Sustainability of national energy systems has a strategic role in current and future energy-environmental policies as it involves key points such as security and continuity of energy supply, mitigation of environmental impact (with special focus on climate-changing emissions) and energy affordability. In this context, modeling tools able to represent a simplified yet detailed configuration of national energy systems become more and more important. These energy models can support the decision-making process towards the so-called energy transition at different stages and spatial scales by producing reliable trajectories of the energy system in a certain time horizon, coherent with given hypothesis and constraints.