Lessons learned on ventilation systems from the IAQ calculations on tight energy performant buildings

During the project QUAD-BBC, several ventilation systems have been studied in residential (individual house and collective dwellings) and non-residential (school, offices) and assessed by the evaluation of an IAQ multi-criteria.
These calculations have shown some typical evolution of pollutants in very tight low consumption buildings and can alert on some possible effects.
For instance, formaldehyde and VOCs criteria are increasing at night when ventilation is shut off which indicates that passive measurement methods are in this case evaluating an average exposure not representative of occupation. It also shows how much airflow should be maintained to reduce the exposure to these pollutants or how much time before occupation the system should be started. Other lessons can be learnt from the pollutions in the kitchen during cooking, the humidity of drying clothes in houses and the impact of occupant behaviour…
Humidity evolution in case of insufficient ventilation in rooms with a high density of occupation (classrooms, meeting rooms…) has also a much stronger impact in a very tight building. The study also shows that the ventilation performance can be improved, especially in main rooms when improving building airtightness. While we could fear the contrary, improved airtightness appears to be beneficial to IAQ in our test cases.
This paper presents the main lessons learnt from the calculation analysis in these buildings.