The subject of the thesis is the analysis of energy renovation in multi-apartment buildings. Three different multi-apartment buildings were selected due to the similarity between their purpose, size and year of construction. Furthermore, they are all located on the same street in Kočevje. In recent years, energy renovation was done for two buildings, while the third is still in its original building envelope. An analysis of thermal bridges present for all three buildings was conducted based on images captured with an infrared camera. The energy renovated and non-renovated parts of the buildings were compared on the basis of the specific transmission heat loss coefficient H'T and the annual heat demand QNH. These values were essential in determining the actual difference between the three buildings. An analysis of energy use of the three multi-apartment buildings was conducted with the help of the KI Energija software. The success of the energy renovation was based on these results. The results of the analysis of the renovated buildings were compared with a hypothetical ideal state with all thermal bridges removed. The results indicate that the energy renovation was successful as heat loss and the annual heat demand drastically decreased and they now comply with the requirements by PURES. However, the thermal bridges were reduced, but not completely removed. Transmission heat losses and annual heat requirements remained considerably high compared to the hypothetical ideal state, indicating the need for further renovation.