The design of energy systems in a process plant requires a good understanding of each subsystem (e.g. processes, heat exchanger networks, utility systems) and their interactions in the context of an overall plant. An effective design method should be able to explore the synergy between the subsystems to the maximum extent and allow users to interact with the design process. To achieve this, the effective way is to combine physical insights with mathematical optimisation techniques. Physical insights are used as a wise man’s brain and eyes, while optimisation techniques are employed as a superman’s power in searching for optimal solutions. In the past, concepts and methods have been developed for handling grassroots design, operational management, retrofit and debottlenecking scenarios. This paper describes the recent research progress at UMIST in developing fundamental concepts and methodologies for analysis and optimisation of energy systems.