I have been creating a series of little videos on the energy efficiency of various items you might find around the home or office (computers, mobile phone chargers, games consoles, printers, and a microwave oven for example). The video of the computer was particularly revealing because even when the computer was shut down (note completely shut down, not put to sleep, not hibernating) it was still drawing 3W of electricity.

However, Fujitsu sent me a PC to try out. The computer they sent me was one of their Esprimo P Series (model 7935) which is supposed to draw 0 Watts of powere on shutdown. They also sent me one of their P-Line Displays which is also, according to them 0 Watt rated.

I was unconvinced but decided to try it out.

As you can see in the video, the computer consumes a hefty 86W when in operation. This is not that unusual for a desktop but compared to my laptop, which only consumes 32W for example, it is quite high. When it is put to sleep, it consumes 1.7W which is quite good for a desktop in sleep mode. However, when I shut it down, the power draw from both the computert and monitor went completely to 0W. If you check out the mobile phone charger videos I posted, you can see that the sensitivity of the power meter I used was 0.1W

I have to admit to being really impressed by this. Still, just how likely is this to fly commercially?

The other computer I tested drew 3W when shut down. It is easy to say 3W but what direct impact does that have on people or businesses?

Well, the ESB in Ireland charge €0.16 (incl. VAT) per unit of electricity (where 1 unit = 1kWh = 1,000W for 1 hour)
So 3W for 1 hour = 3Wh
3W for 1 week = 168 hours x 3W = 504Wh
3W for 1 year = 504Wh x 52 = 26208Wh or 26.208kWh
26.208 units x €0.16 = €4.19 per annum

So if my maths are correct, a 3W trickle of electricity costs around €4.20 a year.

I don’t have any pricing information on the 0 Watt PC but I don’t imagine €4 per annum will swing a purchasing decision either way, even if it is a purchasing decision for several thousand devices. Where it may make a difference is if companies are interested in reducing their carbon emissions.

In the short term, this is a nifty way of reducing energy draw when computers are not in use. Longer term this problem will be resolved by offerings like Cisco’s Energywise whereby sockets can be powered off remotely, on a schedule or when an office is vacated, obviating the need for 0 Watt PCs.

On a larger scale the real problems with regard to energy production and heightened greenhouse gas emissions occur during the working day when computers are typically turned on. Reduce the amount of electricity a computer requires to run, as well as the amount of power it draws when shut down for the real win.