COLLECTiEF aims to enhance, implement, test and evaluate an interoperable and scalable energy management system based on Collective intelligence (CI) that allows easy and seamless integration of legacy equipment into a collaborative network within and between existing buildings and urban energy systems with reduced installation cost, data transfer and computational power while increasing data security, energy flexibility and climate resilience. This is done through developing software and hardware packages to install and smart up buildings and their legacy equipment on large scale, meanwhile to maintain simple and robust communication with the energy grid. The project includes the following objectives: – Enhancement and adaptation of algorithms for creating a CI-based energy flexible network; – Realization of CI-based cost-effective system components with easy deployment and maintenance; – Demonstration and testing of a CI-based energy network in the real environment; – Testing and implementing a scalable and customizable occupant-centric fusion sensor network for accurate and non-invasive environmental monitoring; – Designing and implementing a smart, user-centric and user friendly digital platform for interacting with users and controlling technical building systems; – New business model for energy services including a clear model for commercialization of COLLECTiEF system. This will be achieved by building on technologies developed in previous EU-funded projects and by expertise from the scientific and commercial partners of this proposal, involving a number of highly innovative SMEs. The provided scalable solutions will integrate seamlessly with existing legacy equipment, and will facilitate demand-side management of multiple buildings, enhancing energy flexibility and resilience in urban areas.