The building in question is the Jastrebarsko Police building, the Ministry of the Interior of the Republic of Croatia, I.B. Mažurinić, 1, 10450, Jastrebarsko. The energy renovation project for this building will reduce annual primary energy at 267.384 kWh/a to 77.382 kWh/a or by 71.06 %, the annual thermal energy required for heating will be reduced from 165.347 kWh/a to 36.179 kWh/a or by 78.11 % and a reduction of CO2 will be 53 130.33 kg/a reduction of 74.28 %. After energy renovation, the current energy class of the building D will change to the expected energy class B.