Urban systems now house about half of the world's population, but determine some three quarters of the global economy and its associated energy use and resulting environmental impacts. The twenty-first century will be increasingly urban. Sustainable development therefore needs first to be defined and analyzed, and then realized in urban settings. Energy is one of the key challenges, but also one of the key opportunities in the required urban sustainability transition. The book is the result of a major international effort to conduct the first comprehensive assessment of energy-related urban...