Scenario-based simulation of greening adaptation strategies in a dense historic urban fabric: a comparative analysis for the case of Naples, Italy

• Simulated results indicate PAT reduction of about 2–3°C and strong MRT decreases under integrated greening scenarios. • UTCI and PET show consistent improvement across scenarios, reflecting reduced thermal stress. • Integrate and reversible greening reconciles climate adaptation with heritage conservation constraints. • Shading and green spaces improve social interaction and urban livability. Urban overcrowding and heat-absorbent materials, combined with a lack of greenery, create a harsh microclimate in older city centers. In the case of Naples (Italy), these critical issues are further exacerbated by the effects of climate change, which increases the frequency and duration of heatwaves, thereby heightening the vulnerability of the urban fabric and negatively affecting residents’ quality of life. This study proposes a simulation-based evaluation of greening strategies in the Castel Capuano area (Naples, Italy) as solutions for climate change, with particular attention to their compatibility with historical and architectural constraints. The methodology uses ENVI-met simulations to compare three scenarios: baseline, green roofs, and an integrated greening strategy. The analysis, conducted at five control points, assesses four key parameters: potential air temperature (PAT), relative humidity (RH), mean radiant temperature (MRT), and wind speed (WS); and two human thermal comfort indices: Universal Thermal Climate Index (UTCI) and Physiological Equivalent Temperature (PET). The results indicate that, under the simulated extreme summer conditions, green roofs alone provide marginal benefits, while the integrated greening strategies show the highest microclimatic improvements among tested scenarios, including average reductions in potential air temperature exceeding 1 °C, pronounced decreases in mean radiant temperature, localized variations in airflow patterns, and relevant improvements in thermal comfort indices, with UTCI decreasing by 4–6 °C and PET by 8–10 °C within the modelled scenarios. The integrated approach emerges as the most effective strategy for mitigating the Urban Heat Island and enhancing microclimatic comfort. Moreover, it has the potential to enhance overall urban livability by making public spaces more usable, safer, and more conducive to social interaction. Such multifunctional and site-specific solutions can serve as indicative and context-specific models for other historic centers with similar morphological and climatic characteristics.