Sustainability in industrial energy systems has to be increased to achieve climate goals. However, the share of batch processes in industry and changes of the product portfolio have increased. This makes it more difficult to establish sustainable and yet flexible energy supply systems. Current optimization methods for the synthesis of process heat supply systems do not consider all essential aspects. In this paper, optimization of internal heat recovery with heat exchanger networks and storage integration are carried out simultaneously considering operational constraints of the existing supply infrastructure. Furthermore, within this approach storage units can be considered for both heat recovery and load shifting of steam generator units. Necessary interfaces for coupling of operational constraints and design optimization were identified and the complexity of the combined problem was reduced by simplifications. The combined approach was compared to sequential implementation and proved to yield both economical improvements and more sustainable energy use. (C) 2019 Elsevier Ltd. All rights reserved.