Research On The Design Strategy Of Urban Parks Based On Hot Climatic Adaptability

Along with the rapid progress of civilization,many problems during the development is continuously increasing,including the deterioration of natural climatic conditions and human settlements,frequent high-temperature heatwaves,etc.which affect human activities worldwide.These effects have become hot issues of concern to the world.Increasing urban green spaces(UGS)is one of the convenient solution for easing the UHI effect.Improving the urban outdoor thermal environment is the demand of everyone and the common aspiration of the whole society.As landscape designers,it is our responsibility to respond actively,and give full play to the positive role of gardens,slow down the deterioration of human settlements,adapt to climate change,and improve the thermal comfort of outdoor spaces.Urban green space is a balance beam in the ecosystem.It can affect the overall environment by improving the water vapor and heat in the atmosphere.It plays an extremely important role in improving urban climate and helping cities cope with climate change.The cooling effect of UGS is determined by several influencing factors,however,the previous researches on the microclimate modification effect of those landscape design parameters has been poorly investigated.The current work took Beijing as an example which is characterized by typical climate conditions and city geography.For that purpose,Yuan dynasty relic park was chosen as the most interested domain,and the cooling effect of various landscape parameters has been quantitatively studied.Numerical tools have been applied including ENVI-met and RayMan software to simulate the park for obtaining the special and temporal thermal comfort variation.To that end,physiological equivalent temperature(PET)and standard effective temperature(SET*)are used as the parameters for the evaluation,the impact of urban park green space on thermal comfort is studied,the best proportion of each landscape design parameter and the space effect they formed for achieving a better thermal comfort condition have been obtained.Through a series of measured tests and simulation experiments,the design methods that can effectively improve the microclimate and increase the comfort of urban parks are summarized.The rationality,feasibility and effectiveness of the method are verified by simulating the optimization design of the original site,and provide a reference for improving urban park microclimate and thermal comfort.On the bases of previous works home and abroad,the current work gained more knowledge on the above discussed aspects.The contents of this work including:1.Field measurement of typical case study in the urban green spaces in Beijing.In this part,the landscape parameters are classified according to previous works,and a brief statement about the effect of those parameters on microclimate is provided.Then,measurements were carried out in Bagoushanshui Park,Southern Changhe Park,Yuting Park to find out the climate effect of the landscape parameters.Preliminary discussion has been made according to the results obtained and the main influential parameters with regard to the air temperature and relative humidity have been found.Those parameters include grass,tree,water body,landscape constructions(shading devices and landscape buildings),and several combining manners of them like grass+tree,water body+tree and landscape constructions+tree.Based on the field measurement and questionnaire,the results show that landscape construction is the most effective parameter for cooling among those chosen individual parameters,while the landscape construction+tree is the best among all the individual and combined manners.2.Numerical simulation test of key research objects in Beijing city park.Using numerical simulation,holistic spatial and temporal distribution scenarios of thermal comfort of the park are obtained in terms of physiological equivalent temperature(PET)and standard effective temperature(SET).For that purpose,ENVI-met and RayMan software are used.?PETm and ?SET*m are firstly proposed to more directly indicate the impact of certain urban green space on human thermal comfort.It was found that the most significant influential factor on the moderation of thermal comfort is the higher trees,while the hardened ground exhibits a negative effect.3.Based on response surface method(RSM),the proportions of each individual landscape parameters are optimized to create thermal comfortable outdoor spaces.This part applied the RSM for more properly design the experimental tests to quickly and effectively study the relationship between the proportion of landscape design elements and thermal comfort.The results indicate that when the proportion of grass,trees,water and harden ground is 1:2:2:0.1,the thermal comfort is the most significant,and the outdoor microclimate environment can be optimized to be comfortable.This conclusion suggests that if designers need to improve the comfort of the park,the ratio of water and trees should be kept same.The proportion of grassland tends to be one-half of that of trees or water,and the proportion of harden ground should be reduced as much as possible.At the same time,due to the complexity of the actual design scenario,it should be noted that this conclusion can be used reasonably.The ratio is suggestive and should be based on the purpose of meeting the functional purpose of the urban green spaces.4.The part analyzes the influence of various design elements and their formed space on microclimate and thermal comfort,and systematically discusses the urban park design method based on hot climate adaptability.The design principles and design goals are proposed.The microclimate conditions of different types of space in the Bainiao Garden were analyzed in detail,and the improvement measures were proposed for the problems.Applying the design methods summarized in the fourth,fifth and sixth chapters of the paper,the promoted design of the park is carried out.By simulating the climatic conditions in the optimization scheme,the comparing results of the adaptive expression between the promoted the original sites are obtained which can be verified that the climate adaptive design method can indeed improve the microenvironment inside the urban park.It confirms the rationality,feasibility and effectiveness of the conclusion of the paper.The outcomes of the current thesis can be used to give advices for the design of cities which is a complementary for the theory on the thermal comfort in urban parks.Through the on-site measurement and numerical model simulation,this work provides available scientific base for the city designers and policy deciders.