Analyzing outdoor thermal comfort conditions in a university campus in hot-arid climate: A case study in Birjand, Iran

Outdoor thermal comfort is an important factor in designing urban spaces influencing outdoor activities, social interactions, tourism, wellbeing, and health. Focusing on seasonal differences, this study investigates the thermal comfort conditions and the actual thermal sensation of subjects, and attempts to calibrate the scale of subjects' thermal sensation in a hot-arid climate. Experimental data were collected through a field questionnaire survey consisting of 1361 subjects and on-site monitoring in a university campus. The relationship between PMV and PET thermal indices and real thermal sensation of subjects was established. The evaluation of acceptable PMV range using the actual thermal sensation vote revealed that the common comfortable PMV range overestimated the thermal comfort with the comfortable PMV range being −0.1 to 0.9 in this climate. As a result, an extended PMV model was utilized to consider the effects of expectancy factor. The PET index has shown a stronger correlation with actual sensation vote where the neutral PET temperature range was determined as 16.4 °C to 25.3°C in the field study. Finally, the obtained correlations can be used for predicting actual thermal sensation in designing sustainable and appropriate urban spaces with a high frequency of use and improved comfort level in a campus in the hot-arid climate of Birjand.