Natural ventilation measurement method of buildings based on PM2.5 concentration recovery data

Natural ventilation is a common and important ventilation method, which has an important impact on both building energy consumption and indoor air quality. The measurement of natural ventilation generally requires the use of specific tracer gases or CO2 released by the human body, which is less operable and accurate. This study proposes a measurement method for natural ventilation of buildings based on PM2.5 concentration recovery data. By turning on and off an air purifier, the rise and fall of indoor PM2.5 concentration are controlled, and the data of the rising and falling sections of the concentration are used to combine the mass balance equation to obtain the natural ventilation volume of the building room and the clean air delivery rate（RCAD）of the air purifier. Numerical simulations are used to verify the effectiveness of the method, and two experimental cases are conducted to evaluate the proposed method by comparing it with the traditional CO2 concentration decay method. The results show that the relative errors of the PM2.5 concentration recovery method are 19.4% and 20.3%, respectively, and the relative error of the RCAD value measured by the two experimental groups is 22.1%. This method makes up the shortcomings of the existing natural ventilation measurement methods, does not need to use specific tracer gas, and is easy to operate. It can be used to measure the natural ventilation of buildings and verify the RCAD value of air purifiers under actual conditions.