At the time of writing, the European Green Deal is one of the most debated topics in the fields of environmental engineering, energy, and economics. Arguably, academia has been lacking research on a singular, comprehensive, structural, dynamic, yet measurable view on achieving climate neutrality objectives. This is the main aim of the dissertation and a breath of fresh air for the climate neutrality debate. The European Union is committed to becoming climate neutral by 2050. This task is daunting. More than 50% of the technologies that will be needed to meet the climate neutrality targets will be technologies that have not yet been invented. Moreover, never in history has economic growth been unbundled from the increase in energy consumption. However, the fundamental framework for the path towards climate neutrality will allow to use technological and financial resources in a coherent and unparalleled way. Also, long-term fossil fuel price increase will arguably push industry to become energy efficient to remain competitive. The aim of the research is (I) to assess various factors and to improve assessment indicators enabling energy systems and the economies to move towards climate neutrality and (II) to assess the role of bioeconomy in such transition. This is done by examining: the different levels of and interaction between energy consumers, different environmental and energy indicators, different academic methods, and their interconnectedness, and creating new engineering models. The objectives for achieving the target include: the assessment and comparison of greenhouse gas indicators, the assessment of the energy efficiency performance of the Latvian manufacturing industry and the assessment of the overall energy efficiency policy, the analysis of factors and development of models for successful implementation of energy efficiency policy, as well as the assessment of the impact of the bioeconomy towards climate neutrality. The dissertation thesis is designed as a set of publications, consisting of 5 thematically unified scientific publications. They have been published in high-impact academic journals dedicated to the energy topic and indexed in the international database SCOPUS. The promotion work consists of an introduction and five parts. The introductory part includes the novelty of the research, hypothesis, goals and tasks, dissertation structure, and information about academic approbation. The main section provides an insight into the literature, methodology and presents key results, which are also later discussed. In the end, conclusions are presented and avenues for future research in the specific field are discussed.