Zürich utilizes green roofs to combat urban heat and manage stormwater

Zürich has successfully utilized green roofs to combat rising temperatures and manage urban environmental challenges. For over thirty years, the Swiss city has mandated vegetation on the flat roofs of new buildings, resulting in approximately 40 percent of its flat-roofed structures being covered in greenery.

These green roofs provide significant cooling effects; surfaces are on average 5 degrees Celsius cooler than gravel roofs, with some thick-substrate roofs showing differences of up to 18 degrees. This helps mitigate the urban heat island effect in a region where temperatures have risen twice as fast as the global average. Additionally, the vegetation aids in stormwater management by absorbing rainfall and releasing it slowly, which relieves pressure on aging urban sewer systems.

Beyond Zürich, other cities have implemented similar strategies: Basel has nearly 50 percent green roof coverage, Singapore offers state-funded incentives, Chicago uses expedited permitting, and San Francisco requires a portion of new roof surfaces to be green or solar-powered.