Quantitative outdoor thermal comfort assessment of street: A case in a warm and humid climate of India

Increasing air temperature in urban areas has been a global concern and is mostly attributed to the urban environment's physical changes. As a result, increased urban heat island phenomenon is often observed in cities impacting outdoor spaces' quality of life. This study investigates the factors influencing a street canyon's outdoor thermal comfort. User-perception surveys and empirical measurements using Testo 480 and Testo 870 thermal imager were carried out at selected six grid-points along 600 m long and 12 m wide Besant road, a semi-motorized commercial street in Vijayawada, Andhra Pradesh, India. Based on the thermal sensation questionnaire survey, Physiologically Equivalent Temperature (PET) for all the observation points were computed using RayMan pro. The correlation between the design control parameters identified and observed PET shows that the sky view factor (SVF) and mean radiant temperature (MRT) are major influencing factors determining the street's thermal conditions. Unlike aspect ratio, SVF showed a strong correlation with PET. The results indicate that by modifying physical parameters, significant improvement in overall outdoor comfort can be attained. Further, it was observed that the respondents' comfort sensitivity is higher in range than that of comfort standards, as the respondents showed increased tolerance to high temperatures.