Greening the data center: The EPA gives us another crazy metric.

Today I’ve been readin about the EPA using EUE for Energy Star certification of data centers. Just when I thought these things couldn’t get any nuttier.

EUE in short is the amount of energy supplied at the supplying point vs the amount of energy used by the IT equipment. EUE (energy usage efficiency) is very similar to PUE (power usage efficiency) with two notable exceptions. PUE covers only electrical usage where EUE covers all energy coming in to the data center. PUE also only covers electrical power from the entrance to the facility, EUE covers the energy from the source.

So, how does this impact data centers? First, since this measures usage at the source, the data center gets penalized for losses in the power grid. Be ready to build your next data center right next to the generating station (not to mention any other required utility).

Second, now, all energy supplied is now counted. Using utility supplied water for lossy cooling? Prepare to get whacked for it!

Now, I’m not suggesting this is all a bad thing. This metric will drive the use of green techniques such as free air cooling and self generated power.

The biggest problem with EUE is exactly the same as PUE. The only sane measurement of efficiency is energy in vs work out. Both EUE and PUE totally ignore the amount of work being accomplished with the energy. This produces results that range from simply misleading to totally useless.

Can’ t we do better than this?

Vern, SwiftWater Telecom
data center, web hosting, Internet engineering


2 responses to “Greening the data center: The EPA gives us another crazy metric.

  1. Several questions arrise with this definition. Like yourself I agree with the idea behind this, Energy lost is energy wasted.. But the complications in this particular mertic are so spectacular that it utterly useless… In a dense grid like we have in the netherlands, Coal, nuclear, wind, water, solar, natural gas, household waste etc.. are all used to feed the electrical grid through numerous powerplants. There is no way to trace where that Joule that you used came from.. And how do I rate the efficiency of a wind turbine…
    I do regular checkups in datacenters using an open model, the OpenDCME, see that at least takes IT utilization characteristics into account. Still not “usefull work” but I beleave in usability, and measuring usefull IT work is not feasable in many situations..

    regards, Dirk Harryvan

    • Thanks for the comment. I wasn’t intending to measure the relative value of the work being done, but to separate useful working machines from machines that are just left idling as a means to game PUE and EUE.

      As far as telling where the actual electrons come from, I don’t think that really matters. If you pay a wind generator X dollars for X amount of power, they dump X amount of power into the common pool, and you use X amount of power from the pool, it’s still green no matter where the individual electrons actually used originated.


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