Denver is only getting more crowded. That’s something nearly everyone agrees on, locals and transplants alike. The crowding is contributing to a lot of issues — like major traffic delays at any time of day and rampant development. The city and its residents will suffer in the future from the consequences of these overcrowding stressors without active mitigation. Denver is a great place to live, but what happens if temperatures rise to three digits on a regular basis in the summer? It would be a result of the urban heat island effect — a statistic that Denver ranks third worst in the nation for — and it’s because Denver is situated in an extremely dry climate where traditional city surfaces multiply the heat and aridity.
That’s one of the issues the citizen-formed coalition I-300 tackled with the drafting of the Green Roof Initiative, which garnered enough support to make it onto the ballot for November. The initiative, if approved by voters, will require any developments started in 2018 over 25,000 square feet to include a green roof with solar energy collection. According to I-300 and organizations such as Denver’s Green Party and the Colorado Native Plant Society, these mandated green roofs will improve air quality, reduce the urban heat island effect, create sanctuaries and handle stormwater drainage better than traditional roofs. Some developers are pushing back against the initiative because it will increase their building expenses, possibly hinder affordable housing development and some groups want to keep decisions about construction away from government regulations. Here’s what you need to know about this initiative before voting.
What is a green roof?
A green roof is a flat surface that has a combination of solar panels and vegetation or just vegetation. There are very specific codes that must be adhered to when building a green roof, but the most successful ones require very little maintenance once constructed. There is a spectrum of green roofs, from a few inches of ground cover (think of the moss-covered roofs of Seattle), to a fully accessible seating area or garden.
With vegetation, green roofs are consistently and considerably cooler than current roofs, both for the surface temperature outside and the spaces beneath the roof inside. The insulation that vegetation provides for a building can significantly lower energy demands, both in heating and cooling. Another benefit of more vegetation on roofs in a city is the creation of small sanctuaries for wildlife like bees, butterflies and birds. They can even be sanctuaries for people who find rejuvenation in nature, even if it’s only a little island within the urban jungle. Green roofs also reduce stormwater runoff by collecting rainwater and using it while also improving air quality by scrubbing excess carbon dioxide.
The idea of implementing laws or mandates for green roofs is not a new idea, and San Francisco is leading the United States with the implementation of its Better Roofs Ordinance, requiring new construction to have 15 to 30 percent of its roof made into solar or “living roof” space. Germany requires green roofs in varying degrees as well.
Will it work in Denver?
Denver is not the ideal place to grow vegetation. Plants need more water than what is available in the summer and also have to deal with frosts and snow for more than half the year. But green roofs don’t have to be gardens or farms, though they can be given the right circumstances. Instead, the roofs can include more native species than the typical front yard in Denver does, all of which are accustomed to infrequent waterings and incessant sun.
There are a few examples of green roofs already existing in Denver, which may provide the best information for people on the fence with this initiative. It’s important to note that all of these examples are commercial buildings, though green roofs on residential buildings are also possible and manageable.