The aim of this book is to present the fundamental principles of energy efficiency in construction. It is aimed at professionals, as well as masters’ and engineering school students working in the field of building energy. Volume 1 covers the building context and issues, the building envelope and how to improve it using innovative materials and construction techniques, ventilation and lighting. Volume 2 focuses on heating, air conditioning, domestic hot water production and centralized building management. Its objective is to present solutions that are less energy-intensive, more sustainable and more efficient. Through these different aspects, this book provides readers with the tools and best practices needed to design, renovate and manage buildings, ensuring occupant comfort while reducing environmental impact. It is intended for both professionals and students at universities or engineering schools working in the field of building energy systems.