Abstract The feasibility on a residential energy supply network using multiple cogeneration systems, known as combined heat and powers, is investigated by an optimization approach. The target residential energy supply network is based on a microgrid of residential cogeneration systems without electric power export, and featured by power and heat interchanges among cogeneration systems and hot water supply network where produced hot water is supplied to multiple residence units through networked pipes. First, an optimal operational planning model is developed on the basis of mixed-integer linear programming, where energy loss characteristics of connecting pipes between storage tanks are originally modeled by considering the influence of hot water retention. Second, a hot water demand calculation model considering energy loss from networked pipes is developed to reduce the solution space of the optimization problem. The developed models are then applied to a residential energy supply network for a housing complex composed of multiple 1-kWe gas engine-based cogeneration systems and 20 residence units. The results show that the energy-saving effect of the residential energy supply network is dominated by the power interchange and decreases with an increase in the number of residence units involved in the hot water supply network.