This report, produced by ENEA as part of the EPBD.wise project, offers practical guidance for policymakers and technical experts tasked with developing national ZEB definitions. It sets out a clear calculation framework covering energy demand, renewable energy supply, and operational carbon emissions, and examines how the ZEB concept relates to existing tools including energy performance certificates, renovation passports, and minimum energy performance standards.

The report pays particular attention to the differing challenges of new and existing buildings, the role of building energy flexibility, and the importance of well-defined energy boundaries. It also addresses the specific context of focus countries Bulgaria, Hungary, and Ukraine, where implementation pathways require tailored consideration.

Key topics covered include:

• Primary energy and operational CO₂ emission indicators and thresholds
• On-site, nearby, and distant renewable energy production
• Integration with national building renovation plans and EPC frameworks
• Energy flexibility on both the supply and demand side