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Ductwork: How clean is yours?

Air quality can lead to impaired performance and is a contributor to our health at work, in factories or especially in hospitals, says Ian Wall of Ductbusters.
Ductwork: How clean is yours?
We take the air we breathe for granted. We might notice if the atmosphere is dry or dusty but generally we assume the air around us is good.

But it is the elements in the air which we can't see and smell that should concern us. Dust and debris builds up in mechanical ventilation systems and viruses and bacteria can thrive there.

The resulting poor air quality can be a major problem leading to impaired performance at work, unhappy customers, sickness or even death.

The problem is partly that we don't think about air quality as a contributor to health. In addition, the only legal requirement regarding ventilation hygiene is that systems are regularly inspected and the findings recorded. There is no legal obligation to clean, so when budgets are tight it is easy to put off what may be essential work.

In hospitals, diseases like MRSA and clostridium difficile can thrive and feed on flakes of dead dry human skin which is a component of hospital dust and can build up in ventilation ducts.

In the workplace or apartment buildings, for example, mould building up in ducting can cause breathing problems, and poorly maintained ventilation systems can result in loss of concentration, aches and pains caused by drafts, and even skin problems.

The International Centre for Indoor Environment and Energy, Technical University of Denmark reported: 'It has been shown beyond reasonable doubt that poor indoor air quality in buildings can decrease productivity. The size of the effect on most aspects of office work performance appears to be as high as 6 per cent - 9 per cent. It is usually more energy-efficient to eliminate sources of pollution than to increase outdoor air supply rates.'

Another important consideration is that poorly-maintained ventilation systems waste energy and increase the Climate Change Levy.

Such problems can be avoided by implementing a comprehensive cleaning and maintenance programme for ventilation systems.

This process can be improved by installing the ventilation in the right way from the start. Access is key, ducting should have sufficient access doors and, obviously, they should be easily accessible.

Dr Ghasson Shabha is facilities management MSc course leader at the School of Property, Construction and Planning at Birmingham City University.

'Building professionals must be fully appraised of the risks associated with specifying finishing materials,' he said. 'Areas of concern might include the cleanliness of the internal surfaces of ducting systems, diffusers and grilles.'

Using the PDI Level 3 process - (having ductwork delivered to site wrapped and stored dust-free before installation and bagging off to prevent dust entering the system before handover) may look like a good solution. But it is expensive as the ductwork has to be delivered to site as a single piece, and, despite the precautions, the ducts will need cleaning anyway. It is simpler and cheaper to have the ductwork nested, each part inside the other, delivered in fewer drops and then cleaned.

Once the building has started its useful life, a cleaning and maintenance programme is essential. Facilities and estates managers need to ensure a thorough regular clean. The recommendation is to clean every four years, or 12 months for sterile environments. But this is for guidance only and situations can vary. Estates managers should look for signs of build up of dirt and dust in ducting. And managers can get a risk assessment to identify the state of ducting to remove any doubt.

Melton Mowbray-based specialist cheese manufacturer Tuxford and Tebbutt appointed Ductbusters for a cleaning and installation project in last year.

The task included cleaning of the ductwork in the maturing stores of the creamery, which dates back to 1780. The building's age and nooks and crannies presented some challenges to the Ductbusters team. And, as the site had to remain in use, the team had to work around the employees and the products.

New rigid system

Ductbusters also installed a new ventilation system in the cheese production area, replacing the inefficient flexible system with a new rigid one. Flexible ventilation creates resistance which cuts down airflow, rigid systems improve airflow (reducing energy consumption) and are easier to clean.

'Air quality is very important in producing our award-winning cheeses,' said Alan Whiston, factory manager, of Tuxford & Tebbutt. 'Elements like humidity and temperature are key to the quality of the product but hygiene is, of course, of paramount importance. We realise duct cleaning is essential and we routinely have our ducting cleaned although there is no legislation that requires it. Customers expect us to have a preventive maintenance programme so it's good practice and good business sense too.'

Major food retailers like Marks & Spencer impose their standards on suppliers which include air systems as part of the customer's annual cleanliness audits.

'The new ventilation system was installed in an area where temperature and humidity control are critical in the making of our blue Stilton cheeses. The new system is much better for our employees as it's easier to live with and they don't have to worry about control issues.

While it may be a hidden problem, the importance of installing the right ducting, then cleaning and maintaining it, cannot be overestimated - it saves money and it could save lives!
18 February 2010

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