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. 

Eurovent Certita Certification have a certification programme for rigid and semi-rigid ventilation ductwork systems divided into the following sub-programmes:

• Rigid metallic ductwork systems with circular cross-section (DUCT-MC);
• Rigid metallic ductwork systems with rectangular cross-section (DUCT-MR);
• Semi-rigid non-metallic ductwork systems predominantly made of plastics (DUCT-P);

Each sub-programme applies to ductwork systems fitted with integrated sealing solution as described in the Technical Certification Rules ECP-19.

This programme contains amongst other, airtightness and static gauge pressure limit criteria and is based on European standards.

The certification process is to periodically check the resilience of the company quality system by auditing manufacturing sites and the certified performances of a ventilation system by a third-party laboratory measurement.

The certification brings the supplier products, its technical documentation and quality resilience to a reliable level.

The DUCT program does not cover other types of ventilation ductwork elements like flexible ducts, double-wall ductwork or ductwork made of insulation ductboards.

The Swedish type approval for metallic ducts has been a very important driver for the ventilation business. The requirement based vision has driven the ventilation business since the beginning of the 1970’s  to sustainable solutions with demands on airtightness and strength without a demand for sheet steel thickness. This has led to airtight energy efficient  duct work solutions with as little material as possible.

The Swedish Type approval issued by governmental Boverket is only valid in Sweden but has been widely used in other countries as well. There are two Swedish bodies accredited by SWEDAC to issue type approvals, RISE and Kiwa.

Finland has developed their own approval based on the Swedish type approval and is handled by the Finnish Ministry of Environment, and Eurofins Expert Service Oy is authorized by the Finnish Ministry of Environment to issue type Approvals for building products.

Air infiltration adds to the quantity of air entering the building but may also distort the intended ventilation air flow pattern to the detriment of overall indoor air quality and comfort. The consequences are inferior performance, excessive energy consumption, and inability to provide adequate heating (or cooling) [1].

Because air infiltration is uncontrolled, poor envelope airtightness may affect:

• Indoor air quality: Some rooms may be largely under-ventilated while other are over-ventilated as a consequence of distorted air flow patterns. Also the air circulating in the wall may bring inside pollutants from outside and from building product emissions.
• Energy use: Air leakage may inadequately increase the total ventilation airflow rate; or it may decrease the relative impact of heat recovery (in case of systems with heat recovery devices, the unit will only recover heat on the airflow passing through it).
• Moisture performance: air leaking through the envelope from a warm, humid environment to a cold environment, may cause condensation damage as it flows along materials with a temperature below its dew point. In cold climates condensation damage may occur in materials at the outside of the thermal insulation when air exfiltrates, while in warm climates damage may occur at the inside of the insulation when air infiltrates.
• Acoustic performance: airborne sound may propagate through leakages. It is found that sound transmission loss can be degraded by up to 15 dB under field conditions, mainly because of sound leaks.

References

[1] Liddament M.W., 1996. A Guide to Energy Efficient Ventilation. AIVC, 1996.

TAAC  is the TightVent Airtightness Associations Committee, launched in September 2012 by the TightVent Europe platform, with the primary goal to bring together national associations and experts in order to promote reliable testing/inspection and reporting procedures.

The scope of TAAC includes various aspects such as: building & ductwork airtightness requirements in the countries involved; competent tester schemes in the countries involved; applicable standards and guidelines for testing; inspection of ventilation systems; collection of relevant guidance and training documents; share of knowledge and experience; and information on ongoing research work in the field of building and ductwork airtightness.

At present the participants are from Belgium, Czech Republic, Estonia, France, Germany, Hungary, Ireland, Latvia, Netherlands, Poland, Portugal, Spain, Sweden, Switzerland, UK and the US.

In case you are interested to join this initiative, please write an email to: info@tightvent.eu.

Links:

For more information please see:

• About TAAC: https://tightvent.eu/taac
• TAAC participants: https://tightvent.eu/taac/taac-participants
• TAAC deliverables (publications, webinars etc.): https://tightvent.eu/taac/deliverables
• Becoming a Tightvent partner (for companies): https://tightvent.eu/contact
• Becoming a TAAC member: https://tightvent.eu/taac/contact-join