Constructed WetRoof (CWR) Technology as a new source of irrigation water for Blue-Green Roofs to optimise plant cooling effect on PV Systems

In 2020 a resilient city pilot involving a rooftop constructed wetland started in Amsterdam. Two identical condominiums, 7 floors high, were available for the research on and implementation of innovations in the field of cyclic water management, urban development and the urban energy transition. The difference between the two buildings is that one has a conventional (black) bitumen roof with solar panels and the other has a biodiverse blue-green roof system with solar panels. Not only the effect of cooling solar panels with evapotranspiration from these plants is a goal to be monitored, but also shower wastewater from the condominiums is being transformed into irrigation water for the vegetated buildings in times of drought. Before adding the supplemental irrigation water to the sub-surface water retention system below the vegetated roof, it is purified in a rooftop constructed wetland, referred to as Constructed WetRoof. A fully computerized sensor- and control system, Cloud Water Control®, monitors levels of available irrigation water and adds wastewater to the Constructed WetRoof when needed, to prevent mains water usage for irrigation while maintaining actual plant evaporation at potential plant evaporation levels for growth, biodiversity and the plant-cooling effect.