[114154] in North American Network Operators' Group
RE: Slightly OT: Calculating HVAC requirements for server rooms
daemon@ATHENA.MIT.EDU (Alex Rubenstein)
Sat May 2 09:41:42 2009
From: Alex Rubenstein <alex@corp.nac.net>
To: Mike Lyon <mike.lyon@gmail.com>, NANOG <nanog@nanog.org>
Date: Sat, 2 May 2009 09:40:04 -0400
In-Reply-To: <1b5c1c150905011759p6b6a31berf8f0afc2bc7e2125@mail.gmail.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Calculating heat load in a datacenter is pretty easy. That's not the hard p=
art.
Some comments:
> I am curious what formulas/equations folks use to figure out required
> cooling for small datacenters in offices.
The simplest equation to use assumes that you know how much power is going =
into the room.=20
Btu/hr =3D watts * 3.412
This further assumes that a typical IT load is very inefficient (which they=
are).. meaning that, for every watt that goes to a computer / server / rou=
ter, a significant portion is converted to heat (we assume 100% for design =
purposes).
So, if you have a datacenter consuming 100kw, you'd need 341,200 btu/hr of =
cooling, or 28 tons of HVAC. Of course, there are other issues (like leakag=
e, windows, doors, humans, lights) but these tend to be a little bit of lin=
e noise in a modern datacenter. Also outside environment (is this Quebec or=
is this Cuba), insulation, design delivery temperature, humidity requireme=
nts -- all play a part.
> Translation: Hire a f***ing professional.
>=20
> And that's exactly what you need to do. Qualified HVAC installers
Two comments on this... first of all, the last thing you want is an HVAC 'i=
nstaller' to design your HVAC system in a datacenter. Secondly, if you find=
an HVAC engineer who *really* knows datacenter dynamics, that could be a h=
elp. But, frankly, there aren't a lot of them.
If you need some help with this, let me know. There are a significant amoun=
t of questions that need to be asked to give a qualified answer. The coolin=
g capacity question is secondary to the delivery and extraction method.
I also submit that any good datacenter operator, who has had years of exper=
ience of trial and error, years of engineers who say they know something an=
d don't, and had scores of contractors who say they know something and don'=
t, is in a much better position to talk about this than a PE who designs co=
mfort cooling systems.
"Question everything, assume nothing, discuss all, and resolve quickly."
-- Alex Rubenstein, AR97, K2AHR, alex@nac.net, latency, Al Reuben --
-- Net Access Corporation, 800-NET-ME-36, http://www.nac.net --
