Research On Thermal Environment Of Urban Slow Space In Hot And Humid Region Of China

Under the dual effects of rapid urbanization and global warming,the urban thermal environment in humid and hot region of China is becoming increasingly severe,the frequent heat waves caused outdoor thermal environment more uncomfortable and the risk of thermal safety increasing.Outdoor Slow space with good thermal environment can promote green travel,ease traffic jam,reduce traffic energy consumption,improve air quality,and play an important role in the construction of ecological city.This research carried out thermal comfort survey of pedestrians and cyclists in slow space in humid and hot areas and the thermal response experiments in outdoor unsteady environment.Then determined the thermal requirements of pedestrians and cyclists in different seasons,revised the two-node-model,carried out thermal environment optimal design of slow space,then a method for calculating the thermal exposure time in slow space based on thermal safety was obtained.Firstly,in Guangzhou,a typical city of hot and humid region,the index SAR was used as to divide different slow spaces.The thermal environment level,thermal comfort and thermal requirements of users in different kinds of slow spaces in different seasons were investigated by means of thermal environment measurement and questionnaire survey.The pedestrians in different seasons are evaluated qualitatively and quantitatively.The thermal comfort characteristics of pedestrians and cyclists are defined,thermal environment parameters preferences,thermal demand and thermal sensation range of pedestrians and cyclists in different seasons were determined.Secondly,the experiment of human thermal response in unsteady outdoor environment was carried out to analysis the influence of changes of environmental parameters,changes of environment and changes of human activity on human physiological variable.The correlation between human thermal sensation,thermal comfort and skin temperature core temperature was analyzed quantitatively.Based on the experimental data of human thermal response,the two-node model for predicting human physiological changes was validated and revised.A new two-node model for predicting human thermal response in outdoor unsteady environment in humid and hot region was obtained and also programed FORTRAN software.Thirdly,based on the thermal requirements of pedestrian for slow space,taking the actual outdoor slow space of South China University of Technology as an example,the optimum design of thermal environment was carried out by setting two cases of slow spaces,which were east-west direction and north-south direction.The influence and difference of tree,shrub,grassland and pavement on the thermal environment of slow space were analyzed.The key factors to improve thermal environment in east-west and north-south direction slow space were crown width,spacing between trees,tree height,Leaf area index(LAI),shrub belt and permeable pavement also have improved the thermal environment of slow space.Fourthly,tree shading plays a key role in improving outdoor thermal comfort and reducing the risk of thermal safety.Based on ENVI-met software,the effects of tree parameters on the thermal environment of the area under the tree were simulated and analyzed.The results showed that the order of correlation between tree parameters and SET* was crown width,branch height,LAI and tree height.On the basis of ENVI-met tree model,the thermal safety risk of slow-moving space is analyzed based on the revised two-node-model and FORTRAN software,The method of calculating exposure time of Thermal safety of pedestrians in slow space was obtained.