Comment on EU Cleanliness of Ventilation Systems Draft Standard

18 July 2008

Draft European Standard prEN 15780: ‘Ventilation for buildings – Ductwork – Cleanliness of ventilation systems’ is out for public comment.

Draft European Standard prEN 15780: ‘Ventilation for buildings – Ductwork – Cleanliness of ventilation systems’ is out for public comment. This standard has the potential to help ensure clean, safe air conditioning and ventilation systems throughout the European Union. The European Committee for Standardisation (CEN) has made this standard one which can be reviewed and commented on by anyone who wishes to, not just by the specialists from industry, government and academia who normally populate the committees.

Duct cleaners and those involved in indoor air quality and ventilation system hygiene should go to their national standards organisation to download the standard and the comment forms. A list of the national organisations which feed into the CEN is available here http://www.cen.eu/cenorm/members/national+members/index.asp.

The document has been released in the English language and can also be downloaded from here http://www.triventek-ductcleaning.com/files/TRIpdf110720081805131.pdf. The most important factor is that measurable levels of cleanliness, and of dirtiness, are defined. This provides the clarity which the industry and building owners and operators need. They want to answer the questions: ‘What is dirty?’ and ‘What is clean?’.

There is much discussion of the reliability of various testing and sampling methods, and in the end the vacuum/brush method is selected. This is based on work done at the Technical University of Berlin by Birgit Müller et al. which made comparisons between the wide variety of possible techniques. This work can be reviewed here http://www.triventek-ductcleaning.com/files/TRIpdf180720081327391.pdf.

It makes interesting reading and highlights how important it is to understand which sampling method is being used since gravimetric sampling results can vary 20-fold from one method of sample collection to another. It is worth noting here that more ‘efficient’ sample recovery, i.e. a collection method that pulls more dirt off the duct surface is not necessarily a better method. What users require of the any standard is that the results should agree with a reasonable and prudent ‘common sense’ appreciation of cleanliness and dirtiness.

Moreover it is very important that measurement methods be repeatable, i.e. that a duct surface condition that looks similar to most people, produces similar measurement results. The surveyor needs to be wary of methods where e.g. the pressure exerted when wiping can be variable and difficult to define in the field.

There are some problems with the pre-standard, principally:  The vacuum/brush sampling method is not defined  There is confusion between new build and maintenance scenarios  Some of the trigger levels, i.e. levels at which cleaning is recommended, seem to be too harsh and some of the post-clean verification levels seem too lax (based on the relationship between the vacuum/brush method and the more familiar HVCA/NADCA methods, as identified in Birgit Müller’s work).

Comments and suggestions for improvement of the standard can be downloaded from here http://www.triventek-ductcleaning.com/files/TRIpdf110720081808511.pdf as a pdf file (and in the rather awkward format which suits the CEN comment process). If readers want a Word version of the files, they can contact the author directly by email from the Triventek Duct Cleaning website. Interested parties should not delay in taking the opportunity to review and comment on the proposed standard via their national standards-setting bodies. There is not much time since the CEN will be considering comments from the various national bodies, and from members of the public, from the end of September 2008.

Released By

Triventek A/S