Nowadays fossil resources still play a major role in the energy production and they are responsible for most of the greenhouse gases (GHG) emissions. The increasing global energy demand requires governments, at both high and local level, planning and forecasting their energy demands in order to meet such needs in the most sustainable way, reducing GHG emissions as already stated in international agreement. Cities play a key role in moving towards a sustainable development, since they are the major energy and resource consumers. Starting from 2008, a group of European cities autonomously sets an ambitious target in seeking to reduce their carbon footprint at least by 20% by 2020 [Covenant of Major - Sustainable Energy Action Plan]. In order to help policy maker reaching the goal, in this study a simulation model of one of these cities (Bari, southern Italy) based on system dynamics has been developed. The model considers the regional energy demand and shows the effects of different strategies on carbon emission performance. The goal here is to provide local decision makers with a holistic view in order to give in-depth understanding and leverage the feedback interrelationship of urban energy system. The simulation model allows to test “what-if” scenarios and analyzes the expected results of implementing certain adjustment and control policies. Results provide essential information for the city’s future energy and carbon emission profiles.