The aim of the oPEN Lab is to identify replicable, commercially viable solution packages enabling the achievement of positive energy neighbourhoods within existing urban contexts that are seamlessly integrated into the local energy system as an active micro-energy hub, and to test these technologies and package as an integrated solution at neighbourhood scale. Three open innovation living labs in the cities of Genk (BE), Pamplona (ES) and Tartu (EE) will test combinations of different close-to-market ready technologies and services and study their performance as a unique operating system. Focus is on demonstrating innovations in an integrated approach combining sustainable design tailored to the local context, seamless industrial renovation workflows, renewable energy generation combined with energy storage systems, urban service facilities and smart operation, life cycle thinking and circularity, and this across the whole value chain, targeting the whole life cycle of the building and its neighbourhood, in view of scaling up and wide replication. A user driven and participatory approach with the neighbourhood?s community will be rolled out for a holistic and positive energy vision for the neighbourhood, going beyond citizen awareness raising activities. oPEN Lab is a unique collaboration aligned with the Open Innovation quadruple helix model where a) industry (SMEs, large companies, start-ups and scale-ups in both construction and energy value chains), b) government (local public administration), c) academia/RTOs and d) civil participants (end users, NGOs) work together to co-create and drive structural changes that will result in high TRL levels, with great focus on exploitation of results and wide replication.