The aim of this WaterWarmth project Work Package 6.1 report is to present a number of relevant frameworks available to analyse and/or assess the governance of current heating systems and future energy system innovation, in particular with a focus on aquathermal energy (AE) systems. At the basis of the report was a broad survey of the academic and other literature by project researchers on ways to conceptualise the greater use of AE energy systems in the European Union. To keep the report succinct, and based on discussions by WaterWarmth project researchers, we have decided to present a combination of theoretical approaches to frame and understand AE system transitions instead of the broad collection of frameworks and theories that exist today. These are the Multi-Level Perspective, Strategic Niche Management, Contextual Interaction Theory, the Governance of Change and Community Energy Systems. The report contributes to the project by providing a strategic way to understand renewable energy transition processes, and more specifically, pathways for how AE systems can play a more significant role in a renewable energy system transition in the North Sea Region and beyond. The result is a heuristic that allows practitioners to discover how AE system developments in particular places can be viewed in a broader energy system transition context, the measures that may be needed to guide the transition process, and to gain a deeper understanding about the motivations, cognitions and resources of the actors involved in the energy transition process. To demonstrate the proposed frameworks, we exemplify using two case studies: AE system development at the household in Sweden, and AE transitions in the Fryslân region, in the Netherlands. For the Swedish case we use the Multi-level Perspective (MLP) framework to provide the background of the niche, landscape level and the socio-technical regime which illustrate the influence of policies and regulations, as well as technologies and markets. For the Netherlands case, we place a stronger emphasis on Contextual Interaction Theory (CIT) framework to analyse how the different actors and their characteristics such as motivations, cognitions and resources influence the interaction process in the planning and implementation of AE systems projects. Using the CIT, we are also able to assess how the specific, structural and wider contexts influence the implementation process as well as how the actors interact with each other. Each case provides a unique structuring, both enablers and hindrances, of the institutional and governance dynamics for AE system innovations in their respective countries. Extending from the exemplary studies, we lastly discuss each of the cases as well as broader insights gained when using the approach, and what it can mean for broader AE system transitions in the European Union. This report is intended for multiple audiences including but not limited to practitioners aiming to develop AE systems, academics interested in assessing governance processes around AE system development, policy-makers interested in policies and decision-making to promote AE system development. @en