Windows 7: Why Microsoft's energy-saving claims don't add up

Microsoft's low-light mode doesn't earn it the right to claim its new operating system is eco-friendly

Fred Pearce
guardian.co.uk, Thursday 22 October 2009 10.04 BST
You will have spotted the ballyhoo by now - Microsoft's new Windows 7 operating system is out today. And, rather as when Microsoft launched Vista three years ago, the company is trumpeting its energy-saving credentials. Windows 7 offers "more than just lip service" on eco-friendly features.
Microsoft is not making any specific claims about how much power Windows 7 can save, though in a demo for journalists in California recently, a laptop playing a DVD achieved 20% more battery life with Windows 7 than with Vista.
Microsoft's coyness is fair enough. The energy gains depend too much on the interface between hardware and software.
Instead, it claims to offer green-minded consumers more options. When running Windows 7, individual users can more easily decide how bright they want their screens, for instance. And corporate IT departments will be able to run power-efficiency diagnostics (pdf) to optimise the operation of PCs within their networks.
That is all to the good. Choice is important. But you have to wonder how many IT departments will take the trouble to explore the energy-saving possibilities of the new Windows when, according to Francois Ajenstat, director for environmental sustainability at Microsoft, "probably 70% of business users leave PCs on at night."
First things first, you might say. Arguably Microsoft should be giving its users rather fewer choices and rather more shoves in the direction of using their machines more efficiently.
Take the screen. The biggest energy user for most PCs and laptops, it typically consumes 40-50% of the power. As one of Microsoft's engineering blogs puts it: "The easiest way to save power on a desktop PC is to reduce the display idle timeout to something very aggressive, such as two or five minutes". So the best way for Microsoft to use its software to improve power efficiency would be to set an "aggressive" timeout as the default setting.
But no. Instead, the company has introduced a new low-light mode as an alternative way to save energy without plunging the machine into sleep mode. If this, as seems likely, ends up persuading users that they don't need to bother with sleep mode, or the inconvenience of waking the machine up again, then it sounds like a retrogressive step.
A lot of people say that Microsoft operating systems are much less energy-efficient that the Mac OS X preloaded on Apple machines. I don't want to join the long-running war between Microsoft and Apple over whose universe is best, but there is plenty of analysis out there suggesting that, for many tasks, Apple machines running with Apple operating systems use little more than half as much power as either Apples or PCs that are running Vista.
That may not be the full story, but I have yet to see anyone claiming Vista is better than Apple on the energy front.
But actually none of this is the big issue. The big issue is hardware.
Most commentators say the power savings claimed for Windows 7 won't amount to much until the new system is run on new hardware configured to take advantage. We can be fairly sure that big manufacturers like Hewlett-Packard, Acer and Dell will be bringing out new models to encourage the switchover – just in time for Christmas.
Microsoft certainly hopes so. "For the vast majority of people that get Windows 7, most will move to new hardware," according to Parri Munsell, its director for consumer product management.
Critics say this is hardly surprising. Microsoft makes it so hard to install "7" on an existing machine that most people will adopt it by going out to buy new kit. Could this be a good thing? After all, surely the quicker customers switch to Windows 7 the less their energy demands and the lower their carbon footprint.
I think not.
Eric Williams of the United Nations University calculated five years ago that most of the carbon footprint for a typical desktop computer comes not from running it but from making it. Manufacturing made up a staggering 81% of the footprint, a much greater proportion than for other household electric goods like fridges and TVs.
So if introducing Windows 7 involves buying a new computer that is bad news. By my calculation, almost any likely energy saving from running Windows 7 would be wiped out by bringing forward the purchase of your next computer by more than a few weeks.
That's the story Microsoft won't tell you, and Dell, Acer and Hewlett-Packard certainly won't tell you. If you want to cut the carbon emissions from your computing, the best way is to stick with your old machine – even if you stick with the old operating system.