"Prof Pincetl and colleagues have compiled a valuable and insightful study on constructing the Southern California Energy Atlas, a unique and world leading resource. This book is informative, instructive, and an essential guide to those seeking to build a knowledge base upon which to take actions supporting the transition of the built environment towards becoming zero-carbon, energy efficient, and resilient." - Ian Hamilton, Associate Professor,UCL Energy Institute,London In an era of big data and smart cities, this book is an innovative and creative contribution to our understanding of urban energy use. Societies need energy data in order to understand energy flows and plan for a more sustainable future. However, this data is often either not utilized or not available. Using California as an example, the book describes how to construct a energy data hub for sophisticated, socially-conscious research, and how it may be used to assist local governments and community based organizations to meet their sustainability goals. This methodology maps highly-detailed building energy use to understand patterns of consumption across buildings, neighborhoods, and socioeconomic divisions. The book then details the steps required to replicate this methodology elsewhere, demonstrating the importance of openly-accessible building energy data for transitioning cities to meet the climate planning goals of the twenty-first century. It also explains why actual data, not modeled or sampled data, is critical for accurate analysis and insights. Finally, it acknowledges the complex institutional context for this work and some of the obstacles the project has faced - utility reluctance, public agency oversight, funding and path dependencies. This book will be of great value to scholars across the environmental sectors - especially to those studying sustainable urban energy - as well as to practitioners and policy makers in these areas. Stephanie Pincetl is Director of the California Center for Sustainable Communities at the Institute of the Environment and Sustainability, University of California, Los Angeles, USA.She works on complex urban systems and their socio-environmental impacts with an aim to provide actionable science for a just energy transition. .