Intel tries using normal outside air to cool datacentres

by Sylvie Barak on Sep 19, 2008

Blowing in the wind

INTEL JUST RELEASED a white paper which reckons servers can stick it out in pretty tough conditions, cooled only with outside air and save money to boot.

The Intel report on "free cooling" talks about using something called air-side economisation which sucks in outside air to cool datacentres, pushing the hot air from the machines outside. The simplicity of it sounds stunning but even more stunning is that it could mean the end of the expensive, energy sucking CRAC units currently being used.

Testing to see if machines could actually be cooled by outside air temperatures as high as 32 degrees Celcius, Intel also decided to challenge the notion that outside, unpurified air was bad for servers. Turns out, it didn't do them too much harm.

Setting up a datacentre in New Mexico, with approximately 900 used production servers (standard, single-core, dual-socket, Intel-based machines) in a 93 square metre trailer – divided into two parts – Intel cooled one part with a warehouse-grade DX air-conditioning unit and the other almost only with fresh air.

When the outside air temperature reached over 32 degrees C, Intel switched on the aircon, and when temperatures dropped to below 18 degrees C, Intel warmed the air up a bit by mixing outside air with hot air coming out of the server.

Over the 10-month test, Intel figured its approach, whereby air economisers were used about 91 per cent of the time, saved about 67 per cent of the power needed for a 10MW datacentre, translating into monetary savings of US$2.87 million. Cool indeed.

And as for damage to the machines by humidity and bits of contamination? Well, considering no humidity controls were used whatsoever, and only a bog standard household air filter was put in, the results were not unimpressive.

"There was only a minimal difference between the 4.46 per cent failure rate in the economiser compartment and the 3.83 per cent failure rate in our main datacentre over the same period," noted Intel. Also, "the failure rate in the trailer compartment with DX cooling was 2.45 per cent, actually lower than in the main datacentre," according to the white paper.

Of course, with humidity fluctuations from four to over 90 per cent for machines cooled by outside air, the results were far from perfect, but at 74 per cent fewer KWhs to cool the trailer, Intel shouldn't let a bit of humidity dampen things.