Turning the city's rooftops into a second ground level, Rotterdam is mitigating tons of CO2, while adapting the city to become a resilient and attractive place to live for Rotterdammers.

The Challenge

WWII bombardment destroyed the center of Rotterdam in 1940, and flat roofs now dominate the reconstructed areas. Today, facing climate hazards and high urban population density, Rotterdam is using its rooftops to address its climate challenges and add value to the city.

The Solution

In Rotterdam, colored roofs have officially become part of the city's climate adaptation strategy. Challenges with flooding, air quality, and a lack of green space are all addressed via a multifunctional approach to the development of the roofs. And with 14.5 km2 of unused roof space above the city, the possibilities seem almost endless. Four colors represent four functions: blue roofs retain water, green roofs add biodiversity, yellow roofs produce renewable energy, and red roofs add social value. This holistic approach offers valuable cross-sector co-benefits. The city aims to create 10,000 m2 of yellow roofs, generating 1.25 MW of renewable energy, and construct another 80,000 m2 of blue roofs, which can retain 2,000 m3 of water.

Economic Benefits – Green roofs already reduce water treatment costs by $75,000 annually.

Health Benefits – The Erasmus Medical Centre in Rotterdam has installed 5,000 m2 of green roofs and turned 3,000 m2 into gardens, improving the environment for patients.

About Cities100

Presented by C40 Cities Climate Leadership Group (C40), Sustainia and Realdania – Cities100 2017 showcases leading solutions to urban climate challenges in five sectors: Energy, Waste, Adaptation, Mitigation and Transportation.

Available online and in print, Cities100 provides stakeholders an accessible format to explore achievable solutions for climate action in cities, and will be a useful tool for relevant groups ranging from impact investors and development organizations, to mayors and city governments. You can access the full Cities100 2017 publication online here.

  • Economic
  • Health
Key Impact
1m m2 of multifunctional roofs by 2030
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