Aireven Pty Ltd managing director, Kevin Cronin, explains the importance of humidity control.
The majority of human comfort issues caused by dry air occur in the winter months. This is because the cold outside air can hold very little moisture so when it enters a building and is heated the relative humidity drops.
In an office environment dry air can cause dehydration resulting in headaches, sore throats, eye and skin irritation, contact lens discomfort and lethargy.
Frequently humidifiers can be installed but not operated to reduce a building’s HVAC running costs. This is short-sighted as unlike temperature, where an inappropriate level is immediately obvious, the health problems caused by a low humidity can be attributed to other factors, such as “winter bugs”. And if the problem isn't addressed it can result in decreased productivity.
AIRAH, CIBSE and BSRIA generally agree that the appropriate range of humidity in an office environment for human comfort should be around 50%RH, with a typical range of 40%-60%RH.
A recent study has shown that a dry indoor atmosphere significantly increases susceptibility to airborne viruses. The US National Institute for Occupational Safety & Health showed that infectivity of the flu virus dropped from 77% to 15% when a humidity of 40% or more was maintained.
Alongside printing there are many manufacturing industries where humidity control improves productivity. The food industry has many processes that use humidification such as bread proving, maturing cheese or ripening fruit. Produce also maintains a longer shelf-life when stored at the correct humidity as well as preventing evaporative weight loss that can directly affect profits.
Any manufacturing industry that uses materials affected by moisture will need to humidify. Depending on the sensitivity of the process or materials involved this could be year-round humidification or just during the dry winter months.
The types of manufactured products include those directly affected by humidity such as wood and textiles, or those with sensitive component parts like the coatings on pharmaceuticals, and also products that need high humidity for successful production, like the curing of concrete.
Cooling
For every kg of water evaporated into the air 680W of cooling is achieved. This evaporative cooling effect has often been a welcome side-effect of humidifiers used in hot industrial manufacturing environments but more recently we’ve seen cold water humidifiers being used specifically to provide cooling rather than humidity control.
Evaporative humidifiers are now frequently used to cool exhaust air in AHUs, with the resultant cool thermal energy being transferred into the incoming supply air with heat recovery systems.
It is commonplace for data centres to use evaporative humidifiers to boost cooling alongside “free air cooling” systems, where outside air is used to maintain acceptable internal temperatures.
Humidifying the use of compressor driven mechanical cooling is limited to just the hottest days of the year.
Maintaining the properties of sensitive works of art or antiques requires a consistent atmosphere without fluctuations.
A change in atmospheric conditions can cause slight dimensional changes in materials that over time result in irreversible damage to paintings, furniture, books, sculptures and even the walls, floors and ceilings of the museums and art galleries that accommodate them.
Valuable wooden instruments, from the smallest fiddle to the largest of organs, also need humidity control to ensure they are kept in tune without dimensional changes affecting their resonance.
By maintaining an environment above 40%RH, the moisture in the atmosphere naturally dissipates electrical charge. This effectively combats electro static build-up and prevents uncomfortable sparks or discharges that can occur as a result of friction.
Humidification for anti-static is often used in electronic manufacturing, data centres, munitions, textiles, paint sanding and printing.
About the Author
Kevin Cronin is the managing director of Condair, a leading manufacturer of commercial and industrial humidification and evaporative cooling products and systems.
Cronin is a specialist in humidification, having being involved with industrial humidification and evaporative cooling for the past three decades.
With the development of sophisticated industrial and commercial electric steam humidifiers, Cronin has been instrumental in the introduction of controlled humidity into many and varied applications and sites across the country.
In 2001 he began Aireven Humidifiers. The company has installations in major art galleries and museums, hospitals, universities, science and research laboratories, agriculture, datacentres, and more. He can be contacted at kcronin@aireven.com.au