> I'm not talking about things like circuit breakers or child-safing banisters and railings

For example, in California, all new homes must have solar power, with the requirement that [1]:

> The solar panel system needs to be large enough to meet the annual electricity usage of the building

> builders can decrease the size requirement of a system on a property by incorporating battery storage ... <and> ... by incorporating energy efficiency measures or other demand-responsive measures

1. https://news.energysage.com/an-overview-of-the-california-so...