Evaporative cooling will pay for itself in less than two years
Co-location provider 4D is saving money and cutting its customers’ carbon footprint by fitting a new environmentally-friendly cooling system to its data centre in Byfleet, Surrey.
The data centre, which was built in 2001, used conventional CRAC air-conditioning to cool the servers, but 4D replaced these with units that use the outside air along with some help from evaporation. The move is expected to pay for itself within eighteen months, and will boost 4D’s customers’ green credentials by cutting emissions.
Cooling can use up to half the energy in data centres, which consume around one percent of the world’s electricity. Older sites made their air conditioning units too power-hungry, keeping the buildings colder than necessary to be on the safe side, but new centres use more efficient “free air” cooling systems that rely on the outside air temperature where possible.
Fitting these cooling systems to older data centres has proven difficult, so many are operating at efficency (PUE) levels of 2.0 or more, where more than half the site’s electricity goes into the cooling. PUE, or Power Usage Effectiveness, is the amount of power used by the site divided by the power which reaches the servers.
4D bought 17 coolers from British start-up EcoCooling, which extends the effectiveness of “free air” by using evaporation. “If the temperature goes above a certain level, the air is pulled through wetted filters,” explained 4D technical director David Barker. “If it is too cold, it recirculates it through the warmer air in the room.”
EcoCooling has specialised in providing coolers for those older data centres upgrading to reduce their energy use. The Byfleet centre originally had a PUE of 1.7, using air conditioning units which 4D inherited from the site’s previous owner DHL. With the new coolers, PUE has dropped to 1.146 – which means only about one eighth of the centre’s power goes on cooling and lifts the centre up into the kind of efficiencies normally achievable only in a newly-built site.
The EcoCooling technology was tested for a year in the site’s UPS (Uninterruptible Power Supply) room, and was then installed for the whole building in late 2011. With around half a year’s data, the PUE figure of 1.146 is real, not theoretical, Barker stressed. “This will pay for itself in eighteen months to two years,” he said. “Quicker if the price of electricity goes up.”
To further reduce electricity use, 4D has replaced flourescent lights with LEDs, and has installed efficient UPS systems.
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