How green is my PC?

Posted on 16 Jan 2009 at 15:58

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This tells you they achieve a certain level of efficiency, but exactly what that level is can be trickier to establish. At www.eu-energystar.org you can find a database of currently qualified products. Desktop PCs are divided into three categories, but these are rather vaguely (though quite sensibly) defined, and relatively few PCs are listed in the database compared to other kinds of consumer electrical goods. Monitors, however, are well represented, and it's interesting to see the variation in energy usage between otherwise similar models.

You're probably also familiar with the EU energy efficiency ratings shown on domestic appliances such as fridges and washing machines, with letters from A to G. These don't yet apply to computer equipment, and the European Commission's Eco Label scheme (www.eco-label.com) currently lists no personal computers on sale in the UK.

Another organisation promoting energy efficiency is the Energy Saving Trust (www.energysavingtrust.org.uk). The Trust's 'Energy Saving Recommended' logo is awarded to products that fall into the highest energy efficiency band for their category, and is supposed to help consumers buy better. By now you won't be surprised to hear that very few PCs are listed.

One way to minimise the energy consumption of a new PC is not to choose a more powerful system than you need. Despite more efficient technologies, more and more energy is used every year to power computers. That's partly because there are more of them, but also because new machines offer ever-increasing performance. Most users don't want the same product as last year with a higher eco rating, they want a better product that uses more chips running at higher speeds to do cleverer stuff faster. That does tend to require more energy. Faster PC processors, for example, draw more electricity and create more heat, which has to be dissipated by more and bigger fans, which use more power...

It's easy to be swayed by performance figures, but not everybody needs an ultra fast PC. For everyday Windows tasks, almost any system with a dual core processor will be quite adequate; it's less important to get a top-end processor (CPU) than to install plenty of memory (RAM), and while the former will increase energy consumption, the latter will make little or no difference, while ensuring applications keep running smoothly.

Laptops in general use a lot less power than desktop PCs, and this trend is taken to the extreme in the current crop of 'netbooks' - small, light and cheap laptops that can't do much beyond the basics, and run Windows XP or Linux operating systems rather than the latest Windows Vista, but are easy to carry around. These machines typically use less than 20 watts even with their processors working flat out, so they're an energy efficient choice as well as a bit of a bargain.

The environmental catch with all laptops is their batteries. Like any fuel cell, these have a finite efficiency: using one watt of electricity to charge the battery won't enable it to deliver a whole watt to the device it powers, so energy consumption is effectively higher when running off the battery. More worryingly, batteries take a lot of energy and raw materials to produce, contain toxic chemicals, have a relatively short useful life and are difficult to dispose of safely. Manufacturers are working on greener versions: for example, HP recently announced that it would be offering Sonata batteries from Boston Power that contain fewer hazardous materials, last nearly three times longer before becoming unusable, are easier to recycle, and charge up faster too.