Half of the global population is currently urbanized. Some 75% of global resource consumption takes place within these increasingly interconnected urban settlements, which cover only 2% of the earth's surface. The associated environmental consequences are evident in increasing climatic disorders and the trend is set both to continue and to magnify in intensity, as global urbanisation is predicted to increase by a further 50% by the year 2050. It is thus imperative that we improve the sustainability of current and future urban settlements. For this we need to better understand the physical principles describing urban sustainability and to encapsulate these principles in the form computer models to enable us to test ways to improve it.This is the first book to directly address the physics of urban sustainability and how urban sustainability may be modelled and optimised. Starting with an introduction to the importance and key aspects of the topic, it then moves on to a detailed consideration of the urban climate, pedestrian comfort and the metabolism of urban resources. Comprehensive techniques for the modelling and optimisation of urban metabolism are then described, together with means for defining sustainability as the fitness function to be optimised. It ends with an eye to the future of sustainable urban design and the means available to urban designers and governors to help them to secure a more sustainable urban future. This book will be invaluable both in informing the next generation of urban planners, architects and engineers, and as a tool to current professionals that will directly contribute to the effectiveness of their work by allowing them to more successfully measure and model urban sustainability.