Research On Current Situation And Optimization Strategy Of Street Thermal Comfort In Beijing Old Town Historic Block

The urban development of Beijing is at the forefront of the country,and at the same time urban diseases are becoming more serious,directly changing the urban microclimate environment and thermal comfort.The urbanization process has promoted the rapid development of megacities,urban development is uneven,the buildings in the old town are compact,the available space is small,and the population is more diverse.In the process of the transformation of the old city,it is necessary to weigh all factors,which makes the transformation and renewal difficult,and the development faces difficulties.It also makes the living environment in the old city worse.As mentioned in the Beijing Urban Master Plan(2016-2035),it is necessary to strengthen the protection of historical cities and provide the public with a pleasant and vibrant urban public space.Although the historical Block shows the cultural outlook of a city and is the epitome of the historical development of the city,its environmental problems have become more and more prominent.For example,the quality of the environmental landscape is relatively low,the public space is generally less,and the green area is small and scattered.The living environment and quality of life in the historical Blocks of the old city have gradually declined.At the same time,it has also hindered the protection and development of the historical blocks and the livability of life.The street space in the historical block is closely related to people,providing the residents of the old city with a place for public activities,so the improvement and improvement of the thermal comfort of the street environment is particularly important.Firstly,this paper analyses the domestic and international trend of thermal comfort and related concepts,and then discusses the background information and scope of Beijing Old Town Historic Block.Secondly,it analyzes the overall distribution of the historical Block of Beijing Old Town,and selects six typical blocks to analyze the traffic network,green water system and architectural map.Finally,19 representative streets are selected as articles.Afterwards,in the summer,the portable weather station was used to select real-time monitoring of street microclimate indicators(temperature,humidity,solar radiation,wind speed and direction)throughout the day,and at the same time,questionnaires for thermal comfort status were collected.Based on the measured data,the ENVI-MET software platform was used to fit the current monitoring data with the model data verification to establish a street microclimate dynamic model.After the model is corrected accurately,the street heat comfort distribution map is generated and the thermal comfort value is extracted as the basic data of the analysis.Based on the results of the previous questionnaire,the thermal comfort evaluation indicators were revised to evaluate the thermal comfort of the 19 street spaces.On this basis,the grid method is used to refine the aspect ratio of the public space of the street,the green coverage rate,the architectural shadow ratio and the direct correlation of the microclimate model.Then,using the landscape design method to reconstruct and optimize the street space,with thermal comfort as the entry point,the ENVI-MET software is used again to evaluate the optimization design results,so as to select the street space optimization mode suitable for the old city.Finally,the optimization strategy and optimization mode of the streets in the old town streets of the old city are summarized,and a dynamic evaluation system of thermal comfort is established to provide new ideas and new perspectives for the future renovation of the old city in Beijing.