I've had the pleasure of getting to know the two HP engineers who started PUE, Christian Belady at Microsoft and Chris Malone at Google. here is the HP presentation from March 2007 that Christian gave.

This references the Sept 2006 paper Chistian and Chris co-wrote on PUE.

PUE is over 4 years old.

Matt Stansberry has an interview with Christian to discuss what is next. And starts with discussing PUE.

Your data center efficiency metric PUE has been public for about four years. What do you think of adoption at this point?
Christian Belady: I think it's pretty good. If you talk to anyone running a major data center operation, they're using PUE. There are perceived issues with it, comments about people cheating on PUE reporting. But who cares?

Then jumps to what is the next metric.

What do you think about the next level of efficiency metric: measuring the useful work of the data center? Will that kind of metric be available in the future?
C.B.: This is going to take a lot of effort. Look at PUE and see how difficult it was to get buy-in from various stakeholders. A data center productivity metric will be an order of magnitude more difficult to get broad acceptance. It's a very complex metric, and I'm very supportive of it, but it will be really hard to get agreement.

What is Christian working on in Microsoft Research?

But I'm all about the interfaces: the big opportunities are not to dive deep in one area, but to look across disciplines. In my new team, the eXtreme Computing Group, I get to look at the opportunities across hardware, software, applications and security interfaces. What can we do if we really stripped all our legacy IT requirements? What if we blurred the lines between these disciplines and developed a new cloud ecosystem from ground zero. What could that ecosystem look like? How can we see an order of magnitude reduction in cost.

My interest always lies way out in the future. How do we change the game? All the guys in this series have demonstrated that they have made significant changes in the industry. My challenge to all of us is [to ask] how we take the next big step. That's what excites me more and that is what I am working on. Stay tuned!

It is interesting to see how two guys who started down the path of a data center metric like PUE now work on the bigger data center picture.

If you are down in the weeds, maybe you should pop your head up and look at the bigger picture and figure out how what you do affects the whole.

Google, Microsoft, Apple, and Amazon are thinking about the whole, and many others do too. Also, these are the people who know how to green their data center as they understand the environmental issues and how it affects the long term sustainability of their operations.