Sponge City: Implementing blue-green infrastructures Effective levers for water-sensitive cities and sustainable model solutions for green roofs

The consequences of climate change pose enormous challenges for urban regions in particular, such as dealing with heavy rainfall. In order to avoid flooding and overflows in the combined sewer system, the concept of the sponge city offers the possibility of making urban areas more resistant to climate change. Key elements of the sponge city are blue-green infrastructures such as ponds or green roofs. These ecosystems can store rainwater - nature-based or technically supported - make it usable, allow it to evaporate and seep away, or discharge it in a throttled manner. However, in order to implement the sponge city concept strategically and systematically, it requires comprehensive changes in the existing, complex socio-technical system. Therefore, the project also investigates the conditions for the success of sponge cities. The solutions should meet the demands of the affected population as well as be used strategically by diverse actors.

The first part of the project focuses on the realization of the principle of the sponge city for urban climate change adaptation and on the development of an effective mix of policy instruments for the establishment of blue-green infrastructure. Extensive literature research and workshops with experts will provide information on the status quo. The policy tools developed will address the key drivers and barriers of the transformation towards a climate resilient sponge city. The goal is to identify the ten most effective levers.

The second part of the project focuses on modernizing roofs - for example, by greening them or combining them with solar panels. The project thus aims to identify and promote the most effective green roof types and to address environmental protection requirements by taking into account the environmental impact of components used. This includes analyses of life cycle assessment data and the development of standard solutions for recycling-friendly modernization of the resources used. In addition, the researchers are experimentally investigating pollutant aspects in the laboratory in order to identify components for green roofs that meet the Zero Pollution Ambition. In order to support municipalities and owners in the implementation of the Sponge City concept, the project is developing sample solutions as well as handouts and tender recommendations.