Boston has expanded its sustainability regulations targeting commercial properties, with a new law requiring buildings 20K SF or larger to eliminate their greenhouse gas emissions by 2050.

Boston acting Mayor Kim Janey signed the updated Building Emissions Reduction and Disclosure Ordinance Tuesday, after more than a year of policy discussions and with backing from city officials and community stakeholders. The mandate, known as BERDO 2.0, requires property owners to report building emissions and reach carbon reduction benchmarks annually as part of Boston's push to achieve carbon neutrality by 2050.

"I am grateful for this collaboration with the City Council to actively minimize the challenges associated with climate change and create more resilient communities,” Janey said in a statement.

The update to BERDO, the first since it was enacted in 2013, covers 4% of the city’s buildings, more than the ordinance’s previous requirement for buildings 35K SF and larger. Buildings account for nearly 70% of Boston’s greenhouse gas emissions, the city said, and the 4% of properties targeted by BERDO account for 60% of the city’s building emissions. The ordinance is part of Boston's climate resiliency actions, which include an ongoing initiative to form zero-net carbon neutral building standards for new developments.

The BERDO website includes extensive information on emissions benchmarks for building types, how carbon levels are tracked and offers walk-throughs for property owners on emissions reductions measures. Building owners can implement energy-efficient improvements, switch to electric heating and fossil fuel-free systems, and purchase clean energy, among other measures the city recommends.

Boston can impose fines up to $1K a day for building owners that either fail to meet emissions reduction targets or fail to report emissions data in a calendar year. The updated ordinance was supported by the Bloomberg Philanthropies American Cities Climate Challenge, which supported Boston with additional staff, technical assistance and education campaigns, the city said in a statement.

Some commercial real estate leaders lauded BERDO 2.0 as it was being finalized over the summer. RENU Communities Chief Technology Officer Christopher Gray, whose firm performs energy retrofits at commercial properties, said in August Boston’s BERDO reporting standards are among the strongest in the nation.

Doug Carney, Brigham & Women’s Hospital senior vice president of real estate and facilities, said last month BERDO is going to be a design challenge for the healthcare industry whose facilities consume massive amounts of power.

“We need to do everything humanly possible that’s within the state of the art to accomplish this goal,” he said at a Bisnow healthcare panel. “Don’t worry about 2050 if the technology doesn’t exist today. We have to have faith it will.”