Definition and assessment of indoor air quality classes: sources of uncertainties and rating implications

This paper describes the method, in which human observers assess indoor air quality. This method is at present necessary to determine actual levels of air quality indoors in non-industrial buildings to fulfil comfort requirements specified by the standards. The paper attempts to identify the potential drawbacks of the method, its limitations and the factors influencing these measurements. Examples are given illustrating, how the measurement uncertainty influences the estimated level of indoor air quality. Implications are discussed for the indoor air quality levels and the categories of emissions from building recommended by the current standards. Suggestions for modifications are given and an alternate approach outlined, which both ensure that the intended indoor air quality levels can reduce health risks and can additionally be verifiable in practice.