###### Abstract  
Background and gaps. The topic of indoor air quality (IAQ) in low-energy buildings has received increasing interest over the past few years. Often based on two measurement points and on passive measurements over one week, IAQ studies are struggling to allow the calculation of pollutants exposure. Objectives. We would like to improve the evaluation of the health impacts, through measurements able to estimate the exposure of the occupants. Methodology. This article presents detailed IAQ measurements taken in an energy-efficient occupied house in France. Two campaigns were conducted in winter and spring. Total volatile organic compounds (TVOC), formaldehyde, the particle numbers and PM\({}_{2.5}\), carbon dioxide (CO\({}_{2}\)), relative humidity (RH), temperature (T), ventilation airflows, and weather conditions were dynamically measured in several points. Laboratory and low-cost devices were used, and an inter-comparison was carried out for them. A survey was conducted to record all the daily activities of the inhabitants. IAQ performance indicators based on the different pollutants were calculated. Results PM\({}_{2.5}\) cumulative exposure did not exceed the threshold available in the literature. Formaldehyde concentrations were high, in the kitchen, where the average concentrations exceeded the threshold. However, the formaldehyde cumulative exposure of the occupants did not exceed the threshold. TVOC concentrations were found to reach the threshold. With these measurements performed with high spatial and temporal discretization, we showed that such detailed data allow for a better-quality health impacts assessment and for a better understanding of the transport of pollutants between rooms. indoor air quality; pollutants; low-energy buildings; measurement campaigns; performance indicators +
Footnote †: journal: Medical  
Nevertheless, indoor air quality (IAQ) depends not only on indoor and outdoor pollution sources, but also on airflow through the building envelope (i.e., infiltration and exfiltration) and between rooms induced by ventilation systems and natural drivers such as temperature differences. These airflows can import outdoor pollutants and dilute pollutants from indoor and outdoor sources once they are inside the buildings. In low-energy houses, the amount of outdoor airflow delivered for IAQ is balanced with the needs for energy efficiency. Thus, attention should be paid to secure a good performance of the ventilation systems once they are installed and used in order to avoid underventilation situations with negative impacts on IAQ. Some work has focused on IAQ in low-energy housing, but this topic requires further investigation through campaigns combining precise measurements of IAQ and, as proposed by experts of the IEA-EBC Annex 68 program [8]. Table 1 summarizes some of these campaigns, including the country of the study, the building type, the parameters, the pollutants studied, the devices used, the number of measurements, and the outdoor air ventilation rates. Table 1 shows that IAQ measurement campaigns in low-energy houses are not always combined with outdoor ventilation airflow and envelope air leakage measurements [9], despite their strong impact on pollutant concentrations [10]. However, the influence of outdoor air change rate (ACR) has to be taken into account. ACR is defined as the sum of all the airflows through ventilation components (outdoor ventilation airflows) and leaks normalized by the heated volume of the building. Despite the strong impact of ACR on pollutant concentrations, few studies have measured in a simultaneous and precise manner the pollutant concentrations and ACRs in occupied buildings. The accuracy of measurements of pollutant concentrations is crucial. ACRs are also influenced by weather conditions and occupant activities (closing internal doors and windows, switching mechanical ventilation speed, etc.). The accuracy of measuring ACRs [11; 12; 13; 14] and ventilation airflow [15; 16] is a broad topic of research.