Radon concentration control by ventilation, and energy efficiency improvement

Radon gas is a pathological agent confirmed by World Health Organization in terms of increasing the risk of lung cancer generation when it is inhaled by human in high concentration. This gas comes from soils with uranium content (i.e. granite terrain) and penetrates through the building envelope, such, as floors or basement walls. Its accumulation in indoor spaces increases the radon concentration level, constituting a health problem for occupants. This can be handled by rehabilitation actions in buildings that reduce indoor concentration to acceptable levels.  Ventilation technique can contribute for the same purpose. The gas dilution, by exchanging indoor and outdoor air is an effective mechanism. A priori, this easy to implement and low cost alternative can be recommended when other architectonic options are not feasible. However, the aspects that can compromise energy efficiency in ventilated spaces should also be evaluated. In order to reduce radon concentration from 900 Bq/m3 to 200 Bq/m3, an additional 30000 kWh/year can be needed for achieving indoor thermal comfort. This is showed in some cases where the air change rate required to reduce this concentration is 5ac/h,  This paper presents an approach for understanding radon mitigation by ventilation, the energy lost in the process, and how to reduce such loss by implementing energy efficiency measures.