Indoor air quality investigation of a university library based on field measurement and questionnaire survey

This article presents field studies and questionnaire survey on the indoor air quality (IAQ) in library rooms in University of Science and Technology Beijing in April 2016, with no heating, to find out actual situation of IAQ in university library. Nine rooms equipped without centralized air-conditioning system were carefully selected for the test. Results showed that each room had diverse indoor thermal environment and concentrations of CO2, PM2.5, formaldehyde and TVOC. The concentration of CO2 ranged from 575 to 2400 ppm, PM2.5 concentration was 40–70% of the outdoor, the highest concentration of formaldehyde and TVOC was ~0.042 and 0.285 mg m−3, respectively with half of the upper limit. The concentrations of CO2 and PM2.5 in the holding-reading rooms were higher than that in the rooms only holding books. The situation of formaldehyde and TVOC concentrations was just opposite. The correlations between satisfaction of IAQ and the concentrations of indoor air pollutants were not as a constant, but changing with different rooms. Based on gray system theory, satisfactions were affected seriously by CO2 and PM2.5. One improving plan with the theme of 'ventilating rapidly along with purifying' was determined based on a general mass balance equation. In theory, IAQ can be improved <5 min for the most unfavorable condition. Through analysis, requirements of fresh air and functionality of the space usages should be considered in the ventilation or central air-conditioning system design.