Ensuring accurate outdoor thermal comfort research: How to select representative measurement sites for local climate zone

Abstract

The Local Climate Zone (LCZ) classification has been widely applied to explore urban outdoor thermal comfort (OTC) patterns at the city scale. However, its applicability to represent microscale thermal conditions within individual LCZs remains underexplored. This study evaluates the applicability of LCZ morphological properties for microscale OTC assessment, using a typical open mid-rise residential area (LCZ5) in Wuhan, China, as a case study to assess the spatial variability of OTC within a LCZ. A hierarchical clustering method was used to classify different microscale spatial units, followed by correlation and multiple regression analyses to examine the relationships between LCZ morphological parameters and three objective thermal indices (PET, UTCI, SET*).. Results showed substantial spatial variability in OTC conditions within the LCZ, despite relatively uniform air temperatures. Among all parameters, the sky view factor showed the strongest correlation with thermal indices, underscoring the critical role of solar exposure. Building height and surface fraction were also significantly associated with shading effects, thus the OTC of LCZ5. The regression models explained up to 82% of the variance in mean OTC, with different LCZ parameters showing optimal influence at distinct spatial radii. Based on these findings, we propose suggestions for microscale OTC prediction using LCZ classifications, emphasizing careful site selection to ensure representative measurements, facilitating the practical application of LCZ concepts in climate-sensitive urban planning at street and block scales.