The transition to sustainable heating systems (e.g. district heating systems, heat pumps, solar thermal systems, in combination with thermal insulation) is an essential element of an effective response to climate change. But it requires more than technological innovation alone. It entails a system-wide transition that covers both technical and social components, and addresses the supply, distribution, and demand sides of local energy systems. However, residents and home/building owners are generally considered hard to reach and persuade to make investments, and to let go of currently unsustainable heating systems and adopt those that are more sustainable. This matter is challenging for a myriad of reasons and cost is but one of them. Despite the urgency to lower carbon emissions there is currently a limited market demand for sustainable heating solutions, particularly among building/homeowners in (existing) dense urban areas. Given the urgency of climate change and pressing socioeconomic issues there is a need to develop, implement and test incentives that target home/building owners to make investments. One promising solution is co-creation with citizens and local stakeholders. This report clarifies the different meanings for key terms used in co-creation by taking stock of the growing vocabulary used in different approaches to public participation: by defining and comparing different terms and how they have been used. The report describes the challenges, as well as the benefits, of co-creation as well as the importance of managing expectations, power relationships, and sharing responsibility. The report outlines some of the different methods that can be used in co-creation including workshops, storytelling, online tools and participatory value evaluation which provide opportunities for exploring the abilities and capabilities of those involved and help decide who is responsible for making decisions. The report also describes how co-creation can be assessed, monitored, and evaluated. Organising and managing co-creation are commitments that require thorough preparation, time, and inclusion. In-depth assessments support stakeholders and citizens in making informed decisions about the time, energy, and resource investments necessary for co-creation. Further exploring the process of co-creation, the report details how embedding co-creation in ongoing planning and formal decision-making processes is ideal for enhancing impact and can help reduce disruption and cost where, for example, new infrastructure might be installed as part of broader neighbourhood developments rather than as a standalone project. An increased awareness of complex and sensitive issues needs to be balanced against the flexibility and practicality of the process and keeping co-creation running closely alongside decision-making helps reduce the potential for conflict.@en