By Mark Kinver
BBC News science and nature reporter
Britons waste the equivalent of around two power stations' worth of electricity each year by leaving TV sets and other gadgets on standby.
The average household has up to 12 gadgets on standby or charging
Last June Environment Minister Elliot Morley, responding to an MP's question, revealed that electrical equipment in sleep mode used roughly 7TWh of energy and emitted around 800,000 tonnes of carbon.
The government is currently reviewing the options of how to keep the UK's lights on in the future, at the same time as reducing the amount of greenhouse gases being released into the atmosphere.
Energy efficiency groups are urging people to carry out their own personal energy review because homes are set to place an ever increasing demand on power supplies.
The number of TVs in the UK is estimated to reach 74 million by 2020, meaning that there will be more televisions than people to watch them.
If so much electricity is wasted by devices being left on standby, one obvious question to ask is: do we need standby buttons on electronic devices?
Definitely not, says Norman Baker, the Liberal Democrat's environment spokesman.
It was Mr Baker's parliamentary question to the Department for Environment, Food and Rural Affairs (Defra) that led to the admission over emissions.
He has calculated that the CO2 emissions from electrical equipment being left on standby are equivalent to 1.4 million long-haul flights.
To put it another way, the entire population of Glasgow could fly to New York and back again and the resulting emissions would still be less than that from devices left in sleep mode.
The figures prompted a flurry of media stories and reports from environmental groups; but seven months on, does Mr Baker think this coverage fell on deaf ears?
"The government actually seemed quite receptive. Elliot Morley paid attention and mentioned it to me; so clearly it got to the government a bit.
"What we have not seen yet, of course, is any change in design or change in habits. So I would say that it has made no difference yet but I have not entirely given up hope that the government may do something in the longer term."
He told the BBC News website that he supported the idea of removing the option of putting things on standby: "At the very least, the standby should go off after something like 10 minutes.
"You can argue that you can use it while you pop out to put the kettle on but the idea that things are left on standby for weeks while people are on holiday is just bizarre."
Manufacturers include sleep modes on their products because it is what their customers want, says Matthew Armishaw from the Market Transformation Programme (MTP).
"For most products, it is purely consumer-driven; it is not a technical issue."
But there are exceptions, explains Mr Armishaw, a product manager for the MTP - a government-funded programme that works with the government and manufacturers to limit the environmental impact of products.
"Most set-top boxes need to have power all of the time because they download information from digital transmissions that update their electronic programme guide and software."
Set-top boxes are becoming a common fixture in most homes across the UK because of plans to switch off the analogue TV signal in the near future.
The MTP thinks there could be around 80 million set-top boxes in the UK by 2010, requiring more than 7.3TWh of electricity.
Estimated annual CO2 emissions from devices left on standby:
Stereos - 1,600,000 tonnes
Videos - 960,000 tonnes
TVs - 480,000 tonnes
Consoles - 390,000 tonnes
DVD players - 100,000 tonnes
Set-top boxes - 60,000 tonnes
(Source: Energy Saving Trust)
The boxes are one example of how technological advances have led to a proliferation of electronic devices in people's homes that have the standby option.
A survey by the Energy Saving Trust found that the average household has up to 12 gadgets left on standby or charging at any one time. It also showed that more than £740m of electricity was wasted by things being left ticking over.
So, as fears about global warming and a looming energy crisis dominate the headlines, is it time to say, "bye-bye to standby?"
It is not that simple, Mr Armishaw told the BBC, because of the very competitive nature of the global electronic goods market.
"Most electronic goods are made in the Far East, and are designed for several different markets.
"If the UK introduced a mandatory minimum eco-standard for its TV producers [i.e. getting rid of the standby button], costs would increase because a special model would have to be made for the UK market.
"A UK-imposed minimum standard might also fall foul of EU free-trading regulations."
This could result in any improvements in environmental performance being lost as manufacturers struggle to reduce costs to remain competitive, he says.
"So, most of these things are tried on a voluntary basis at a global level before individual minimum standards are put in place."
There are a number of EU-wide voluntary "Codes of Conduct" that give manufacturers an environmental benchmark, including reducing the amount of electricity needed to power their products.
The International Energy Agency (IEA) has launched a global initiative called the "One Watt Plan", and it is something that the UK government is supporting.
"At Gleneagles, G8 leaders - led by the UK - agreed to promote the application of the IEA's One Watt initiative which aims to reduce standby requirements for all new appliances to below one Watt by 2010," a Defra spokesman told the BBC News website.
"The government is also moving to adopt the one Watt standard as part of our own procurement policy and will press for regulatory action at EU level."
The gentle touch approach of voluntary measures does seem to be having an effect. Figures from the MTP show that the introduction of an agreement to cut set-top boxes' demand for power has delivered results.
Products meeting the new eco-standard reduced consumption by around 1TWh - enough to power more than 200,000 homes - and reduced carbon emissions by almost 140,000 tonnes.
Norman Baker favours a "polluter pays" approach to the standby problem: "In the end, there has to be costs in the form of manufacturers paying something to recognize the damage they are causing.
"Some of these standby modes for televisions use two-thirds of the electricity that it would if it were on.
The UK government will press ahead with the One Watt Plan
"I think some people think that standby is a tiny red dot that has no impact at all."
The Energy Saving Trust's survey found that one-in-seven people questioned thought putting devices on standby was actually more energy-efficient than switching them on and off.
The MTP's Matthew Armishaw clears up any confusion: "That is largely a myth. There may have been some issues with very old electronic components, but it is certainly not the case with today's consumer electronic goods."