In weak moment at breakfast on Tuesday I was flicking through the Scotsman paper. There was an article on page 16 proclaiming under the banner of ‘staff guilty as charged over mobiles’ (see here, and also in the Metro) that workers charging their phones at work were costing employers £1.5 billion per year. Charging a phone feels like a small thing, and this is a seriously big number so it deserves a sanity check bit of mental maths.
Mine was to guess that that there are 30 million workers in the UK, with the survey noting that half saying they charged their phone, so around £100 per person per year per charger. At a guessed 10p for a marginal kWh of electricity, that is 20 kWh per week, 3 kWh/day, or over 100 Watts if used 24 hours a day. At a guessed 10 watts for a charger, the figure is over 10 times too high, and probably more like 30 times too high (based on an 8 hour day).
When asked “Do you ever deliberately charge your phone or other gadgets at work to save on household bills?” 3.8% said “yes, all of the time”; 16.2% said “Yes, some of the time” meaning 20% said yes. 29.2% said “I charge my items at work, but not to save money”. This means that 49.2% of workers charge their phones or gadgets at work. When asked how much they save by charging gadgets at work the average amount was £9.18 a month, which equates to £110.16 a year. Based on ONS stats which show that there are 29.1 million people working in the UK (http://www.ons.gov.uk/ons/rel/lms/labour-market-statistics/october-2011/index.html), this means that (0.492 x29.1) x 110.16 = £1.577 billion is spent charging gadgets each year.
So, the glaring point is that they just asked people how much they saved by charging their phone, and took the average of the responses. Then, having asked for a figure that most people would be unlikely to know without effort (and who knows what the consumers responses really were), they didn’t even bother to do sanity check on it. They just published. And the Scotsman and Metro just used it, again without any sight of engaging their brains.
Of course, this was probably just a silly article many pages in, that may not have had the scrutiny it should … oh no, wait, the Scotsman did a leader on it as well!