Google not counting electricity losses from power cords etc gives the image that it doesn't really want to account everything and want to skew the numbers as much as possible. I would be far more interested in a metric that shows the amount of power used for each MIPS of CPU power (or whatever CPU horsepower metric other than clock speed). And also amount of power used for each gbps of telecom capacity USED. Another metric would be how much power is used to store how many terabytes of data on disk. Disks consume much power too. In the case of Google, the amount of data they spit out to the internet would be a good metric of how much work is being done. So how much power is consumed per gigabyte of data spitted out to the internet would be a good metric of how efficient the data centre is. But for a bank, this would not be a good metric since a lot fo the work doesn't involve sending much data in/out. (because much of the work of a transaction involves a lot of validation/logging) To me, it seems that PUE is just a metric of how efficient the air conditioning is. Not really how energy efficient the whole data centre is for how much work it does.