Supervisors Vallie Brown and Rafael Mandelman are planning to introduce the legislation in September this year so that it can be signed by Jan. 1, 2020, KPIX5 said.
Brown told the TV channel that buildings in the city generate "a whopping 44 percent of San Francisco's greenhouse gas emissions." "We'll never achieve our net zero carbon climate goals until all our buildings go all-electric," she said.
She said the measure would cut emissions in new and rehabilitated buildings in the city to zero because those municipal buildings are already powered by greenhouse gas-free hydroelectricity.
If the legislation takes effect next year, San Francisco will become the second Bay Area city to keep natural gas out of city-owned structures.
Last week, Berkeley city passed a similar bill to become the first city in California to ban natural gas in new buildings starting Jan. 1, 2020.
Berkeley extends the ban to all new homes constructed in the city, and will eventually apply it to commercial buildings and multi-unit residential structures, media reports said.