Bioclimatic comfort difference with the effect of urbanisation: the case of Uşak city, Turkey

Rapid human population increase in cities following industrial revolution caused irreversible changes in the physical structure of urban areas by increasing the rate of built-up surface to an unprecedented level. Both the altered physical environment and dense anthropogenic activities in the cities affected also atmospheric environment and climate characteristics in the cities. Today, more than half of the world population lives in cities while nearly 70% is estimated to live in cities by 2050. Turkey’s industrialisation and urbanisation process followed a similar way and cities faced a rapid and distorted urbanisation after especially 1950s. Today, over 80% of Turkish population lives in urban areas. Therefore, dwellers in Turkish cities are exposed to unfavourable bioclimatic conditions both due to existent and future urban climatic characteristics and the density of anthropogenic activities. This study is dealt with the effect of urbanisation on bioclimatic comfort conditions in Uşak, a medium-sized Turkish city, between the Aegean and the Central Anatolia regions in the western part of the country, where Mediterranean transitional climate characteristics are dominant and population increases. In the study, 14-year hourly data obtained from two meteorology stations located in urban and rural areas were used to calculate bioclimatic comfort values using PET (Physiological Equivalent Temperature) index and RayMan software. As a result of the study, the urban area was found to be warmer than the rural (2.4 °C, 1.6 °C and 2.2 °C on the average, maximum and minimum PET values). Urban area is exposed to 5.9% and 28.0% more heat stress than rural throughout the year and during the summer period, respectively. As a result of the study, suggestions were made to make landscape designs that take into account the physical geographical conditions for current and future urbanisation movements in order to optimise bioclimatic comfort conditions in cities. In this context, in order to improve the bioclimatic comfort conditions in the city, expanding the areas covered with soil and plants, creating artificial water areas, implementing roof garden applications, vertical and horizontal planting works, and creating wind corridors are some of the suggestions. It is thought that the determined suggestions will contribute to the slowing down of climate change on a global scale, as well as providing bioclimatic comfort in cities.