Introduction: Urban open spaces, as the lungs of cities, play a role far beyond beautification. These spaces provide a platform for social interactions, recreational activities, and the enhancement of citizens' mental health. However, one of the fundamental challenges in the design and utilization of these spaces is ensuring thermal comfort, particularly in hot and humid climates. Bandar Chabahar, located in southeastern Iran, has a hot and humid coastal climate. Due to its high tourism potential and unique geopolitical position, it is considered a critical location regarding outdoor thermal comfort. Despite extensive research on thermal comfort worldwide, few studies have comparatively examined adaptive behaviors among different groups of people in hot and humid climates. This research gap has created a unique situation in Chabahar because of the simultaneous presence of a native population with long-term acclimatization and non-native tourists with short-term adaptation. Therefore, the present study is designed with the primary objective of quantitatively and qualitatively assessing outdoor thermal comfort in Chabahar's urban spaces and identifying the behavioral and psychological adaptation techniques employed by individuals (both natives and non-natives).
Materials and Methods: This research is applied in purpose and mixed-method (quantitative-qualitative) in nature. For objective thermal comfort assessment, the modified Physiological Equivalent Temperature (mPET) index was used. This index was calculated using the RayMan Pro 3.1 software model. For subjective thermal comfort assessment, a questionnaire based on the ASHRAE 55-2004 standard was randomly completed by 149 individuals present at coastal and inland sites. The survey period was March 19–20, 2022, and March 21, 2022, coinciding with the peak tourist presence in the region. Additionally, regression equations based on climatic variables were developed to predict thermal comfort. Data analysis was performed using descriptive statistics, multiple linear regression, and Pearson correlation coefficient in the MATLAB software environment.
Results and Discussion: Findings from the mPET index showed that thermal comfort conditions prevail only 20% of the year in Bandar Chabahar. The highest frequency of thermal comfort occurrence is observed from November to April. Hourly analysis revealed that in December, January, and February, daytime hours (especially 9:00 to 15:00), and in March, April, and November, nighttime hours (18:00 to 03:00) are the most suitable time windows for outdoor activities. Questionnaire results showed that 98% of respondents were non-native (tourists), and their peak presence in open spaces occurred after 19:00, which fully coincided with the calculated thermal comfort hours. This alignment is a clear example of behavioral adaptation (choosing the time of presence). Regression analysis results indicated that personal characteristics and behavioral choices (clothing type, time of presence, and location choice) explain 64% of the variance in actual thermal sensation (subjective thermal comfort). The correlation coefficients between the mPET index and ASV, as well as between mPET and Y_DS, also demonstrate the high validity of the mPET index in hot and humid climates and its predictability using climatic variables.
Conclusion: This study showed that despite the hot and humid conditions of Chabahar, individuals can achieve acceptable thermal comfort through behavioral (choosing appropriate time, location, and clothing) and psychological adaptation. However, poor urban network design reduces the efficiency of wind drainage in natural cooling.