Study on Outdoor Thermal Environment around Cooling Towers of Large District Heating and Cooling System in Summer in Tokyo—Field measurement and coupled simulation of conveciton, radiation and conduction

Micro-climatic changes in urban area represented by notorious urban heat island phenomena proceed remarkably worse in recent years due to the changes of land covering and the increases in artificial heat release accompanied by urbanization. In order to soften outdoor thermal environment at pedestrian level, contributions of various factors to the micro-climate in urban area should be analyzed and estimated. In Japan a lot of District Heating and Cooling (DHC) systems have been introduced in the large cities, such as Tokyo. As the heat load of the distributed buildings is released together from the cooling towers of the DHC system in the summer, the deterioration of the outdoor thermal environment around these cooling towers may be occurred. In this study, in order to study the outdoor thermal environment in the summer around the cooling towers of a DHC system in Tokyo, Japan, 1) the actual situation of the outdoor environment around the cooling towers is investigated by field measurement, 2) a simulation program adapted to complex urban area coupled with convection, radiation and conduction is developed and used to predict the outdoor environment around the cooling towers. The velocity, temperature, and humidity are obtained from the simulation and compared with the field measurement results. The spatial distributions of SET* is also calculated using the above results to estimate the thermal comfort at pedestrian level.