Indoor environmental quality in existing public buildings in China: Measurement results and retrofitting priorities

Through a large-scale questionnaire survey across China and indoor physical measurements of typical cities in the four climatic zones, this study investigates the current status and retrofitting priorities of the IEQ of existing public buildings in China. The public buildings in China mainly present uneven indoor hot and cold distributions and draft sensations. The utilization ratio of natural light is low, and glare often exists. HCHO and TVOC are not major concerns of indoor air quality, but affected by the region and season, the PM2.5 and PM10 concentrations exceed the limits of the Chinese standard. All the buildings present excessive noise. Respondents generally demand improved indoor air quality and thermal environment, and different control strategies should be adopted across regions with different local climatic conditions and behavioural habits. For the thermal environment, the indoor air distribution should be optimized and the indoor humidity ratio increased in winter in northern regions of China. For the luminous environment, the indoor illuminance value should be decreased and the lighting quality improved. For the acoustic environment, the sound insulation and sound absorption performance of the building envelope should be improved. For indoor air quality, the purification capacity of the air conditioning system and the airtightness of the building envelope should be strengthened. According to the outdoor air quality, different channels can be opened to introduce fresh air. For example, when the outdoor air quality is good, fresh air can be directly introduced to improve the service life of the filtering system and reduce energy consumption.