SOUTH PORTLAND — The Planning Board has embraced proposed zoning changes needed to put a new Mill Creek Master Plan into action. But it rejected a related proposal that would require certain property owners to report their utility use in the downtown neighborhood targeted for sustainable redevelopment.

Approved last year, the master plan reimagines the city’s downtown commercial district, which is dominated by mid-century shopping plazas, as a more attractive, walkable, livable, mixed-use urban village. City officials have said they hope to expand the growing desirability of the Knightville neighborhood next door and mirror Portland’s Old Port district.

The board voted unanimously Tuesday to recommend a series of zoning amendments that would allow taller buildings in a landscape with more streets, sidewalks, businesses, homes, workers and residents. The Mill Creek area stretches from Broadway to E Street, and from Waterman Drive to Cottage Road, where a Hannaford supermarket dominates a prime waterfront parcel.

However, the board voted 4-2 against recommending a proposal that would require larger Mill Creek property owners to publicly report their annual utility use, with the majority of members saying it would be an unconstitutional invasion of privacy. The board will forward both recommendations to the City Council for consideration and action in the coming weeks.

The proposed Energy & Water Use Benchmarking ordinance would be the first of its kind in Maine and is modeled after similar laws passed by at least 20 cities across the United States. It’s part of the city’s overall effort to reduce energy use and increase environmental sustainability under a climate action plan approved in 2014.

Utility benchmarking – a technical term for tallying and comparing similar things – is a process promoted by the U.S. Environmental Protection Agency through its voluntary Energy Star efficiency program.

The city would track the utility performances of larger commercial and residential properties through the EPA’s Energy Star Portfolio Manager, a website tool that allows users to compare energy use, water consumption and greenhouse gas emissions of similar buildings nationwide.

Board members Isaac Misiuk, Adrian Dowling, Kevin Carr and Chairman William Laidley opposed the measure as intrusive government overreach and a potential invasion of privacy.

“I find that to be unconstitutional,” Misiuk said. “If it’s not reworded to make it voluntary for private residences and private businesses, I won’t be able to support this.”

Board members Kathleen Phillips and Taylor Neff backed the benchmarking proposal as a progressive move to encourage conservation, promote building upgrades and foster sustainable development.

“It might encourage some people to make some improvements,” Phillips said. “The trickle down to reduce emissions and greenhouse gases and energy costs are all a plus.”

Endorsed by the city’s Energy and Recycling Committee, the ordinance wouldn’t require Mill Creek property owners to make energy-saving improvements, though some have suggested that could be a future goal, along with expanding the ordinance to other neighborhoods. The city would seek data for electricity, natural gas, heating oil and other energy sources used in heating, cooling, lighting and other operations.

The ordinance would apply to commercial buildings with at least 5,000 square feet of gross floor area, which includes attics and basements. There are 30 such buildings in the Mill Creek area now. It also would apply to about 23 municipal and school buildings citywide that have at least 5,000 square feet of gross floor area.

In the future, it would apply to residential properties with 10 units or more, of which there are currently none in the Mill Creek area.

The city would start collecting utility data May 1, 2018, for the previous year and publish it on the municipal website, allowing building owners, tenants and others to compare the energy efficiency of targeted properties with similar structures across the United States.

City officials expect some pushback from property owners or tenants who might not want to share utility data publicly, so they’re talking about offering an incentive: a $5,000 reduction in city fees related to the future development of any property under the new Mill Creek Master Plan.

U.S. cities that have adopted similar utility benchmarking ordinances include San Francisco, Seattle, Boulder, Austin, New Orleans, Atlanta, Minneapolis, Chicago, Philadelphia, New York City and Boston.