On the influence of decommissioning an area thermal substation in a district heating system on heat consumption and costs in buildings – Long term field research

•The decentralization of the district heating system increases its energy efficiency.•Proper regulation in thermal stations has an impact on reducing heat consumption.•The costs of preparing domestic hot water depend on the type of the thermal station. Modernization of the existing district heating systems is a necessary activity to improve their energy efficiency in the field of generation, distribution and use of the heat. This paper presents the results of several years of field research carried out for 13 multi-family buildings supplied from the district heating network. The benefits associated with the decommissioning of a bifunctional area substation and the use of compact heat exchanger thermal stations with weather automation in each analyzed building were demonstrated. The use of a weather controller in the area substation contributed to a reduction in the corrected heat consumption in a heating system by 23.6% the following year. As a result of the reconstruction of the area substation into individual stations in the buildings, the actual heat consumption for domestic hot water demand decreased by an average of 29% over 10 years, and the annual unit heat consumption for this purpose decreased by an average of 0.13 GJm−3. Considering the influence of the district heating system modernization on the corrected annual heat consumption for space heating, a reduction of heat consumption by 17.8% in the building B4, 20.4% in the building B7 and 23% in the building B13 was obtained.