Study On The Influence Of External Windows On Energy Consumption Of Office Buildings In Hefei Under Dynamic Natural Ventilation

At present,the scale and volume of the construction industry is unprecedentedly huge,and the degree of urbanization in the country has reached an unprecedented level.The proportion of public buildings’ total power usage is about 38% of total construction power consumption,and the exterior windows’ energy consumption represents more than 40% of the overall energy consumption of buildings,so it is important to study the energy efficiency of exterior windows of buildings.The energy-efficient window design is the critical element of the building power saving work,and it helps the target of double carbon.The relevant study still needs to be advanced and most of the existing studies,when discussing the practical effect and influence law of external window natural air ventilation on the energy usage of buildings,either directly define the number of ventilation changes or fix the number of air changes on the basis of a certain time period.In this paper,based on the practical meaning that the number of indoor air changes in buildings is not fixed in real life,a dynamic coupled simulation calculation method of natural ventilation and indoor thermal environment is adopted according to the actual meteorological parameters in Hefei,and a coupled benchmark model with time-by-time variation of natural ventilation is obtained to carry out a simulation study of building energy saving under the conditions of actual dynamic natural ventilation based on the benchmark model in Hefei,a typical city in a hot summer and cool winter zone,to compare and The simulation study was carried out to analyze the natural ventilation potential and the influence of energy consumption of office buildings under different forms of natural ventilation with the design of external window size and thermal performance,energy saving effect and carbon emission benefit.The principal work of this study is as following:(1)Using Fluent and De ST-Vent Plus software,the building wind pressure coefficient model and multi-area network ventilation energy model were established respectively.Through a series of analysis and settings to Vent Plus algorithm module,a coupled model of natural ventilation and room temperature climate was built,and the reasonable ventilation and control plan was set as the benchmark model and plan for numerical simulation under the full-text time-varying natural ventilation.(2)From the perspective of natural ventilation potential analysis,the number of natural ventilation hours in Hefei can reach about 1539,accounting for about 18% of the total number of hours in the whole year.The ventilation potential in typical cities in hot summer and cold winter areas is quite considerable,and the passive technology of natural ventilation in buildings has high utilization value.From the analysis of dynamic ventilation frequency of natural ventilation,although the ventilation frequency of unilateral natural ventilation is far less than that of other natural ventilation forms,its natural ventilation rate is slightly better than other natural ventilation forms.(3)The annual energy saving rate of unilateral natural ventilation has a significant negative correlation with the increase of the window-wall ratio,ranging from 15.39% to18.65%,and the window-wall ratio should be 0.3 to 0.35;The annual energy saving rate of mixed natural ventilation is between 16.65% and 17.17%,and the window-wall ratio should be 0.3;The annual energy saving rate of cross-flow natural ventilation is between 16.56%and 17.41%,and its window-wall ratio should be 0.3.(4)The yearly savings trend of natural ventilation with the addition of windows K all maintain a notable positive linear trend,with the whole year average energy savings of13.46%～17% for hybrid and 16.74%～13.50% for cross-flow natural ventilation,and16.79%～14.60% for single-side natural ventilation.The annual energy saving rate of natural ventilation also shows a significant linear decreasing trend with the increase of SC value of exterior windows.The annual energy saving rate of mixed natural ventilation reaches between 16.68% and 15.46%,the annual energy saving rate of cross-flow natural ventilation reaches between 16.48% and 15.20%,and the annual energy saving rate of single-side natural ventilation reaches between 17.26% and 14.90%.Figure [61] table [10] reference [88]...