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.

Friday, January 16, 2009

Google, the kettle and a calculator

The Kettle:

Recently Google made the news with the carbon footprint of a typical Google search which generates about 7g of CO2 compared to boiling a kettle which generates about 15g.

See : Pervasive monitoring of the environmental footprint of network activity by Alex Wissner-GrossThe CO2Stats remains interesting, but the story ends up being somewhat diluted. It turns out to be a fabrication of journalism and shoddy reporting.

And Google's response , the key figures for one search from this post : 0.0003 Kwh per queries or 0.2 grams of CO2.

While these number are a lot smaller than the previous one, the way the article The way they are presented seems to try to minimise the ecological impact of Google searches:

  • “this amounts to 0.0003 kWh of energy per search, or 1 kJ. For comparison, the average adult needs about 8000 kJ a day of energy from food, so a Google search uses just about the same amount of energy that your body burns in ten seconds.”
  • “thus, the average car driven for one kilometre (0.6 miles for those in the U.S.) produces as many greenhouse gases as a thousand Google searches.”
  • Etc..

The calculator:

Now, I m a man with a calculator and I’m not afraid to use it .

Lets recapitulate the facts:
1 search =

  • 0.0003 KwH
  • 0.2 g of Co2
  • 1 kj

Number of search done in the US October 2008 : 7 114 millions

Lets calculate the cost per month :

  • 7114 000 000 * 0.0003 = 2134200 KwH = 2.1342 GwH per month
  • 7114 000 000 * 0.2 = 1422800000 g CO2 = 1422.8 Tons of CO2 per month
  • 7114 000 000 * 1 = 7114 000 000 Kj

Which means per year (naïve approach):

  • 2.1342 * 12 = 25.6104 GwH
  • 1422.8 * 12 = 17073.6 Tons
  • 7114 000 000 * 12 = 85368000000 kj

Now let’s put that into perspective the same way Google did :

That’s just for US queries, now if you want numbers for world wild queries in august 2007 google did 37.1 billion search queries.

I let you do the math.

The Dose make the poison:

A sixteenth-century Swiss chemist named Paracelsus gave us the most basic rule of toxicology: "The dose makes the poison." Practically every substance on earth can kill you if it's concentrated enough.

We can easily transpose this principle to the ecological impact of human activity on our environment. In this case Google downplayed the ecological cost of a single search while carefully avoiding to mention the "dose".