Boston Advances Towards Carbon Neutrality through New Building Policy

By Fay Harvey  

BOSTON — The Boston Zoning Commission has amended the city’s zoning code to mandate that most new large buildings achieve net-zero carbon emissions from the day they open. This change will bring the metropolis one step closer to its 2050 carbon-neutrality goals. 

After July 1, 2025, new project filings with 15 units or more—a minimum of 20,000 square feet—or existing buildings looking to add at least 50,000 square feet, must comply with the novel zoning requirements. Additionally, small and large projects, as defined by the city, must report on carbon emitted through construction and material manufacturing processes. Large projects will also be required to conduct an embodied carbon life cycle assessment analysis.  

As buildings account for 71% of Boston’s carbon emissions, the city’s new zoning addendum will significantly reduce overall greenhouse gas emissions. 

“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, the City of Boston’s chief climate officer, in a statement. “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.” 

The new policy builds upon previous building codes and city ordinances, including the Specialized Stretch Energy Code, which promotes energy conservation through electrification and fossil fuel reduction as well as the Building Emissions Reduction and Disclosure Ordinance (BERDO) which requires buildings of a certain size to report their energy and water usage annually while adhering to yearly emission limits. 

“By making new large buildings net-zero emissions immediately with this policy, we accelerate BERDO’s timeline and avoid costly retrofits. We also improve air quality, keeping our families healthier,” said Hessann Farooqi, executive director of the Boston Climate Action Network, in a statement. “When we build the right way, we chart a faster, less expensive course to fight climate change. I’m thrilled that Boston is taking this historic step, creating a model for cities everywhere.” 

Policy changes surrounding hospitals, general manufacturing sites and labs are being handled with a phased-in approach due to the unique engineering and ventilation these types of facilities typically require. However, labs must comply with net-zero emission limits by 2035, while hospitals and general manufacturing buildings have until 2045. 

The newly approved policy excludes renovations, additions of 50,000 square feet and changes of use. Projects in these categories are encouraged to execute energy-efficient upgrades in combination with large-scale adaptive reuse plans, falling in line with the city’s plan of lowering carbon emissions through shifting reliance off of fossil fuels and onto renewables.  

“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 in a statement. “By embedding sustainability into new projects, we set Boston on a direct path towards a cleaner and healthier future for generations to come.”