| Along with the unprecedented rapid process of urbanization,the scale of Chinese cities has been expanding continuously,and urban congestion,energy shortage,climate warming and other ecological and environmental problems have been becoming more and more prominent.In particular,the micro-climatic environment of cities has been worsening continuously,and northwestern China shows a conspicuous dry and hot climatic feature,marked by a high air temperature,aridity and dust storms.It is necessary for us to,with the help of the multidisciplinary updated research achievements,pertinently propose effective methods to alleviate the pressure of urban environment and improve the livable quality of cities.With this as a starting point,and with “meeting the heat comfort demand of human bodies in external spaces in dry and hot regions” as a specific objective,in connection with the technique of parametric automatic optimizing,this paper attempts to set up a set of methods and paths of automatic generation and optimizing of the spatial layout of street zones based on heat comfort demand,so as to apply to the micro-climatic improvement of street zone scales in cities in dry and hot regions.This paper studies the micro-climatic environment of the urban street-zone hierarchy.First,this paper makes a brief introduction to the four climatic factors that have a major impact on urban micro-climate: wind,solar radiation,temperature and humidity;analyzes and interprets the interaction and correlation between the basic types of buildings,the spatial forms of streets,plot ratio,building density,open-space layout,high-rise building layout and other urban spatial forms and the climatic factors of cities according to the different hierarchic sequence of mono-buildings-building complex-street zone-city.With “exploring the optimism of outdoor heat comfort of human bodies in summer in dry and hot regions” as an objective,this paper controls the parameters of urban form factors through the generic algorithm based on the Rhino and Grasshopper computer platform,and carries out climatic simulation by using Ladybug and other plug-ins,thus generating the optimal proposal of street zone layout under the given conditions.First,under the condition of the changeable plot ratio and building density,this paper optimizes the street zone layout in dry and hot regions,and conducts regressive analysis to the degree of the impact of form factors on the average outdoor human-body comfort of street zones by analyzing the changing trend presented by the form indicators of street zones along with the UTCI optimization and using mathematical statistics,and screens out relevant factors and forms the quantitative regressive equation.Next,under the given condition of the same plot ratio and building density,this paper selects such four street-zone types as pavillon type,strip type,micro-pavillon type and courtyard type for the experiment of street-zone layout optimizing.According to the optimizing result unfolded by the research,this paper carries out comparative analysis to the characteristics of such four street-zone types as column type,strip type,dot type and courtyard type and the degree of their adaptability to regions with a dry and hot climate.Third,based on the conclusion reached under the condition of an ideal street-zone model,this paper selects a street zone in downtown Kashi City for an actual study of street-zone layout optimizing.By conducting the mixed layout of street-zone scales to such three basic types as micro-pavillon type,strip type and pavillon type,this paper obtains a better layout proposal than the original base,further indicates that generic algorithm can evolve and develop steadily under the specific restrictive condition of the actual case,and works out a pertinent ideal layout proposal through optimization.Finally,this paper summarizes the urban design strategy based on the demand of outdoor heat comfort in dry and hot regions,systematically proposes the innovative research achievement,effective techniques,etc.of this paper,and also points out the limitation of using the optimization algorithm for the street-zone layout of cities under the condition of dry and hot climate,and thus proposes the prospect and suggestion to the study of the micro-climate of future cities. |
