The IEQ 2025 conference, co-organised by ASHRAE and AIVC in Montreal, Canada, on 24-26 September, was also the 45th AIVC, 13^th Tightvent and 11^th venticool conference. The conference gathered experts worldwide to exchange the latest research, advances and practices on ventilation, indoor environmental quality, resilience and more. For the TightVent community, a key part of the programme was the dedicated focus on building airtightness, addressed in four sessions and workshops.

Below is an overview of the airtightness-focused sessions:

1. Workshop: Durability of the Building Airtightness [Chairs: Valerie Leprince, PhD, Cerema, Lyon, France and Andres Litvak, PhD, Cerema, Bordeaux, France]
2. Airtightness Applications, Repeatability, and Lessons Learned [Chair: Cara Helen Lozinsky, P.Eng., Carleton University, Ottawa, ON, Canada]
3. Tools for Envelope Leak Detection and Evaluation [Chair: Marianne Touchie, PhD, University of Toronto, Toronto, ON, Canada]
4. Airtightness of Building Components [Chair: Marco Simonetti, Department of Energy (DENERG), Italy]

The sessions on airtightness in Montreal highlighted the growing importance of accurate measurement, innovative solutions, and long-term durability in delivering energy-efficient and healthy buildings.

For full details on the presentations and abstracts, please refer to the compiled document with session information.