Santiago de Compostela is well-known for its historic core of exceptional quality, a World Heritage Site. Due to its mild climate, its large amount of green areas, and its compact urban pattern with mixed functions, it has a low residential energy consumption, but not in its historic core, in which monumental buildings of different ages combine with residences in a pedestrianised urban environment. The European 20-20-20 targets present big challenges to historic areas such as Santiago. The present study assesses Santiago’s strengths and weaknesses in terms of urban planning and energy efficiency, and explores what local planning can do for the adaptation of the historic centre to energy-efficiency considerations. The findings show that local plans have not paid attention to environmental issues, and only recently is local planning involved with such considerations. They also suggest a limited commitment of the local authorities to energy efficiency goals, and serious lack of knowledge about the actual energy situation. A proactive role of the local government towards energy efficiency requires the commitment of all stakeholders. The presence of El Consorcio, gathering the most important local stakeholders, and its successful past experience on urban regeneration, suggests positive outcomes if the city is willing to change its passive role.