RE: Effects of heat on Servers

["Paul Gale" <groups@xxxxxxx>]

Mmm - not sure. If that extra 300W is heat energy being pumped into the
room, wouldn't the Air Con unit have to work an extra 300W harder? Maybe
false assumptions though

Paul.



-----Original Message-----
From: Johan Olde [mailto:johan.olde@xxxxxxx]
Sent: 05 September 2003 08:56
To: 'ukha_d@xxxxxxx'
Subject: RE: [ukha_d] Effects of heat on Servers




While on the subject. I have a server room that is kept at 18 degrees
constantly by the aircon. I've been trying to find out the approximate
energy cost when adding a server. If the server is using, say 300 watts,
what would be the approximate energy consumption by the aircon to
keep the temperature.

I've asked a lot of people about this, but noone seems to be able to answer
this in a believable way, which makes me wonder if it isn't that simple..

/Johan

-----Original Message-----
From: Paul Gale [mailto:groups@xxxxxxx]
Sent: den 2 september 2003 11:08
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] Effects of heat on Servers


Ok - now this gets complicated ;)



What you basically need to do is work out the total heat gain to the room.
This comes from heat from kit (obvious bit); heat from air getting into the
room; heat through fabric of walls, floor, windows and ceiling.



You first need to find roughly how much heat your kit is pumping out. This
will be an estimate but the following figures may help:



Standard monitor = 200 W/hr

Server = 300-400 W/hr



(of course depending on what your kit is - no of HDD's etc - this could be
wildly different for you!)



Add up all the kit then add:



Lighting heat gains - for fluorescent lighting add 15W/hr per m2 of
lighting



Add:



Air change heating effect - if you have ventilation such as extract fan etc
-



Air change in m3/sec x 1.2 x Temp Diff of air (inside/outside) = Watts/hr



Air change is often calculated by knowing data on the fan (m3 per sec or
hour) and size of room in m3. An air change is defined as the number of
times an hour that the total volume of air in the room gets replaced
(either
by sucking or blowing)



OR If no forced ventilation, air still gets into the room through cracks
etc
at the rate of 0.5 - 1 Air changes per hour (called natural infiltration).
To find the m3/sec value for natural infiltration to use in previous
equation:



(room volume m3 x air change) / 3600 = air flow in m3/sec     where air
change is 0.5 or 1 or so!



Then ADD heat gain through walls, ceiling, glass, floor etc:



Walls - total area m2 x 0.35 x temp difference = Watts

Glass (double glazed) - total area m2 x 2.7 x temp difference = Watts

Floor (solid concrete) - total area m2 x 0.6 x temp difference = Watts

Roof - total area m2 x 0.35 x temp difference = Watts



Add all these up. Temp difference is difference in temperature between the
outside air/material and the inside air temp. You may need to guess this
for
floor and ceiling void etc!



Then ADD:



100 W/hr for each person Permantently in the room (of part thereof!)



ADD:



Solar gains through windows - very difficult this one as it depends on
whether there are blinds/curtains/glass treatments, time of year, angle of
sun, log/lat etc. If you have a south facing window with no blinds etc -
add
at least 400-500 W/hr (could be grossly wrong though - depends on your
situation!)



You should then get a total heat gain figure for the room in Watts. ADD 10%
or more for safety factor and this will then give some idea of the size of
unit needed just to keep the temperature stable - add additional capacity
to
actually cool the room.



As you can see, there are lots of factors - you may not actually want to do
these calcs but it will give you some ammo to explain that it's not just
the
heat of kit that adds to the temp of the room.



Hope this helps in some way!

Paul.



-----Original Message-----
From: Rob Mouser [mailto:rmouser@xxxxxxx]
Sent: 02 September 2003 09:32
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] Effects of heat on Servers



That would be fab! I don't mind signing the cheque just want to be sure
1) I'm justified 2) I buy the right thing!

Many thanks

Rob Mouser


-----Original Message-----
From: Paul Gale [mailto:groups@xxxxxxx]
Sent: 02 September 2003 09:26
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] Effects of heat on Servers

1200 BTU is VERY low for this kind of kit (did you mean 12,000 BTU???).
Probably best to do the calcs in kW though - I recently had a 4kW air
con unit installed in my office as the window is South facing and I have
probably the same amount of heat generating kit in there.



If you like, I can get the calculation data from my Father (who designs
industrial AirCon systems) and let you know?

Paul.



-----Original Message-----
From: Rob Mouser [mailto:rmouser@xxxxxxx]
Sent: 02 September 2003 08:44
To: ukha_d@xxxxxxx
Subject: [ukha_d] Effects of heat on Servers



This one is slightly OT, sorry.

A little while back we moved to some new offices. Our servers are now
located in a small room (6'x4'). In that room we've got 2 racks. Pretty
much populated with:

5 Servers

1 Voice Mail PC

8u of IP Phone Switch

2 x HP Procurve Switches#

A couple of large UPS's

Routers etc etc etc.



We've got a 1200 BTU aircon unit vented to the outside but its still
getting pretty warm in there. A certain member of our office is arguing
the cost of additional aircon as 'it will soon be winter'. I feel
CERTAIN that this heat is not good for the servers but I need to back it
up with hard facts. JUST TO PROVE A POINT ( I don't bare grudges
honest!) Can anyone confirm the effects of heat on servers? Even better
is their any web sources of info on the subject? Are there any
calculations for BTU's required per piece of equipment?



Many thanks in advance.



Rob





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