Optimising District Heating Systems: Heat Consumption and Network Modelling for the Integration of Sustainable Solutions

District heating is considered to have a key role in the transition from the current energy systems to the future energy solutions. This will involve developing new District Heating Network (DHN) or the expansion of existing ones, and addressing the challenges posed by integrating decentralized renewable technologies that operate at lower temperature levels. This work introduces a methodology for the initial design of DHNs, leveraging a national Geographic Information System (GIS) database containing building stock information, including thermal properties, and a city road map. A routing algorithm has been developed to geospatially connect buildings with production sites accommodating multiple decentralized heat sources, using the Minimum Spanning Tree (MST) to minimize the total network length. A thermal model of the network analyses heat losses and temperature evolution along the network to optimize pipe sizing. This approach was validated through a case study based on an existing subnetwork in Lausanne. The results demonstrate that proper pipe sizing significantly reduces heat losses, translating into economic benefits by minimizing the value of lost heat that could otherwise be delivered. Moreover, lowering the network’s operating temperature improves compatibility with renewable energy technologies but increases heat losses due to the larger pipe diameters required. Finally, the potential for the expansion of the network was assessed. The methodology is highly versatile, allowing it to be applied to any city with access to geolocated building data and thermal characteristics. It can be employed during the planning and design stages to determine optimal pipe diameters and source temperature requirements.