Experimental validation and TRNSYS modeling of a modular hydroponic roof system for thermal performance assessment

This study investigates the thermal benefits of a novel modular hydroponic roof system designed for retrofitting flat roofs. Unlike traditional green roofs, this system leverages Deep Water Culture (DWC) hydroponics, where plant roots are submerged in a nutrient-rich water solution, enhancing both thermal regulation and urban agriculture potential. A prototype was developed as part of the Italian PRIN research project “Fud-Of-Sithy” (Favor the Urban Development OF Sustainable agrIculture Through Hydroponics). The system is first described in terms of its geometric and thermal proprieties. Then, the results of an experimental campaign conducted in summer 2024 at the University of Catania (Italy) are presented and used to validate a transient building energy model in TRNSYS. Experimental findings indicate that the proposed 1,00 m² hydroponic module, with a 30 cm water depth, maintains water temperatures between 24-29°C under outdoor air temperatures of 34-36°C and peak solar irradiance of approximately 800 W/m². This leads to significant reduction in the roof’s external surface temperature, by more than 20°C at midday, when the water tray is in direct contact with the roof. As a result, the cooling load of the building is substantially reduced, contributing to improved energy efficiency.