The building in question is the Faculty of Technology at Law No 2, 10040 Zagreb. After implementing the energy efficiency measures, the annual thermal energy required will be reduced by 363.948 kWh/a and by 54.31 % annually, the annual primary energy will decrease by 478.419 kWh/a and by 38.46 % respectively, and a reduction of annual CO2 emissions by 41.79 %. The current energy class E will change to the expected energy class B.