Enhancing Urban Sustainability: Water-Saving Bio-Solar Green Roofs in Mediterranean Climates

Green roofs are expanding due to their advantages, but may face water deficits in the summer. However, bio-solar green roofs integrating renewable energy and green infrastructure could positively contribute to sustainable urban development and enhance environmental management. Therefore, the current study aims to experimentally investigate the benefits of bio-solar green roofs over conventional green roofs. The experiments were conducted in Rende, in southern Italy, which has a Mediterranean climate. Comparing soil temperature and relative humidity helps in understanding temperature, water reduction, and the irrigation cycle in both conventional green roofs and bio-solar green roofs. The analysis revealed that the soil surface temperature was higher in conventional green roofs than in bio-solar green roofs, with a difference of 4.8 degrees C to 9.8 degrees C, and exhibited the same trend in the case of bare soil. However, the bare soil humidity declined less than that of green roofs, possibly due to plant evapotranspiration. The analysis of the irrigation cycle in conventional green roofs and bio-solar green roofs shows a difference of 41.2%. While the relative humidity of conventional green roofs dropped from 97.7% to 32.5% at noon on the third day and fell below the 40% threshold required for succulent irrigation, the relative humidity in bio-solar green roofs was higher than 73.7%. According to the outcomes, bio-solar green roofs could have lower temperatures and reduced water consumption, thereby enhancing the cooling impact of green roofs. The results will improve knowledge on the subject and be useful for policymakers in sustainable urban development by presenting a solution to real-world problems through practical and innovative building technologies.