On Tuesday November 7th of 2017 Denver voters passed Initiative-300 Denver Green Roof Initiative requiring new builds of 25,000 square feet or larger to feature a green roof addition. This can can come in the form of a solar panel array or green, vegetative space.
The grass roots ordinance will help Denver reach some of its 2020 sustainability goals like achieving better air quality and producing 20% of the food consumed in the city locally. The initiative states that green roofs, “clean our air, reduce a buildings energy consumption, manage storm water, and create biodiversity for bees birds and other insects”. Not to mention it pushes building owners towards energy freedom, in the form of solar panels.
In short, the ordinance requires new buildings that are greater than 25,000 square feet, or additions to buildings that put them over 25,000 square feet to allocate a certain amount of the roof to these sustainable practices. The chart below shows how much green space is required given square footage of the building.
Ordinances like the Denver Green Roof Initiative are somewhat new, but are expected to be on more and more ballots in the coming years. As of now, Denver joins San Francisco, CA as the only cities in the country to pass such bills. Toronto, Canada also has a similar ordinance in place.
This bill will not increase taxes nor rent for tenants of buildings that are required to have green roofs. While it will be a slightly higher cost to builders, and building owners, the long term benefits of either solar arrays or vegetation improve the longevity of the roofs, as it is estimated they will last 2-3 times longer. The savings of not having to replace roofs every 10-15 years will be passed along to tenants. Considering the energy rebate benefits, and the lack of monthly energy bills if builders choose to go with a solar array to fulfill this requirement, the buildings would be cash flow positive over the lifetime of the solar panels.