Pedestrian-Oriented Microclimate Optimization for Urban Plazas: Integrating Movement Patterns with Thermal Comfort Simulation

Urban plazas in hot-humid climates face severe heat exposure risks due to high sky view factors and limited shading, yet conventional thermal mitigation strategies predominantly rely on plaza-wide performance metrics that misalign with actual pedestrian exposure patterns. This study proposes a pedestrian-oriented microclimate optimization framework that integrates agent-based pedestrian movement simulation (PedSim) with coupled CFD microclimate modeling to enhance outdoor thermal comfort precisely where people walk and congregate. A representative urban plaza (32,300 m2) in a hot-humid climate was analyzed under extreme summer design conditions. Three scenarios were systematically compared: (1) baseline configuration, (2) plaza-wide greening optimization (uniform distribution), and (3) pedestrian-oriented optimization guided by exposure-weighted movement hotspots. Microclimatic variables were simulated using urbanMicroclimateFoam (OpenFOAM), incorporating coupled airflow, heat/moisture transport, radiation, and vegetation modules. Thermal comfort was quantified using Mean Radiant Temperature (MRT) and the Universal Thermal Climate Index (UTCI) at both plaza-wide and pedestrian hotspot scales. Winter simulations were further conducted to assess seasonal trade-offs. Results demonstrate that under identical green coverage ratio (6.6%), the pedestrian-oriented strategy achieves substantially greater thermal comfort improvements in high-use areas. Compared to the baseline, hotspot MRT and UTCI were reduced by up to 5.0 °C and 3.0 °C, respectively, whereas the plaza-wide scheme yielded only marginal improvements (ΔUTCI < 1 °C). Notably, the pedestrian-oriented layout outperformed plaza-wide optimization within hotspots by 0.8 °C UTCI reduction without compromising winter thermal comfort, maintaining 100% thermally comfortable area ratios in both scenarios. This research reveals that the spatial configuration of vegetation is equally critical as coverage quantity for pedestrian thermal exposure. By explicitly linking tree placement to movement patterns, the proposed framework offers a human-centered, resource-efficient pathway for climate-responsive urban design, providing actionable insights for mitigating heat stress in densely populated open spaces without increasing green infrastructure costs.