Simulating the effects of planning strategies on urban heat island and air pollution mitigation in an urban renewal area

Urbanization has caused increasingly severe heat island effect in cites, which also has worsened air quality in the urban areas due to a combination of factors. To reduce the impacts, several studies have proposed strategies based on different planning and design principles. Although some strategies were found to be useful for mitigating air pollution or urban heat island, the simultaneous effects were rarely discussed in the past studies. Therefore, this research tries to develop a framework that is able to evaluate the relative benefits of different mitigation methods on both urban heat island and air pollution, using a scenario-based computational fluid dynamics (CFD) modeling method. Six scenarios of different strategies were comprehensively evaluated and compared. It is found that pavement materials and rooftop greening showed more significant effects on reducing the heat island temperature and air pollutant concentration than that of changes in building volumes and water bodies in the study area. In addition, there are differences in mitigation effects on the two impacts, suggesting that careful comparative analysis should always be done before implementing the strategies. The proposed method could be very useful in the process of developing coping strategies for both heat island effect and air pollution in the urban areas.