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...