Studies on the Specificity of Outdoor Thermal Comfort during the Warm Season in High-Density Urban Areas

With the acceleration of urbanization in China, high density has become a significant feature of urban development. Although high-density development provides convenience, it also results in numerous environmental and climatic problems, such as the urban heat island effect, haze and extreme weather. These issues have reduced the comfort levels of the urban outdoor environment, led to increased energy consumption and had serious impacts on social development and the lives of residents. Improving the comfort of the outdoor urban environment is vital, especially in the current tendency for high-density urban developments. This paper focuses on a typical urban district in Shanghai, where we have gathered ambient meteorological data and human thermal sensation votes during spring and summer through monitoring and questionnaire research. Correlation analysis was conducted to examine the relationship between thermal sensation votes and comfort indexes (PET, UTCI). The findings indicated that the neutral PET during spring and summer was 22.30 °C and 24.55 °C, respectively, whilst the neutral UTCI was 18.75 °C and 26 °C, respectively, with the neutral temperature in summer being significantly higher than that in spring. Upon comparing the evaluation indices, it was found that the correlation between the UTCI and average thermal sensation votes was stronger; thus, the UTCI better represents people’s thermal sensation in the Shanghai area. Finally, regression analysis demonstrated that the acceptable PET range for 90% of cases during both seasons in Shanghai is between 25.0 °C and 32.1 °C, and the UTCI range is between 24.2 °C and 27.7 °C. This study presents theoretical criteria for evaluating environmental thermal comfort, laying the foundation for practical paths to optimize urban design for climate responsiveness in high-density urban areas.