Very few countries have mandatory requirements for ductwork airtightness. In Europe this is the case for Spain and Estonia.

Spain has the strongest requirements, with a maximum ductwork permeability of ATC 4 for all new and retrofitted buildings according to “Reglamento de instalaciones térmicas de los edificios” (RITE) since 2007, with a mandatory justification by test according to UNE-EN 12599:01 to prove compliance. However, the authors mentioned that in practice ductwork is not always tested and there are no sanctions if a ductwork does not comply with the requirements.

In Estonia, the requirements for ventilation systems in buildings require class ATC 4 (class B) or better for the whole system and recommend ducts and components of Class C or better. The requirements for the airtightness class of the ventilation ductwork are usually set by the ventilation designer based on the specific requirements of the building or room. the airtightness test is not always mandatory, and it depends on the customer’s requirements and designer’s requirements in HVAC Project.

More details can be found in the AIVC Technical Note 73 [1].

References

[1] N. Hurel and V. Leprince “AIVC Technical Note 73 – Overview of the trends in building and ductwork airtightness in 16 countries”, AIVC Ventilation Technical Report, Sept 2024, Available: https://www.aivc.org/sites/default/files/TN73.pdf