Thermal Demand-Side Management to Reduce Peak Flows and Support Supply Temperature Reduction in District Heating Networks: A Case Study in Italy

Lowering supply temperatures in existing district heating networks facilitates the integration of renewable energy sources and waste heat, but the higher mass flow rates required to maintain heat delivery can introduce hydraulic constraints. This study investigates how thermal demand-side management can create hydraulic margin for supply temperature reduction. A mixed-integer linear programming model optimizes substation start-up shifts within ±15 min, while hydraulic simulations and energy balances assess the resulting operating conditions. The methodology is applied to a district heating network in northern Italy serving 146 substations. An optimized schedule for a single cold reference day reduces the network peak mass flow rate by approximately 23% and reduces daily peaks on all additional days assessed without further optimization. The resulting hydraulic margin accommodates higher mass flow rates, indicating an estimated potential to reduce supply temperatures from 120 °C to approximately 105–108 °C while preserving daily thermal-energy delivery. Hydraulic simulations at daily network peaks show that the baseline minimum substation differential pressure is preserved. These results demonstrate the potential of thermal demand-side management in enabling lower-temperature operation and enhancing the sustainability of existing district heating networks.