Keep it Clean
Andrew Steel, Managing Director of Airmec Essential Services, explains the importance of understanding the standards around duct cleaning.
The introduction of the TR19 Air updated duct cleaning guidance by the Building Engineering Services Association (BESA) rightly received a lot of media coverage, all of which helps to underline the importance of correct processes. When it comes to duct cleaning, most people refer day-to-day to the TR19 Guides to Good Practice and they are often cited as a requirement by insurers.
So, why do you also see mention of BS EN15780? This 2011 British Standard for cleanliness levels in ductwork made things a lot clearer by classifying different risks according to a building’s intended use.
In a nutshell BS EN15780 has defined the levels of cleanliness that should be achieved, pragmatically by taking into account a building’s intended use and the vulnerability of its occupants. The TR19 guidance tells you how best to achieve the appropriate levels.
TR19 Air and TR19 Grease Fire Risk Management of Grease Accumulation within Kitchen Extraction Systems continue to be widely recognised, familiar industry standards for most practical purposes and Airmec is of course a member of the BESA and a member of the Vent Hygiene Register.
BS EN15780: Ventilation for buildings – ductwork – cleanliness of ventilation systems was introduced as the UK’s national implementation of the European EN15780, and TR19 was in any case amended in line with it. The classifications that the British Standard introduced, are now part and parcel of the TR19 duct cleaning methodology. So at least we have no ambiguity on cleanliness levels – the two standards complement each other. As a building manager you will however want to check that your contractor is conversant with and applies both standards when scoping and quoting for work at your premises.
Differences
It’s not just duplication. There are subtle differences, especially on new systems, where BS EN15780 cross-references with other standards that apply to HVAC systems. Crucially, BS EN15780 defines the frequency of risk assessment surveys, the basis of all good management to ensure you are addressing current risk. For most facilities this is two years, annually for higher risk environments.
The BS EN15780 guidelines apply to both existing and newly installed systems, and there are three different prescribed levels for each type of system. As a rough guide, the three levels divide premises into:
- Low risk – for low occupancy rooms, such as storage rooms
- Medium risk – for higher occupancy rooms, such as general offices, hotels, restaurants or schools
- High risk – for specialist environments, such as treatment areas in hospitals and laboratories
For example, we know that dust levels should be less than 3.0g/m2 in a medium risk building, which would include most offices, hotels, restaurants, schools etc. However, that rises to 4.5g/m2 or less for re-circulation and secondary ductwork. So, ventilation system specifiers, installers, commissioning engineers, cleaning specialists and facilities managers all have unambiguous guidance on cleaning standards, procedures and validation. And when building managers can more easily understand their obligations, they can manage their overall running costs.
No room for doubt
Finding a way around the Standards and Guidance maze will never be easy. In any case, strictly speaking both standards can only offer guidance on best practice. They are not mandatory, but a court of law or insurance loss adjuster might be expected to look dimly on non-compliance with such widely accepted practical advice.
If you work with a trusted specialist contractor, there should be no room for doubt over the duct cleaning regime that you need, as they will know exactly what cleanliness levels to achieve. Doing too little is potentially dangerous and leads to inefficiencies: doing too much can mean paying too much.
