The European target of cutting greenhouse gas emissions by 20% by 2020 has generated a substantial body of energy efficiency policies, but real-world observations indicate that energy savings realized in practice fall short of energy savings estimates based on physical principles incorporated in engineering models. A partial explanation of this trend consists in what is called 'rebound effect' or 'take-back'. As an increased consumption of energy services following an improvement in the technical efficiency of delivering those services, the rebound effect highlights a variety of tensions between the pursuit of wellbeing and the need to remain within ecological limits.