Back in April 2014, London experienced elevated levels of air pollution, reaching the apex of the government’s air quality index. But what effect does this have on data centres?
If you have a closed circuit system such as DX, Water Cooled or Indirect Air, then you can sit back and relax when it comes to the operational safety of your facility. However, with the push to become more energy efficient, there has been a growing trend towards direct fresh air cooling solutions.
WHEN IS A SOLUTION NOT A SOLUTION?
Many companies often opt for fresh air cooling to reduce their operational costs and carbon footprint. However, when the environment in which it has been deployed has not been considered, the solution can instead be a problem.
London’s air pollution levels reportedly reached crisis point in April, further compounded by unusual atmospheric conditions blowing up dust from the Sahara desert. The Met Office forecast of a level 10 on air quality prompted them to issue warnings that London could experience the worst smog seen in years. Unusual atmospheric instances like this are often unforeseen. However, ASHRAE, a globally respected society that educates through research and standards writing in the built environment, recommends that data centres should be kept clean to ISO Class 8. What this means is that the facility should ideally employ control over the level of contamination allowed within the data centre. This can be achieved by using MERV 8 filtration to continuously filter the room air or by using MERV 11 or MERV 13 filtration to filter any air entering the data centre.
But, does every direct fresh air solution comply with such stringent filtration guidelines? The quantity of dust contamination can usually be identified by visual inspection of the IT equipment, as well as the frequency in which the filters are replaced. If this is proven to be the case within a facility, then it could already be a problem. The corrosivity of dust can be estimated by determining the deliquescent relative humidity, at which the dust becomes wet and therefore conductive. Dust with high deliquescent relative humidity is generally more benign, while dust with low deliquescent relative humidity is generally more corrosive.
When contemplating the use of direct fresh air cooling within a data centre environment, one should always consider where that air is being drawn from. When Future-tech has proposed and built direct fresh air solutions in data centres, we often need to change the standard filters that come with ‘off the shelf’ units. As a minimum, EU4 and EU8 bag filters are commonly used together to provide protection from air born particulates. Considerations like this make the solution more suitable, not only for minimising contaminates in the data centre, but for reducing the ongoing costs of filter replacement.
It can often be difficult to justify why direct fresh air is not the ideal solution when the alternative could be two or three times more expensive. However, when one considers the long-term outlay of hardware replacement, the cost in terms of operational expenditure becomes easier to quantify. Location plays a large role in the construction of data centres and while free air cooling might be beneficial to the environment, it may not always be beneficial to your infrastructure. What has not been discussed here is the presence of dissolved solids, such as sea salt, and gaseous contaminants, such as chlorine, both of which will enter a data centre through EU4 and EU8 filtration. These two contaminants in particular will cause significant and rapid damage to IT equipment.
If you would like to know more or have any questions relating to the affects pollution has on data centres please contact Future-tech today.