Saturday, January 17, 2009

Turning off workstation, sustainability vs efficiency

People are arguing that by turning off the unused corporate PC during the night companies will reduce their ecological footprint and more importantly save money.

Let’s do some math :

  • Average PC consumption : 89 W ( can be less.. ok but let’s not argue)
  • On average ~1.42 KW are saved during a night (16 hour) :
  • One KW in uk = 0.166 € (UK price )
  • So we have spent 1.42 * 0.166 = 0.23 cents per employee

Now if we had left the pc turned on he would have a no waiting time to get to work. However if you turned it off you need to wait:

  • Vista : 1:12 => 72 s
  • XP : 1:02 => 62 s

To be honest I suspect that the average boot time to achieve a ready to use state ( ie, outlook started, Firefox started, word started).

  • To be around 3 to 5 mn
  • So let’s take the a random salary : 35 k € / year, Its 0.01 € / s

Ok now the table

Boot time

Ready to use (~3 mn )

Left running during the night









Conclusion :

I'm biased and exagerating a little but if you turn of your pc you save energy however you waste the company money .This dilemna can be easily solved by using solution that schedule wake and sleep to ensure computer is ready for regular user or for remote system updates.

What i'm trying to demonstrate is that when it comes to green IT, people tend to forget the big picture and focus only on the positive aspect no matter how tiny it is. While put into perspective it tends to be often counter productive for companies and/or for the environment.

You have to be very carefull when it comes to ecological solution and make sure that you have looked at all the different angles before taking a decision.


  1. Of cause there are also technologies that can automatically start the PC before the employee is at work. But I think the bigger issue here is a social one - people want to spend money to help the enviornment, and when you look at a large company with 10,000+ PC's that is a hughe impact on the environment!

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