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Boston Approves Net Zero Carbon Zoning

By Jay Fox

Boston Mayor Michelle Wu announced the approval of an amendment to the city’s zoning code that will accelerate Boston’s efforts to become carbon-neutral by 2050. Approved by the Boston Zoning Commission on January 29, 2025, the amendment creates a first-in-the-nation zoning rule requiring many new developments to achieve net zero carbon emissions or face fines.

Known as Net Zero Carbon (NZC) zoning, the amendment affects new projects with 15 units or more or a minimum of 20,000 square feet, as well as additions to existing buildings when said additions are larger than 50,000 square feet. The ruling applies to new projects filed after July 1, 2025.

Mayor Michelle Wu of Boston.
Mayor Michelle Wu of Boston.

The regulation does not apply to renovations, additions under 50,000 square feet, and changes of use, which is meant to encourage large-scale adaptive reuse projects that combine energy efficiency upgrades. Life science labs have until 2035 to comply with the amendment, while new hospitals and manufacturing plants have until 2045.

“Around the world and here at home, the dangers of climate change are clear and intensifying. To protect families across our neighborhoods and keep our city running, we need urgent action to ensure resiliency for the safety and well-being of all Bostonians,” said Mayor Michelle Wu. “By embedding sustainability into new projects, we set Boston on a direct path towards a cleaner and healthier future for generations to come.” 

The amendment does not only address operational carbon. Both large and small projects will be required to report on their embodied carbon, and large projects (those over 20,000 square feet) will be required to conduct a life cycle assessment analysis.

“This Net Zero Carbon Zoning policy represents a tremendous step forward in reducing Boston’s carbon footprint by requiring most major new buildings from now on to be net carbon neutral in operations from the moment they open,” said Brian Swett, Chief Climate Officer for the City of Boston. “By addressing both operational and embodied carbon in new developments, we’re not only tackling emissions but also beginning to understand and reduce the carbon intensity of our building materials.”

“If this policy had been in effect for large buildings beginning operation in 2023,” according to a release issued by the City of Boston, “it would have reduced Boston’s total annual greenhouse gas emissions by 0.58%, which is equivalent to all waste-related emissions in the city.”

The full release can be read here.

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Author: Jay Fox
Categories: Article, News