The start of the 21st century has marked an incredible change in the world of Energy. In fact, in a world which is more uncertain than ever (sudden changes in energy prices, shale and oil gas, emergence of new players, geopolitical tensions in Ukraine, Iraq, etc), the only real issue in which there is a general consensus remains that of Energy Savings and Energy Efficiency. This book aims to build a general picture of the world of modern energy by focusing on the major climatic and geopolitical challenges. It also explores the most recent developments in environmental regulations, notably those related to Energy Efficiency and Energy Savings, seen without any doubt as the founding roots of the so-called Energy Transition.According to Myriam Maestroni, a leading expert on Energy in France and Europe, these two pillars of the “New World of Energy 2.0”» can be broken down at international, European, national and local levels, not only because of the changes in the rules and the perceptions of policy-makers regarding energy efficiency, but also, and especially because of the concrete ground level realities, public, entrepreneurial, local or associative initiatives and technological innovations.The book, written in close cooperation with two top experts in the global energy world, Michel Derdevet and Jean-Marie Chevalier- also records the opinions of some of the best French and international leading figures who are highly engaged to contribute through their proposals, analysis and actions, to the emergence of the new world of «Energy 2.0», amongst which Bruno Lechevin, Fatih Birol, Johannes Meier, Marc Beckers, Ann Robinson, Stephen Howard, Juliet Davenport, Gregor Paterson-Jones, Jean Marie Chevalier, Robert Bell, Michèle Sabban, Corine Lepage, Gabriele Albertini, Jeremy Rifkin, etc.