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Green roofs in Basel

Last updated: Sep 7, 2023

Summary

Since the 1990's, Basel has succeeded in implementing through financial incentives and regulations a number of green roofs in the city, up to 40% of roof surface in Basel, thus allowing to tackle several urban environmental issues.

Problem

Just like many European cities, Basel experiences high temperatures, urban heat island effect, habitat loss and greenhouse gases emissions.

Solution

Green roofs were found to offer opportunities to combine energy saving, climate change mitigation and adaptation, and biodiversity objectives. In Basel, these programmes were initially driven by energy-saving, and subsequently by biodiversity conservation. By combining financial incentives (i.e., municipal investments in incentive programmes providing subsidies for green roof installation) and building regulations (requiring all new and renovated flat roofs to be greened), the city managed to develop since the mid-1990s the largest area of green roofs per capital in the world. The programmes were funded from the Energy Saving Fund, made up of 5% of all customers’ energy bills in the Basel canton. By including stakeholder participation, the programmes didn’t face resistance and benefitted from high media coverage.

Outcome

Although there is no recent official estimate available, the Basel’s greened flat roof area must be about 40% of roof surface in Basel. This green roof strategy is expected to bring lower temperatures and to create a habitat for plant and wildlife, while reducing surface runoff and purifying the air.