The Potential of Cool Materials Towards Improving Thermal Comfort Conditions Inside Real-urban Hot-humid Microclimate

Abstract

The urban heat island (UHI) phenomenon has become a major concern for city sustainability in the wake of global warming and rapid urbanization. This has resulted in increased heat stress and worsened outdoor thermal comfort in urban microclimates. The study demonstrates that heat stress can be mitigated by reducing air temperature and surface temperature with the integration of cool materials into the urban environment using computational fluid dynamics, under representative climatic conditions. The thermal comfort conditions are examined at pedestrian height and the diverse vertical levels by evaluating two climatic parameters: first, the reduction of ambient air temperature and surface temperature characterizing the mitigation (cooling) intensity, and second, the alteration of airflow velocity. The analysis shows that the proposed intervention can effectively decrease surrounding temperature and promote airflow. Cool materials, when applied simultaneously on both buildings and ground, generate a more pronounced mitigation effect than on only the ground or the buildings as it results in a large reduction of air and surface temperature, that is, of 2°C and 6°C, respectively. For airflow velocity, it is highest for combined cool materials, with maximum effect at the time of highest solar irradiance. The study is expected to inform architects, urban designers and people involved in construction engineering regarding retrofitting mitigation of UHI under representative climatic conditions.