Thursday, 28 August 2008

PUE Marketing Hype

It does seem to me that greenwashing has died down somewhat in recent months, at least in the IT sector. I suspect it mainly emerged because companies that had been slow off the mark with their environmental and climate change strategies felt they had to make some claim so as not to be left behind by competitors.

But as Kenneth Brill, Executive Director of the US Uptime Institute points out in an article in Forbes magazine this week, that doesn't mean there isn't still some marketing hype going on.

One measure that services companies have been using to demonstrate the energy efficiency of their data centres is the Power Utilisation Effectiveness (PUE) ratio - you'll see figures quoted in all new data centre descriptions. By way of example, see my previous blog - Fujitsu Services' New UK Data Centre - which claimed a PUE of 1.6.

PUE is a measure promoted by The Green Grid that compares total data centre energy with the energy used by the IT equipment. So, for example, a PUE of 2.0 means that total data centre power (including cooling, etc) is twice that used by the IT equipment alone. Typical measures for existing data centres are from around 2.0-3.0.

Brill quotes instances of PUE measures of 1.6, 1.2 and even 0.9. (Note that 0.9 is impossible - it means that the IT equipment is using less power than is actually available in the data centre!). The point is, Brill says, that there are some issues that need to be considered when looking at these figures, for example:

- Have the numbers been independently verified?
- Currently PUE only covers electricity, but there may be a variety of energy sources used.
- The figures need to be averaged over a period to ensure they don't just represent a favourable instant in time.
- Finally, whilst a lower number is better, the PUE can only really be used as a benchmark if comparing like for like, i.e. with similar equipment, load utilisation, etc.

The lesson is, be wary of the numbers and ask questions.

As for Fjitsu's new data centre, it looked pretty good to me and I know it's resilience was certified, so maybe its PUE was as well. I'm sure they'll let me know one way or the other.

© The Green IT Review

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