RAV model: Study on urban refined climate environment assessment and ventilation corridors construction

Urban ventilation corridors play a crucial role in regulating urban climate, alleviating urban heat island effect and deterioration of air quality. Considering various factors influencing the city wind environment and based on GIS evaluation methods, we establish a refined assessment model for urban ventilation (RAV model), which provides a reference for the ventilation corridors design. In case of Xi'an, a typical inland city in China, the thermal load index composed of land surface temperature and PM2.5 concentration is introduced to distinguish the urban cold islands and heat islands. The RAV model is calculated according to six influencing factors related to urban spatial morphology, including water body, green land area, road density, average building height, building density, and urban terrain. Furthermore, we have developed ventilation assessment maps with spatial resolutions of 100 and 10 m, which are more refined than the scale of existing studies. On this basis, combined with urban wind environment and the thermal load map, a multi-stage air duct system is generated by using the least-cost path method. As a result, the study area revealed six candidate first-class air ducts, as well as the metropolitan area of Xi'an revealed four candidate second-class air ducts. The evaluation results are more pragmatic than those based on frontal area density. This study provides quantitative reference for urban climate zoning optimization and ventilation corridor control strategies in the process of cost effective and environmentally habitable cities.