Research On Optimal Layout Strategy Of Parks In Zhengzhou Based On Cooling Effect Of Surrounding Blocks

The acceleration of urbanization is leading to the deterioration of urban thermal environment,so it is imperative to create a good and comfortable urban thermal environment.Urban park is an important part of modern urban construction.By changing the design elements of the park,we can explore the correlation and influence mechanism between park space and thermal environment,so as to improve the microclimate environment of urban space,alleviate the heat island phenomenon and enhance the living comfort of residents.At present,the research on microclimate of urban parks mainly focuses on univariate or multivariate research content of park design elements,and few analyses can combine park and surrounding block environment to explore the cooling mechanism of park design elements.Based on the hot and humid weather in summer in Zhengzhou,this study focuses on the cooling effect of Zhengzhou city Park on surrounding blocks,aiming at city blocks with different building heights,fully explore the influence of park design elements on the microclimate of surrounding blocks,and the quantitative relationship between the design elements of the park and the cooling amplitude of the surrounding blocks is analyzed,in order to put forward the optimal design strategy of urban park in the block,it has practical significance for guiding the construction of urban park and improving the outdoor thermal comfort of residents.This paper firstly calculates the average surface temperature in different buffer zones in Zhengzhou parks,and finds that the average cooling distance of parks is308.5 m,and the average cooling range is 1.43℃.Furthermore,the correlation analysis between park design elements and the cooling range and range of the park was carried out,and four key design elements,including park area,landscape shape index,green space area proportion and water area proportion,were screened.In order to explore the influence of park design elements on the cooling amplitude of blocks with different building heights,ENVI-met and Grasshopper software were used to build a model and simulation,the orthogonal experimental design method was used to develop a four-factor and three-level orthogonal table,and 54 representative working conditions were set for urban blocks with different building heights.The influence of park design elements on the microclimate control and cooling amplitude of the surrounding blocks was analyzed in the early,middle and late hours of the simulation results.The results show that:(1)In the case of the same park area,the temperature drop at noon is more obvious than that in the morning and evening.Under the condition of high-rise building block,the park has obvious trend of outward expansion and cooling.Parks with large landscape shape index(complex shape)have higher average wind speed within the whole block;The cooling effect is more obvious within the whole block of the park where the water area is larger.(2)Aiming at blocks with different building heights,range analysis was used to quantify the order of primary and secondary influences of each design element on the temperature drop amplitude in the morning,middle and evening hours of the park: At noon time,each factor can exert the maximum effect of improving the thermal environment,among which,in high-rise blocks,the influence of each factor is greater than that in low-rise blocks,and the temperature drop amplitude of each factor can increase by 0.09℃ to 0.21℃.In low-rise blocks,the proportion of water area at noon has the greatest influence on the cooling range of the park.When the proportion of water area is maximum,the park has the maximum cooling range of 0.59℃,followed by the proportion of green area.In the high-rise building blocks,the maximum temperature drop in the park at noon was 0.72℃,followed by the landscape shape index.(3)Aiming at blocks with different building heights,analysis of variance was used to calculate the significance and contribution rate of each park design element:In low-rise blocks,the order of significance at noon was: water area ratio > green space area ratio,and water area ratio was the largest contribution rate.In high-rise building blocks,the order of significance at noon is: water area ratio > landscape shape index,and the contribution rate of water area ratio is still the largest.The results showed that the proportion of water body area could significantly improve the cooling range of the park.(4)The design strategy applicable to the cooling effect of parks in Zhengzhou is preliminatively optimized and further refined in the experimental scheme: for high-rise building blocks,under the condition of suitable land use,the construction of a large area of parks can significantly improve the cooling range and thermal environment comfort,the proportion of green space should be maintained at60%-70%,and the appropriate landscape shape index should be greater than 1.2.For low-rise blocks,it is suitable to build small parks,with the green space accounting for70%-80%,and the appropriate landscape shape index is less than 1.2.Water body is the most positive influencing factor,keeping 20% of the area can significantly reduce the average temperature of the whole block,adjust the relative humidity in the air combined with vegetation,and improve the comfort level of residents’ living environment.This study combines the cooling effect of the park with the surrounding block environment,carries out research and analysis from the global perspective close to the practical significance,builds the multi-tool data interaction method based on the visual programming platform,summarizes the optimal combination of urban park design elements in blocks with different building heights,and proposes the optimal design strategy of urban park in blocks.To provide guidance and suggestions for the construction of Zhengzhou city park.