The TightVent Airtightness Association Committee (TAAC) had four meetings over the past year, including one in-person meeting in Dublin, held just before the AIVC-TightVent-venticool joint conference in October 2024, and three virtual sessions. The main topics discussed during these meetings included:

• Building airtightness measurements for very airtight buildings: Two complementary presentations addressed appropriate air pressure measurements, delivered by Michael Wehrli (theCH, Switzerland) and pressure build-up duration by Joachim Zeller (Ingenieurbüro Zeller, Germany).
• Impact of air Pressure measurement location: Adeline Mélois (Cerema, France) presented model-scale wind tunnel studies, while Kevin Verniers (Renson NV, Belgium) shared case studies on air pressure differences across building envelopes.
• Revisions and proposals for airtightness standards: This included a proposal for a new regression method and uncertainty calculation for ISO 9972 by Valérie Leprince (Cerema, France), as well as a discussion on the revised German airtightness standard (DIN 4108-7) presented by Oliver Solcher (FLiB, Germany). Additionally, Federico Pedranzini (Politecnico di Milano, Italy) addressed ductwork airtightness measurements.
• New testing facility for air leakage investigation: Markus Diel (DLR, Germany) introduced the ATLAS (Adaptable Testing Laboratory for Air Sealing) for advanced air leakage studies.
• Performance evaluation of humidity-controlled decentralized ventilation systems: Gilles Flamant (CEDEUS, Chile) presented a case study on social housing in Chile
• National updates: Participants shared updates on airtightness and ventilation regulations from their respective countries (Belgium, Czech Republic, France, Germany, Greece, Netherlands, Spain, Switzerland, and the UK) as well as insights from TightVent partners (Build Test Solution, dooApp, Lindab, Retrotec, Acin).

Looking ahead, TAAC members plan to continue their collaboration on airtightness and ventilation topics, further strengthening this international network of experts spanning more than 20 countries.