Green roofs and walls are considered to be important suppliers of ecosystem services and contribute to a healthier and more biodiverse environment. However, this has never been investigated in a comparative and integrated way for different types of green walls and roofs, which hampers an optimal implementation of these systems. In the framework of the EcoCities project we will perform exactly such an integrated and comparative study. EcoCities will develop and assess approaches for using green walls and roofs to (i) reduce urban pollution, (ii) optimize element cycles, (iii) mitigate water and climate extremes, (iv) enhance urban nature conservation and pollination and (v) improve both mental and physical health of citizens. It will provide a sound evidence base for urban green planning and implementation, exploring the potential for innovation in better linking environmental, social and economic ecosystem services (ES). The study entails an in-depth comparison for all ES listed above between different (regarding plant species and substrate composition) systems of both existing and experimental green walls and roofs. This will lead to an estimation of the relative value of each system in the framework of the ES it provides. For all systems, monetary benefits and costs will be calculated, also taking into account the spatial scale at which these systems are applied. In the second half of the project’s duration, the (preliminary) results will already be applied in a number of different test cases in at least four Flemish cities. Ultimately, a catalogue and scenario assessment tool with online visualization will be made publicly available, which can be used by stakeholders (local governments, companies, private persons) to deliberately choose the type of system required for the ecosystem service(s) they aim at in a particular area. The same tools will support policy makers in their decisions towards a sustainable and healthy development of urban areas.
The project entails a collaboration between Hasselt University, PXL, Antwerp University, and the ‘Wetenschappelijk en Technisch Centrum voor het Bouwbedrijf’. The environmental economics group at the Hasselt University will be leading the work packages on assessing the monetary benefits and costs.