The monograph is devoted to the research of energy sector - from extraction of resources to final energy consumption - applying ecodesign methods for assessment and analysis, as well as defining principles to be taken into consideration in order to make necessary improvements in a system for reduction of environmental impacts. Chapters of the monograph present cases studies on Life Cycle Analysis (LCA) used at products' feasibility study level finding out if relevant resources and energy technologies are competitive, as well as at the products manufacturing levels. The ecodesign principles and tools presented in the studies, for example life cycle analysis, multi criteria analysis, system dynamic modelling, etc., when synchronised, provide better results in achieving the set goals. The research results described in the monograph can be used for national policy development - development of various planning documents, strategies, regulatory acts. The information provided in the monograph is useful for researchers, field specialists, employees of municipalities and companies, students, policy makers, and other interested parties.