Bridging objective and subjective heat stress: A human-centered multiscale review of urban thermal experience

Urban heat stress research has rapidly advanced in measuring and modeling thermal exposure, yet a persistent gap remains between objective heat stress (OHS) and subjective heat stress (SHS). Existing reviews often examine these streams separately and lack a unified human-centered perspective for explaining their divergence. This study conducts a PRISMA-guided systematic review of 223 studies, including OHS-focused studies (n = 68), SHS-focused studies (n = 56), and conceptual or mechanistic studies that support the analysis of OHS–SHS relationships and underlying mismatch mechanisms (n = 99). The results reveal clear structural differences between the OHS- and SHS-focused research streams. OHS studies generally rely on environmental variables and thermal indices, forming relatively consistent methodological pathways across city, street, and person-based exposure levels. In contrast, SHS studies are more heterogeneous and context-dependent, with data sources ranging from individual-level surveys and interviews to participatory sensing, thermal walks, and large-scale digital traces such as social media. The review further identifies three recurrent sources of OHS–SHS mismatch: (1) differences in observation units, (2) scale-dependent representations of heat processes, and (3) limited integration of physiological processes linking environmental conditions to perceived experience. Building on these findings, we propose a human-centered integrated framework that conceptualizes heat experience as a process linking environmental exposure, physiological response, and perceptual–expressive outcomes, with behavior acting as a key modulator. This framework provides a conceptual basis for multi-source integration, cross-scale validation, and discrepancy-based heat-risk assessment, supporting a shift toward more experience-oriented urban heat governance.