Structural optimization of an energy supply system from economic viewpoint

An optimal planning method of system structure is proposed to determine kinds, numbers and capacities of equipment for an energy supply system installed in commercial and public buildings from economic viewpoint. In this method, they are determined together with maximum contract demands of utilities such as electricity and natural gas so as to minimize the annual total cost in consideration of system's annual operational strategies corresponding to seasonal and hourly energy demand requirements. A numerical study is carried out for an office building with total floor area of 15000 m(2). Through the study, the following are clarified: (a) the optimal system structure for the office building; (b) the economic effects of the optimal system compared to other typical energy supply systems; (c) the influence on the optimal system structure of the future efficiency improvement and initial capital cost reduction of equipment.