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Ductwork cleaning – clearing the air

After installation, ductwork cleaning is a vital necessity for fire safety, indoor air quality and hygiene. Gary Nicholls, Managing Director of Swiftclean, tracks the development of ductwork hygiene principles from guidance to specification, and looks forward to a new TR19 Air, currently under review.

Since the publication of TR17 in 1998, the industry has looked to the BESA, or the HVCA as it was then, for guidance on the best approach to regular ventilation ductwork cleaning. TR17 was the result of the pooled expertise and experience of a number of specialist ductwork cleaning providers, Swiftclean among them. For the first time, TR17 set out guidance for the regular cleaning of ductwork for ventilation and kitchen extract systems.

This successful guidance document was followed in 2005 by TR/19, with a revised version being issued in 2013. These documents laid out the importance of cleaning ductwork for both hygiene and safety purposes. In the case of kitchen extract ductwork this was largely for fire safety in addition to hygiene, while in general ventilation ductwork, the concern was more for indoor air quality and the health benefits for occupants.

For the first time, tables indicating the frequency at which ductwork was to be cleaned in accordance with its purpose and usage were introduced. TR/19 also introduced a requirement to classify ductwork systems according to the use of the buildings which it served as high, medium or low, recognising more clearly that clean ductwork is essential for better quality indoor air and the health of those who use the premises.

The importance of clean kitchen extract ductwork was thrown most sharply into focus with the introduction in 2019 of TR19® Grease, the new specification which concentrated solely on the cleaning of kitchen extract systems for fire safety and hygiene purposes. The build-up of grease caused by airborne fat, oil and grease which arises naturally from cooking, represents a severe fire hazard if not controlled adequately. Common perception was that this would need to be a severe build-up, whereas, in reality, anything over an average of 200 microns – a thin film of grease no thicker than half the thickness of an average business card Is the point at which grease extract ductwork systems should be cleaned.

TR19® Grease brought a radical change in status from guidance to specification, bringing with it stricter obligations to comply with the law through the specification. Its introduction, understandably, was swiftly followed by a keen expectation by insurance companies for compliance to be observed and clearly documented, in order to ensure that buildings insurance would not be compromised.

TR19® Grease was created by lifting out section 7 of the previous TR/19 and giving it status as a standalone specification. The remainder, TR19®, was also reissued without section 7 to provide guidance on the cleaning of mechanical ventilation ductwork. As you might expect, TR19® itself is now under review and will eventually be reissued as TR19® Air, likely later in 2022.

Little did we know when TR19® Grease was launched that ventilation and indoor air quality were shortly to become such essential topics. The present pandemic has thrown the importance of clean indoor air sharply into focus. At the start of the Coronavirus crisis, it was not entirely understood how Coronavirus was transmitted. We now know that surface contamination is less indicated in transmitting the virus, which is largely airborne. Indoor air quality is therefore critical, as is clean ductwork and effective ventilation. The revision of TR19® and development of a new TR19® Air is now vitally important.

We have, for example, seen far too many instances of schools trying to provide fresh air by opening doors and windows regularly throughout the winter months, letting out heat and preventing constant ambient temperatures, also essential for effective learning. Doubtless, there will be a push to provide more properties, particularly schools, with new ventilation systems, which will benefit future generations year-round, as well as helping to alleviate the current crisis.

What will be vital is that we design, install and maintain these systems in accordance with TR19® Air principles. TR19® already contains most of this information, but we are constantly refining this on the basis of experience and expertise gained by the industry over many years. What we have all concluded is that the system must be easily accessible to facilitate ongoing cleaning, and therefore a healthy indoor atmosphere.

Like TR19® Grease, TR19® Air will also no doubt recommend using a cleaning provider registered with the BESCA Vent Hygiene Elite (VHE) scheme, using competent technicians trained to BESA recognised levels.