Effects of orientation and dimensions of shading structures on thermal comfort

Shading structures can block strong solar radiation and improve pedestrians' thermal comfort in subtropical regions. However, the type, size, and orientation of such structures affect their shading performance. This study explored the effects of the dimensions and orientations of shading structures on pedestrians’ thermal comfort in subtropical Taiwan. In this study, the high accuracy of the Ladybug simulation tool was confirmed through comparison of its results with field measurements. After accuracy confirmation, this tool was used to calculate the physiological equivalent temperature (PET) under shading structures with various dimensions and orientations during the day in summer. The effective aspect ratio (eAR) was developed in this study as a dimensional parameter for shading structures. The simulation results indicated that within the eAR range of 0.22–4.0, lower eAR values were associated with higher average PET values and a greater proportion of time spent by pedestrians under the shading structures in discomfort in summer. The shading orientation also affected thermal comfort. Formulas for predicting PET from eAR were developed in this study, and a simple reference table that indicates the relationships of the dimensions and orientation of shading structures with thermal comfort was created. This table provides a reference for shading-related policy making and shading structure design. The results of this study have been applied to local building codes in Tainan City, Taiwan.