Positive urban thermal experience depends on both the non-extremity and variability of thermal stress in the built environment. To date, the majority of outdoor thermal comfort research has proposed to mitigate thermal extremes while overlooking the contribution from the richness of thermal conditions comprising those mild and ever-changing thermal stimuli. The fundamental research question of this thesis examines what makes the outdoor thermal experience around urban public places neither extreme nor boring. Urban districts in central London, Paris, Vienna, Cambridge and Rome were chosen as the study areas, each having its own unique climatic, spatial, social, and cultural context. A wide range of outdoor thermal conditions were investigated at the courtyard and district levels, where the in-situ human physiological and psychological responses at dynamic states were monitored for follow-up data analysis.

The data collections are multidisciplinary, including numerical simulations, fixed and mobile meteorological monitoring, as well as transect walk surveys with physiological measurements and psychological questionnaires. The data-analytic techniques feature the (co-)variance analysis, multiple linear regression, unsupervised machine learning, and hybrid clustering algorithms. All of these approaches emphasise the importance of integrating the built-environmental and human factors into assessing the outdoor environmental qualities of historic urban districts or new urban designs, especially for evaluating the thermal experience of pedestrians in both sedentary and motional states.

The contributions of this thesis lie in connecting the classic adaptive-thermal comfort theories and the new thermal alliesthesia and thermal pleasure theories in real urban environments. Through the simulation-based thermal mapping and the human-centred survey campaigns, the core hypotheses were tested that compact urban districts with suitable nature- and water-based solutions can effectively improve urban thermal diversity, and that enriched thermal environments can significantly promote outdoor thermal pleasure, walkability and general urban experience. The final conclusions have enabled further discussions on climate-responsive and sensation-inclusive urban designs for promoting thermal performance, thermal health and thermal wellbeing.