Research shows that urban greenspace not only enhances air quality but also supports biodiversity and the mental health of residents. The city of Basel, Switzerland has successfully interjected greenery into its concrete jungle by making urban greenery (and all of its benefits) a legal requirement for new buildings.

Basel’s city planning authority made green roofs compulsory 15 years ago, which has added much-needed green space defuse to humidity and cool buildings more quickly during the summer season, translating to less energy spent on air conditioning systems.

As part of Basel’s biodiversity strategy, the law makes green spaces mandatory on all new and retrofitted buildings with flat roofs, and since green roofs become compulsory on all new construction projects, more than one million square meters of rooftop greenery have been established. The implementation of urban green space into the construction laws ensures that these sustainable changes in Basel’s architecture will be long-lasting.

“Here in Basel, we noticed that [flat roofs] were not being used enough and [could be] valuable areas for nature,” explains Dr. Stephan Brenneisen, a researcher at the Institute for the Environment and Natural Resources in Zurich. “That’s why we started, together with our colleagues from the building department, and in particular, the then Director Barbara Schneider, to integrate these areas into the planning law, to define guidelines and this to implement these projects in Basel.”

As the world suffers from heat waves and record high temperatures, Basel prepares to meet the future that climate change holds for its residents. The city hopes that their green construction success will encourage other regions to adopt similar policies, for their own good and for the planet.