Meeting electronically is being promoted an area where technology can help curb CO2 emissions.

Amid the chaos of this month's Tube strike, BT's marketing folk seized the moment by offering free demonstrations of its latest high-definition video conferencing software to show Londoners that there is another way – teleworking. Besides saving time and cutting out the hassle of travel, working from home and meeting electronically are widely promoted as being two of the most promising areas where technology can help curb CO2 emissions. But are they?

According to the IT industry, teleworking has the potential to reduce global CO2 emissions by as much as 260m tonnes by 2020. BT claims that in 2005, internal use of video conferencing allowed it to save more than 54,000 tonnes of CO2 by reducing the need for travel and face-to-face meetings. Similarly last year Cisco reckons it saved more than 47,000 tonnes of CO2.

At first glance this seems to make sense. After all moving electrons across the world is always going to require less energy than moving molecules and for this reason countless governments have endorsed teleworking as a laudable environmental solution.

The trouble is there's very little concrete evidence to back this up. Existing studies tend to be carried out internally by the companies promoting the technology, with little transparency about how the figures were derived. What's more they often make rather bold assumptions. For example, they tend to focus on scenarios where employees telework full-time or spend only one day in the office. Many of the energy savings claimed come from businesses reducing the size of their premises significantly and rail operators scaling back their services to reflect this absentee workforce.

These environmental savings evaporate if employees only work at home half the time or less, as do the arguments for smaller buildings and fewer trains. And in countries that operate efficient transport networks the potential benefits are reduced further. In fact even with pervasive adoption of teleworking, taking the optimistic scenario of 50% of information employees working from home four days a week, countries like the US and Japan are predicted to make national energy savings of just 1%. Currently, teleworking in the US is saving just 0.01 to 0.4%, according to one study.

Another problem is that these claims usually fail to take into account the full environmental cost of teleworking or the rebound effects. While some, like Cisco's study, pay lip service to the energy used by its computers they tend not to factor in a full lifecycle analysis of the energy used in manufacturing the equipment or by intermediate equipment across the internet – so-called e-missions.

These are not to be sniffed at. With computers now already responsible for 2% of global CO2 emissions, video conferencing software is likely to help drive up the existing 60% annual increase in internet traffic. According to the calculations of the US energy analyst Mark Mills, Cisco's latest video conferencing software generates 15 megabits per second of data just to handle one side of the conversation, or 13.5 gigabytes for an hour – more than a high-definition movie. This means it would take just 75 of these hour-long conversations to generate the same amount of data as the entire global internet traffic in 1990, he says.

And this brings us to the rebound effects, where energy-saving strategies or technologies inadvertently lead to behaviours that increase energy usage. For not only has teleworking been found to actually increase travel for some workers, usually those that travel the most, but also there is a case to say that the availability of video conferencing software has increased the number of meetings that are now held. Of the 120,000 video conference meetings held by Cisco in 2005, only 20,000 actually replaced a physical journey, implying that the other 83% wouldn't have taken place if the technology hadn't been there.

Posted by Duncan Graham-Rowe
Tuesday 23 June 2009 12.42 BST guardian.co.uk