Social learning is an important element of the reflexive governance approaches needed to enable sustainability transitions. One such approach is participatory backcasting (PB), which involves development of a desirable future vision and a pathway towards this vision. Social learning has been reported as an outcome of different PB projects, including those performed in the infrastructure sector. This study examined the importance of sharing and transferring knowledge and new perceptions developed during PB projects among the individuals directly involved in these projects to and within their formal and informal groups and organisations (e.g. local authorities, DH companies, equipment producers, consumer associations). Mechanisms that need to be incorporated into PB processes to support knowledge sharing/transfer were identified as: (1) use of actor role profiles to identify individuals with bridging/connecting/change agent capability for inclusion in a PB process; (2) strong participant engagement in co-creation activities during the PB project; and (3) PB process design to achieve the multiplier effect (e.g. capacity-building workshops for local researchers and authorities). These mechanisms were successfully tested using the case of two PB-based projects seeking sustainability in the heating sector of the Ukrainian city Bila Tserkva and the Serbian city Niš. It was concluded that further investigation of mechanisms for knowledge sharing/transfer and experimentation within PB processes is a promising research area for enabling sustainability transitions in the heating sector.