Improving street walkability: Biometeorological assessment of artificial-partial shade structures in summer sunny conditions

Abstract

Recent rapid urbanization has rendered outdoor space a key quality-of-life factor, yet walkability studies especially in hot-humid climates have seldom considered human biometeorology. This site-level study investigated microclimatic functions of an overhead structure in improving walkability, and identified biometeorology-related factors influencing pedestrian behaviour. A walkway with overhead tinted glass cover, demarcated into sunny zone and shaded zone, was equipped with hanging aluminium fins. Human thermal sensation was approximated by physiologically equivalent temperature (PET) and universal thermal climate index (UTCI), both closely related to global solar radiation and black-globe temperature. Pedestrian flow was tallied by demographic factors to assess the choice between shaded or sunny zones. Compared with sunny zone, shaded zone slashed maximum global solar radiation by 432 W/m2 in full effect to achieve 90% solar radiation reduction. The maximum cooling in air and black-globe temperatures reached 0.8 °C and 6.1 °C respectively. The overhead structure imposed minimal effect on wind field in both zones. Contrast in maximum PET and UTCI between the two zones reached 8.2 °C and 5.3 °C respectively. In shaded zone, the dominant biometeorological condition was moderate heat stress or slightly warm sensation in contrast to strong heat stress or warm sensation in sunny zone. An overall preference for shaded zone was detected. Pedestrian gender and age, namely female and elderly, were significantly associated with shaded zone preference. The findings could inspire a biometeorological perspective in understanding walking behaviour and pedestrian-friendly facilities. Biometeorological-sensitive design of artificial shade could improve walkability in urban environment that increasingly demands climate change proofing.