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Green building legislation and, in particular, green roof legislation has been implemented outside of the United States for decades as one means of mitigating urban heat. In the past decade, local and state governments in the United States have joined in with a marked and steady uptick in the enactment of their own green building legislation. In the wake of the June 2017 announcement that the United States intends to withdraw from the Paris climate accord, representatives of many U.S. cities (including Los Angeles, Atlanta, and Salt Lake City), states, and companies have pledged to meet the U.S.’ greenhouse gas emissions targets under the Paris climate agreement. As a result, green building and other measures to mitigate air emissions, temperature increases, and environmental impacts within cities have become an even hotter topic of municipal discussions. As of Jan. 1, 2017, San Francisco gained the distinction of being the first U.S. city to mandate solar and living roofs on most new construction.

Denver now seems poised to follow in San Francisco’s green infrastructure footsteps. This year, the Denver Green Roof Initiative succeeded in getting a new initiative (Initiative 300), which would require many new buildings to install green roofs or solar panels to mitigate heat, onto the Nov. 2017 ballot. Critics argued that the city should incentivize rather than mandate the green roofs and the legislation was opposed by a sizeable contingent, including the Downtown Denver Partnership, Denver Mayor Michael Hancock, and the organization “Citizens for a Responsible Denver.” Nevertheless, the initiative passed.

The initiative, as drafted, is modeled after San Francisco’s recent mandate and would modify the local building code to require green roofing or solar photovoltaics on a portion of the rooftops of new buildings over 25,000 square feet. The rooftop requirements increase 10 percent for every 50,000 square feet and are capped at 60 percent dedicated coverage for buildings of 200,000 square feet or more. Despite the passage of the initiative, it is yet to be seen how Initiative 300 will be implemented. Initiative 300 requires the creation of a technical advisory board to guide the creation of more detailed policies and procedures. Denver City Council also has the ability to change the ordinance with a two-thirds majority after a six-month period has elapsed. To that end, the next several months will likely include robust discussions regarding construction and implementation of green infrastructure mandates, generally, and Initiative 300, specifically, that may inform other municipalities considering similar initiatives.

Further discussion on the topic can be found in my upcoming article “Mitigation of Urban Heat Islands: Greening Cities with Mandates vs. Incentives,” which will be published in the Winter 2018 issue of the ABA Section of Environment, Energy, and Resources (SEER) publication, “Cities.”