Experimental Research On Indoor Air Quality In Different Ventilation Modes Of Residential Buildings In Xi’an

Indoor thermal environment and indoor air quality are important components of the indoor environment.The thermal environment is vital to thermal sensation and aims to provide the best thermal comfort for people.Indoor air quality accompanied by long-term environmental pollution problem with low concentration.The concentration of pollutants is generally close to or even far lower than the corresponding national norms.Indoor air quality is directly affected by the type,nature and concentration of indoor air pollutants.This paper analyzed and compared the indoor thermal environment of ten residential buildings in Xi’an with the level of pollutants,and obtained a suitable and popular ventilation method and focuses on another typical residential building for research.The purpose was to evaluate the natural ventilation and a portable air cleaner of residential buildings significantly accelerated PM2.5 removal,but increased the noise levels in rooms when on setting.Online monitoring,statistical analysis,and multi-index evaluation were assessed to the indoor air quality of seven natural and three mechanical ventilation apartments in Xi’an,Shaanxi.Temperature,relative humidity,formaldehyde,CO₂concentration and PM2.5concentration were selected to analyze.At the same time,outdoor gas phase parameters were also involved in the comparison.The results showed that the most serious indoor pollution were PM2.5 in autumn and winter in natural residential buildings,followed by poor ventilation in mechanically ventilated bedrooms,which leaded to high CO₂concentration,and formaldehyde concentration met national norms,the comprehensive index values(PMV_HCHO)were distributed.Indor to overcome the disadvantages of the above two ventilation systems,a residence was selected to carry out a detailed measurement of different ventilation boundary conditions.The results showed that when the external window of the residence was perpendicular to the outdoor wind direction during the monitoring period.Different door and window combinations had different effects on the indoor thermal environment,CO₂and PM2.5 concentration,and the indoor environment was also affected by the layout of the building.The difference from the ten houses was that the average daily concentration of indoor PM2.5 does not exceed the standard（75μm/m³）,but they all showed consistent regularity:the PM2.5 concentration of living room was always higher than two bedrooms.In order to ensure that the indoor CO₂concentration during sleep was below the limit（1000ppm）,it is recommended to correct the window-to-wall ratio was most when the air infiltration rate was below 2.715h^-1and the per capita use area of the space was below11m².In order to ensure the comfort of the indoor environment,it is recommended to correct the window-to-wall ratio below 0.1,when the air infiltration rate was above3.748h^-1and the per capita use area of the space was below 19m².This study evaluated the effect of natural ventilation and a portable air cleaner by artificially manufactured high PM2.5.Natural decay,total decay,clean air delivery rate,cleaning energy efficiency,and correct window-to-wall ratio was calculated to evaluate the effect of each purification condition.Natural ventilation can reduce the indoor PM2.5concentration by more than 90%,but there will be a pungent odor after pollution;the natural ventilation and a portable air cleaner took a short time and had a good purification effect.The purification of portable air cleaner varied with the correction of the window-to-wall ratio and the different placement positions.