Seasonal thermal performance of geopolymer wall with phase change material and green façade: Southern Italy study

• A data-driven method is used, featuring violin plots, energy balance analysis, and detailed thermal gradient mapping. • The green façade system offers essential microclimatic shading and thermal lag, primarily during high-radiation events. • PCM latent heat storage enhances indoor buffering, achieving a significant 16% reduction in total indoor heat release. • ven in winter with inactive PCM, the system's thermal inertia successfully minimizes internal temperature fluctuations. • The setup yields a 12% amplitude reduction , 3 W/m² lower peak heat flux, and a 4.8°C drop in exterior surface temperatures. This study presents a comprehensive experimental assessment of a full-scale geopolymer wall system enhanced with phase change material (PCM) and a vertical green façade, tested under real-world climatic conditions in Southern Italy. The research focuses on the synergistic thermal behavior of this hybrid passive system across transitional and winter seasons, an area underexplored in current literature. A geopolymer-based panel was monitored in two configurations—standard and PCM-enhanced—on a rotating test cell equipped with high-resolution heat flux and temperature sensors. Additionally, the PCM-enhanced panel was coupled with a modular green façade system using evergreen vegetation. Over a five-month monitoring period (September–January), detailed measurements revealed that the integrated system effectively reduced thermal fluxes by up to 3 W/m 2 and surface temperature amplitudes by 12% during warmer months, while offering significant thermal inertia and buffering capacity during colder periods—even when the PCM remained inactive. Violin plots and cumulative energy analyses demonstrate that PCM integration reduced heat release into the indoor environment by 16% and enhanced overall energy moderation. The green façade further improved microclimatic conditions by delaying thermal peaks and mitigating surface temperature extremes. A complementary simulation analysis further quantifies the annual energy implications of each façade configuration, extending the experimental evidence. This study contributes rare empirical data supporting the co-deployment of PCMs and green envelopes as a viable, passive, multi-seasonal strategy for energy-efficient building envelopes.