In October, the city council of Santa Monica, California, approved a sweeping ordinance requiring all newly built single-family homes, as well as duplexes and low-rise multifamily buildings, to have zero net energy (ZNE) consumption. According to the 2016 California Green Building Standards Code (CALGreen), whose definition was adopted for the ordinance, a ZNE home is one that produces as much renewable energy on-site as it consumes yearly. The ordinance is the first of its kind in the world, officials say.

The state of California already has an upcoming code requirement on the books for all new residential construction to achieve ZNE by 2020. But Santa Monica has often adopted its own ambitious policies on environmental issues as a way to drive change elsewhere, says Dean Kubani, the city’s chief sustainability officer. “Many practitioners and cities in California aren’t aware this code change is coming in 2020—or they don’t believe the state will be ready,” he says. “Taking this action now gives us a pathway toward this goal, helps raise awareness, and drives home the importance of the issue.”