Data centres a neglected area of MEP

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Data centre construction is a booming trend of the new century, especially as advances in IT infrastructure accelerates. However, data centres are a neglected area of MEP, and are often lumped under the FM banner, according to Imdaad operations executive director Ali Hassan Al Suwaidi.

“The increasing sophistication of technology has meant that MEP is fast encroaching on the realm of IT, but the sector must not let its role be subverted by the IT sector. Data centres are often not planned correctly in terms of modular expansion and capacity increases, which is where the MEP sector stands to play a major role.

This also underlines the importance of both MEP and FM professionals to remain at the forefront of latest developments through ongoing education and professional development,” comments Al Suwaidi.

In the US, data-processing environments were estimated to consume about 1,5% of total electricity consumption. Estimates of the total power cost for data centres in the US now range as high as $3,3 billion. Data centre power consumption has roughly doubled in the last five years, and is expected to double again in the next five years to more than 100 billion kWh.

New blade server technology

This increase has coincided with the adoption of new blade server technology. Traditional data centres were intended to accommodate 2 kW to 3 kW per rack. However, power requirements for blade servers today can be as high as 20 kW to 30 kW.

In addition to increased power supply requirements, the new high-density environments – with numerous blades packed tightly into a rack – generate significantly more heat than traditional servers, and therefore require more cooling capacity. A survey conducted by Emerson Network Power found that, by 2011, 64% of all data centres will not have enough electricity to handle all critical computing functions.

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However, a 2007 EPA report to the US Congress concluded that the reduction of data centre energy consumption by 50% by 2011 was possible. For example, most data centres have implemented best practices such as the hot-aisle/cold-aisle rack arrangement. Potential exists in sealing gaps in floors, using blanking panels in open spaces in racks, and avoiding mixing of hot and cold air. Computational fluid dynamics (CFD) can also be used to identify inefficiencies and optimise airflow.

Recent technologies, such as digital scroll compressors and variable frequency drives in computer room air conditioners (CRACs), allow high energy efficiencies to be maintained at partial loads.

High-density data centres (up to 30 kW per rack) require supplemental cooling units, which are mounted above and alongside equipment racks, and pull hot air directly from the hot aisle and deliver cold air to the cold aisle. Compared with conventional CRACs, supplemental cooling units can reduce cooling costs by up to 30%.

Colder is not necessarily better

Dr Albert Esser, vice-president of power and data centre infrastructure solutions at Dell, advises that some common misconceptions have to be tackled as well. For example, data centre managers have historically assumed that colder is better. Actually, the opposite is true, declares Dr Esser: “A data centre with a higher set point for air and water temperatures can actually improve energy efficiency. In particular, our research has shown that in a typical data centre, a temperature of roughly 25 degrees Celsius is optimal for Dell hardware.”

Temperatures lower than that typically increase the burden on the air-conditioning system, while temperatures lower than that typically trigger an increase in server fan activity (the latter being OEM specific). “At Dell, we have focused on industry-leading, low-flow/ high-efficiency fan technology; 23,8 degrees Celsius is, in most cases, the inflection point at which the combined air-conditioning and server fan activity consume the least power,” says Dr Esser.

Data centre design can also have a significant impact on overall power efficiency. Fortunately, simple modifications such as moving cooling capabilities closer to equipment, using data centre aisles to augment the plenum raised floors, and spacing servers optimally throughout racks to eliminate hot spots can have a major impact on cooling efficiency and power consumption.

Dell Middle East has just launched the 11th generation of its Poweredge servers and Precision workstations, based on the next generation of Intel’s Xenon processors. Features include optimal visualization, system management and usability. Dell’s Poweredge R710 is said to provide the industry’s best performance per watt. Embedded in all the new servers is the Dell Lifecycle Controller, which delivers integrated manageability through a single access point.

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