Simulation study of summer microclimate in street space of historic conservation areas in China: A case study in Changsha

Abstract

Under the background of global warming, the thermal comfort in summer in historical conservation areas in China has also been significantly negatively affected. How to optimize the spatial pattern of the street space of historical conservation areas to improve the thermal comfort in summer in these areas undoubtedly deserves the consideration of scholars. In this study, Taiping Street, a historical conservation area in Changsha, China was taken as an example. Combined with the actual conditions of Taiping Street, the models with different street interface densities, different sizes and positions of open space, and different D/H (the ratio between the width of a street and the height of its surrounding buildings) were built through ENVI-met. The measured meteorological data from 10:00 to 20:00 on July 12, 2022 in Changsha are used as the initial meteorological data for simulation. The effects of the difference in the above factors on the thermal comfort of street space of historical conservation areas were explored through simulation analysis and comparison of the thermal comfort in different models. In the study, it was found that the thermal comfort of street space in such a historical street space with narrow roads was significantly affected by architectural shadows. As a result, among the simulated models, the higher the street interface density in the street in the east-west direction is, the better the overall thermal comfort of the area is. The lower the street interface density of the street in the north-south direction is, the better the overall thermal comfort of the area is. by adding a small open space in the middle of the north-side of the building, the thermal comfort of the area can be improved. The higher the D/H ratio is, the better the thermal comfort of the model is. During the renewal of historical conservation areas, people should make full use of the architectural shadows in such historical blocks to improve the thermal comfort of the area. Besides, the commonly-used method of constructing ventilation corridors to improve the thermal comfort of the block did not have an obvious effect in this study and might not make obvious improvements in similar street spaces of historical conservation areas.

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“…in which Pi is the i-th simulated value, Oi is the i-th measured value, O is the average value of the measured values, and N is the number of measurements. These three indicators have been widely used to analyze the accuracy of the simulation results in urban microclimate research [61,[64][65][66]. The measured and simulated air temperature and relative humidity on 13 May 2023 are shown in Table 6.…”

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