District energy (DE) systems use central heating and/or cooling facilities to provide heating and/or cooling services for communities and can be particularly beneficial when integrated with cogeneration plants for electricity and heat. This book provides information on district energy and cogeneration technologies, and the systems that combine them, with a focus on their modelling, analysis and optimization. Topics covered include a brief introduction to district heating and cogeneration; background material on thermodynamics and exergy analyses; models for cogeneration, heating and district heating, and chilling and district cooling; descriptions and analyses of configurations for integrating cogeneration and DE technologies; economics of cogeneration and DE; environmental impact of cogeneration systems, including wastes and carbon dioxide emissions and their allocations; modelling and optimization of cogeneration-based district energy systems accounting for economics and environmental impact; developments and advances in technologies and systems for cogeneration and DE; and future directions. Examples and case studies are included throughout the book to illustrate the material covered, and to demonstrate the importance, benefits and value of cogeneration and district energy technologies in achieving sustainable and efficient energy systems.