Evaluation of urban green walls benefits in Mediterranean area: species selection, definition of sustainable irrigation strategies and ecosystem services assessment

The increasing climatic and environmental pressure on Mediterranean cities makes it necessary to adopt Nature-Based Solutions (NbS) capable of integrating climate adaptation, environmental mitigation, and urban regeneration. In this context, vertical green walls represent a type of green infrastructure particularly suited to compact urban fabrics, where limited land availability requires an efficient use of building surfaces. This PhD thesis analyzes and evaluates an experimental prototype of a vertical green wall implemented in the urban context of Matera, with the aim of investigating its environmental, ecophysiological, and management performance under a hot-arid Mediterranean climate. The research adopts an integrated and multidisciplinary approach, combining the selection of native plant species, microclimatic and air quality monitoring through low-cost sensors, optimized closed-loop irrigation management, and the quantification of ecosystem services through biophysical modeling. The experimental study highlighted that the green wall is able to produce measurable effects on local microclimatic regulation, reducing thermal fluctuations and increasing thermo-hygrometric stability in proximity to the building envelope. The monitoring system also made it possible to observe dynamics of reduced concentrations of certain atmospheric pollutants and to confirm the role of vertical vegetation in the interception and deposition processes of fine particulate matter. At the same time, the analysis of water management demonstrated the possibility of limiting consumption through a system of collection, storage, and recirculation of rainwater, configuring the green wall as a resilient and replicable infrastructure in contexts characterized by water stress. The preliminary assessment of ecosystem services, carried out through the application of the i-Tree Eco model, enabled a quantitative estimation of carbon sequestration and storage, atmospheric pollutant removal, and hydrological effects, while also highlighting the limitations of the tool when applied to vertical greening systems. Finally, the experimental results were framed within the recent national regulatory framework on ecosystem services, with particular reference to UNI/PdR 162:2024, emphasizing the potential of green walls as multifunctional green infrastructures and as possible operational units for future schemes of ecosystem service enhancement and certification. This research therefore contributes to the development of a replicable methodological framework for the design and evaluation of green walls in the Mediterranean context, moving beyond a purely aesthetic perspective and recognizing these systems as active components in climate adaptation strategies and urban sustainability.