Temporal distribution of human thermal comfort conditions in and around Diyarbakır city, Turkey

Diyarbakır city, in the torrid southeast Anatolia region, harbours significant socioeconomic potentials and a population of over 2 million. Climate factors affect human activities in the city due to heat stress in summer which increases with climate change. Therefore, it is important to analyse outdoor human thermal comfort conditions (OHTCCs) to take required actions for the sustainability and improvement of socioeconomic life. This paper evaluates OHTCCs for the city over a 10-year period for rural and semi-urban sites and 5-year period for urban site. Physiological Equivalent Temperature (PET) and RayMan, a bioclimate model, were chosen to determine OHTCCs from meteorological parameters. Results indicate that the frequency of heat stress is higher in urban (32.0%) than that in rural (25.6%) and in semi-urban (23.4%) sites while that of comfortable conditions is highest in urban (17.2%), followed by semi-urban (17.1%) and rural (15.8%) sites. Percentage of the cold stress is lowest (13.6%) in urban, followed by rural (21.4%) and semi-urban (22.4%) sites. High variability of summer heat stress over the sites can be explained by surface characteristics and local air circulation patterns. Semi-urban site provides some advantages for experiencing less heat stress since it has the mixed surface characteristics with vegetated and structured zones which can supply moisture to the environment to moderate OHTCCs. It is suggested that authorities should consider the urban planning and implementation actions to improve physical environment and human quality of life and to ensure the sustainability of economic activities.