Th is book is an overview of existing Th eoretical background, Legal bases and best practice examples on existing Energy Saving Technologies. Chapter 1: Energy Saving Technologies in Generation, Conversion of Electrical Energy Th e overview of Energy Saving Technologies, and its application of practice examples promoted by European strategies in power supply. - cogeneration, traditional, DER - effi cient control systems - smart metering concept Chapter 2: Energy Saving Technologies in Transmission, Distribution of Electrical Energy Th e technological overview for energy transmission, distribution, such as: fl exible AC transmission systems, DC transmission systems, effi cient control and metering system. Chapter 3: Energy Saving Technologies: in Industry Th e overview of Electric drives as Energy Saving Technologies are given in particular: optimal selection of electric motor power and application of frequencyregulated electric drives are described as well as SCADA system application; monitoring of unauthorised connections. Chapter 4: Energy Saving Technologies: in Public and Private Sector Th e technological overview of effi cient lighting, energy consumption by transport, street lighting system as a practical example of energy saving technologies. Chapter 5: Legal Bases on Existing Energy Saving Technologies Th e overview of EU Directives on Energy Effi ciency, on Promotion of the use of energy Energy Eff ective Lighting, and Energy Performance of Buildings Directive are described; the main concept and application areas as well as benefi ts from using those concepts are described in the chapter.