Sustainable Heating Implementation of Fossil-Free Technologies (SHIFFT) is an Interreg 2 Seas-funded project focused on the adoption of low-carbon heating in existing residential and community buildings. The specific objective of SHIFFT is to increase the adoption of low-carbon technologies and applications in sectors that have the potential for a high reduction in greenhouse gas emissions. SHIFFT envisages achieving this by accelerating the market adoption of sustainable heating solutions for replacing fossil technologies used for domestic heating. One way to do this is by having six co-creation pilots located in four countries in the 2 Seas region. With the co-creation pilots SHIFFT aims to achieve a reduction of 3,422 tons CO2 emission/year resulted from the installation of sustainable heating systems and behavioural change in heating practices by 4,295 households through co-creation and related measures. In SHIFFT, co-creation refers to a participatory process where citizens, public authorities, and other (local) stakeholders provide input, co-define problems, co-design a solution, a plan or policy to achieve a beneficial outcome for all parties participating, and do this in the domain of sustainable heating. The aim of this report is to identify challenges, barriers, lessons and tips for replication and transfer of successful co-creation to other cities. A three-step approach was used with each co-creation pilot first conducting a stakeholder and situational analysis (February 2020). Second, co-creation action plans were developed (June 2020). These were implemented eventually implemented (July 2020 – December 2022). The process was supported by a co-creation expert team consisting of academic partners. The six co-creation pilots are: Bruges, Mechelen (Belgium), Middelburg (Netherlands), Fourmies, Hauts-de-France (France), and Norwich (United Kingdom). Implementation of the action plans was greatly hindered in the first nineteen months of the project due to the COVID-19 pandemic, which led to lockdowns and other restrictive measures and which made it impossible to implement many real-life (in person) co-creative actions. In the face of the greater difficulty pilot hosts had to resort to less effective online modes of co-creation. After the COVID-19 pandemic restrictions were lifted in the Spring of 2022 implementation of (adapted) action plans could be begun in real-life settings. After the Summer of 2022 implementation processes and the number of actions implemented intensified, more particularly in the pilots Bruges, Middelburg, Fourmies, and Mechelen. In total, over 60 activities were deployed, resulting in about a hundred sub activities. Performance of the co-creation pilots was measured using five key performance indicators. In terms of CO2 emission reduction impact, the co-creation pilots jointly (i.e., on aggregated level) managed first to achieve (and exceed) the goal of 3,422 tons CO2 emission/year. They then reached 224% of this target (i.e. 7,677 tons CO2 emission/year). Four out of six pilots met their individual CO2 emission reduction impact goals. In terms of households engaged, the co-creation pilots jointly (i.e., on aggregated level) managed to exceed the household engagement goal of by engaging 6,769 households. Four out of six pilots achieved their individual household engagement goal. Other performance indicators on which co-creation pilots were monitored pertained to investments made, behavioural change and social networks formation. The pilots did quite well on the latter. Average investments in co-creation pilots were estimated to be about €196,538,293. Challenges encountered in the co-creation pilots pertain to instrumental framing, letting go of traditional (i.e., top-down) ways of working, departmental interests, dependence on local stakeholders, personnel turnover, the COVID-19 pandemic, having to do with challenges and risks potential adopters perceive (like high upfront costs and negative ‘myths’ about sustainable heat options), and lack of (access to) information. 4 In different ways the co-creation pilots contributed to setting the right conditions under which (more advanced) co-creation in sustainable heat can be implemented in the future. This approach entails both co-creative action and being tailored in combination with sustainable heat policy, which is necessary to persuade local stakeholders when implementing co-created plans. The co-creative three-step approach developed in SHIFFT can be considered for use and for scaling in locations outside the initial SHIFFT co-creation pilots. Scaling pertains to replicating certain successful SHIFFT pilots in other cities or even regions, sharing the approach and tools developed (i.e., action plan approach, monitoring approach, CO2 impact tool, expert team support) with expert platforms on heat transitions, or expanding ongoing local practices and projects to adjacent streets or neighbourhoods. Most of the scaling modes mentioned are, in fact, already set in motion. @en