An Epistemic Indoor Air Quality Assessment Protocol for Air-Conditioned Offices

Long-term measurement could be the best approach to determine the average pollutant concentration of an indoor environment for decisions on mitigation measures. This approach requires considerable measurement effort for accurate results and hence indoor air quality (IAQ) assessment methods that need less effort have been developed. This study proposes an epistemic approach for assessing an acceptable office IAQ against certain indoor air pollutant exposure limits. Together with the prior understanding of failure rates of IAQ determined from a number of extensive survey studies, a sample test result of pollutant levels and the uncertainties of different sampling schemes, the probability of satisfactory IAQ for an assessed air-conditioned office could be quantified. In particular, assessment of an acceptable IAQ for some air-conditioned offices in Hong Kong was demonstrated by taking CO₂ as an example pollutant. Accuracy of the failure rates was improved by the application of sampling correction factors and Bayesian statistics. The probabilities of an acceptable office IAQ were evaluated against a CO₂ level limit. This approach would be useful for IAQ assessment in some air-conditioned offices.