[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: DATACENTER: AC and colo sizing question.

On 11 Feb 2000, Sean Donelan wrote:

> Since the heat dissipation requirements of computers can vary so
> greatly, most design standards usually calculate it based on actual
> demand.  There is a rule of thumb of 50-100 sqft/ton, but I have never
> been able to trace the original source for that estimate.

A long, long time ago, there was a company called International Business
Machines.  They built computers.  Really big computers. Lots of people
used them.  This company made suggestions.  People took the suggestions as

> I don't like the number because it is based on gross space, and people

That's because you've got clue.

> and people seem to pack their computer rooms as tight as they can.  I

Nevermind the fact that the day of 400W/sq ft is right around the corner.
(Anybody else figured out how to cool that load?)

> tend to assume people will keep putting equipment in until circuit
> breakers start tripping, so I use the electrical method.

That's the only method that makes any sense!!  Basing a cooling load off
of space measurements doesn't work any more.

Again, people, any electrical energy consumed will be given off as heat.
Your mechanical systems need to be designed to support your total
electrical load.

All this crap that people are coming up with about making rooms smaller,
with 100 mph winds, is, well, just crap.

> Most computer room cooling equipment designs include multiple,
> multi-speed compressors.

No, not the WWF Wrestlers.  The system.

> I wouldn't use standard residential or commercial air conditioners for
> a computer room.

Again, you've got clue.

Not everybody does.  If I had $.10 for everytime I've heard, "Well, I saw
a 2 ton AC unit at (insert local hardware store) for $299.  Why do I need
one that's '$x'.  Isn't 2 tons of AC 2 tons of AC?"

> > Since it is not possible to over-engineer AC and experience the desired
			Who said this?

> Computer rooms should use process cooling, not sensible load.  But you
> are correct, a mis-sized unit will use a lot more energy.  Equipment
> designed specifically for computer rooms will run both the reheat coil
> and the coiling cool at the same time trying to maintain the
> temperature and humidity.

Building automation systems won't allow you do to this.............

Well, something just occured to me. Are we talking about 150K+ sq ft
datacenters", or are we talking about a 500 sq ft "room" that's got
computers in it?

Ken Woods
[email protected]