Thermal comfort assessment in semi-outdoor bus stations under hot–humid climates: effects of microclimate and exposure duration

The thermal comfort of semi-outdoor bus stations in tropical cities represents a critical applied climatology challenge for understanding passenger responses to complex microclimatic conditions and shaping public travel experience. However, such transitional transit spaces have received limited academic attention. This study addresses this gap by combining field monitoring and questionnaire surveys at tropical semi-outdoor bus stations to evaluate microclimatic conditions alongside passengers’ thermal sensations and preferences. During commuting hours, the mean air temperature reached 31.5 °C, with high relative humidity (64%) and light wind (0.3 m/s), and most passengers preferred a cooler environment. Multiple thermal comfort indices were examined and compared against reported thermal sensations. The Predicted Mean Vote (PMV) and Adaptive Predicted Mean Vote (aPMV) overstated thermal sensations, while the Standard Effective Temperature (SET*) yielded lower thermal neutrality. The Physiologically Equivalent Temperature (PET) aligned better with users’ thermal perceptions, yielding a neutral temperature of 28.1 °C, within the acceptable range of 24.7–31.4 °C. Air temperature and globe temperature were closely and positively correlated with PET. Waiting time was identified as a key psychological adaptation factor, and a time-adjusted PET (tPET) approach was developed by incorporating dynamic exposure duration effects. Its improved correspondence with thermal sensation underscores the importance of integrating microclimatic and temporal psychological effects into the assessment of thermal comfort in semi-outdoor transit spaces. This study extends biometeorological assessment frameworks and provides practical guidance for the climate-responsive design of semi-outdoor bus stations in hot and humid climates.