Marilyn Data Centre Uses Vertical Air Cooling


Vertical air cooling improved French designers’ energy efficiency – and inspired the name of their data centre

Celeste, a French high-speed Internet access provider, is to launch its power-efficient Marilyn data centre at the end of September, featuring vertical air cooling and an innovative flywheel-based UPS system.

The data centre took only ten months to build, according to Celeste chief executive Nicolas Aubé. As of February the 200-bay, 900-square-metre data centre was still at the concept stage, he said.

Power backup

Located in the Île-de-France region near the A4 motorway, Marilyn has already attracted the interest of banks, hosting companies and other IT services firms, Aubé said.

Celeste’s Marilyn data centre is so-called because it is designed to use a vertical flow of air, through several storeys (it looks like five floors on diagrams we have seen). Instead of solid floors, it has a series of metal grilles, which reminded Celeste’s staff of the iconic picture of Marilyn Monroe from the film The Seven Year Itch (a version of which is shown here). Vertical hot and cold aisles are formed by partitions on each storey

According to the, when the outside air temperature is less than 23C  (80 percent of the time), it uses free air cooling with no refrigeration. Some refrigeration is used if the outside temperature rises, until at 35C or above, all the  air is recycled and air conditioning is used. This also happens if the air is very dry.

Celeste is promising “100 percent” availability (more precisely, 99.995 percent) for Marilyn, with backup features including a generator that will take over for the entire data centre in the event of a power failure.

The generator is apparently a late addition to the scheme – in October 2010 Aubé told IT journal ITespresso that the data centre wouldn’t include a generator because its high-availability needs were met with the existing power infrastructure.

The 99.995 percent availability rate is supported by supports backup features such as hot-swappable hardware and redundant computing infrastructure and electrical circuits. The redundant systems mean components can be replaced on the fly, so that maintenance can be carried out with no downtime.

Fresh-air cooling

Marilyn has a PUE efficiency rating of 1.3, meaning 2.31 MW out of 3 MW will be directly usable by the IT equipment. That’s in line with other “green” data centres, such as a Hemel Hempstead facility opened by Gyron in July, which claimed a PUE of between 1.2 and 1.3. The industry average PUE is 2.5, according to Gyron.

For power backup, the data centre uses an unusual feature – two flywheel-powered UPS systems, which take over in the event of a power failure until the generator comes online. These UPS systems, which have only become feasible for data centres in recent years, allow Marilyn to dispense with lead batteries.

Marilyn is scheduled to open for business on 26 September.

A study published in August found that data centre power use has grown significantly less than predicted over the past few years, largely due to the 2008 economic crisis. The study, carried out by a consulting professor at Stanford University, found that electricity used by data centres worldwide increased by about 56 percent from 2005 to 2010.

This might seem a big increase, but experts had predicted energy use would double over this period. In the US data centre electricity use grew by about 36 percent, according to Koomey’s figures.

This report is translated and extended from an article by Rénald Boulestin, Silicon France. Editing by Peter Judge and Matthe Broersma.

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