The paper shows the process of the development of the sustainable energy action plan (SEAP) for the city of Zagreb and analysis of the interaction between measures, which are used for the reduction in energy consumption and CO2 emissions. The energy savings and CO2 reduction potential of measures are compared in a scenario and individual approach. Sectors of energy consumption listed in SEAP are buildings, transport and public lighting. The buildings sector is divided into public buildings, residential and commercial buildings. The transport sector is subdivided on public transport, public vehicles and private and commercial transport. Measures for CO2 emission reduction are selected by a discussion with relevant stakeholders and most effective measures from the previous SEAP. Mutual interaction between measures, which influences the total result of energy consumption and CO2 emissions reduction, is done through simulation in LEAP. In this way, it can be shown that measures have either synergetic, negative or neutral interaction between them. The analysis showed the negative interaction is prevailing and scenario approach resulted in 16.23% lower CO2 reduction potential than the individual assessment of each measure. It is recommended to use a scenario approach in the development of SEAP for the assessment of measures CO2 reduction potential. This will provide more efficient planning of measures for the reduction in CO2 emissions on a local level and avoid overestimating of the CO2 reduction potential when developing SEAPs.