Low temperature district networks (LTNs) are a solution to provide simultaneous heat and cooling to multiple buildings for areas, districts and regions. Since the operating temperature is generally below 30°C, the amount of heat supply from renewables and waste heat can be increased. In addition, long term thermal storage such as borehole fields is often used to balance seasonal variation in heat demand and supply throughout the year. LTNs which include new grid topologies and components need to be evaluated in order to enable their further development and application.
The objective of this project is to evaluate, using a multi-energy network optimisation model, the energy performance of a recently constructed renewable district energy system (RDES), including a LTN. The RDES connects multi-usage building to a borehole field which can be regenerated with heat supply from hybrid solar panels and waste heat (free-cooling) from building. Buildings have bi-directional heat exchange with the LTN. Monitoring data of heat and cooling demands were used as an input into the optimisation models and results were compared with monitoring data of electricity demand for the building technologies to validate the models. Following validation, new scenarios with electric storage (batteries) and additional heat storage were evaluated. Results from the optimisation provided insights on how the district electricity self-sufficiency could be improved through installation of batteries or a more effective usage of existing heat storage.