The Study Of Performance Gap Between Design Expectations And Actual Operations Of Natural Ventilation In Buildings

Natural ventilation is one of the main means of designing green buildings.It can not only reduce airconditioning consumption but also improve indoor air quality.In the stage of architectural design,the effect of natural ventilation design mainly relies on computer fluid analysis software to simulate the wind speed,airflow distribution,indoor temperature and pressure distribution in the building,so as to meet the requirements of the standard.However,after the actual operation,the indoor ventilation effect will be affected by various factors such as the indoor layout and the opening conditions of doors and windows.With the development of natural ventilation technology and research methods,it is an urgent issue to be studied and validated whether the expected design of natural ventilation in building design can achieve the desired effect after the building is put into operation.In this paper,by summarizing the research status of natural ventilation simulation and experiment at home and abroad,it is found that there is a lack of quantifiable evaluation system in natural ventilation research,and most of them only stay in the verification stage of simulation software.Through literature research,the application status and research methods of natural ventilation technology were first sorted out.And three representative natural ventilation evaluation indicators for indoor comfort,air change times,and air age were summarized subsequently.But in the actual situation,the outdoor wind environment changes rapidly.In order to eliminate the accidental and transient nature of the outdoor environment,it accurately reflects the amount of outdoor wind reaching the room in naturally ventilated buildings,and better reflects the indoor natural ventilation effect.In this study,the “indoor and outdoor wind speed ratio” evaluation index was used as the main parameter used in this study.Natural ventilation is influenced by many factors such as the outdoor environment,architectural space and structural modeling,interior layout,door and window opening and closing conditions,and so on.Based on the study of the difference between the expected and actual operation of natural ventilation design,this paper mainly focuses on the outdoor environment,the opening and closing conditions of doors and windows,and the interior layout.A small double office in an office building on the Southeast University campus was selected as a research sample.Using Flovent software and a single variable method was used to simulate and analyze the influence of the above three factors on the indoor ventilation effect.Through the comparison of simulation results,it is concluded that in the design stage,the imperfections of the surrounding buildings may cause a gap of approximately 40% between the design side and the operation side.Different wind direction options and indoor layout will also bring different indoor ventilation effects.Meanwhile,if the doors are closed,the ventilation efficiency is about 50% lower than when the windows and doors are fully open.The location and number of windows will also affect ventilation.In this paper,a combination of experiment and simulation was used to conduct on-site test monitoring of the indoor ventilation of the research sample,and all doors and windows were manually controlled to open and close.The experimental results not only obtained the influence of different doors and windows on the indoor ventilation during the actual operation,but also provided a reference for the simulation data.Finally,by comparing the simulation data with the experimental data,the difference between the expected and actual operation of the natural ventilation design of the building is summarized.Based on the causes of the differences,the suggestions for reducing the differences were initially proposed to provide reference for ventilation design.