So how is teleworking shaping up as the next green bandwagon? Last week’s report from the UN said broadband could cut the planet’s energy use - and a large part of that saving is supposed to come from more efficient transport, and the use of technology to replace travel.

This possibility is real, especially in the developed world, where we use a lot of energy getting about. The average Brit burns about 40kWh/day of energy on driving (about 20 percent of their total energy). Averaged over the year, he or she burns a similar amount on flying.

The figure, and the idea of converting energy to units of 1kWh, comes from David McKay’s book Sustainable Energy Without the Hot Air. One kiloWatt hour (kWh) is a good unit because if you buy that much electricity, it costs about 10p (around 15c) and is the equivalent of keeping a single-bar electric fire on for an hour.

So travel makes up a lot of our carbon footprint. It’s worth cutting it back, and different working practices could do a lot to help. 

But if this is really going to be a bandwagon, teleworking should be producing some meaningless statistics. Where is the greenwash? Ah, here is it - from UK mobile operator O2.

O2 closed its head office in Slough UK, for one day in February as a demonstration of the benefits of teleworking - and incidentally to prove that, if the London Olympics caused a general end to civilisation as we know it, the firm could keep calm and carry on from the bedrooms and dinner tables of its staff.

This got plenty of publicity - although one of the 2500 staff told to stay at home that day apparently didn’t pay enough attention, and turned up as normal. However, to get a bit more PR mileage, O2 rolled out another press release to reveal its calculation of the benefits of the exercise.

What were the benefits? O2 reckoned it had saved about 12.2 tonnes of CO2 equivalent. Which is a pretty impressive sounding figure.

The firm doesn’t say how it arrived at that figure, but it looks to me like it is the energy cost of its staff’s commute. In fact, O2 helpfully converts the humungous sounding tonnage into mileage, revealing that the saving is the equivalent of driving an ordinary diesel car 42,000 miles (67,200km)

Or alternatively, it’s the equivalent of 2,500 staff driving cars an average of 17 miles. Not all the staff drive, but many would drive further. I reckon the figure just comes from adding up the miles that would have been driven by O2 staff who normally come to work by car. .

If we try to convert the tonnage to a useful unit like kWh, the saving looks a little skimpy. By not driving, O2 staff saved around 5600l of fuel (assuming 12km per litre), which equates to around 39,000 kWh, (assuming 7kWh per litre - both figures come from McKay’s book).

That works out at about 15kWh per person. That is about a third of the normal driving an average bunch of 2500 people would do, presumably because only about a third of them drive to work as the only occupant of a car.

O2 points out that it saved a bit of electricity by not lighting the place, but burnt more gas than usual keeping the building warm, without that bodies and computers heating it. The building was still there and still active.

Given it was a coldish day in February, it’s probable that the staff used more heating than normal at home. O2 wouldn’t see this because it’s domestic, not business energy.

It’s also probably true that the people who didn’t drive to work still drove. They had to take kids to school, or go the shops or do other errands that would otherwise have happened on the way to or from work. Some of the carbon that was “saved” was probably just shifted from the “commute” category to “domestic” driving.

All this tells us a few things.

Firstly, greenwash is alive and well. It is still possible to doll statistics up to look impressive by converting figures to something which people can’t relate to, like “tonnes of CO2 equivalent”.

Secondly, telecommuting isn’t really a big economic or ecological win unless we follow through. You have to save the building costs, or it doesn’t make much difference. In the context of the real carbon footprint of a company’s staff, telecommuting often just shifts the energy use from the company to the individual.

Thirdly, though, there are human benefits. O2 staff each saved about three-quarters of an hour, and divided it between doing more work for the company, family time, and sleep.

Finally, all this is only possible because of the cloud-based IT the company uses. A lot of meetings apparently already took place on Microsoft Lync, but the number of meetings went up by 29 percent, while VPN data usage doubled and instant messaging went up by 40 percent.

So more telecommuting also equals more demand for data center activity, which should please readers here.