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Summary Cooling water systems (CWS) are one of the main energy and water using operations in industry. Existing CWS in operation provide high improvement potentials in environmental and economic performance through optimized operation and system control. Industry often fails to realize these potentials, given that the efficiency measures as well as their technical, economic, and ecological impact are mostly unknown because of the lack of appropriate approaches. This article presents a holistic approach to the systematic identification and assessment of efficiency measures that support industry in improving the operation and system control of large‐scale CWS consisting of one or multiple cooling towers, heat exchangers, and pumps. Based on material flow analysis coupled with process modeling, a material and energy flow model of CWS is developed. The model enables the investigation of different adjustments in operation of CWS in order to identify and assess specific efficiency measures. The approach is applied to a CWS of a real manufacturing facility. The results show, first, high validity of the approach as compared to a real system. Second, the effectiveness of the approach, given that the model allows fast and simple identification and assessment of efficiency measures that save up to 16% energy and 24% water in the presented case study.

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The demand for electrical power in industrial production processes often leads to increasing energy costs for companies. In the course of a more sustainable power generation in the future, companies are faced with time-dependent energy prices, which have the potential to influence energy costs significantly. In order to manufacture the products at minimal decision-relevant total costs, planning approaches for production scheduling have to consider energy costs. To date, time-dependent energy prices are only considered in few production planning approaches in the field of job-shop scheduling and in some individual planning approaches in the field of simultaneous lot-sizing and scheduling. Up to now, a general model formulation for the consideration of time-dependent energy prices in lot-sizing and scheduling and an investigation of appropriate conditions for an energy-oriented production planning is missing. In this contribution, the energy-oriented general lot-sizing and scheduling problem is introduced as an extension of the respected general lotsizing and scheduling problem. The cost saving potential is analyzed by considering energy in the lot-sizing and scheduling problem compared to classical planning approaches and appropriate frame conditions are investigated within a structured parameter analysis. In the numerical study, this leads to a total cost saving potential about 1.04% and an energy cost saving potential about 9.69%. In particular, a high volatility of the energy prices and a direct transfer of this volatility in form of short periods of constant energy prices increase this cost saving potential.

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