Assessing cost-optimal energy performance in EU buildings: Insights from the third calculation round

The building sector plays a crucial role in achieving the European Union's objective of a zero-emission and fully decarbonised building stock by 2050. The Energy Performance of Buildings Directive introduced the cost-optimal methodology as a key instrument for defining cost-effective minimum energy performance requirements for both new and existing buildings. Within this framework, Member States are required to perform cost-optimal calculations every five years to verify and update national regulatory requirements where necessary. This paper provides insights into the most recent national cost-optimal reports submitted in 2023 (third calculation round). The results show the cost-optimal energy performance levels at building level (primary energy demand and global costs) as well as at building element level (cost-optimal U-values). The analysis indicates a positive evolution in the application of the methodology with the cost-optimal primary energy for new building below 100 kWh/(m2y) and for existing buildings below 150 kWh/(m2y) in most cases. The global costs vary widely, but with most values below 1000 EUR/m2 for new buildings and below 800 EUR/irf for existing buildings. Significant variations are observed across macro-climatic zones, particularly for new buildings, due to differences in climatic conditions, calculation approaches, and economic assumptions. Given the current climate and energy challenges, the cost-optimal methodology remains a critical policy instrument for supporting the progressive improvement of building energy performance and advancing the decarbonisation of the European building stock.