Stormwater management, heat island effect, smog and more

Green roof legislation is being passed around the world. In 2009, Toronto mandated green roofs on industrial and residential buildings. In July 2016, Cordoba became the first city in Argentina to require green roofs. France’s new legislation mandates at least partial coverage with green roof or solar technology be on all new construction, effective March 2017.

So, why do we not see more green roofs on commerical structures in the United States?

This is a good question, especially given green roofs’ propensity for addressing urban challenges like excessive stormwater runoff, heat island effects, smog and other issues. Although green roofs are not mandated across the United States yet, San Francisco is making strides to improve this. 

San Francisco green roof bill  

In October 2016, San Francisco instituted the first U.S. requirement that newly constructed buildings of ten stories or more have 15–30 percent of their roof spaces covered by vegetation, solar panels or a combination of both. As explained by the city’s Planning Department, “Rooftops are 30 percent of San Francisco’s land area, and an untapped resource… the legislation would encourage a higher and better utilization of valuable roof space.” Building owners may opt out for a fee, but if development follows the path of Toronto—which has had an expansive green roof law in place since 2009—the vast majority of businesses are likely to comply with the new roofing guidelines. 

Setting a precedent 

Passage of the San Francisco green roof bill set a precedent in the U.S. that other cities will likely be quick to follow. After all, every metropolitan area has to find ways to effectively manage stormwater discharge based on EPA guidelines and their own unique infrastructure challenges, yet not every city has the means to put financial incentives in place for sustainable rooftop development. Besides, initial analyses of the cost effectiveness of meeting San Francisco’s “Better Roofs” requirement by ARUP engineers are encouraging: They found that “a living roof provides net financial benefit to the building owner, while providing significant additional benefits to the tenants and the broader community.” 

As policies are continually put in place to reduce upfront costs for developers who install green roof systems, and bills are introduced to require the inclusion of vegetation and/or solar panels, we can expect to encounter green roofs more often throughout our daily lives. By staying ahead of these changes and understanding the importance of vegetated roofing, you have a leg up on the competition.


What else should you take into consideration?

Check out the following articles to learn the ins and outs of vegetated roofing. 

Additional articles: 

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