Research On Natural Ventilation Control Strategy For Office Buildings In Cold Regions Using Air Conditioning

Natural ventilation is the preferred ventilation scheme for green buildings,playing a very important role in achieving the "dual carbon" goal,improving the comfort of the building environment,and improving indoor air quality.Available natural ventilation can reduce the use time of air conditioning equipment in summer,reduce building energy consumption,and help to achieve "carbon peak and carbon neutrality" as soon as possible.Therefore,in the design phase of office buildings and the operation phase of air conditioning and ventilation systems,how to use natural ventilation technology to improve indoor environment and air quality,achieve regulation of thermal environment,and reduce energy consumption of air conditioning equipment is the focus of this study.Taking Shijiazhuang City as an example,this thesis studies the indoor thermal environment and energy saving potential of natural ventilation for office buildings in cold climate areas.The main contents of this thesis are as follows:(1)Simulation calculation and analysis of thermal storage characteristics of building walls.The finite difference method is used to calculate the temperature change inside the wall,and the temperature change of the wall surface inside the wall is obtained.(2)Simulation calculation and analysis of ventilation mode and ventilation period.Import temperature and heat source changes into numerical simulation software as boundary conditions,conduct numerical simulations of all day ventilation,and explore the effects of ventilation modes and wind speed on indoor thermal environment;Conduct natural ventilation measurements on a building room in Shijiazhuang at different time periods,and compare the experimental test data with the simulation results to verify the accuracy of the model calculation results.On this basis,indoor thermal environment simulation was conducted for different ventilation periods at night,with the number of hours f that do not meet the comfort level and the percentage of cooling potential J as evaluation indicators.The conclusion was drawn that during the hot summer season,among the simulated 9 different ventilation periods,the natural ventilation time is from 22:00 to 08:00 the next day,which has the best cooling effect;Secondly,from 22:00 to 09:00 the next day,from 00:00 to 08:00,their cooling capacity is 1.42,1.36,and 1.35 times that of natural ventilation throughout the day;If the ventilation duration is increased and the window opening time is moved forward,ventilation from 20:00 to 08:00 the next day will reduce the cooling rate.(3)Numerical calculation and analysis of energy-saving potential during different night ventilation periods.The results show that during the air conditioning usage period in May and September,nighttime ventilation can reduce the power consumption of the air conditioning by about 45%-51.35%,and from June to August,it is about 29.53%-38.41%.But in hot summer from 07:00 to 08:00,ventilation for an additional hour will increase the heat removal by 11 W/m2;The natural ventilation time is extended to9:00,and then turning on the air conditioning saves 7%-12.98% energy compared to turning on the air conditioning at 08:00;If the air conditioning is turned on at 08:00,the best ventilation and energy-saving effect is achieved from 22:00 to 08:00 the next day,followed by 20:00 to 08:00 the next day.The use of natural ventilation scheme can reduce the power consumption of summer air conditioning by 6.93 k Wh/m2-10.31 k Wh/m2,and can reduce energy consumption by 30.84%-47.85%.This thesis provides a reference data for the application of natural ventilation technology in cold regions.