A general model framework is developed which describes regional and municipal energy systems in terms of data-flow networks. It provides a highly flexible tool for dynamic and stochastic minimization of primary energy demand, emissions of pollutants, and monetary cost. Included are conventional energy-supply techniques, rational use of energy via heat-exchanger networks, heat pumps and cogeneration, demand-side measures such as insulation of dwellings, and utilization of renewable energy sources.