California air quality regulators on Sept. 22 voted to require all new space and water heaters sold in the state by 2030 have no emissions, a step toward phasing out the use of natural gas for heating homes and businesses.

The provision was adopted by the California Air Resources Board at a public meeting as part of a larger plan to reduce smog and bring the state into compliance with federal air quality standards over the next 15 years.

California has been at the forefront of efforts to phase out the use of natural gas in buildings. Since 2019, more than two dozen cities have passed measures to reduce the use of gas in buildings, and last week the state’s utilities regulator eliminated subsidies for extending natural gas lines to new homes or commercial buildings.

Buildings are responsible for about 5% of the state’s nitrogen oxides emissions due to natural gas combustion, according to CARB. They also account for about a quarter of the greenhouse-gas emissions that contribute to climate change.

Under the plan adopted on Sept. 22, CARB will develop standards for space and water heaters. New equipment sold beginning in 2030 will have to meet those standards. The rule is expected to rely heavily on heat pumps, which use electricity for heating, according to a staff report published last month.

Environmental group RMI estimated that the zero emissions standards would reduce 154 million metric tons of climate-warming emissions, equivalent to 19 million homes’ annual energy use, in their first 15 years.

SoCalGas, the state’s largest gas utility and a unite of Sempra Energy, said it supported the state’s goal to decarbonize buildings and said its own infrastructure would play a role by transporting clean fuels such as hydrogen.

“A growing body of research shows that electrification combined with clean fuels and carbon management deliver the most affordable, resilient, and technologically proven path to improved air quality and full carbon neutrality,” Christine Detz, a SoCalGas spokesperson, said in an email.