Cooling buildings and growing food: performance evaluation of a hydroponic roof system in a Mediterranean climate

The aim of this research is to assess the thermal and agricultural benefits achievable with a novel deep water culture (DWC) and modular hydroponic system prototype developed in the framework of the Italian PRIN research project “Fud-Of-Sithy” (Favor the Urban Development OF Sustainable Agriculture Through Hydroponics). First, the experimental mockup is characterized with its geometrical, thermal and plant cultivation features. Then, the results of an experimental campaign carried out during the 2024 summer season at the University of Catania campus (Italy) are presented and discussed in terms of water (i.e., nutrient) temperature, reduction in roof surface temperature compared to a traditional roof configuration and crops harvest for various vegetables. The results revealed that a well-insulated module of about 1 m2 extension and 0.30 m water depth can guarantee a stable water temperature, in the range of 25- 28 °C, when the outdoor air temperature is as high as 34-36°C and the peak solar irradiance is of about 800 W/m2. The first crops harvest included 0,125 kg of lettuce and 1,045 kg of basil, with growing cycles of about 25 days for the lettuce and 27 days for the basil.