San Francisco threat to green roofs?

The San Francisco Examiner reports that ‘Beginning January [2017], new commercial and residential buildings of up to 10 stories in height will have to install rooftop solar systems for heat or electricity under legislation unanimously approved by the Board of Supervisors.’ You have to read down to discover that ‘In addition to the rooftop solar effort, The City is expected to debate in the coming months follow-up legislation related to the creation of living roofs on new buildings, which supporters say create such benefits as reducing stormwater runoff into the sewer system, reduce pollution and help residents connect to nature.’ This was a mistake: a single law should have required roofs to have either solar panels, or vegetation or both. But why limit the legislation to walls? It is just as important for vertical walls to be either solar or vegetated.