Numerical investigations on radon migration from building walls into indoor atmosphere under natural convection

Radon exhaled from building materials infiltrates the indoor atmosphere and is transported into the indoor space by buoyancy-driven airflow. This paper investigated the dynamic coupling of radon concentration in the building wall area and indoor space. An indoor radon migration model under natural convection caused by temperature gradient was established. The radon exhalation rate, average Nusselt number, and average Sherwood number at the building wall and indoor space interface were quantified. The mechanism of radon migration from building materials into the indoor atmosphere was elucidated. Results show that natural convection influences the flow of indoor air and the radon concentration distribution, which increases with the increase of temperature gradient.