This book reviews the history and evolution of district heating networks, with a focus on current and future issues of the district heating sector. Novel developments in the field of low temperature district heating are studied, limitations for safe operation and avoidance of bacteria are considered, and the associated improved performance of the system with fewer network losses is presented.This book showcases how the evolution of district heating networks is linked to the increased use of renewables and de-carbonized heat sources with specific focus to waste heat streams and solar energy...