The thesis describes the current status of the building envelope, of the building which is Duplex where I live since birth. It is located in Ljubljana, more precisely in Zgornem Kašlju. In energy performance of individual structural sections, thermal transmittance was determined
by using the online software tool U-Wert. The energy balance of the object was created with the help of the program TOST. The results that I have received before renovation have shown that the current building envelope does not meet the requirements prescribed by applicable laws. After results is describeb the proposed renovation of the building. Then there are presents new results after renovation. The thesis presents the effects of typical thermal bridges which occur at the facility before and after renovation. The results obtained showed that the differential transmission loss between simplified and the actual consideration of thermal bridges before renovation higher than the results after the renovation. The reason for this is that we had before the energy renovation more thermal bridges. With energy renovation the influence of some thermal bridges was limited or have been removed.