The topic of the final work is the design of an underfloor and wall heating system for a school building of 1400 m2 located in the city of Rijeka. The school building consists of two floors. In all rooms of the school building for heating purposes the floor heating panels are provided, underfloor heating with low temperature hot water regime 38/32 °C. Air – water heat pump is used as a heat source. It is important to note that ventilation losses are partially covered by preheating the outside air before entering rooms. The calculation of the mechanical ventilation system was not completed, and it is not part of this final work. Also, the calculation of the wall heating was not completed because there was no need to install it. First, the heat load for the winter period of all rooms and the school building was calculated according to a standard HRN EN 12831 by the computer software IntegraCAD. Then, in order to compare the results, a manual calculation of the design heat load for the winter period of one room was preformed. With the data of the heat load for the winter period of each room was calculated the underfloor heating. After that, the capacity of the heat source, which in this case is air – water heat pump and water tank in the underfloor heating circuit were selected. Furthermore, the pump and the expansion vessel were selected according to the performed calculations. In the end, for the needs of domestic hot water according to the appropriate calculations, separate air – water heat pump and storage tank for domestic hot water were selected. The calculation of the heat load for the winter period and the calculation of the underfloor heating were made in the computer software IntegraCAD. The calculation of the pipe grid was made manually in Excel. The drawing defining the layout and assembly of the equipment was partially made in the computer software IntegraCAD, and partially in AutoCAD. The connection and the regulation scheme were made in AutoCAD.