Impact of ventilation systems and energy savings in a building on the mechanisms governing the indoor radon activity concentration

Highlights: • The radon entry in a building mainly depends on the indoor depressurization level. • Ventilation system and airtightness affect both depressurization and the air change. • Energy savings could have a strong impact on the indoor radon concentration. • The numerical tool developed in this study could help decision making. - Abstract: For a given radon potential in the ground and a given building, the parameters affecting the indoor radon activity concentration (IRnAC) are indoor depressurization of a building and its air change rate. These parameters depend mainly on the building characteristics, such as airtightness, and on the nature and performances of the ventilation system. This study involves a numerical sensitivity assessment of the indoor environmental conditions on the IRnAC in buildings. A numerical ventilation model has been adapted to take into account the effects of variations in the indoor environmental conditions (depressurization and air change rate) on the radon entry rate and on the IRnAC. In the context of the development of a policy to reduce energy consumption in a building, the results obtained showed that IRnAC could be strongly affected by variations in the air permeability of the building associated with the ventilation regime.