San Francisco has become the first city in the U.S. to approve green (in both senses of the word) roofs, requiring all newly-constructed buildings to have 30% of their roof space set aside for green roofs (also known as living roofs) and/or solar panels. Scott Wiener, a member of the San Francisco Board of Supervisors, proposed the new legislation on September 6th of this year. The city’s Board of Supervisors has to give its okay to the legislation later in the year for it to become law, but this is considered a formality. After January 1st, all newly-constructed roofs will have to be either 30% green, 30% solar panels, or a combination of both. Existing legislation required all buildings of 10 stories or less to include solar panels over 15 percent of their roof area, so the new law ups the ante.
The proposal was originally suggested at the Cities Alive 2013 conference hosted in San Francisco by Green Roofs for Healthy Cities (GRHC). (GRHC is a membership-based industry association developing the green (vegetative) roof and wall industry in North America through education and advocacy.) The plan is developing in tandem with the campaign to create more solar rooftops in the city. Coincidentally, one of the city’s famous “painted ladies,” which are a set of much-photographed Victorian-era houses in Alamo Square, recently had installed on its roof a solar array by Sunrun, under a solar lease program.
“The solar requirement and the green roof requirement have always been two peas in a pod,” Wiener was quoted as saying. “They make roofs more environmentally sustainable, cities more environmentally sustainable, and take a very underutilized space to either create clean energy or help us with energy efficiency.”
Green roofs are not cheap. Jeff Joslin, director of current planning for the City Planning Department, estimates that they cost from $10 to $30 per square foot. When it rains heavily in the city, the sewage system is overwhelmed by runoff from storm drains, and waste is released into the ocean and the bay. Supporters of the legislation hope that green roofs will slow down the entry of water into the drainage system and thus help prevent runoff. According to the San Francisco Bay Area Planning and Urban Research Association (SPUR) Green Roof Task Force, living roofs, in addition to reducing stormwater runoff, can create energy savings, improve air quality and prolong the life of the roof.
“Our research has shown that greener, better roofs bring many benefits to building owners and the general public alike,” said Laura Tam, Sustainable Development Policy Director at SPUR. The California Academy of Sciences building in Golden Gate Park is currently the best-known example of a living roof in San Francisco.
Jeffrey L. Bruce, Chair of GRHC, said, “On behalf of all GRHC members and association partners, congratulations to the City of San Francisco and those who contributed to this policy. We look forward to watching San Francisco become a greener, healthier, and more resilient city.”