## 4 Conclusions  
With the aim of reducing the negative impact of adverse outdoor microclimates on the volume of visitors to commercial streets, this paper adopts PET as the microclimate comfort index by taking into consideration the climatic conditions of Changsha, a typical city with a hot summer and cold winter, as well as the accuracy of assessing the outdoor microclimate environment and the difficulty of obtaining the indexes. Combining outdoor microclimate comfort with the techniques used to design commercial streets, alongside the premise of ensuring the functions of commercial streets, it is hoped that the revitalization of commercial streets through \"micro transformation\" will be realized and that some references for the future design of commercial streets are provided. By analyzing typical pedestrian commercial streets in regions with hot summers and cold winters, the typical street patterns are reasonably derived. The outdoor microclimate conditions are simulated via the experimental method of controlling variables for the main morphological parameters of the typical street pattern (street flow line, open space, and greening layout) in order to compare the advantages and disadvantages of the microclimate environment, and the impact of street morphology in summer on the microclimate conditions is obtained. The results show that a smooth airflow corridor, an appropriate airflow passage shape, and a reasonable greening layout are the key to improving the microclimate environment of streets. This study uses ENVI-met to explore ways in which to optimize the spatial structure of urban pedestrian commercial streets so as to improve their thermal comfort. ENVI-met is designed to essentially explore the highly complex interactions among urban architecture, vegetation and atmosphere, based on fluid mechanics and thermodynamic equations [58]. The relevant simulation results are representative of a certain kind of case. This study carries out an overall consideration of the spatial form characteristics of pedestrian commercial streets in the regions of China in which it is hot in the summer and cold in the winter, simulates patterns through the reasonable control of variables, and points out, according to the simulation results, that from the perspective of the street moving line, a ventilation corridor must be formed in order to improve the thermal comfort of these streets in summer according to the dominant wind direction. From the perspective of street open space, it is necessary to form a larger air inlet in the dominant wind direction to improve the thermal comfort of pedestrian commercial streets. From the perspective of green plants, it is helpful to provide colder air to the pedestrian commercial streets by prioritizing the planning of larger areas of green plants at the air inlet in the prevailing wind direction in summer. In addition, priority should be given to planar green spaces in areas with good ventilation, and scattered green spaces in areas with poor ventilation. However, although the conclusions based on the relevant scenario models have guiding significance for the optimization of the spatial structure of pedestrian commercial streets, especially those in the regions of China in which it is hot in summer and cold in winter, the effects of the relevant strategies vary due to the different specific circumstances of the pedestrian commercial streets. Therefore, more research in this aspect is undoubtedly conducive to better understanding how to optimize the spatial structure of the regions in China in which it is hot in summer and cold in winter, thus improving thermal comfort in these regions. In addition, this study focuses on improving the summer thermal comfort of these regions by optimizing the spatial structure of their streets, but does not propose direct strategies regarding how to optimize the thermal comfort of pedestrian commercial streets in the winter.