How green is my PC?

Posted on 16 Jan 2009 at 15:58

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Computers use more power than you might think, but there are lots of ways to keep your consumption down.

Compared to appliances like your cooker, electric fires and tumble dryer, you might think the electricity used by your PC equipment would be a drop in the ocean. Think again. It's true that computer systems draw hundreds rather than thousands of watts, but that still adds up, and the real killer is that many of us now have our PCs switched on continuously for hours every day. Over a year, you're likely to be using twice as much power to run your desktop computer as your electric oven.

In fact, the EU reckons home office equipment is the fastest rising contributor to electricity usage in the average home. And at the global scale, IT equipment contributes as much to global warming as air travel.

The good news is that you can do something about it. Changing your computing habits could slash your PC power consumption. We're not just talking about shaving off a few percent: many users can halve their computer energy consumption without much effort at all. Over time, by choosing more efficient products when you replace or upgrade, even bigger savings can be made.

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There are two reasons to cut your energy usage: to reduce the effect of power generation on climate change, and to save cash. On the first of these, there's been a lot of debate about global warming and whether it's caused by human activity or just one of those things that the universe throws at us from time to time to keep us on our toes.

You can choose to believe the latter if you like, but in 2007 the United Nations Intergovernmental Panel on Climate Change - a group of experts that you could think of as something like an environmental equivalent of Jeff Goldblum's character in Independence Day - reviewed the evidence and concluded that 'warming of the climate system is unequivocal' (they have to talk like that, they're scientists) and that it's more than 90% certain this is caused by us. Well, let's face it, it's not the squirrels doing it.

Sadly, this time we can't neutralise the threat by uploading a virus to the mothership. Our best hope seems to be to stop chucking gases into the atmosphere that contribute to the 'greenhouse effect', which allows solar radiation to gradually increase the temperature of the planet.

Whoever came up with the phrase 'greenhouse effect' wasn't doing the public understanding of science many favours, since technically it doesn't work anything like a greenhouse, but the phenomenon is now well understood and has been shown to exist by many different research projects. For example, studies of Antarctic ice, which preserves records of changes to the Earth over geological timescales, have found that levels of carbon dioxide remained stable below 300 parts per million for nearly half a million years, then rose above that level within the last century and are continuing to rise. The carbon dioxide level and the average global temperature appear to track each other closely over time. Are you getting that prickly feeling that starts when the alien battle cruisers hove into view?

Power generation is one of the main sources of greenhouse gas emissions, and it's estimated that IT accounts for about 10% of the UK's energy consumption. Significantly, that's a figure which is going up rather than down. So using our computers more efficiently could make a big difference.

More immediately, electricity costs money. Prices have fluctuated a lot in the last couple of years, but at the moment we're paying somewhere in the region of 10p per kilowatt hour including VAT (5% on fuel), depending on supplier and tariff. A complete computer system will consume several hundred kilowatt hours per year, even if you use it only a few hours per day - so the costs shouldn't be huge, but they're certainly worth looking at. Above, we look at some specific facts and figures on how much it might cost to power your PC and where the savings can be made.