Research on Evaluation of Ventilation Efficiency and Spatial Optimization in Urban Neighborhoods

Urban ventilation corridor is one of the effective ways to improve urban microclimate, reduce urban heat island effect and alleviate air pollution. By constructing a theoretical framework for evaluating the ventilation performance of urban neighborhoods and quantitatively assessing the ventilation performance of 57 neighborhoods in the main urban area of Hefei City, the worst ventilation performance was found in Shuanggang Street, and then a spatial optimization strategy for the wind environment based on the old neighborhoods was proposed. The results showed that: 1) Hefei ventilation efficiency formed a “one main and one time” dual-center distribution structure mainly in the old city (within the Second Ring Road) and the new city (Binhu New District), and the ventilation efficiency decreased slightly and then increased from the core outward, with an average value of 3.27. 2) CFD numerical simulation was used to analyze a variety of spatial layout schemes in winter and summer, and it was concluded that it was necessary to build a new ventilation system that conformed to the dominant wind direction. The spatial optimization strategies, such as constructing potential ventilation corridors that follow the dominant wind direction and changing the height and density of buildings at the block obstruction points, can improve the quality of the wind environment of the block, promote the diffusion of pollutants, and improve the comfort of the residents, thus providing theoretical support for the ecological renewal and reconstruction of the old block.