Thermal Comfort Evaluation And Spatial Optimization Of Urban Parks

The acceleration of global urban energy consumption,the increase of emission of waste gas pollutants and the continuous coverage of natural surface by artificial structures have led to the frequent occurrence of extreme high temperature weather in recent years,which directly affects the physical and mental health of urban residents and the comfort of outdoor activities.As an important part of urban outdoor space,the ecological elements of urban park are of great significance to improve local microclimate,alleviate urban heat island and improve residents’ enthusiasm for outdoor activities.Therefore,based on the objective space selection and subjective space preference of the crowd,this paper evaluates the thermal comfort of urban parks in summer and puts forward suggestions for urban park space optimization in order to provide reference for the existing urban park space optimization and future urban park construction.In this paper,ten comprehensive parks in the main urban area of Chongqing are taken as the research objects,and the micro meteorological data including air temperature,relative humidity,wind speed and wind direction are measured in the hot summer from 08:00 to 20:00 in July to August.Meanwhile,the subjective spatial preference,objective spatial distribution and spatial physical characteristics of the population are investigated and recorded.Secondly,by using envi-met numerical simulation tool and selecting pet thermal comfort evaluation index system to simulate and calculate the temporal and spatial distribution of thermal comfort in each park.At the same time,Arc GIS nuclear density analysis tool was used to get the thermal map of the population distribution in different parks.The results show that:(1)the thermal environment of the park is the most comfortable at 08:00 a.m.and the most uncomfortable at 14:00-16:00 p.m.;(2)the increase of wind speed has a positive effect on reducing air temperature;(3)the perception of air temperature is the most sensitive,followed by the wind,and the least sensitive to humidity;(4)the change range of road space thermal comfort and water space is the largest in the whole day The degree is the smallest;(5)in the morning,the surrounding space of the building is always the most comfortable.With the increase of the solar radiation,the thermal comfort of the surrounding space of a single building becomes worse,or even becomes one of the most uncomfortable spaces.The thermal environment around the group building is very comfortable all day,but the size of the comfortable space will change;(6)there are differences in the preference of different gender and age groups to visit the garden.Then,the spatial-temporal coupling analysis of thermal comfort distribution,pedestrian objective space selection and pedestrian subjective space preference is carried out.At the same time,based on the coupling results,the current situation of urban parks is evaluated and the characteristics of high-quality spatial elements are proposed.The coupling results show that:(1)in the morning,people prefer open space and regular vegetation space,and in the afternoon,they prefer private space,covered space and natural vegetation space;(2)no matter how comfortable the thermal environment is,21-40% of the space population with canopy density is the most distributed;(3)the common pavement of granite and gravel has poor attraction to pedestrians;(4)the existing landscape design can not improve the thermal environment Comfort is not enough to attract pedestrians.When the space thermal environment is not comfortable,the allocation of public facilities will affect the spatial choice of pedestrians;(5)the crowd subjectively overestimates their love for the coverage space,underestimates the demand for private space and the acceptance of low canopy space.Finally,based on the basic principles of improving the thermal environment comfort of the park space,meeting the diverse needs of different groups of people,improving the utilization rate of the park space and protecting the park’s own characteristics,this paper puts forward suggestions on the overall optimization of urban space and the optimization of individual park space.