Robust control of net-zero offices with integrated hybrid supply system and energy storage

Commercial office buildings are a key target for energy reduction measures. One method of reducing commercial buildings' energy consumption is to make them more autonomous – creating more of their own energy, disposing of their own waste, collecting their own water; ultimately being as sustainable as possible (i.e. self-sustaining). A move towards these energy autonomous systems could be accomplished by the use of renewable and co-generation energy sources. However, there are a multitude of these energy sources available, such as combined heat and power (CHP), thermal energy storage and electrical energy storage plants, heat pumps, photovoltaics, etc. Making these systems work together presents a control challenge for their efficient use, especially since they can have a simultaneous effect on both the thermal and electrical energy networks. This paper describes a robust multi-input multioutput (MIMO) controller applicable to any configuration of the aforementioned systems, with the control goal of minimising the electrical grid utilisation of an office building while maintaining the thermal comfort of the occupants. The controller employs the inverse dynamics of the building, mechanical/servicing systems, and energy storage with a robust control methodology. This inverse dynamics provides the controller with knowledge of the complex cause and effect relationships between the system, the controlled inputs, and the external disturbances, while an outer-loop control ensures robust, stable control in the presence of process uncertainty and unknown disturbances. Results indicate that the control strategy is effective in minimising the electrical grid use and maximising the utilisation of the available renewable energy – towards net-zero office buildings – and shows the potential for deployment in future energy-autonomous office buildings.