Indoor air quality analysis of 8 mechanically ventilated residential buildings in northeast China based on long-term monitoring

Abstract

In this study, 8 residential buildings with installed fresh air systems were selected to monitor indoor air quality. Data on temperature and concentrations of formaldehyde, VOC, CO2, and PM2.5 were collected. Phenol reagent spectrophotometry and GC–MS were used to test for the concentrations of formaldehyde and VOC on site. Indoor air quality sensors, window sensors, fresh air system sensors, and smart sockets were used for long-term monitoring online. The test results showed that the indoor air quality varied with seasonal characteristics. The concentrations of PM2.5, formaldehyde, and CO2 exceeded the national standard in winter, summer and transition seasons, respectively. The fresh air systems had obvious effect on reducing indoor concentrations of formaldehyde, VOC, and CO2. Fresh air systems reduced the concentration of formaldehyde by 52.4 % when in use. The TVOC concentration under closed condition was 0.641 mg/m3, and the annual average was 46.8 % of it.The CO2 concentration exceeded the national standard only during the early stage of heating, with an average concentration of 1133 ppm. However, only the medium and high-efficiency filtration fresh air systems significantly reduced PM2.5 concentration, and using air purifiers to assist in common coarse filtration was a worthwhile choice.