Reducing your organisations’ power consumption need not be mutually exclusive with profitability. Over the last several years, BT has managed to cut data centre power usage by 60–70%, while lowering costs along the way. In fact, investment in our efficient, 21st century data centres became profitable in less than 18 months.

“We want the market to follow us, and reduce the global carbon footprint for IT services.”
- Steve O’Donnell“We’re really very far out ahead in thought leadership on this,” says Steve O’Donnell, Global Head of Data Centre and Customer Experience Management for BT, adding “We want the market to follow us, and reduce the global carbon footprint for IT services.”

High Impact
To provide some sense of scale, BT’s data centres, the largest in Europe, use close to 0.7% of the total power output for Great Britain. With that high level of impact on the grid, and the bottom line, countries and companies that want to reach their sustainability goals while continuing to grow need to address this issue. Or, perhaps more to the point, companies that hope to grow need to set and reach sustainability goals.

Forces that contribute to the rising IT power bill include increased computer usage, “always-on” connectivity, dual-core processing, and a growing number of applications vital to the workplace and everyday life. “We’re under tremendous pressure to increase capacity,” say’s O’Donnell. And while collaborative technologies that enable telecommuting and conferencing save tremendous amounts of power by reducing travel, IT services still need to be made as efficient as possible.

Inefficient by nature
Now if a charitable organisation asked you to make a cash donation and then said only 7% of your contribution would make its way to the people who need it, you’d probably find that an unacceptable level of efficiency. Still, that’s what goes on in the typical data centre. Half of the power consumed goes to cooling alone, 7% gets lost in the national grid, and between 25% and 40% vanishes during AC to DC conversion – leaving only that 7% actually powering the servers. The good news is that with such low levels of efficiency to begin with, there’s plenty of room for improvement. “What we need,” O’Donnell tells us, “are engineering solutions.” Here’s how BT does it.

“Most DC powered data centres use 300 or more volts, which can actually kill someone if they make a mistake…”
- Steve O’DonnellFresh air cooling
The traditional formula for computer cooling is that for every 1 kilowatt used to actually run a computer, you need 1.2 kilowatts of power to cool it. With fresh air cooling as pioneered by BT, refrigeration becomes unnecessary for a majority of the year, reducing those costs by approximately 85%. BT also runs its servers hotter, extending parameters to between 5 and 40 degrees Celsius, further reducing cooling costs. Presently, BT has 107 data centre sites using fresh air cooling as well as 5600 telephone exchanges.

AC/DC Back in the black
Conventional data centres use alternating current at high voltage: taking AC from the grid, converting it to DC – in often cheaply made and inefficient hardware – and losing 25-40% of the power in the process. BT has learned to deliver DC power straight to computers, at much lower voltages. “Most DC powered data centres use 300 or more volts, which can actually kill someone if they make a mistake,” warns O’Donnell. But by using low voltage DC power in our “Metro-Nodes,” we are able to cut power consumption by 40%. Computers powered directly by DC are also more reliable, produce less heat and can be stacked closer together.

In the real world
All of the technology and engineering wizardry we’ve discussed so far, while considered cutting-edge, is well-tested and proven in the real world. BT, today, has thousands of fresh-air-cooled and DC-supplied technical suites in operation around the globe. Reliability statistics for these centres are higher than Uptime Institute’s Tier 4 (the global standard for data centre operations) reference model, costs are down, and there have been no longevity issues operating at higher temperatures.

The next generation
BT has met its promise to reduce power consumption by 60% from 1996 to 2006. Our next goal is to get that number to 80% by 2016. To begin that journey, Steve O’Donnell and his team are looking at improving CPU utilisation through enhanced virtualisation, and taking a more holistic approach to data centre design. As the first European company to join Greengrid.org, BT is particularly interested in helping guide the IT market towards improved energy efficiency. Organisations that invest in making their data centres more efficient will not only save on overall expenses, but benefit from social and customer goodwill increasingly associated with real progress towards sustainability.