People are spending an increasingly large proportion of their time indoors, and increasingly that indoor climate is controlled by air conditioning systems.
The air is carried from central air handling units by networks of ducting, or ductwork, to the terminal diffusers or registers to be supplied into the occupied area.
Typically a parallel network of extract ducts take vitiated, warm, air back to central fans for discharge or re-circulation, depending on the design or conditions.
The supply ductwork becomes dirty to at a faster or slower rate, depending on the efficiency of filtration.
It should be noted that no filter is 'absolute'; all filters let some percentage of the dust 'challenge' through, however well-fitted they are.
At extract ducts the air carried will naturally be more or less contaminated by textile fibres, skin flake, paper dust and other materials generated within the space, and this is significant for hygiene to the degree that the precious conditioned air is re-circulated.
The health, comfort and even mechanical efficiency downsides of this fouling of the building's 'lungs' is recognised by a worldwide body of academic research, which underlines the fundamental message that you can't get clean air out of a dirty system.
The ill-effects of so-called 'Sick Building Syndrome' are often minor but chronic fatigue, headaches, lethargy, upper respiratory tract infections and irritation of mucous membranes such as the eyes.
These are most significant to health and productivity precisely in the sort of air conditioned buildings where 'intellectual work' is done such as banking, insurance, software development, customer service and all forms of administrative work.
The astute facility manager needs to look at the 'intellectual energy bill' in a building i.
the staff salaries and costs of employment.
What is the cost of a 1% drop in peak performance because the worker is not feeling 'quite right'? This sort of calculation, besides the moral, litigation/insurance and employee attractiveness aspects, will convince the directors that action should be taken.
Other hygiene-sensitive areas include hospitals, schools, universities, laboratories and many industries such as food, pharmaceutical and electronic.
Hotels and apartment blocks can be badly affected by an 'off' odor from dirty systems, and are often most vulnerable to the mechanical effects of 'drag' or clogging in small-bore bathroom extract systems.
So why are ducts not routinely cleaned like any other surface in the building? It's probably because they are 'out of sight and out of mind'.
A wide variety of equipment to tackle duct cleaning is available, starting with initial inspection to check system condition through a variety of dust dislodging, extraction and collection equipment, and finally quality assurance testing and ongoing hygienic maintenance products.
The purpose of duct cleaning tools and equipment is to make the duct interior accessible for inspection and cleaning.
Most of the time and cost of duct cleaning is taken up in getting to the duct, i.
entering the room, moving furniture, setting up a step ladder, removing ceiling panels, finding the duct and opening it up e.
by using an existing opening such as a spigot to a flexible connection, or cutting a new access hole, and attaching the extraction device.
Once the cleaning tool, be it a rotary brush, high-volume compressed air nozzle or a robot, is entered into the duct, the time taken to do the actual cleaning is relatively little.
Hence the economic importance of using tools with 'reach' certainly more reach than a simple vacuum cleaner The concept of 'access to' the duct being the main time consumer is one of the reasons why it is in fact a lot easier to learn how to estimate duct cleaning than many newcomers think it will be.
Nonetheless, technical and commercial training is available to help new starters sell their work, to evaluate the 'health' of air conditioning systems, to carry out the work, and to offer ongoing hygienic maintenance programs to keep systems clean and in top hygienic condition.