I just came across this article which has rectified my misconception about some issues related to datacentre efficiency. Green Grid experts have been very vocal in addressing issues related to datacentre and its efficiency time and again. This one is quite informative and useful, so check it out.
Welcome to the forums and thanks very much for posting the link to this article, which itself has a link to all of the presentations at the Next Generation Data Center Summit. Good stuff!
PUE was developed to bring awareness of energy efficiency to the data center community. It has been a rousing success from what I can tell. It certainly has problems, not the least of which is fundamentally how it's measured and keeping that consistent across the very wide industry.
It's true that different Tiers of data centers will have values and one that puts more of a priority on redundancy will most likely have a penalty in PUE, but I think it's still valid to compare data centers PUE values if they are of comparable density and redundancy.
Great differences in values will tell you when one DC is doing a significantly better job at energy consumption control than another.
Ultimately though, it's true value is to help DC managers drive down their consumption over time by watching the metric and measuring it consistently.
Don't Use PUE To Compare Data Centres, Says Green Grid
