I-CUB: 'Indoor Climate-Users-Buildings': Relationship between measured and perceived indoor air quality in dwellings

Assessment of indoor environmental quality has recently moved to a combined methodology of both measurements and questionnaire surveys. In this study, we have used data from the national survey of the Swedish housing stock, BETSI, conducted in 2007/2008, during the heating season. The study included, among others, measurement of selected indoor air pollutants and an extensive questionnaire survey on the occupants' perception of their dwellings. Measured concentrations of the air pollutants NO₂, TVOCs and formaldehyde were aggregated into one Indoor Air Pollution Index (IAPI) on a continuous scale between 0 (excellent Indoor Air Quality; IAQ) and 10 (poor IAQ). The perceived IAQ was assessed by the occupants on a 5-point category scale from very good to very poor. On the entire scale of IAPIs, 92% of the respondents in single-family houses perceived the IAQ as very good or good and 8% as acceptable, while in the apartments, the ratings 'very good' and 'good' accounted for 58%, acceptable for 33% and 9 % for 'poor' and 'very poor', respectively. In both building types, the tendency of IAPIs was shifted to lower values (good IAQ). Analysis of IAPI-medians showed no statistically significant differences between and among the air quality perception ratings.