This article examines the hidden data gaps limiting the success of the Energy Performance of Buildings Directive (EPBD) and presents practical, policy-relevant insights to improve actual building energy performance.
Gülben Çalış - Vice chair in İnşaat Mühendisliği Bölümü and professor at Ege Universitesi, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü | LinkedIn profile
(Note: Opinions in the articles are of the authors only and do not necessarily reflect the opinion of the European Union)
The effective implementation of the EPBD is significantly constrained by persistent and systemic data deficiencies within the building sector. A fundamental limitation arises from the lack of comprehensive, high-resolution building stock data, including reliable information on construction age, envelope characteristics, thermal properties, installed technical systems, and renovation history. Existing datasets across Member States are often fragmented, outdated, and methodologically inconsistent, which restricts their usability for robust policy design, compliance monitoring, and performance benchmarking. A critical structural weakness also stems from the disconnect between calculated and operational energy performance. While Energy Performance Certificates (EPCs) are largely based on standardised, asset-based methodologies, actual energy consumption data from smart meters, building management systems, and Internet of Things (IoT)-enabled devices are rarely integrated into national EPBD frameworks. This disconnect generates a persistent performance gap, under which regulatory compliance fails to reflect actual in-use energy performance. Moreover, the absence of interoperable digital infrastructures, particularly the weak integration between Building Information Modelling (BIM) platforms, digital building logbooks (DBLs), cadastral databases, and EPC registries, further constrains data usability. The lack of harmonised taxonomies, standardised data formats, and shared metadata protocols severely limits cross-sectoral data exchange and large-scale analytics.
This article addresses this gap by analysing the existing data-related barriers to full EPBD implementation and developing recommendations to strengthen data availability, interoperability, governance, and usability. By examining current data practices, the analysis provides policy-relevant insights to support more robust monitoring, enforcement, and long-term planning for building energy performance improvements.
The EPBD relies fundamentally on data quality, accessibility, and interoperability to inform policy design, compliance monitoring, and evaluation of legislative impact. Without robust data infrastructures, the directive objectives, such as improving building performance, phasing out inefficient stock, and meeting 2050 climate goals, cannot be reliably tracked or enforced. The revised EPBD explicitly recognises the need for national interoperable databases that aggregate data from multiple sources, including EPCs, Smart Readiness Indicators (SRI), and measured energy consumption. Member States are now required to develop such systems, which are interoperable with other digital building information repositories [1].
However, the persistence of fragmented and inconsistent data ecosystems continues to undermine these intentions. Building energy data currently resides in silos, including EPC registries, cadastral systems, utility records, and independent building surveys, which do not readily communicate with one another. This impedes the ability to derive consistent building performance indicators across jurisdictions. Furthermore, many Member States still lack sufficiently comprehensive or interoperable national building databases, which further limits the usability of building performance information at the EU level.
Detailed building stock characterisation is a known limitation in the current implementation of the EPBD. Many EPC datasets provide limited information on construction age, envelope characteristics, technical systems, and renovation history. The lack of high-resolution and validated data diminishes the reliability of aggregated stock assessments and undermines confidence in performance analytics. A key challenge is the reliance on assumptions and default values rather than verified data from building owners or technical assessments [2].
Studies investigating the quality of EPC data illustrate how these certificates often fail to capture critical physical attributes and renovation details, partly due to methodological inconsistencies and limited validation controls. Where EPCs are used for large-scale analysis, misalignments and missing values can generate misleading performance benchmarks. Research further shows that data completeness and accuracy vary significantly across EU Member States, limiting the feasibility of cross-regional comparative studies [3].
The integration of technical building systems (e.g., HVAC, renewables, control systems) into national datasets is also currently limited. A recent EU project review confirmed that in many Member States, EPC issuance does not systematically link to BIM documentation or digital logbooks, restricting opportunities for enriched data reuse.
Despite EU-level ambitions for standardisation, Member States still adopt highly divergent data collection methodologies, classification approaches, and EPC calculation procedures. Differences in climate zoning, reference building modelling, and primary energy factors further challenge the comparability of performance metrics. The European Parliament’s EPBD implementation report acknowledges that this lack of harmonisation weakens collective progress evaluation and impedes coordinated policy responses [4].
The heterogeneity of EPC schemas is evident in national registries: some regions require more than 100 data elements in their EPC templates, while others use simplified or regionally varied XML formats, inhibiting interoperability and comprehensive analytics [5].
These inconsistencies not only complicate EU-wide benchmarking but also impact market actors. For example, investors and financial institutions face challenges in evaluating energy risks or opportunities across different markets because of incompatible data structures and reporting practices. Analyses of reporting challenges indicate ongoing discussions about harmonising reporting templates across jurisdictions to facilitate comparability and investment readiness.
A persistent and well-documented challenge for building energy policy is the discrepancy between calculated energy performance and measured performance in operation, often termed the performance gap. Conventional energy performance assessments embedded in EPCs are typically based on static, asset-based methodologies that assume standard usage patterns and ideal conditions. However, actual energy use is affected by occupant behaviour, system commissioning, maintenance practices, and environmental conditions.
Recent research emphasises that quasi-steady state modelling methods, commonly used for EPC calculations, often fail to represent real-world dynamics, particularly in the case of cooling demand in warm climates, where discrepancies between simulated and measured data can exceed 40–50% [6].
Furthermore, studies exploring the SRI highlight discrepancies between traditional EPC ratings and dynamic digital performance indicators, showing how buildings with similar static energy ratings can perform differently when integrated with smart technologies that affect energy management and responsiveness [7].
Despite the proliferation of smart meters, building management systems, and IoT sensors, measured energy consumption data are rarely incorporated into national EPBD compliance frameworks. Integration barriers include data privacy concerns, lack of standardised protocols for data exchange, and the absence of legal mandates for operational data reporting in EPC templates. Digitalisation advocates argue that incorporating measured metrics into EPCs and national databases could significantly enhance their credibility and usability.
Advancing the EPBD’s effectiveness necessitates integrated digital infrastructures that support data exchange across BIM models, EPC registries, cadastral systems, and digital building logbooks. However, the current digital landscape remains fragmented, with limited semantic alignment between systems.
Research into openBIM integration highlights the potential of Industry Foundation Classes (IFCs) and structured energy data formats (e.g., XML-based EPC schemas) to enable richer digital representations of buildings. Such integrations facilitate lifecycle data continuity and operational analytics, but they require methodological mapping and harmonisation across domains [5].
The concept of a DBL, as envisioned in the EPBD recast, would serve as a unified repository for energy performance data, renovation history, and smart readiness information. Yet, most national databases lack connectivity or architectural foundations to support seamless DBL implementation. Proposed data models for DBLs underscore the need for semantic alignment, shared taxonomies, and interoperable data structures to maximise analytic value [8].
Academic analyses collectively highlight broader semantic interoperability challenges in building energy management systems, where divergent device data formats and system representations restrict scalable analytics and cross-platform integration.
In addition to technical barriers, institutional and governance issues affect the availability and usability of building energy data. Responsibilities for data stewardship are often fragmented among municipal authorities, national statistical bodies, energy utilities, and private stakeholders. The result is inconsistent data governance frameworks, unclear data ownership rights, and limited incentives for data sharing.
For example, efforts to make EPC and building energy data publicly accessible through georeferenced platforms encountered legal and technical barriers related to privacy, data protection regimes, and varying interpretations of GDPR requirements. These challenges demonstrate the fragility of data sharing even where technological solutions exist [2].
Institutional capacity disparities affect the ability of local authorities to maintain high-quality databases or deploy digital integration solutions, further amplifying regional inequities in the implementation of the EPBD.
The data limitations outlined above have direct consequences for the EPBD monitoring, enforcement, and long-term strategy development. Without reliable and interoperable datasets, enforcement authorities cannot effectively identify non-compliance or prioritise inspection resources. Consequently, some buildings may achieve regulatory thresholds on paper while performing poorly in practice, diluting policy effectiveness.
Long-term renovation planning, central to achieving climate neutrality by 2050, also suffers when underlying data are weak or outdated. Effective renovation trajectories require high-resolution insights into building conditions, retrofit histories, and real-world performance trends, which current datasets rarely provide.
Furthermore, the lack of integrated data limits policy synergies across areas such as urban planning, energy poverty mitigation, and green finance. For example, combining building energy data with socio-economic and occupancy data could enable more targeted social interventions, but the absence of interoperable datasets prevents such holistic planning.
Overcoming the identified data barriers requires coordinated action across technical, institutional, and regulatory domains:
The effective implementation of the EPBD hinges on overcoming persistent data-related limitations. Building stock data deficiencies, fragmented data landscapes, the performance gap between theoretical and actual energy use, and constrained digital interoperability collectively hinder the directive’s potential. However, policy reforms under the EPBD recast, combined with targeted technical and governance measures, offer a viable pathway to overcoming these barriers. Strengthening data availability, interoperability, and governance will not only support more robust EPBD monitoring and enforcement but also enable evidence-driven investment decisions and equitable, long-term renovation planning across the European building sector.
[1] European Parliament. (2023). Report on the proposal for a directive of the European Parliament and of the Council on the energy performance of buildings (recast) (Committee on Industry, Research and Energy). https://www.europarl.europa.eu/doceo/document/A-9-2023-0033_EN.html
[2] Geissler, S., Charalambides, A. G., & Hanratty, M. P. (2019). Public access to building-related energy data for better decision making in implementing energy efficiency strategies: Legal barriers and technical challenges. Energies. https://doi.org/10.3390/en12071215
[3] Piro, M., Mauthe Degerfeld, F. B., Ballarini, I., & Corrado, V. (2024). The challenges for a holistic, flexible and through-life updated energy performance certificate. Sustainable Energy Technologies and Assessments, 69, 103922. https://doi.org/10.1016/j.seta.2024.103922
[4] European Parliament. (2021). Report on the implementation of the Energy Performance of Buildings Directive (Committee on Industry, Research and Energy). https://www.europarl.europa.eu/doceo/document/A-9-2021-0321_EN.html
[5] Ugliotti, F. M., & Stradiotto, E. (2025). Integrating EPC data into openBIM workflows: A methodological approach for the digital building logbook. Sustainability, 17(13), 6005. https://doi.org/10.3390/su17136005
[6] Aste, N., Huerto-Cardenas, H. E., Pero, C. D., Leonforte, F., Buzzetti, M., Adhikari, R. S., Montevecchio, E., & Blavier, C. L. S. (2025). Energy efficiency in buildings: The gap between energy certification methods and real performances. Energies, 18(22), 6015. https://doi.org/10.3390/en18226015
[7] Calotă, R., Bode, F., Souliotis, M., Croitoru, C., & Fokaides, P. A. (2024). Bridging the gap: Discrepancies in energy efficiency and smart readiness of buildings. Energy Reports, 12, 5886–5898. https://doi.org/10.1016/j.egyr.2024.11.060
[8] Gómez-Gil, M., Karami, S., de Almeida, J.-P., Cardoso, A., Espinosa-Fernández, A., & López-Mesa, B. (2024). Envisaging a European digital building renovation logbook: Proposal of a data model. Applied Sciences, 14(19), 8903. https://doi.org/10.3390/app14198903
