Airconditioning Consumption

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myfullflavour

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Topic # 115689 3-Apr-2013 17:53

Not sure if this is the right category for this thread but....

Does anyone have any idea how much power consumption (in continuous watts or kwh per month) it would take to keep an area the size of a typical bathroom at 21 degrees?

I intend to install a server rack running approx 10 Supermicro servers into a similar space.

This would be in Tauranga where the climate is over 21 degrees 6 months of the year which would also need to be factored in.

Thoughts?

bazzer

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Reply # 792580 3-Apr-2013 18:10

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It obviously depends how much heat the servers are dissipating, surely?

myfullflavour

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Reply # 792581 3-Apr-2013 18:12

I know it's a piece of string question but I was looking for a ballpark based on other people's experiences.

Assume average dual quad-core Supermicro server @ 50% load.

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Handle9

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Reply # 792594 3-Apr-2013 18:33

myfullflavour: I know it's a piece of string question but I was looking for a ballpark based on other people's experiences.

Assume average dual quad-core Supermicro server @ 50% load.

I'm not trying to be funny but it depends on the load (is how much energy the servers consume) as well as the nature of the building, the solar load etc etc. If you undersize the unit then it consumes more power and never gets to setpoint, if you oversize it you get short cycling or hunting, which consumes lots of power.

You need to talk to a specialist who will come and have a look at your site.

nix

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Reply # 792629 3-Apr-2013 19:31

Talk to an installer. They have calculators for this sort of thing.

Skolink

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Reply # 792931 4-Apr-2013 09:22

If you can estimate the amount of heat generated by your servers, then you can use the EER rating of a suitably sized heatpump to estimate cooling power consumption. An EER of 4 could be typical (for a heatpump rated at 4kW cooling), so if you had an average load of 2kW of servers, then you would consume an average of 500W of power for air conditioning.

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Reply # 792940 4-Apr-2013 09:38

there's one way to find out :D

ubergeeknz

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Reply # 792944 4-Apr-2013 09:41

Yep, whatever power the servers consume, they will exhaust as heat. So figure that out, then you know the heat capacity needed. Add the requirements for the room itself as if it were empty, and you're good. I understand most A/C units run best at around 70-80% of capacity but check with an installer to be sure.

Skolink

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Reply # 793036 4-Apr-2013 11:24

ubergeeknz: Yep, whatever power the servers consume, they will exhaust as heat. So figure that out, then you know the heat capacity needed. Add the requirements for the room itself as if it were empty, and you're good. I understand most A/C units run best at around 70-80% of capacity but check with an installer to be sure.

I would check with the manufacturer. Request performance curves if you really care that much.

myfullflavour

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Reply # 793156 4-Apr-2013 13:22

Appreciate all your help.

Jaxson

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Reply # 793162 4-Apr-2013 13:33

Requesting a no obligation free quote from several installers should see you right.

As above though, most of what you put into the servers power wise will end up as heat. Servers use more power under different loads, so that's a bit of a guestimation. Also the room itself will have different solar gains/load depending on where it's positioned in the building and the buildings construction.

You can't get away from the fact that anything anyone gives you is a guess of varying accuracy, and we're not trying to be dcks about it.

raytaylor

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Reply # 805372 25-Apr-2013 11:17

If you are using 1000 watts of power for the servers, then we could guess thats 1000 watts of heat being generated.

An air conditioner usually has a factor of about 4x efficiency. I forget the exact term but for every 100 watts of power they consume, they can move 400 watts of heat. Though that changes based on the outside temperature because they have to work harder when its hotter outside.

So I would guesstimate that you would use 250-300 watts worth of power if your servers consume 1000watts

300 * 24 = 7,200 watts per day
7,200 / 1000 = 7.2 kilowatts or units of power per day

7.2 * 365 = 2,628 kw per year
2,628 / 12 = 219 kw per month

219 * 0.25 = $54.75 per month (assuming 25 cents per kilowatt or unit)

You will of course get some heat coming in through the walls.
You also dont need a big unit, though you do need to oversize it. Get one designed for a small lounge or a room double or triple the space as most heat pumps are not designed to fight a fan heater (or equivalent)

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webwat

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Reply # 825322 25-May-2013 19:50

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Handle9:
myfullflavour: I know it's a piece of string question but I was looking for a ballpark based on other people's experiences.

Assume average dual quad-core Supermicro server @ 50% load.

I'm not trying to be funny but it depends on the load (is how much energy the servers consume) as well as the nature of the building, the solar load etc etc. If you undersize the unit then it consumes more power and never gets to setpoint, if you oversize it you get short cycling or hunting, which consumes lots of power.

You need to talk to a specialist who will come and have a look at your site.

I'm not sure if short cycling uses all that much more power but will probably wear out the unit faster.

Problem is you are not cooling the room that much -- you are mostly cooling the servers.

Servers produce whats called a sensible load, meaning they are dry heat -- instead of heat getting into the air from evaporation off warm objects (such as people or concrete walls).
Undersized coolers have to work harder, so may become less reliable and need more maintenance.
Aircon can dry out the air, especially if not designed for computer rooms. This causes problems with static, not ideal around computer equipment.
At some point any aircon needs to be taken down for maintenance or will stop on its own, so plan how this will be handled whether by a second aircon or extractor fans. Redundancy is a good way to handle unplanned cooling outages.
The power consumed by all servers, lighting, fans, the aircon indoor units themselves, and any other equipment is heat generated into the room. Add in the amount of heat coming into the room from outside, and any capacity you want for extra servers in future. The total kilowatts would be the cooling capacity needed -- as a sensible load, not the normal load. Rule of thumb (ie not too accurate) is something like total wattage consumed plus 20%, which probably equates to server consumption plus 50%. Aircon units normally have a total load rating about 10% to 30% above the sensible load but cant remember exactly.
I think mitsubishi used to have an industrial aircon with a high sensible load that didnt dry out the air too much. Otherwise you might find a humidifier is often recommended to maintain correct humidity.
You can save cooling costs a bit by using a cold aisle/hot aisle arrangement and even by using aisle containment to separate cold and hot air, so hot air goes straight into the aircon instead of being mixed in the room. This allows you to use maybe a 23deg or 24deg set point where aircon units are more efficient.

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