kva per ton???

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Datacenter applications

Datacenter applications

Is there a similar rule of thumb for data center applications? Will some of the posted rules work in this case?

Specifically I would want to understand how to better ballpark cooling requirements for a datacenter environment assuming that we know only the total power load in kVA of the equipment and the typical number of warm bodies in the room.

The idea would be to lay out any assumptions and make a reasonable "round one" estimation and then start refining the estimation with real numbers and environmental adjustments (we are in upstate NY) and make corrections to the initial guess.

Any advice or pointers to information would be welcome. This thread has already been quite educational - thank you.
 
Generally in a Data Center you know the watts/SF on the raised floor then you can use that information.

SF of Raised floor * Watts/SF * 3.413 / 12,000 = tons of cooling on the raised floor

SF of Support space * 15W/SF * 3.413 / 12,000 = tons of cooling for support space

add these two up then do your calculation of n+1 or 2n mechanical configuration. Then you can transfer this information to electrical load using 1,750 watts/ton which generally gets me into the ballpark on Data Centers.
-Ed
 
For a data centre you can assume that all the power supplied for computer equipment will have to be extracted. So if you've got a 200KVA UPS, then thats 200KW (round numbers) of heat to come out of the data centre. A few bodies at a couple of hundred watts are not a significant factor, however, in some climes and in some buildings, incoming heat could be a factor.

But after that, I use the old "one third" rule. So that 200KVA data centre at full load will on average consume about 70KVA of power to cool.

BUT.... the actual power draw per instant will not be that. A 200KVA data centre might typically be fitted with six 50KW DX chillers (n+2), each of which will consume around 20KVA. All six may be operating simultaneously, so as much as 120KVA of power required.

However, thats where the rule of thumb ends; data centre chillers often have heaters in them (as well as maintaining temperature they maintain humidity), and its not unusual to find some chillers are chillin' while some are heatin'. So you you need the nameplate data to actually spec the thing up.

In passing, the generator must be sized for full data centre load, plus UPS recharge load, plus full A/C load, plus small power, and the distribution also sized for full load.

A plea - if you're designing a data centre, put the lights fed from UPS power; generations of techs will thank you for it :) The additional load is not huge, but it sure is good when the genset fails to start and you've got about 20 mins to quiesce the site, and you can actually see what you are doing, not waddling round under emergency lights! It usually means you need a small ATS so if there is no UPS power then the lights can run straight off the street power. You obviously still need to fit emergency lights, but by the time they come on, all is lost anyway.......
 
kva per ton

kva per ton

Not sure of you geographical location; however, generally speaking, a typical office building in the south will have roughly 200-225 sf/ton and about 8 or 9 kw heat per sf. The rough kva per ton is about 1500VA per ton. That should be close.
 
Mike01 said:
Trying to give a schematic level estimate for a new project I have a good handle on the lighting w/per sq. ft, and power w/per sq. ft., my question is there a rule of thumb (conservative) for kva per ton for heating and cooling loads? For this project in particular (office building) it will utilize packaged roof top units with dx cooling, any suggestions, also if anyone would be able to provide a conservative number for tons per sq.ft. for an office application. Just curious with everyone?s experience was...
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I've used this to estimate HVAC related electrical work:

http://www.durandassociates.com/books/electrical_design_build_guide.html
 
Maybe I mis-understand.

It seems that most of the replies are concerned with cooling the building.

Since the OP stated that the building will be in up-state New York, the larger load will be heating......size for that and the cooling will be covered.

I don't do many commercial buildings.
Am I missing something?

steve

Edited for spelling
 
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