Investigations of indoor air quality of large department store buildings in China based on field measurements

- Indoor air quality in the nine large department stores across seven cities is investigated.
- Correlation analysis of pollutant concentrations is conducted.
- Theoretical analysis of the increment of fresh air for the underground space is proposed.
- Space functionality is recommended to be considered in HVAC design and operation.
- Location of above/underground is recommended to be considered in HVAC design and operation.

This paper presents a large-scale field studies on the indoor air pollution in large multi-storey department store buildings in seven Chinese metropolitan cities. From the year 2013-2015, nine buildings equipped with centralized air-conditioning system were carefully selected for the onsite test. Results show that each building has diverse indoor thermal environment and concentrations of CO2, formaldehyde and TVOC. Mean concentrations of CO2, formaldehyde and TVOC in the measured buildings range from 560 to 997 ppm, 0.02-0.31 mg/m3 and 0.074-0.636 mg/m3 respectively. The highest rates of exceeding the standard limit in the tested buildings were found as 36.8% of CO2, 53.2% of formaldehyde and 40.3% of TVOC. There are significant correlations between indoor and outdoor concentrations of CO2, formaldehyde and TVOC. The pollutant concentrations are different in different merchandise sections. Furthermore, significant differences and colorations of the pollution concentration are revealed between that of aboveground and underground floors. A mathematical model for the calculation of the increment of fresh air for the underground floors of a department store building is proposed based on the theoretical analysis and the assumption of steady-state airflow condition. This model provides quantitative relations of a required amount of additional fresh air of the underground floor referencing to the aboveground floor of the same building. Based on this research, it is recommended that the factors of space functionality and usage as well as the location of under-aboveground floors of the department stores should be taken into account in the design and operation of the HVAC systems.