Advancing towards sustainable development will be impossible without the active participation of informed and aware citizens and decision-makers. This publication will provide the unspecialised decision-makers, citizens, students and policy-makers of the future, with significant information about a dynamic sector-energy- and a space-city- that are critical for sustainability. Cities and the energy field are now on the verge of dramatic changes. Urban energy systems are capital intensive and have long lives. Immediate change is difficult and innovation is crucial for inefficient patterns to be transformed into more intelligent systems. Strongly entrenched ideas start to vacillate and new investments challenge the inertia of old infrastructures. New concepts, values and technological breakthroughs emerge, linked to policy and market initiatives, public expectations and scientific developments.