Nowadays, issues connected with a reduction of energy consumption in the development of systems using renewable energy consumption are crucial in both scientific studies and industrial use. In this book we show results of the analysis of different energy sources in single family houses. Advantages and disadvantages of systems with heat pumps, solar collectors and gas boilers, depending on their location, are discussed. Pros and cons were analysed from technical, ecological and financial sides. Moreover, the possibility to design installations using a modern BIM technology is presented in the example of a ventilation system. Another chapter shows different solutions regarding external walls dedicated for carbon zero kindergartens in Italy. Then, the influence of the primary energy factor of hydropower plants on the energy performance of buildings is discussed. Finally, legal aspects of air protection, in the context of air pollutants from fuels in Europe are presented.