EVALUATION OF INDOOR AIR QUALITY IN A SPLIT-UNIT AIR-CONDITIONED CANTEEN IN NATIONAL UNIVERSITY OF SINGAPORE

Abstract

Since most University students spend a significant amount of time in canteens for dining and social networking, hence ensuring good indoor air quality (IAQ) in University canteens is fundamental to student’s health. This study aims to evaluate and provide insights on the relationship between occupancy level and IAQ in a University canteen that adopted split-unit air conditioning system. Both Singapore Standard 554:2016 and ASHRAE 55:2013 were used as guidelines to assess the standard of IAQ in this particular canteen. In order to achieve a comprehensive analysis, two complementary approaches, i.e. objective measurement and subjective assessment, were adopted to construct a holistic conceptualisation of IAQ. For objective measurement, IAQ parameters were measured using scientific instruments such as ppbRAE and DustTrak. For subjective assessment, online surveys were conducted to study diners’ perceived thermal comfort and experiential air quality in the canteen. Results of the objective measurements have shown that IAQ parameters such as air temperature, humidity ratio, carbon dioxide (CO2), PM2.5, PM10, bacterial and fungal growth are positively correlated to occupancy level; as the number of occupants in the canteen increases, IAQ parameters increase correspondingly. Regrettably, most of the IAQ parameters measured in this canteen are not in compliance with SS 554:2016, especially at high occupancy level. In particular, the air temperature, PM2.5 and PM10 have exceeded the standard requirements significantly, while Relative humidity (RH), air movement, CO2, total volatile organic compounds, bacterial and fungal counts were only marginally within standard with a number of outstanding data. The subjective assessment survey results have shown that as many as 29% of the respondents were not satisfied with the IAQ in the canteen which is significantly higher than the predicted percentage of dissatisfaction (PPD) based on ASHRAE 55:2013. Recommendations were proposed to improve the IAQ so that it will comply with the local standards and increase diner’s satisfaction in the future.