Over in Australia last week, speaking at a datacentre event, I listened to a few other presentations where some new ideas were being put across for low-cost, low-carbon approaches to datacentre cooling. Well, I say new ideas, but the two most interesting were actually based on technology that's been around for thousands of years in one case and tens of years in the other.

Let's start with the ancient one - the use of stove chimneys. When looking at ancient stoves and, in particular, smelting ovens, there is often a chimney topping off an enclosed environment which has an opening at the base to let air in. Server racks provided by a company called Chatsworth Products take the same approach.

The idea is that the use of fans and forced air is minimised, as the design automatically pulls cold air in at the bottom, uses trunking to distribute it equally within the rack, using the updraft caused by the chimney as the main means of drawing the cold air in. A by-product is that the air used in cooling is highly specific - you are not cooling down the air in the datacentre, only the air that passes through the racks. In this way, the datacentre can be run at any temperature you choose - purely ambient or at a set level for the comfort of datacentre personnel. The volume of chilled air required will be far less than that generally needed in typical datacentres, and with power costs for cooling running at one or more times those of the power costs required for running servers, switches, storage and so on, this could be a major saving.

The other item is something from a company called KyotoCooling. Here, a simple rotary heat exchanger as used since the 1960s as a heating mechanism, is reverse plumbed to give cooling capabilities instead. With KyotoCooling, a "wheel" consisting of coiled corrugated metal sheeting is laid in a room, with a floor in line with the wheel, and a wall in line with its centre creating four quadrants of space.

To envisage this, try to picture a large square with a horizontal and a vertical line creating four equally sized squares within it. The wheel will then lie along the horizontal line. Cold air is drawn in to one quadrant from outside of the building and is passed through the small, high surface area metal channels in the wheel into the quadrant below and is vented back to the outside. The ambient temperature air cools the wheel down as it passes through. The wheel turns slowly (about 4-7rpm), taking the mass of cool metal from the outer quadrants in to the inner ones. These two quadrants work in the same manner as the outer ones, except that they deal with the air from and to the datacentre. Hot air from the datacentre is drawn into one quadrant and through the cool metal of the wheel, and is then vented back in to the datacentre as the source for cooling the data centre itself.

With an optimum efficiency at around 22 degrees Celsius, the KyotoWheel is good enough to be used across the majority of the major datacentre communities in the world. That it still works up to 32 degrees Celsius, but at lower efficiencies, means that it can still be used to offset expensive standard air conditioning systems in the vast majority of data centres.

So - no strange chemicals being pumped around, little in the way of moving parts other than a slow moving wheel and a few large air-moving fans. Lower maintenance than air conditioning, longer predicted lifetime, and fewer problems in recycling or dumping. Seems like a pretty good idea, all round.

The downside? The wheel has to be built in a volume all to itself, and some of these wheels can be big - up to eight metres in diameter with a thickness of around half a metre. Finding space to retrofit such solutions may not be easy in the majority of cases - but for new-build data centres, KyotoCooling looks like something worth looking at.

Combing the two approaches could lead to even greater savings, and with the prospect of ever-rising energy costs, such step-change capabilities in energy saving must be high up on the list for any datacentre manager, or for business people looking to direct savings in energy across their organisations.

By Clive Longbottom, service director, Quocirca