The Denver Green Roof Initiative is on the ballot this November, proposing rooftop gardens on larger buildings across the city. Toronto was the first North American city to require rooftop gardens approximately 7 years ago. Many U.S. cities, including Washington, D.C., Chicago, and Portland, Ore., offer incentives for solar energy systems and rooftop gardens.
Those opposed to the measure are questioning the cost of green roofs; green roof advocates acknowledge higher upfront costs while citing studies showing substantial energy savings over time, with a return on investment potentially within five or six years, The Denver Post reports.
Builders could also incorporate solar panels to offset some of the initiative’s rooftop garden coverage requirements, which would start at 20 percent of the roof area and ratchet up to 60 percent, depending on the structure’s total square footage and type. Residential buildings of four stories or less would be exempt.