The paper presents a numerical analysis of air temperature distribution in a heated space. A mathematical model, as well as boundary and initial conditions, were defined. Heat flux on the walls and window is set as a boundary condition, while the temperature is assigned to the heating element. The control volume method was chosen for solving the mathematical model, and the problem was solved numerically. Using the Ansys Fluent software, three different cases of free convection between the heating element and the air in a room were analyzed. In the first two cases, the heating element is underfloor heating, while in the third case, the heating element is a radiator or an electric heater. The results are presented as temperature fields and velocity vector fields. Additionally, tabulated values of temperatures at characteristic points and values of convection heat transfer coefficients are provided. The highest temperatures are achieved with radiator heating, and the lowest with underfloor heating set to 20 ºC. Air flows in a clockwise direction, and the temperature distribution is more uniform in the cases with underfloor heating compared to the case with radiator heating.