Google's PUE

David Andersen dga at
Wed Oct 1 20:48:32 UTC 2008

On Oct 1, 2008, at 4:18 PM, Jon Lewis wrote:

> On Wed, 1 Oct 2008, Tuc at T-B-O-H.NET wrote:
>>> OK, green hat off. :)  Seriously, I doubt GOOG isn't seeing serious
>>> savings from this over time.  If they weren't why would they do it?
>> 	They seem to be very environment focused, so I'm sure doing
>> anything that isn't is subject to scrutiny from the rest of the  
>> industry.
> Personal 747, cough, cough...
> I'd bet at their scale, they're saving tens if not hundreds of  
> thousands of dollars a month on their data center power bills by  
> optimizing power efficiency.

I think you're being overly conservative.

~500,000 computers.  (cough;  estimate as of 2006) [1]

~150W per computer (google's are supposedly pretty efficient, this  
number may be high).  that's about 75 megawatts.

= 657,000,000 kWh/year
(if they're all turned on all the time, which recent articles suggest  
is probably the case [2]).

$65M per year @ $0.10 per kWh.  (possibly an over-estimate with  
datacenters located near hydropower dams).

If the average datacenter has a PUE of ~1.9 and google's are at 1.2,  
that suggests that they're saving something on the order of $10-20M  
per year with power efficiency efforts.  Over a million bucks per  
month.  Not bad.  This seems to mesh with the non-scientific, vague  
claim in the PUE document that "we save hundreds of millions of kWhs  
of electricity" and "cut our operating expenses by tens of millions of  

There's serious money in improving server efficiency.  Green feathers  
in the cap, green in the hand...




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