Decarbonization roadmap and compliance to Art. 26 of energy efficiency directive for an existing fossil fuelled district heating system

Article 26 of the Energy Efficiency Directive defines the efficiency criteria for district heating and cooling (DHC) systems and it offers operators two compliance paths: increasing shares of renewable sources/waste heat (Option 1) or reducing greenhouse gas (GHG) emissions for heat generation (Option 2). Using an existing 100 % gasfuelled and high-temperature district heating network as a case study, the effects of the two options are evaluated by combining resource screening, energyPRO simulations, and COQ emission accounting for the years 2025 (baseline), 2028, and 2035. For Option 1, the current DH system configuration meets the 2025 target. According to the defined roadmap, the HECHP operation doesn't match the target for 2028 (70 % against the requested 80 %). Compliance is reached again in 2035 by adding a 15 MW high-temperature heat pump to recover heat from wastewater treatment plants. However, with respect to Option 2, all simulated configurations breach the COQ emissions targets, exposing also a mismatch between the two compliance pathways. The study bridges engineering analysis with a policy lens, providing insights for Member State transposition, showing where accounting rules and the "efficient DH" definition could evolve to translate compliance into a concrete contribution to the decarbonization of the thermal sector.