Operating behavior and corresponding performance of mechanical ventilation systems in Chinese residential buildings

The purpose of this field study was to evaluate the ventilation practices of occupants, the performance of ventilation systems and the indoor air quality in mechanically ventilated apartments by means of mechanical ventilation and indoor air quality data collection. A one-year measurement study was conducted in 36 apartments in 5 cities across three different climate zones in China. The average daily open-system operation duration in Chinese apartments was 9.1 h. Approximately 11.1% of residents tended to operate the mechanical ventilation system nearly all day. Most residents operated the system intermittently. The duration of operation increased from summer to winter as the outdoor air particulate matter (PM) 2.5 concentration increased. The average efficiency of mechanical ventilation systems was approximately 50%, and the median air change per hour (ACH) was approximately 0.56, which is much lower than the nominal value. Most mechanical ventilation systems can possibly maintain the indoor air quality of residential buildings at a moderate level. This study is expected to contribute accurate field data for mechanical ventilation system evaluation and design in Chinese residential buildings.