Predicting Outdoor Thermal Comfort in İstanbul: A Potential Climate View for 2100

The climate change effects on outdoor thermal comfort are increasingly examined in the literature. This study investigates the differences in the physiologically equivalent temperature index in İstanbul between 2010 and 2100, under the Representative Concentration Pathways 8.5 scenario. The analysis utilizes meteorological data such as temperature (°C), relative humidity (%), wind speed (m/s), and cloudiness (octas) at 06:00 a.m. (morning) and 12:00 p.m. (noon) to assess changes in outdoor thermal comfort conditions over time via RayMan Pro (v3.1 Beta). Study findings demonstrate that in December, January, February, and March, the physiologically equivalent temperature category changed from “very cold” to “cold” at 06:00 a.m., and from “cool” to “comfortable” at 12:00 p.m. In June, July, and August, the values that were “comfortable” at 06:00 a.m. were changed to “slightly warm,” and the transition from “warm” to “hot” conditions was observed at 12:00 p.m. only in June. Although the category did not change, physiologically equivalent temperature values increased from 36.10°C to 38.5°C and from 38.5°C to 41°C in July and August, respectively. Those values are close to the “very hot” category. In conclusion, the predicted outdoor thermal comfort in İstanbul will worsen in 2100, providing important guidance for climate-related disciplines and future studies.