To understand the role proper conditioning of air plays in data centres, Climate Control Middle East turns to Olivier Delépine. Here, he throws light on cooling and air filtration from the points of view of energy efficiency and reliability.

How important is the role of air filtration and cooling in data centres?

Air filtration and cooling in data centres is very critical for the trouble-free operation of IT equipment. Not doing it properly will cause down times and premature failures of IT equipment.

Cooling should be properly designed in accordance with the requirement of the IT equipment and with ASHRAE guidelines, so that it is sufficient to maintain the desired temperature in a data centre, and to avoid hot spots while consuming minimum power. Properly designed, the cooling system helps customers achieve a lower power usage effectiveness (PUE) and savings in OPEX.

Copper creep and silver termination are common modes of IT equipment failures due to environmental contamination.

• Copper creep corrosion is the corrosion of copper plating to copper sulfide on printed circuit boards and the creeping of copper sulfide over the printed circuit boards, electrically shorting adjacent circuit-board features.
• Corrosion of silver termination, in surface-mounted components, to silver sulfide leads to the loss of silver metallisation and eventual open circuiting of components, such as resistors.

What is the difference between air filtration systems used in data centres and the ones used in an ordinary office environment?

The purpose of an air filtration system for an office space is to provide healthy environment to human occupants, whereas an air filtration system for a data centre is designed to provide clean operational environment for IT equipment. For instance, filtration for ordinary office spaces is designed to eliminate bacteria, while filtration for data centres is designed to eliminated NOx and SOx in the air.

Which types of filters are most suitable for data centres?

The room air may be continuously filtered with MERV 8 filters, as recommended by ASHRAE Standard 127 (ASHRAE 2007). Air entering a data centre may be filtered with MERV 11 or MERV 13 filters, as recommended by ASHRAE (2009b).

How can humidity and dust affect data centres, particularly in countries like the UAE and others in the Middle East?

Particulate (dust) contamination is characterised by its quantity and its corrosivity. The quantity of dust contamination can be normally identified by visual inspection of the IT equipment and by the frequency of filter replacement. The corrosivity of the dust can be estimated by determining the deliquescent relative humidity, which is the relative humidity at which the dust becomes wet and, therefore, conductive. Dust with high deliquescent relative humidity is generally more benign; dust with low deliquescent relative humidity is generally more corrosive.

Do you agree that the largest part of the Total Cost of Ownership of a data centre is attributable to powering and cooling and not the cost of the equipment?

Predicting and measuring Total Cost of Ownership (TCO) for the physical infrastructure for data centres is required for return-on-investment analysis and other business decision processes. In addition, an understanding of the cost drivers of TCO provides insight into opportunities to control costs.

Many users are surprised when they consider that the TCO for the physical infrastructure may be comparable to or larger than the TCO of the supported Information Technology equipment.

The TCO of a rack in a data centre is approximately USD 120,000 over the data centre lifetime.

In many cases, this cost is comparable to the cost of the IT equipment that a rack is likely to contain over the data centre lifetime. Approximately half of the lifetime per rack TCO of USD 120,000 is capital expense, and half is operating expense.

The respondent is the Vice President, UAE and Gulf Countries, Schneider Electric IT Business Unit. He can be contacted at olivier. delepine@schneiderelectric.com