The engineering and deployment of off-the-grid energy production systems for buildings addressing the renewable energy technologies (e.g. wind, solar, fuel cell) and integration of these systems to the city level grid applications with the ICT-based sub-systems becomes a necessity. The role of integration concepts, performance monitoring and analysis methodologies and sophisticated control strategies through the seamless integration of people, ICT devices and computational resources gain significant importance for reducing the energy consumption and the operational costs. This paper addresses an energy plus building concept that operates on energy-efficient basis while capturing retrofit opportunities that scale from a single building to multiple buildings at cities level. The proposed concept is developed based on two research areas; (1) Building energy supply-side (microgrid) management and (2) Building energy demand-side management complementing with the integrated energy production from off-the-grid renewable energy sources, building energy diagnostics and predictive control, ubiquitous wireless sensing technologies, and microgrid power electronics and power control to exploit the potential for reduction of building energy consumption, thus addressing the deficit of insufficient tool support. The research findings will be demonstrated in an appropriately selected research building in Hannover, Germany integrating different energy efficient production/consumption systems addressing the renewable energy technologies coupled with energy storage systems and building energy management systems comprising scalable and robust sensing network platforms, energy performance monitoring and data warehouse technologies.