The article discusses how managing and saving energy is crucial due to the Earth's limited resources and increasing pollution. It focuses on energy used in buildings, emphasizing the need for efficient management in both homes and commercial spaces. The book provides detailed information on energy supply, management, auditing, and technology for saving energy. It is meant for students studying energy management and building services, as well as professionals working in the building sector. In essence, the book aims to help individuals and organizations understand and implement measures to conserve energy effectively in buildings.