Doctoral Thesis “Decision-making in transition to sustainable energy” has been elaborated by the author Reinis Āboltiņš at the Institute of Energy Systems and Environment of the Riga Technical University. The goal of the Thesis is to create an algorithm of decision-making, which takes into account existing knowledge about barriers and policies that hamper or facilitate development of sustainable energy by focusing on identifying and analysing stages and steps of decision-making throughout policy lifecycle, as well as identifying suitable methods of analysis at each stage and step of making decisions to support decision-making about energy and climate policy, and integrating those in the decision-making process with the purpose of ensuring a policy lifecycle leading to sustainable energy system. The tasks of the Thesis are: 1) Analyse existing pool of knowledge and know-how about decision-making aids and the impact of decision-making on the choice of policies for energy transition. a. Review methods for making decisions about the best suited policy portfolio for developing and maintaining a sustainable energy system; b. Review the use of methods of analysis in several policy areas (renewable energy, energy user’s behaviour, agriculture, climate, energy efficiency) to illustrate the critical role of methods in decision-making about policies; c. Assess the relevance of policies in the interest of reaching climate goals. 2) Analyse policy lifecycle to establish, which elements are essential for decision-making and policy making leading to sustainable energy; 3) Analyse the impact of the sequence of steps required for qualitative decision-making on policy choice and policy lifecycle; 4) Formulate recommendations for an algorithm of decision-making in a policy lifecycle encompassing: a. Identification and description of steps of decision-making within a policy lifecycle; b. Identification and description of elements of decision-making relevant for each step of decision-making. The Thesis includes and introduction, three chapters, conclusions, and a list of bibliography. Introduction outlines the topicality of the subject, goals and research tasks, the hypothesis, scientific innovation and applicability of the Thesis. It also briefly explains the context in which the analysis and conclusions of the Thesis are applied. Chapter 1 (Literature analysis) provides an overview of key notions and concepts and sources of scientific thought on the topic of the Thesis. This covers concepts such as energy transition, sociotechnical transition, technology learning curve, adoption of innovation, RES support logic, barriers to the adoption of renewables and energy efficiency action, energy users’ behaviour, policy and decision making, policy mix, policy implementation and policy review. It also explains elements, processes and aspects of energy transition. Chapter 2 (Methodology) looks at four stages of a policy lifecycle: 1) policy inception, 2) decision making about policies, 3) policy implementation, and 4) policy review. Each stage of a policy lifecycle encompasses two or more steps forming clusters of steps corresponding each stage. Decision making steps in each cluster reflect the needs and actions relevant for the particular stage in a policy lifecycle. Further, four elements key to every step are analysed: 1) task, 2) methods, 3) expected outcome and 4) risks associated with skipping the step. Particular focus is placed on the role and use of methods of analysis facilitating decision making throughout different stages of a policy lifecycle. Chapter 2 follows the stages and steps of decision making. First, the overall logic of a policy lifecycle is explained. Second, decision making steps and clusters of decision-making steps are explained. This is done by exploring tasks, methods of analysis, expected outcomes and risks. Third, the relevance of application of methods of analysis throughout a policy lifecycle is explained in Chapter 3 (Results) by exploring the role of each method reviewed, with a focus on the value added by the use of a method to support decision making. Use of methods of analysis suggested as adequate for the purpose of producing information necessary for qualitative decision making during each step of decision making is repeated several times throughout a policy lifecycle. Therefore, a detailed review of each method follows the overall explanation about the place and role of a method in each decision-making step. Overview of the methods of analysis begins with linear regression and progresses with multicriteria decision analysis methods (Analytical Hierarchy Process and TOPSIS), Hugs, Carrots and Sticks approach, as well as decision tree method, to finalise this chapter with an insight into the Climate Policy Integration approach to analysing interactions of energy and climate policy and evaluating the level of priority of climate policy goals over other policy goals. Chapter 3 (Results) reviews methods and approaches to analysing policymaking relevant to energy and climate policies that lead to climate neutrality through sociotechnical transition with examples represented by case studies, which focus on highlighting the relevance of applying methods of analysis in decision making throughout the policy lifecycle. To support the thread of relevance of decision making throughout policy lifecycle Section 3.6. of Chapter 3 focuses on integrating methods and approaches for analysis into an algorithm for policy analysis, decision-making and policymaking. Finally, Chapter 4 (Conclusions) summarises key findings of the Thesis, focusing on the practical applicability of the generated algorithm in policymaking.