Economizers hit the big time - by Peter Judge

Views and Opinions on Green IT (Nov 15 2010)

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   Moves to promote economizers in data centers have been controversial, but they may be bearing fruit - in the form of products from big manufacturers.

    This week in London, APC by Schneider Electric announced EcoBreeze, a pre-packaged cooling system for data centres, which uses outside-air cooling. APC says it improves the efficiency of cooling systems available “off the shelf”, and it is designed at least partly, to meet the ASHRAE 90/1 standard for energy efficient building.

    Now ASHRAE, the American Society of Heating, Refrigerating and Air-Conditioning Engineers makes standards for efficiently heating and cooling buildings, and those standards are often cited in building codes around the US.

    When ASHRAE  90.1 was announced earlier this year, started a storm of protest from data center owners including Google and Microsoft, who said it was too prescriptive, requiring the use of “economizers”, which reduce the use of refrigration plants by “free air cooling”, which uses outside air temperatures to cool the air circulating in the server room.

    While economizers are undoubtedly a good idea, objectors said they would prefer to be judged on their results, instead of being forced to use a particular method. ASHRAE responded by explaining the different options in the standard, which would allow different methods - and the objectors said that building regulators might not understand the opt-outs.

    With that argument around hovering in the air, APC announced an economizer-based system in London last week which it claims could change the dynamics of the market.

    Previously, economizer systems have been constructed to order, on site, using components from multiple manufacturers, said APC’s director of innovation John Bean Jr. EcoBreeze units are built in factories and shipped in the - increasingly ubiquitous - standard shipping containers. One 40ft shipping container can provide up to 400kW of cooling (and requires a much lower power to provide that, depending on the ambient air conditions).

    Bean was clearly aware of the controversy, and dealt with the weaknesses of free air cooling, and the evaporative systems used to extend the range at which they work.

    Firstly, the system does not circulate outside air in the IT room. There is a heat exchanger where outside air cools a closed loop of inside air. “If you kill two-tenths of one percent of your servers with outside air, you will offset all the savings you make by improving efficiency,” Bean said. “Is shaving a few PUE points worth that risk?”

    Secondly, the evaporative cooling system is designed to minimise the risks associated with using water. This too circulates in a closed loop, and electromagnetic pulses are used to keep it free from a build up of microbes that could foul the system - and when the outside temperature falls and it’s not needed, it is drained completely, so there’s no risk of frozen and burst pipes.

    The arrival of containerised cooling raises questions. Will it affect the internals, perhaps making traditional raised-floor structures obsolete, as Bean said it can deliver cooling best through a wall vent.

    Will it marry up with container-based or modular data centers, to make very quick-but-efficient facilities? How about ordering four containers of servers, and one of cooling, and just putting them all in a big shed with power and water?

    

   And what about the regulations? Is EcoBreeze just an artificial result of ASHRAE’s standard? Was it created to meet a boom in economizers created by over-zealous zoning regulators?

    

   I don’t think so. APC chose to launch it at DataCenterDynamics’ London event, and Bean thinks it will grow fastest in Europe, where ASHRAE standards have no particular legal status. “We notice more progressive thinking in Europe,” Bean said, adding that US building laws move slowly and will always be a patchwork, so there never will be a blanket requirement for free air cooling in the US.

    

   Europe also has a more favourable climate for free air cooling - although Bean’s presentation suggested that even Florida has enough hours of free air cooling to make EcoBreeze viable there.  

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