SGI has launched a modular data centre that uses outside air instead of chilled water to cool the IT gear inside, making it highly energy efficient, the company said Monday.

The Ice Cube Air is also highly modular. SGI is offering three models, the smallest of which is 8 feet long, or big enough for four server racks, and starts at $99,000 without the IT equipment. Customers can put four of the modules together for a capacity of 16 racks.

"Our intent is to make it easier to buy a modular data center, by offering a product that lets customers start small and has that expandability quotient," said Bill Mannel, SGI vice president of product marketing.

The Ice Cube Air draws in outside air for cooling, widely seen as the most energy efficient method. If the climate is too warm to use fresh air cooling year round, SGI will install evaporative or direct expansion cooling systems for backup, and there's a traditional chiller option for customers that want it.

But SGI believes fresh-air cooling can be used in all climates at least part of the time. "We believe air cooling is a solution that can be used everywhere. It won't work every day everywhere, or every hour of the day everywhere, and that's why we offer backup cooling systems as well," said Mannel.

An Ice Cube Air cooled by fresh air only has a Power Usage Effectiveness (PUE) of 1.06, he said. PUE is a ratio of the total power going into a data centre against the amount that actually reaches the servers, as opposed to being used for cooling systems, for example. Most traditional data centres have PUEs of 2.0 or higher.

SGI also offers a 20-foot Ice Cube Air big enough for 10 racks, and a large module that's two 20-foot modules sandwiched together. Like the 8-foot module, the medium and large Ice Cube Airs can also be snapped together in fours. They are all on sale now, worldwide, Mannel said.

The containers can hold any vendor's gear and SGI will pre-install racks or customers can roll them in on site. The racks can all handle a maximum IT load of 25kW, which is as much as most customers should need.

Containerized data centres have taken off gradually since Sun Microsystems launched the first high profile product, called BlackBox, about three years ago. They're now sold by several vendors including IBM, Dell and Hewlett-Packard, which recently opened a dedicated facility to build them.

They allow customers to add extra compute capacity quickly, if a data centre expansion project is behind schedule, for example. They're also used in remote locations, by the military and other customers.

Like SGI, more and more vendors are moving away from standard shipping containers. I/o Data Centers, one of the newer entrants to the market, said a few months ago it would sell custom built portable data centres.

SGI recommends the air-cooled models for all customers unless they need to transport them long distances, in which case it will continue to sell the more rugged standard shipping containers.