The topic of this diploma thesis is heating of apartment buildings, where an attention was focused on thermal comfort in heated rooms. The first theoretical part brings results of CFD simulations which compare radiators with floor heating. The second part consits of practical application o the given building. There are two options in this project - heating by radiators or floor heating. The third part describes two experiments - measurement of indoor environment in two rooms and measurement of gas consumption in apartment buildings with different heating concepts. In the last part the mean radiant temperature is simulated. There are compared different kind of heating, which have impact to distribution of mean radiant temperature in the room. The personal software was created for deeper understanding of mean radiant temperature.