The public health impacts of hot cities are increasingly well documented. Increased mortality, especially among vulnerable low income populations, is one outcome. Others include exacerbation of existing disease conditions for anyone having to live there, such as diabetes, asthma and other respiratory illnesses.
A group of Denver residents wants to do something about it. Current efforts to garner 10,000 petition signatures for a November ballot initiative are underway. The initiative would require green roofs or a combination green roof/solar array on new construction and major renovation of more than 25,000 sq. ft. in “gross floor area” after January 1, 2018.
Buildings with 25,000-49,000 sq. ft. would be required to cover 20% of available roof space with green roof. Requirements scale up to 60% required for buildings with more than 200,000 sq. ft. The proposed ordinance also has a “cash in lieu” provision of $25 per sq. ft., funds that would be directed to the Denver Office of Sustainability.
Mandated green roofs are required in just a few locales—San Francisco and Toronto, for instance. Other cities, including Philadelphia, Seattle and Washington, D.C., encourage use of green roofs through incentives. The practice is part of green stormwater infrastructure and helps cities meet mandatory stormwater rules. The climate cooling benefit that green roofs provide is secondary.
To mandate the use of green roofs for urban heat island mitigation is new. The University of Colorado-Denver student behind the effort says she’s driven by recent election results to act in positive ways to effect climate change. “I’m very passionate about climate change, and with our recent election, it’s time for our citizens to take the initiative and battle some of the climate changes we are experiencing,” Madison Backer told the Denver Post in the story “Should Denver require rooftop gardens to reduce heat island effect?” by reporter Jon Murray.
The Colorado Apartment Association’s incoming president Rocky Sundling released the following statement to the Denver Channel. CAA represents 2,820 members with 252,068 apartment units. The CAA says that while green roofs “are a great solution to the urban heat island effect, are an effective roof insulator, and are aesthetically pleasing,” they are costly to install and maintain. “Allow the market to work and let buildings that choose to install green roofs experience the competitive advantage that these roofs will likely provide. Other buildings will follow to maintain competitive equality. We have seen this voluntary building standard work very effectively with the LEED energy certifications. We believe the green roofs program will have similar success by allowing the market to demand their installation.”
The Denver Green Roof Initiative has a GoFundMe site.
The Denver Post
NewTerrain March 15, 2017