Research On The Optimization Of Thermal Comfort In High Density Urban Pocket Parks

In high-density urban areas,pocket parks are usually distributed in any available space to enhance the public’s perception and utilization of these green spaces.However,the dense distribution of greenery can lead to inefficient ventilation and heat dissipation in hot summer and cold winter zone of China,making pocket parks stuffy.This study focuses on the design of a pocket park in a high-density urban area of Zhuzhou City from the perspective of enhancing thermal comfort.Firstly,based on the field research and relevant design codes,the spatial characteristics of building groups in high-density urban areas are simplified,extracted and classified,and a number of factors affecting thermal comfort are reasonably assigned.Second,based on field surveys,four main impact factors were selected including tree planting spaces,height under tree branches,tree Leaf Area Index(LAI),and proportions of trees,shrubs,and grasses.Then,9 typical greening schemes were selected by orthogonal test method from the combination of different impact factor options.After that,the Universal Thermal Climate Index(UTCI)of each scheme in summer was simulated by ENVI-met,and the extreme difference analysis was used to rank the influence degree of those four factors on thermal comfort and the corresponding most optimal green structure scheme.The results showed that:(1)In high temperature and humidity environment,too much greenery will weaken the ventilation and heat dissipation in the pocket park,which will increase the stifling heat,so it is necessary to control the greenery density,vegetation form,and matching method appropriately;(2)In high-density urban areas,building enclosure,building density,and green structure combination have a greater impact on site temperature;(3)Of the six building layout spaces,Layout IV and Layout V will have more shadows generated by the buildings,resulting in lower average site air temperatures and therefore better thermal comfort;(4)The buildings in Layout 1,Layout 2,Layout 3 and Layout 4 are only on one side of the pocket park,which affects the shade range and ventilation effect,and the area directly receiving solar radiation is larger,so compared with Layout 5 and Layout 6,the thermal comfort effect is more dependent on the role of green structures to regulate.Through quantitative analysis,this study proposes corresponding optimal design strategies for pocket parks under different building enclosure spaces,which is conducive to alleviating urban summer heat pressure,improving the quality of human living environment,and promoting sustainable urban development.At the same time,this set of design decision methods proposed by the study is conducive to improving the efficiency of solution finding in the design phase.