EINSTEIN addresses the scientific and technical challenges related to the optimization of energy efficiency in existing buildings. This is achieved through the development of a new innovative modular simulation-based building control system. This has the ability to: (i) exploit real-time holistic building simulation (integrated with diverse building systems), (ii) directly enable automated control actions of a building and its surroundings (adaptively) and (iii) provide considerable energy savings to the building (by an optimized algorithm). EINSTEIN will formulate and integrate a number of new control strategies to be used with the simulation-based building control system to provide the building manager with the optimum energy efficiency solutions for their building and its use by its occupants. It will not only eradicate errors between ‘as-built’ and ‘as-designed’ conditions but also include predictive analysis with respect to how the building will perform, taking into account future weather predictions and occupant use. The control strategies will be tested and validated on a number of existing buildings.