Energy policies accompanying the transition towards a sustainable development process must be supported by technical analyses in which future energy scenarios are modeled and evaluated. This paper analyzes possible decarbonization scenarios in Italy for the year 2050. They envisage high electrification of transports and residential buildings, high use of renewable energies, and a modal shift towards public transport. The energy scenarios are evaluated using a software program, EnergyPLAN, starting from a reference model developed for the year 2014. Special attention has been given to the modeling of data that are unavailable in the literature, such as the time profile of heating and cooling demands, obtained with the degree-days method and validated by elaborating the results of the modeling of the residential building stock, this latter was dynamically simulated in TRNSYS. The results show that to obtain a significant decrease of greenhouse gas emissions and fossil fuel consumption, it is necessary not only to promote a deeper penetration of renewable sources, but also their integration with other technologies (cogeneration, trigeneration, power-to-heat systems, thermal storage, vehicle-to-grid operations). In fact, renewables technologies alone can raise some critical issues, such as excess and/or shortage of electricity production and non-sustainable exploitation of biomass.