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Power trip - a guide to green computing

Power-hungry devices are filling our homes, affecting both the environment and our bank balances. We show you how to save energy and money by using your IT equipment wisely

Try making a list of the electronic goodies in your home and you're sure to come up with a collection that will surprise you. As you're viewing a technology website, it's safe to assume there'll be at least one desktop or notebook PC in the home.

You may also have a printer, scanner, digital camera or router. Home entertainment and communications equipment is an even bigger category, with many homes now boasting mobile and cordless phones, satellite boxes, games consoles, audio systems, mp3 players and hard disk recorders.

Then there are our washing machines, dishwashers and kitchen gadgets, not to mention the elaborate network of lights and heaters that ring many homes. The extent to which we now depend on electricity for essentials tools and life's little helpers is quite astounding.

It's also of great concern to a growing number of scientists, politicians and charities, because everything we've mentioned so far has one thing in common: they all devour power, and some of them eat it up all day and night.

Collectively, these devices have a significant impact on the amount of fuel used to generate the power they consume. The total energy consumption per household is used to calculate what's called a carbon footprint. This footprint is just a simple way of measuring how much carbon dioxide people contribute every year to the greenhouse gases that many fear are warming our planet.

With politicians of all persuasions realising that ecological issues are a hot topic, and those who were once sceptical about global warming, such as Sir David Attenborough, now changing their tune, definitive information and advice is hard to come by.

So we decided to investigate the issue, attempt to dispel myths where we found them and develop a set of practical ways in which technology enthusiasts can make a difference, however small.

Where the power goes

Power consumption is gauged by measuring in watts (W) the amount of energy a device consumes per second and expressed in kilowatt hours (KWh).

A typical PC with monitor consumes around 120W, while an electric kettle would consume 1800W. Although these figures seem to indicate that computers are not a major factor in driving up household bills and carbon emissions, you have to consider how long each device is used for.

Typically, a kettle might be turned on four times a day for a two-minute boil. That's only eight minutes a day, which means a total daily consumption of 1.7KWh. A PC that's used for home entertainment and internet browsing might be turned on for many hours at 120W. More than half of the respondents to our survey said their PC was switched on for 40 hours a week or more, which works out at 4.8KWh. Therefore the PC can make a significant net contribution to global warming.

Nearly all the high-drain devices in a home (dishwashers, vacuum cleaners, microwaves, electric showers, kettles and washing machines) are used for only short periods so there is little scope for using them more economically, apart from choosing the most energy-efficient models when the time comes to replace them. By law, multi-coloured EU energy labels must be attached to all domestic appliances, rating them from A++ to G, where G is the most power-hungry. By choosing equipment in the A bands you'll be doing yourself, and the planet, a big favour.

Unfortunately, computing and home-entertainment equipment is not tagged with the same easy-to-understand energy labels, but it's a sobering fact that many widescreen plasma TVs consume more power than a fridge-freezer. If you have a plasma TV, do you turn it off when you're not watching it? Significant savings can be made simply by switching things off when you're not using them - everything from DAB radios to electric lights.

The same goes for computer equipment, which is sometimes left running overnight when downloading from the internet or backing up data. If the PC is performing a lengthy operation, at least turn off the monitor. The computer will work perfectly well without it. Also, check whether the program you use for downloading or backing up has a 'Turn off this PC when finished' option. If so, use it.

Standby for action

Turning off devices when they're not in use makes sense, but when you turn something off, is it really off? The switches on many electronic devices merely set them to standby mode where they consume a reduced amount of power, but are ready to respond to commands from a remote-control unit. Standby power is also used to keep internal clocks ticking and to store user options and presets. While standby mode is preferable to leaving a device fully powered, research conducted around the world has revealed that vast amounts of power are wasted by devices left in standby mode. In Australia, a staggering 13 per cent of the country's domestic electricity is consumed in this way. While the UK figure is lower at six to eight per cent, it is still highly significant.

When in standby mode, many appliances consume just a few watts, but some televisions, DVD recorders and set-top boxes use up to 15W, and there are compact hi-fi systems that draw up to 25W. The only way to be sure how much energy your equipment uses, both in fully operational and standby modes, is to measure its power consumption with an energy meter. You won't find these alongside the light bulbs in the local supermarket, but good electrical retailers have them, or you can order a basic model online from www.maplin.co.uk for £27. Plug it into a mains socket, then into the equipment you want to monitor and read its power consumption from the digital display.

The only way to completely disable such devices is to switch them off at a wall socket, but for those that need internal clocks, that's not always practical.

Having identified where the power goes in your home, you can take action. Obviously you won't want to switch off completely any device that has an essential timer, such as a video recorder, but there's no reason not to power down other devices when they're not being used. If this seems too onerous, or you think you might forget to switch off, why not fit simple mechanical timers to the appropriate power sockets? These can be bought very cheaply from local suppliers, and at the time of writing we found them for sale on the internet for as little as £6 for three.

Another approach that's especially useful for PC owners is to use a power-management block such as the OneClick. This device shuts off the power to all the peripherals attached to a desktop PC (it doesn't work with notebooks) once the computer is shut down. It's a great idea, providing you don't connect a router to this supply if there are other PCs in the house that need to connect to the internet. The One-Click panel provides sockets for up to six devices, including the PC, for £30.

If you're really committed to saving energy, the Electrisave meter (at around £80) clamps onto the cables of the mains supply and beams its readings to a portable meter that is programmed with current electricity prices. The device displays how much power is being used throughout the home, its cost, and the volume of greenhouse gases being generated.

There are national and international initiatives in place to encourage manufacturers to reduce the standby consumption of appliances to as little as 0.5W, and manufacturers are also being pressured to fit devices with power switches so that they can be switched off without having to grovel around on the floor looking for a mains plug. These are factors you should consider the next time you are upgrading or replacing computing and entertainment equipment. If you vote with your wallet, manufacturers will eventually get the message. PCs will soon be available with the Eco-label flower symbol, which means that they'll use less energy during their lives, and fewer harmful substances in their manufacture (http://ec.europa.eu/environment/ecolabel).

Practical approaches to saving power

Apart from switching off equipment or putting it into standby mode when not in use, there's a host of simple steps to minimise the energy footprint of IT and entertainment equipment. Simply turning down the brightness of a TFT monitor reduces its power consumption by several watts, as does turning down the volume of amplified speakers. Mobile phone chargers and other chargers with a transformer in the plug should be removed from their sockets when not in use. Some handheld PCs and mobile devices can be charged by plugging them into the USB port of a PC instead of using a separate charger.

Just because you're using a computer system, doesn't mean it all has to be switched on all of the time. Printers, scanners, speakers and networking equipment such as routers can all be turned off when you're not using them. Many printers can be set to auto-power mode in which they switch themselves off after a set period of inactivity, but can be quickly awakened by the PC when required. Some scanners have this feature too.

You can save paper by printing on both sides of each sheet, and save ink by using draft printing modes and smaller font sizes for working versions of documents. While these actions don't save power directly, they save it by reducing the need to produce replacement consumables. If your printer has no power-saving mode, you could consider saving all your print jobs for printing as a batch at the end of a computing session.

Most notebook PC users are familiar with the power-management options in the Windows control panel. Through these, hard disks and monitors can be set to turn off after a period of inactivity, and the entire computer can be set to hibernate, with the current state of Windows being saved to hard disk for a prompt recovery without restarting. For notebook users, the aim of power management is to maximise battery life, but it makes just as much sense to use similar options on a desktop PC to save mains power and its accompanying carbon emissions.

What difference can you really make?

There aren't many situations in life where you can make a contribution to the common good while at the same time saving money, but energy conservation is one of them. For every pound saved on an electricity bill, you're also saving 6kg of carbon dioxide, which is what a coal-fired generating plant would emit while making this much power.

Even if you're rolling in money and can easily afford to pay high electricity bills, you owe it to the rest of the world not to be a net contributor to global warming, so the least you can do if you're not prepared to save energy is to buy it from a green energy supplier obtaining some or all of its energy from renewable sources. Find out more at www.greenelectricity.org

Written by Paul Wardley

This article was created: 28 November 2006.
This article was last edited: 13 September 2007.

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