Cities strive to move towards a more sustainable city. In the process of energy transition in the built environment, moving from usage of fossil fuels towards renewable energy is the process obstructed which results which result in little or no action. This research will focus on several cases in Europe and analyse the cases with a focus on its management, policies and actors. The research will compare theory with practice on the process that tends to go towards the implementation of sustainable solutions in the built environment, focusing on energy efficient solutions in particular. Finally, it will conclude with the found bottlenecks in each theme and each case, which leads through a synthesis to a conclusion that can cover some solutions to overcome these bottlenecks.