Demand side digitalisation: A methodology using heat cost allocators and energy meters to secure low-temperature operations in existing buildings connected to district heating networks

With regard to the green transition toward 4th generation district heating (4GDH), a critical element is ensuring low operating temperatures in networks. This can help leverage the technical and economic potential of connecting renewable energy sources and recovering excess local heat. Poorly controlled and operated heating systems in existing building stocks limit the possibility of lowering the operating temperatures of district heating networks. Hence, digitalising the demand side can afford new opportunities for building services by monitoring heating systems and improving operations to secure the expected comfort in existing buildings with lower temperatures. Accordingly, this study investigated the innovative use and integration of data from heat cost allocators, district heating energy meters, and temperature sensors to improve space heating system operations. Based on the measurements, the methodology focused on identifying the critical flat in the building with the highest heat demand and calculating the minimum possible operating temperature. Five Danish multi-family buildings were considered as case studies in the investigations, highlighting good agreement between the new weather-compensated control curve and the measurements. Almost 75% of the total space heating consumption was distributed under outdoor temperatures exceeding 0 °C in 2021, whereas only 0.5% was associated with the lowest outdoor temperature of −9 °C. This clearly suggests that design conditions rarely occur during the typical operation of systems and that the radiators are oversized and suitable for operation at low temperatures for most of the heating season. Notably, it was documented that supply temperatures of 48–53 °C were sufficient to secure the expected comfort at an outdoor temperature of 0 °C, without any extensive energy renovation in the buildings.