New city-owned buildings will be carbon-neutral under updated climate plan

Those new standards, which could be implemented through a change in the city’s zoning codes, — and might include incentives such as low interest loans, or fines — could be in place in 18 months, officials said.

With more than half of the city’s greenhouse gas emissions coming from large commercial and industrial buildings, the new standards will help Boston reach the carbon-neutral goals that were laid out in the Paris Climate Agreement, officials said. Boston and more than 200 other US cities agreed to abide by that international agreement after President Trump withdrew from it in 2017.

“We want to be designing buildings for the next generation of Bostonians,” Patrick Brophy, the city’s chief of operations, told reporters Monday. “If we don’t do this now, then who? . . . If not now, when? So we need to start looking at ways to build new buildings, and set a standard for others to follow.”

Going carbon-neutral generally means having no net emissions after balancing out existing emissions with efforts – such as planting trees – that pull carbon from the atmosphere.

Walsh plans to sign an executive order requiring that all city-owned buildings be built carbon-neutral when he returns from the international C40 Mayors Climate Summit in Copenhagen, which he is attending this week.

The Climate Action Plan update follows the release in January of a Boston Green Ribbon Commission report that laid out actions the city could take to reach its goal of going carbon-neutral by 2050.

City officials said they want to explore ways to reduce demand for energy, for instance by increasing efficiency; to convert all appliances to electrical; and to buy 100 percent renewable energy.

The Green Ribbon Commission, which conducted the analysis at Walsh’s request in 2016, called for the city to take aggressive action, such as charging drivers congestion fees for using major roadways in Boston, or requiring that all cars be electric.

Walsh’s update does not go that far, though city officials said they continue to explore ways to improve the region’s transit system, and to encourage alternative forms of transportation, such as bicycles.

But they called the focus on constructing new city buildings with carbon-neutral standards, and retrofitting existing large buildings, a critical step the city can take immediately. The plan adopts some of the recommendations that were laid out in the Green Ribbon Commission analysis on buildings.

The city says that 86,000 buildings will have to be retrofitted by 2050: 80 percent of the buildings that will exist by then are already built.

The city said it will consider incentives to encourage owners to retrofit their properties and meet “carbon emissions performance standards.” The new standards could cut emissions by 40 percent before 2050, officials said.

“Climate change is the defining challenge of our time,” Walsh said in a statement. “As a coastal city, Boston is at the frontlines of this global crisis, and we understand the urgency.”

City Councilor Matt O’Malley, who initially called for the city to explore carbon-neutral building during a hearing in 2017, praised the mayor’s announcement.

“The strategies detailed in the updated Climate Action Plan will be transformative for building a sustainable and resilient city,” said O’Malley, chairman of the Council’s Environment, Sustainability and Parks Committee.

Elizabeth Turnbull Henry, president of the Environmental League of Massachusetts, said that “the City of Boston has reaffirmed that we require bold and comprehensive approaches in the race towards net-zero emissions.”

She said her group “appreciates the city’s ongoing commitments to decarbonize in response to the climate crisis. This plan update is a meaningful step forward.”

Milton J. Valencia can be reached at milton.valencia@globe.com. Follow him on Twitter @miltonvalencia.