Experiments of three cases, such as steady operation, unsteady operation with opened door, and unsteady operation with opened window, were carried out in a residential room having air carrying energy radiant air-conditioning system. Three Computational Fluid Dynamics (CFD) models were established based on the experimental results to study the indoor thermal environment and condensation risk of these three cases. The synergistic operation model described by the temperature synergistic formula, relative humidity synergistic formula, PMV synergistic formula, and energy consumption synergistic formula was proposed based on the thermodynamic analysis. The verified CFD model shows that the vertical temperature gradient between the human head and ankle height is less than 0.6 ℃ and the air velocity in the occupied zone is about 0.1 m/s. There is a boundary zone with low condensation risk under the radiant orifice plate of both steady and unsteady cases for about 12 cm and 6~8 cm, respectively. The synergistic influence analysis of air supply and opening degree on PMV and energy consumption was conducted based on the unsteady experimental results. The synergistic evaluation index of mixing ventilation was presented, offering optimal advice on air supplying settings for different opening degrees of outside door and window.