The increasing energy demands of the digital world need to be addressed if we are to avoid severe global warming, argues regular commentator Bill Thompson.
Thousands of computers will be left on standby over the holiday
This Christmas period offices will be empty of staff as the country shuts down for the extended celebration that has become the norm over the last few years.
Many staff will head home from work on 22 December, not to return until 2 January.
They'll leave behind the wreckage of the Christmas party, a pile of unopened mail and, if they are at all typical, a lot of glowing lights.
Unfortunately, the lights won't be on the office Christmas tree but on the monitors, photocopiers, fax machines, phone rechargers and PCs that will be left on standby or, worse, turned on throughout the break.
According to research carried out by office equipment supplier Canon, based on figures from the National Energy Foundation and Infosource, more than six million PCs will be left on over Christmas, consuming nearly forty million kilowatt hours of electricity.
Together with the printers and other hardware they will waste enough electricity to microwave 268 million mince pies, pumping 19,000 unnecessary tonnes of carbon dioxide into the atmosphere, at a cost of around £8.6m.
To a large extent this waste is a result of carelessness and a failure to think, as few machines need to be left switched on when they aren't in use. We have, as a society, been too lazy about this for too long and it is time we became much more aware of the energy costs of our hi-tech lifestyle.
However, there is a wider problem since many of our beloved technological toys are remarkably inefficient and use more electricity than they really need to.
PCs are probably the worst culprit, because standard power supplies have changed relatively little since the original IBM PC was launched in 1981.
At that time, power supplies had to convert high-voltage alternating current to multiple direct current voltages for the different components - an inefficient process which results in a lots of wasted energy.
Portable devices are also a problem. According to energy research and consulting firm EPRI Solutions, there are six to 10 billion mobile power supplies in use around the world, and as anyone who has tried to find the right supply for their mobile phone in a pile of cables and plugs will agree, the current situation is ridiculous.
Fortunately, there is now a movement for change, especially among large energy-users.
In September, two Google engineers gave a talk at the Intel Developer Forum at which they proposed a simpler and more efficient power supply for PCs, while back in January founder Larry Page, called for a single power supply standard for portable devices.
Companies are also being asked to reduce the number of computers they use in their data centres.
One way is by running several "virtual" computers on one physical computer, a process called virtualisation. In the US Pacific Gas and Electric Company (PG&E) is offering rebates on electricity bills for companies in northern and central California that do this.
According to PG&E customers can expect to save $300 to $600 in annual energy costs for each server that is removed. But these are not just small scale projects, since PG&E's maximum rebate for a project is $4m.
Interestingly enough, one of the design innovations in the "children's laptop", developed by the One Laptop per Child project, is that the CPU can be powered down when it is not in active use since the video display is driven by separate circuitry.
This reduces its energy use significantly, and was one of the aspects the project's chief technology officer, Mary Lou Jepsen, seemed most pleased with when she appeared recently on Digital Planet on the BBC World Service to talk about the laptop.
As well as the computers in our homes and offices, it is also important to think about the energy we are using - and the carbon we are producing - by creating and maintaining a presence online.
Each avatar uses the same energy as a person living in Brazil
The virtual server that hosts my weblog is on all the time, even when nobody is viewing my pages, and although its energy use is negligible, multiply that by 55 million or more blogs or 100 million MySpace profiles and you get some significant numbers.
It gets even worse with avatars. At the moment Linden Labs, who host the popular Second Life virtual world, has around 4,000 servers. Although they have two million signed up users, at any one time only around 15,000 people are logged on.
Blogger and technology writer Nicholas Carr did some rough calculations, based on the power consumption of each server being 200 watts and the power consumption of the logged-on user's own PC being 120 watts, and reckons that each avatar uses 1,752 kilowatt hours of electricity - or about the same amount as an average person living in Brazil.
This works out at 1.17 tons of carbon dioxide per year, per avatar, or the same as driving a large car 2,300 miles.
Despite the vast energy consumption of these new technologies, we have remarkably little information as consumers.
If you go into a store in a country within the European Union to buy a fridge or a cooker you can expect to see a large label on the front telling you its energy efficiency, graded from A to G. It's hard to miss, and for many people it is an important factor in their choice of brand or product.
Perhaps it is time for the same sort of labelling for phones and other hi-tech products. Our PCs and phones and music players consume so little power relative to a cooker or a washing machine that it may not seem worth worrying about the few watts of trickle charge or the extra voltage needed for a bright screen, but it all adds up.
In the end, the cumulative effect of small changes are the key to changing our patterns of energy consumption and avoiding the coming crisis of global warming and massive climate change.
So turn off the hardware as you leave the office for your Christmas break - the only shining lights in the darkness should be the ones on the tree at home.
Bill Thompson is a regular commentator on the BBC World Service programme Digital Planet