GREEN GUIDE PART ONE
Controlling the atmosphere
John Barker of Humidity Solutions discusses the role that humidity control plays in greening climate control.
W
hen writing about humidity control for the Green Guide, I had fi rstly to think about what we mean by green?
Is it the energy used by the equipment itself? Do we consider the source of the energy? Electric is greener than gas at the point of use. Should the calculation take into consideration the whole system costs? if we supply power to one item but it reduces the combined energy costs then this is surely green?
Is it the packaging the product arrives in? Is it the consumables and how they can be recycled or whether the system is required at all? Is it the miles that the product must travel from manufacturer to site? Will the product provide a benefi t which prevents wastage in the future such as reducing scrap in a manufacturing process?
The answer, I suggest, is all of the above. To be truly ‘green’, we cannot look at any one of these single points in isolation without considering the rest. So, with a humidifi er the fi rst question is why should it be required?
One reason – and at no time in recent history has it been more relevant – is to protect human health. The importance of the role humidity control plays in indoor air quality has been increasingly highlighted in recent years, and how vital it is to an individual’s health and well-being. Being comfortable in an environment where you work, play or rest is essential. As cold, outside air is brought inside and heated during the months of October to March, the relative humidity becomes very low and creates an environment with very little moisture in the air causing cracked lips, sore eyes, dry skin and reduced defences against bugs, bacteria and viruses. In the summer, air-conditioned offi ces may well produce a comfortable temperature, but the air conditioning strips moisture from the air during the cooling cycle – leading again to potentially similar conditions as in winter. Humidity
32 June 2020
control can therefore be argued as a good option for at least ten months of the year.
Manufacturing performances can be greatly improved with humidity control. Paper dimensional stability is improved, glue cures harder and stronger, precious artefacts don’t decay, plants grow, timber doesn’t crack, meat cures, vegetables last longer, coils don’t freeze, static is eliminated and hot yoga provides the desired balance of heat and humidity – all when the humidity is set to the correct level for the process or activity.
So yes, humidity does have a large role to play in helping to provide a good indoor air quality.
With this established it is then worth considering the type of humidifi er to use. This is dependant on so many factors that it is worth discussing with a specialist for advice to match your specifi c application. It is always temping to look at the cold-water adiabatic humidifi ers – the ultrasonic and high-pressure water spray humidifi ers or the evaporative solutions. These systems off er excellent control, can provide up to large outputs, and operate off very low energy loads. Fantastic, these seem to be the ‘green’ humidifi ers that we are looking for - and they often are.
However, this is where the whole system needs to be considered. All these humidifi ers cool the air as they evaporate the water into humid air. Why? Changing state requires a lot of energy. Therefore, to change water into humid air - which is a gas - requires heat energy. The water supply contains very little heat energy. To evaporate, the process therefore takes the heat energy from the surrounding air - so cooling it down.
This can be an advantage – imagine one of these systems in a printer where the presses are kicking out a lot of heat energy. To humidify using a cold-water system has low running costs but in addition you are getting free cooling from the process – a double win. You are controlling the
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