The present study goal is to observe how the radiant ceiling performs in energy savings and thermal comfort in a ventilated office using CFD simulation. The boundary conditions for each CFD were all described. The profiles of air temperatures, Predicted Mean Vote (PMV), Predicted Percentage of Dissatisfied (PPD), and Draft Risk (DR) were examined to satisfy the comfort criteria of the ASHRAE standard. The effects of varying the temperature of the cooling panel, the air supply temperature, and the presence of air changes per hour (ACH) in the office space on thermal comfort and energy saving were investigated. A mesh is merged using more than 6 million optimized tetrahedral nodes. This investigation was reviewed to ensure that the program was consistent with the experimental results. The current study used the k- ε turbulence model after comparing it to previously published experimental results. Heat transmission by radiation was simulated using the Discrete Ordinates DO radiation model. This study found that the case selection (case 23252) actually has the advantage of energy-saving air conditioning, and its temperature is fixed at 25 °C, which is beneficial because the cooling water used in the cooling plate needs less energy than air in order to cool it (which has a large specific heat capacity and density). In this case, lower quality thermal systems such as geothermal energy or solar energy sources can be used to condition both the water and air supply.