| As an old passive cooling technology,natural ventilation has been the research focus in the field of passive building.Different from the passive design strategy to improve building's thermal stability,natural ventilation can meet the requirements of human comfort and energy saving by coordinating and making full use of the cold and heat resources generated by the climate.At the same time,the design of the building scheme has the greatest impact on the property of natural ventilation.Residential buildings account for the largest proportion in domestic urban construction,and their natural ventilation is the most widely used among civil buildings.As the design of residential buildings varies greatly,the effect of natural ventilation is also significantly different.The internal heat disturbance of residential buildings is small and easy to be affected by the climate.However,due to the large depth of buildings caused by urban land,the ventilation for comfort can not be effectively organized in the fitting period of natural ventilation and cooling.Therefore,the reasonable design of natural ventilation of these buildings is of great significance.The system design of the natural ventilation must take indoor ventilation and site ventilation into account,and is affected by climate conditions,the surrounding environment of the building,the layout of the building and the characteristics of the building itself.In this paper,the building with different characteristics were simulated in Xi'an under the ventilation conditions of hot season.Thus some effective natural ventilation design strategies were proposed.Specifically,the research about natural ventilation design is carried out on the design of the windward wall's plane shape of residence,the design of the opening in the windward wall and the plane shape of Xi'an urban residential buildings.The main research work is as follows:(1)The research group carried out on-the-spot survey,modeling and house type evaluation of Xi'an urban residential buildings.Through classification,the types of residence investigated were unit residence of plate type or plate-and-tower type and independent residence of tower type or plate-and-tower type.Through the process of type selection,the three prototypes of residential spatial combination of Xi'an was constructed as the research objective of this paper: the residence of ABA type,surrounding tpye and A-BC-A type.(2)The modeling method basing on similarity theory is used to construct the typical housing with the highest similarity with the system prototype considering the physical parameters of the influencing factors of residential ventilation,and to form a systematic method to chose the typical housing.(3)In this paper,the wind environment simulation of typical residential buildings in Xi'an was carried out to study the factors of building design on natural ventilation,such as the plane shape of the windward wall,the design of opening in the windward wing-wall and the plane shape of the residential building.Through the research of CFD numerical simulation,this paper mainly discovers that the natural ventilation condition of the room can be improved by the shape design of residential building,and obtains the adaptability regularity of natural ventilation matching with the characteristics of the residential building,as well as the effective strategies of natural ventilation which are fit to the stage of architecture design and as follows.(1)The following results is about the plane shape of the windward wall.Firstly,the natural ventilation property of the building with concave-convex windward wall is better than that of the building with straight windward wall.Secondly,compared with the convex shape of the windward wall,the concave shape of windward wall is a more favorable choice for natural ventilation.And some design strategies for natural ventilation are put forward for the convex and concave shape of windward walls of residential buildings,which is as follows.(a)When the shape of windward wall is concave,the east windward wall of the protruding volume is not proposed to set the window,and the natural ventilation capacity of residential buildings can be enhanced by increasing the ratio of the opening area to the wall area which is located in the north windward side of the protruding volume or increasing the bay of the protruding volume;(b)When the windward wall is with the convex shape,windows should be set up in the protruding wing wall to facilitate the indoor air distribution.Concerning the plane arrangement of the building,it is suggested that the central traffic core and the adjacent rooms should be extruded,and the external walls should be kept flush,so as to form an integral protruding volume without discontinuity on the windward side.One side of the bay window is adjacent to the climate,so the natural ventilation property of the housing is better.(2)In this paper,the effect of the east windward wall as wind stopping wing wall to strengthen the natural ventilation capacity and optimize the ventilation conditions of the residence was verified many times.Therefore,in order to strengthen the natural ventilation,it is suggested to adopt the irregular windward shape design.(3)Based on the study of natural ventilation of large depth residential buildings with surrounding and A-BC-A spatial arrangement,it is found that the natural ventilation capacity of leeward residential units in inverted I-shape buildings is the better than rectangle and convex plane shape.In order to effectively improve the ventilation conditions of leeward residential units,it is suggested to adopt the building shape design with inverted I-shape plane.Through the simulation of indoor wind environment and study of natural ventilation design,we can grasp the characteristics of urban housing design from the perspective of building technology,which can better meet the housing users' requirements of thermal environment quality,and is of great significance to climate adaptive housing design and building energy saving. |
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