Study On Standardized Evaluation Method For Natural Ventilation Performance Design Of Buildings

With the rapid development of green buildings and healthy buildings in our country,building performance simulation software is an essential and important tool in the process of modern architectural design.Through computer numerical simulation of natural ventilation in buildings,the effects of wind speed,wind pressure,airflow organization and so on in buildings can be predicted,thus providing qualitative and quantitative reference information for architectural design schemes.However,there are still many problems.Different CFD numerical simulation software has different emphases,different numerical simulation report lacks comparability,and natural ventilation performance design method lacks standardized and standardized processes.Therefore,based on the comparison between the expected side technical index and actual operation side performance of natural ventilation design,this paper conducts a detailed study around the model fineness and wind direction analysis,and proposes a standardized evaluation method for natural ventilation performance design.Firstly,the paper systematically combed the influencing factors of the standardized evaluation method of natural ventilation performance design through carrying out domestic and foreign literature research.This paper summarizes several kinds of influencing factors,such as model fineness,grid division,selection of calculation model and discrete format,setting of boundary conditions,selection of meteorological parameters and evaluation index of natural ventilation effect.It also summarizes the existing research results and corresponding specifications in the aspects of physical models,calculation field,indoor furniture,indoor plane layout,door and window model,grid optimization,turbulence model,determination of wind parameters,etc.,and thus summarizes the key influencing factors in the whole process of natural ventilation performance simulation.Secondly,starting from the difference mechanism between the design expectation of natural ventilation performance and actual operation,the paper puts forward "indoor and outdoor wind speed ratio" and "relative error" to evaluate and compare the indoor natural ventilation effect.Taking typical office buildings as the research object,the comparative analysis of simulation and measurement is carried out,and the influence degree of surrounding buildings,indoor layout,door and window opening and closing on indoor natural ventilation is discussed.It is found that the relative error of the ratio of simulated and measured indoor and outdoor wind speed under the influence of door and window opening and closing is as high as 150.0%,the relative error of considering only a single target building is 78.0%,and the relative error of indoor furniture being empty is 28.7%.Therefore,the standardization method of model fineness is established.Thirdly,the paper selects three different types of office buildings to carry out natural ventilation numerical simulation and field measurement respectively,and takes the natural ventilation difference analysis model as an index of comparison between different results.In the case of Yifu Building Hall,the minimum error of 5.6% between the simulated wind speed and the measured wind speed is obtained when the four wind directions are analyzed.In the case of Xuefu,when considering the four wind directions,the error of wind speed at the measuring point is only 0.3%.In the case of the core incubator,the minimum error of 1.5%between the simulated wind speed and the measured wind speed at the measuring point is obtained by using the eight-wind direction analysis.By comparing the differences of different ventilation condition settings in the above cases,it is proposed to replace the "dominant wind direction method" with the "full wind direction method" to evaluate the indoor natural ventilation effect,which can significantly reduce the error of natural ventilation performance prediction and establish a standardized method for wind direction analysis.Finally,the paper analyzes the differences of evaluation indexes under different set working conditions through the above discussion on model fineness and wind direction analysis methods.The existing simulation process is summarized and standardized from two aspects of physical model and wind boundary conditions,and suggestions on standardized evaluation methods for natural ventilation performance design of buildings are put forward.This provides reference for standardization of wind environment simulation and performance optimization design.