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HeriTACE, FuturHist and CALECHE bring research and practice together to explore how historic windows can be upgraded while preserving their architectural character.
How can historic windows be improved to meet today's energy performance and comfort requirements without compromising their heritage value?
This question was at the heart of the second webinar in the series “Future-Proofing Historic Buildings for the Clean Energy Transition: Dialogues with FuturHist & HeriTACE”, held on 15 October 2026 in collaboration with the EU projects FuturHist and CALECHE.
The webinar brought together researchers and practitioners to discuss renovation strategies, technical challenges and practical tools for improving the performance of historic windows. The event was followed by an in-person workshop at Cerema in Strasbourg, providing an opportunity to explore specific technical questions and identify priorities for further research.
Historic windows often combine valuable architectural details and traditional craftsmanship with technical challenges related to airtightness, heat loss and indoor comfort. Although replacement may appear to be a straightforward solution, retaining and upgrading existing windows can help preserve original materials and character while supporting the energy renovation of historic buildings.
Alexandra Troi from Eurac Research and Stefan Möller from Holzmanufaktur Rottweil, representing FuturHist, presented sustainable alternatives to full window replacement. Drawing on research and practical experience across four historic window typologies, their contributions explored how renovation approaches can be adapted to different building characteristics and conservation requirements.
HeriTACE researchers Nathan Van Den Bossche from Ghent University and Paul Klõšeiko from Tallinn University of Technology addressed the methods and challenges involved in improving the airtightness of historic windows.
Airtightness is an important consideration when renovating historic buildings, influencing heat losses, draughts and indoor comfort. However, interventions must also account for the characteristics of existing windows and their surrounding building elements.
The presentations explored approaches to optimising window airtightness while retaining valuable heritage components, highlighting the need to combine performance improvements with a careful understanding of existing building systems.
Élodie Héberlé from Cerema, contributing to the CALECHE project, presented decision-support tools, renovation protocols for wooden windows and practical approaches to in-situ airtightness testing.
These methodologies can help professionals assess existing windows, compare potential interventions and make better-informed renovation decisions. Field testing is particularly relevant for understanding how windows perform in their actual building context, complementing laboratory measurements and theoretical calculations.
Following the webinar, an in-person workshop brought together window experts from different professional and research backgrounds. The exchange focused on three technical questions:
The workshop provided a space to share experiences, discuss unresolved questions and identify areas where further research and improved assessment methods could support practitioners.
The webinar and workshop highlighted the importance of combining building physics research, practical craftsmanship and on-site assessment when developing renovation strategies for historic windows.
For HeriTACE, these exchanges contribute to the wider challenge of future-proofing heritage townhouses by improving energy performance and indoor comfort while respecting their architectural and historical value. Collaboration between research projects also helps connect complementary expertise and bring technical knowledge closer to the professionals involved in the renovation of historic buildings.
The full webinar recording is available on HeriTACE YouTube.
Stay tuned for the next webinars in the “Future-Proofing Historic Buildings for the Clean Energy Transition: Dialogues with FuturHist & HeriTACE” series, which will continue bringing together researchers and practitioners to exchange knowledge and explore practical approaches to the sustainable renovation and future-proofing of historic buildings.
The 52nd Breakfast at Sustainability's "Cultural traces and carbon footprints: Aligning Heritage Preservation with Energy Efficiency" will take place online on 24 November 2026, 10:00 to 12:00.
The International Conference on Moisture in Buildings (ICMB27) will take place at Ghent University, Belgium, from 13–17 September 2027. Abstract submissions are open until 30 November 2026.