Research On Urban Local-scale Spatial-temporal Thermal Environmental Characteristic Analysis And Thermal Comfort Evaluation

In recent years,the rapid developments of urbanization construction have greatly influenced the original large scales of natural underlying surface geometry and thus changed the urban spatial layouts.Within the urban canopy layer,the underlying surface land use structure with high heterogeneity and diversified type distributions have affected the local-scale surface energy balance.As a result,varied local thermal environment conditions occurred,especially affecting the human thermal comfort feelings.Therefore,accurate analysis and quantitative comprehensive evaluation of the spatial and temporal distribution characteristics of the local-scale thermal environment and thermal comfort in urban space appear necessary measures for realizing green,ecological,environment-friendly urban construction.This thesis aims at the actual urban complex spatial patterns,takes the spatial-temporal characteristics of thermal environmental and thermal comfort levels as research objects,focuses on the evaluation analysis and detailed discussion of the thermal environment and thermal comfort states under multiple diversified spatial patterns through the methods of field survey and numerical simulations.These results provide theoretical basis and evaluation tools for further improving urban local-scale thermal environmental comfort and suitability.This thesis firstly discusses the non-synchronized problems for the thermal environmental data measured by mobile survey.Based on the current temporal correction models,this paper proposes an improved model by considering correlation coefficients that are influenced by the underlying surface conditions,and the distance between the stationary weather stations and the mobile location points.Through the field measured data of multiple mobile points and stationary weather stations,equations for calculating the correlation coefficients are obtained for respectively applying to the air temperature and relative humidity in pedestrian space.The proposed model is named as “multiple-distance-underlying surface”model.With three spatial verification methods,comparison analysis between the model calculation results and field measured data shows that the improved model presents higher accuracy and broader practicability.Secondly,this chapter takes an actual complex urban region as study area,and conducts thermal environmental mobile survey measurements in both August and January.Spatial and temporal characteristics and rules of local urban heat island intensity(UHII)are detailed analyzed in different aspects,including the local UHII of weather station points,the local UHII along the mobile route and also the spatial distributions with spatial interpolation processing in two seasons.Through thecorrelation analysis between averaged UHII values in multiple city blocks and the corresponding underlying surface characteristic parameters,results illustrate that the local UHII values are greatly influenced by spatial layouts and present obvious spatial-temporal differences across the whole research region.Based on the results,this thesis also concludes a set of technical process for local-scale thermal environmental study,namely the city block division,mobile data processing,spatial interpolation,and characteristic analysis.In addition,this thesis then conducts quantitative analysis for human thermal comfort conditions in local spatial environments,and the discussions of the effects on thermal comfort caused by spatial influential factors.According to the Local Climate Zone scheme,nine typical local areas are selected.Through the field measurements,questionnaire surveys,and statistical analysis during hot summertime period,spatial distribution characteristics of human thermal comfort evaluation indicators and also the corresponding human responses to different thermal environmental parameters are detailed discussed.Then the value ranges corresponding to different thermal comfort evaluation degrees are obtained.Additionally,the weight ratios of multiple basic characteristic parameters contained in four spatial considerations are calculated by using the Fuzzy AHP method,and then four integrated spatial characteristic parameters are generated.The quantitative relationships between integrated parameters and thermal comfort indicators are discussed.Then through sampling experiments and thermal comfortable ranges,multiple combinations of four integrated parameters are generated as theoretical references for creating thermal comfortable urban planning and spatial design.This chapter determines spatial factors considering different land use types,building geometry parameters,and underlying surface constitution parameters.Based on the basic local energy balance calculation model,large numbers of numerical experiments under control variate method are conducted.Then multiple linear regression equations expressing the relationships between thermal environment and thermal comfort indicator average values and the spatial factors,and the relation expressions between the indicator average values and hourly values are obtained as simplified calculation models for research region.Comparison results between simplified models and basic calculation models show that their calculated results' laws and trends are generally the same.In addition,by further comparing the calculated results of simplified models and the field measured data in multiple city blocks show that the average absolute errors are actually affected by surrounding environments of local regions.In the end,with the developed simplified calculation models,this chapter develops a user-friendly evaluation software which could realize the dynamical calculations for hourly evaluation indicator values and also the spatial and temporalvisualizations.Taking the Pre-planned and Post-planned actual research region as evaluation objects,the corresponding hourly distribution maps of thermal environmental and thermal comfort indicators are described and compared,including the air temperature distribution maps,specific humidity distribution maps,wind speed distribution maps,local UHII distribution maps,thermal comfort indicator distribution maps.Additionally,according to the suitability ranges of different evaluation indicators,the comprehensive suitability degree distribution maps of each indicator can be illustrated.Then by defining the threshold values of local UHII and thermal comfort evaluation indicators,the problem area distribution maps are also expressed.By comparing the spatial distributions of these indicators between Pre-planned and Post-planned research region,results show that the general thermal environmental and thermal comfort levels of Post-planned research region are improved,the suitability hour ratios have increased,and the problem areas also have significant decrease.To conclude,based on the deep layers of model establishment and data analysis,this thesis completes the contents of field measurements,comparison verification,model establishment,software developments,case study discussion for local-scale thermal environment and thermal comfort research.Multi-dimensional spatial-temporal characteristics of local thermal environment and the comprehensive thermal comfort levels are detailed analyzed and illustrated,which provides theoretical evidence and technical basis for further optimizing and improving local-scale regional thermal environment and thermal comfort levels.