Scaling positive energy districts: Lessons learned from European case studies and pathways to replication

Positive Energy Districts (PEDs) are positioned as an operational instrument to support the EU climate-neutrality agenda and the “100 climate-neutral cities by 2030” mission, yet their implementation remains methodologically heterogeneous and strongly constrained by local physical and infrastructural conditions. This study addresses these limitations by proposing and operationalising an archetype-based urban building energy modelling (UBEM) workflow in the TREEPED decision-support environment, which fuses geographic information system and energy performance records, upscales calibrated archetype results to district totals, closes a boundary-explicit energy balance under a declared accounting rule set and couples it to an annualised life cycle assessment (LCA). Retrofit reduces space-heating demand by 24.1% in Bucharest, 31.2% in Copenhagen and 33.4% in Parma. Only Parma achieves a positive annual electricity balance (+8.78 GWh yr⁻¹), whereas Bucharest and Copenhagen retain deficits of 296.1 and 1.6 GWh yr⁻¹ , respectively. Copenhagen also continues to import biomass-fired district heat, which is treated as a boundary-crossing carrier rather than as locally generated renewable energy. Parma nevertheless remains in monthly deficit for four months, with its self-sufficiency ratio ranging from 21% to 79%, demonstrating that annual positivity does not imply intra-annual self-sufficiency.LCA reveals marked indicator-dependent trade-offs across the three retrofit pathways: Bucharest reduces both life-cycle GWP by 14.1% and CED by 14.6%, Copenhagen lowers CED by 26.4% but increases life-cycle GWP by + 35.8% and Parma reduces use-phase GWP by 79.2% but life-cycle GWP by only 1.24%. Results indicate that PED “positivity” is strongly boundary and context dependent. Operational optimisation alone therefore does not ensure improved life-cycle environmental performance.