Urbanization and climate change have intensified urban heat island effects, significantly affecting outdoor thermal comfort (OTC) in cities. Traditional methods of assessing the influence of urban environments on OTC often rely heavily on computational simulations, neglecting the integration of user-centric data and comprehensive environmental monitoring. This research addresses the critical gap by employing a multi-domain, mixed-method approach to evaluate the influence of building facades on outdoor thermal comfort, specifically in the Acquabella district of Milan. To address the gap, this study suggests a structured workflow beginning with a participatory workshop and a long-term survey to gather demographic data and user perceptions, identifying areas of significant thermal discomfort. These insights inform the simulations conducted using ENVI-met software, which model the Physiological Equivalent Temperature (PET) across different facade geometries and material properties. Real-time validation is achieved through a thermal walk, which includes field measurements and on-site evaluations to capture situational thermal perceptions. The research findings underscore the substantial impact of facade materiality on thermal perception. The study also reveals that aesthetic preferences and psychological factors play a crucial role in thermal perception, highlighting the necessity of integrating these aspects into urban design strategies. These findings are synthesized into a decision matrix that guides the design of retrofit strategies. Proposed solutions focus on modifying facade materials, increasing vegetation, and optimizing the built environment based on user feedback. Simulations of these design proposals using ENVI-met demonstrate significant improvements in thermal comfort, validating the effectiveness of the proposed interventions. This thesis presents a comprehensive framework for assessing the multi-domain influence of facades on outdoor thermal comfort, advocating for the integration of user-centric data and participatory approaches in urban design. The methodology and findings offer valuable insights for policymakers, urban planners, and researchers aiming to enhance urban thermal environments and address the challenges posed by climate change and urbanization.