Austria participates in IEA EBC Annex 94 through AEE INTEC and the Building Construction and Building Conservation group at TU Wien to further develop practical, internationally comparable methods for in-situ assessment of energy performance under real operating conditions. The focus is on determining the Heat Transfer Coefficient (HTC) as a key indicator to reduce the "performance gap" between calculated and achieved heating and cooling performance. The aim is to provide robust measurement, validation and diagnostic approaches that support retrofit planning, quality assurance and evidence-based policy and funding schemes in Austria, while also feeding Austrian expertise into international standardisation.

The Austrian partners contribute across several Annex priorities. Existing HTC estimation and measurement approaches are extended for different building types and climate conditions—explicitly including cooling periods and times outside the traditional heating season. Measurement data, simulation and monitoring are combined to improve the accuracy of HTC determination and to systematically reduce uncertainty. In addition, analysis and diagnostic methods are developed to identify thermal weaknesses and the root causes of performance deviations. This includes scalable data acquisition such as drone-based thermography as well as AI-supported fault classification and screening methods. A further focus is the creation of standardised, quality-assured datasets from real measurements, test facilities and simulations as an open resource for research and application.

Expected outputs include more robust and broadly applicable HTC methods and a consistent framework for verification, validation and uncertainty assessment, improving comparability across approaches and easing transfer into standards and guidelines. For practice, transparent diagnostic and screening workflows will support retrofit decisions, enable prioritisation of measures and make operational quality verifiable—without invasive investigations. Open, curated datasets and documented procedures will provide a solid basis for further innovation, the scaling of measurement campaigns and the derivation of performance indicators. Results will be disseminated to Austrian target groups and fed back into relevant professional communities, teaching and stakeholder processes.

Germany, Austria, France, Belgium, United Kingdom (Lead), Spain, Netherlands, Denmark, Italy

Project leader

DI Franz Hengel
AEE – Institute for sustainable Technologies
Feldgasse 19, 8200 Gleisdorf
E-Mail: f.hengel@aee.at

Project partner

Rene Kurzbauer
TU Wien
Forschungsbereich Hochbau und Gebäudeerhaltung
Karlsplatz 13/210, 1040 Wien
E-Mail: rene.kurzbauer@tuwien.ac.at