CAMPUS 21 focuses on the energy-efficient operation of public buildings and spaces. It brings together the expertise of national research centres from Germany (Telecommunications), Ireland (IT in AEC, Artificial Intelligence), Austria (Building Physics), and Spain (Information Technology); the management experience of Public Authorities and bundles this with the process expertise from multiple industry sectors, such as Construction & Facilities Management, Building Services Systems Manufacturers and Energy Providers.CAMPUS 21 develops, deploys, and tests a Hardware-Software-Platform for the integration of existing ICT-subsystems supporting energy, building, and security systems management. The key technological innovations of CAMPUS 21 are (i) integration concepts for energy management systems (WP3) including the related middleware components (WP4), (ii) methodologies for intelligent, optimised control of building services systems (WP5), and finally (iii) algorithms and tools to support load-balancing between renewable micro-generation, storage systems, and energy consuming devices in buildings and public spaces (WP6).This is complemented by the development of key business elements, including: (iv) new business models for integrated energy management and the underpinning novel procurements schemes (WP1) and (v) the development of Performance Metrics and a holistic Evaluation Concept for Systems Integration (WP2).CAMPUS 21 uses existing demonstrators and living laboratories as a nucleus for up-scaling and expanding the project scope from single building to campus scale. Three sites are used for research and validation of energy and cost savings, a university campus, a multi-purpose sports arena and an indoor sports complex.Due to its cross-sectoral membership, CAMPUS 21 goes across the whole innovation chain. It contributes with ground-breaking innovation to the establishment of world-class infrastructures and the economic recovery plan of the European Union.