed into law in August, allows ADUs by right in single-family residential zoning districts across the state, the legislation allows municipalities to draft bylaws setting dimensional requirements for their construction.

Norman, in an interview Monday, said the idea to establish a ratio of open space to housing was inspired by the Planning Board’s proposed amendments to the city’s cluster development ordinance, which establishes a ratio of open space to housing for developers who wish to build housing units on open land.

“The city of Greenfield has spent two years working on this open space cluster development project and the point of that was to preserve and protect open space — more housing on less land, that was their mantra,” Norman said. “That got us to thinking, are they looking at the smaller end of the scale? The cluster development [ordinance applies to parcels that are] 5 acres or more. … The open space issue is not just an issue for big landowners, it’s not just for the very wealthy. It’s for everybody who has their little piece of land.”

Seated next to Speight and Jackson in his Grinnell Street house, located on an approximately 9,500-square-foot parcel of land, Norman noted that in a home like his, which he said had very little open space, construction of an ADU would exemplify “sardine zoning” or densely packed housing.

The city’s current regulations on ADUs, which are subject to change with the passage of the Affordable Homes Act, allows attached ADUs, or units built within a home or connected to a home, to be built by right in residential zones, while the creation of detached ADUs requires a special permit.

Speight and Jackson spent the last two weeks collecting signatures from residents across Greenfield in support of the proposed regulation.

“People are concerned about keeping the equity of their homes, and they appreciate the open spaces that they have had since they originally purchased their homes. That’s what they enjoy as their living space,” Jackson said. “People were eager to sign this petition, because they value their open spaces, and the city just has to become more clear on what they’re talking about and what they’ve decided on for values of the real properties, how it’s going to affect people.”

After Norman noted that the construction of an ADU on a single-family parcel, as discussed at a Sept. 24 Board of Assessors meeting, would convert the property to a two-family home under state law, Speight weighed in, saying that while he understands the city’s need to build more housing, the city’s efforts would be put to better use if it focused on creating opportunities for first-time home buyers.

Speight said by-right ADU production without further regulation will create an opportunity for out-of-state landlords to buy out properties, develop ADUs for rent, and, by densifying the parcel, squeeze as much profit from it as possible.

After the City Clerk’s Office confirms the names of the 110 people who signed the petition, the issue will be brought before the Appointments and Ordinances Committee and Planning Board for review in the coming months.

“ADU is not the answer to affordable housing; neither is creating this high-density housing. I’ve said this over and over again, we need to be creating a pathway to home ownership, and there’s many ways to get there,” Speight said. “We have no rent control here, so how are we addressing affordable housing? You know, the marketplace is at the hand of the landlord. The only way you’re going to beat that game is to become a property owner.”

Anthony Cammalleri can be reached at acammalleri@recorder.com or 413-930-4429.