The building in question is the winter pan Mladost, Trg Krešir Ćosića 10, 10000 Zagreb. For energy renovation of the building, the annual thermal energy needs will be reduced by 363.370 kWh/a and by 73.55 %, the annual primary energy will be reduced by 792.814 kWh/a and by 62.76 % respectively, while reducing CO2 discharges by 61.86 %. The current energy class E will change to the expected energy class B.