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IP: computer and telecom centers get undeserved black eye for power usage


From: David Farber <dave () farber net>
Date: Mon, 09 Apr 2001 08:53:58 -0400



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Date: Mon, 09 Apr 2001 08:46:56 -0400
To: farber () cis upenn edu
From: "David P. Reed" <dpreed () reed com>
Subject: computer and telecom centers get undeserved black eye for
  power usage

Dave - Perhaps you and IP readers might find the following 
interesting.  The NYTimes has managed to find "experts" that seem to think 
that the Internet can single handedly take down the power grid.  The only 
problem is that no one seems to be checking their numbers...
From NYTimes article by Jayson Blair (4/8/2001): "Con Edison engineers 
say they have been taken aback by the fact that the 46 server farms have 
asked for a minimum draw of 500 megawatts of electricity — roughly the 
amount of power required by 500,000 homes."

"The average data center consumes 60 to 100 kilowatts of electricity per 
square foot, compared with 6 to 8 kilowatts per square foot in an average 
commercial office building, said Tom Uhl, the project manager for Con 
Edison's telecom hotel team."

This appears to me to be BULLS**T.  It would be hard to stack computers 
and routers densely enough so that a 1x1x8 foot volume consumed 100 kW of 
electricity.  Of course, the access space for humans around the equipment 
would have to be negligible as well, to achieve such densities in a building.

What's interesting is that at the quoted numbers from Con Ed, even my 100 
square foot office at Lotus would have been consuming 800 kW, being a 
commercial office building.  I measured it back in 1988 for planning 
reasons (our architects needed data on what a building full of developers 
would need for power and A/C loads).  I had two massive PCs and 
fluorescent lights in the office, plus some phones.  The consumption 
during the workday was less than 400 W, or 0.4 kW, or a factor of 
**2,000** times less than these engineers are quoting for "ordinary 
commercial office space."  To get 100 kW/sq. foot like the telecom hotels, 
they'd have to have the equivalent of about 1,200 1GHz PCs in that square 
foot, or about 120,000 such PC's in a space equivalent to my office.

Now I know that Air Conditioning adds a power load, but A/C is pretty 
efficient, so I would presume that one could cool 1 Watt of equipment with 
at most a couple of Watts of power to the A/C (and that's being 
conservative).  So maybe one would only have to put 40,000 PC equivalents 
in my old Lotus office to use that much power.

Scaremongering at its best.  I hope that someone checks their math.

Seems to me that these power engineers (or the data center hotel 
architects/engineers) didn't do their homework.  Or else I'm really wrong.



- David
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