How do you design for ductwork airtightness?
Leakage in ventilation duct systems is important to keep to a minimum in order to save energy and keep the designed performance for a good indoor air quality. The tightness can be built by quality products and a professional installation or be sealed off afterwards by a sealant which is transformed into a gaseous state using heated compressed air. The aerosolized particles then seal the whole leakage of the ventilation system.
To design ventilation duct fittings in the proper way it is important to have the right shape on each product both after production but also during transport and handling. Each product has to have purpose designed seals, all seals like tape or mastic made on the installation site are extremely hard to achieve in a professional manner.
The ducts and duct fittings like bends, connectors or transformations are normally not so difficult to achieve and there are some certification programs that guarantee that the system is the promised quality. Technical components like dampers, silencers, filter boxes are normally a bit more difficult and are sometimes produced by a company only focusing on this specific component where no certification program is available. In 2010 the standard EN 15727 Duct and ductwork components, leakage classification and testing was developed to help the ventilation business focus on airtightness for the whole system even if the components are produced by different suppliers.
The installation will be focused on in the standard EN 12599 handing over and the design and calculation will be addressed in EN 16798-3 performance requirements of ventilation.
At the installation phase it is important to follow the supplier installation instructions and use the proper recommended sealings, screws and clamps the right way. To test air tightness during the installation before the system is built in or insulated is also wise to be able to fix any possible problem. To have the installer himself test the system during the work will be very educational and will lead to professional, fast and insightful staff.