The thermal comfort and buoyancy-induced motion of air in a room are determined by the interaction of different types of heat transfer and of thermal storage in building components. Heat transfer includes energy transport by radiation, convection, and conduction (within air and the building fabric). The driving forces of buoyancy of air become more pronounced for tall spaces. Therefore, proper modeling of these interactions becomes more crucial in the design of large enclosures. In atria, in particular, solar and infrared radiation are important because of large-area glazing. The boundary conditions for airflow, surface-to-surface radiation, and building dynamics are linked by surface temperatures that may vary in time and space. Numerical methods for the direct coupling of computational fluid dynamics with thermal dynamics and radiation are proposed and demonstrated at a case study building of IEA Annex 26.