Study On The Renovation Of Office Building Ventilation System In Chongqing

The research on building energy conservation has been attracting the attention of scholars all over the world.Office buildings have high energy consumption and a large proportion in public buildings,so they have great potential for energy conservation.Ventilation plays a very important role in building energy saving,especially in the transition season,ventilation can achieve good energy saving effect.Hybrid ventilation combines natural ventilation with mechanical ventilation and has the advantages of two ventilation modes.Therefore,based on the national key research project of the 13 th five-year plan "research and demonstration of key technologies for improving the indoor physical environment of existing public buildings",this paper studies the transformation of the hybrid ventilation system of existing office buildings in transition seasons.The author investigated the air conditioning system and ventilation status of 33 existing public buildings in Chongqing,considered the natural ventilation conditions of different rooms,proposed the hybrid ventilation system renovation program for the existing office building,demonstrated the feasibility of implementing the transformation of hybrid ventilation system in existing office buildings,and proposed the solution which was in view of the direct transformation of the existing problems in the air-conditioning system.Based on the analysis of the survey data and the results of the experimental study,this paper conducted a quantitative analysis of the demand air volume of the hybrid ventilation system,the suitable ventilation frequency range of different types of rooms in Chongqing office buildings was obtained.Based on the measured data of natural ventilation,the author revised the theoretical derivation formula proposed by De Gids and Phaff,and predicted the range of natural ventilation of office buildings in the transition season.After simulating the seasonal load of office buildings with DeST software,the author classifies the load levels of office buildings in Chongqing.The author thorough ventilation formula used to calculate the transition season ventilation cooling demand corresponding air changes and the size of the total air volume,through scheme comparison and analysis,optimizing the retrofit scheme,determine the design of the mechanical ventilation of air changes,and further confirmed by the method of numerical simulation hybrid ventilation system has a good running effect.Based on the thermal comfort theory and the quantitative analysis of ventilation,the author puts forward the technical requirements for the retrofit design of the hybrid ventilation system.Author reference typical meteorological year data in Chongqing and the civil building indoor heat environment evaluation standard(GB/T 50785-2012),it is concluded that the transition season in Chongqing indoor comfort temperature range between 16 ~ 26 ℃,and the design temperature of the ventilation room was determined with the temperature as the upper and lower limit.CFD software FLUENT was selected to simulate the velocity field and temperature field of the room,and the recommended wind speed of the exhaust outlet was given.The operation strategy of the hybrid ventilation system is put forward.With the real-time indoor and outdoor temperature as the monitoring parameter,the upper and lower limit of the design temperature of the ventilation room as the critical temperature,the start and stop of the air conditioning system and the mechanical ventilation system can be automatically controlled.And the applicability of the system is analyzed.The utilization rate of natural ventilation in the most unfavorable period is very low,13%.The utilization rate of the hybrid ventilation system is higher,greater than 68%,and the total number of available days is 103.The paper points out that it is necessary to reform the mixed ventilation system.