Abstract
The quality of urban community microclimate will affect the health of the outdoor space environment and residents' environmental behaviour. Urban development in China has generally entered an era of "reduction and connotation" development, and the gradual evolution of community fabric has become a national consensus for urban development. How to assess the impact of urban community texture evolution (density, spacing and height) on micro climatic environmental factors (temperature, humidity, wind speed, solar radiation) is the subject of research in the new era. The research shows that the microclimate environment between buildings is sensitive and complex. At present, more economical community renewal schemes in Chinese cities may hurt the microclimate environment, which needs to be evaluated by scientific means. Therefore, this study takes Fengchi Community, located in Suzhou City, Anhui Province, China, as an example, which has been gradually planned and renovated by the Government since 2018. In this paper, the evolution of Fengchi community texture was divided into three stages: before 2018, 2018-2020, and 2020-now. The influences of microclimate and environmental factors corresponding to the evolution of community texture were evaluated by computer-aided technology. The specific steps include: First, determine the scope of 3D modelling and evaluation, and use the Weather Tool software to interpret the characteristics of the community environment comprehensively; Then, in order to increase the stability, accuracy and reliability of the comparison results, the parameters of the computational domain, grid generation, boundary conditions, solver setting and residual control of the numerical model are controlled. Then, the communities in the three stages of reconstruction are simulated and analyzed, and the simulation diagram and analysis data are obtained. Finally, the evolution of microclimate environmental factors was evaluated, and the evaluation indexes were initially established, and the evaluation methods were constructed. The results show that: 1) the computer-aided technology can accurately and intuitively reflect the influence of community texture evolution on temperature, wind speed and other microclimate factors, which is conducive to adjusting the reconstruction plan in the future. 2) The different aspect ratios and height to thickness ratios of streets and alleys in the community have a significant influence on the microclimate environment of the community. The narrower the windward side of a building is, the greater the windward pressure it is subjected to. The thicker the building is, the smaller the leeward wind pressure is. 3) The paper proves that measures such as widening streets and lanes, reducing building thickness, reducing part of buildings, and reserving vegetation impact ventilation, cooling, and shading of the community. They are all reasonable measures to improve the microclimate environment. The computer assessment method proposed in this paper can provide a reference for the microclimate assessment of the communities facing reconstruction in China. The optimized community reconstruction scheme can effectively mitigate the negative impact of climate disasters such as urban heat island on urban development. The next step of the research will be to evaluate different types of community texture renovation plans in different regions to improve the perfection and reliability of the assessment indicators and assessment methods of the impact of community renovation on microclimate in China.
