The improvement of energy efficiency is one of the main challenges we need to address to reach the objectives set by the EU 20-20-20 Strategy. Cities are responsible for two-thirds of the global energy consumption and this proportion is expected to grow further. Cities represent complex systems in which physical assets, strategic and economic activities as well as most of the world population are concentrated. Hence, to achieve relevant and enduring results in addressing energy efficiency issues, it is necessary to broaden our vision from the building scale to the whole urban structure. Urban planning is increasingly considered a crucial element in the long-term energy efficiency strategies.