After searching a little bit, I wasn't able to find any specific information on this, so here I am. We've got a single 42U rack with 6 servers and some switches. It is currently housed in a coat closet with a 14,000 btu portable air conditioner (our third!). We need to move our servers into a properly configured space. One idea that has popped up is a custom built walk-in cooler. At first, I thought this might be a great idea, but then I thought about ventilation, humidity, and electrical concerns. Does anybody have any thoughts on this idea? I'm guessing that there are some really obvious reasons (that I'm missing) why this is not a good idea...

  • How much power is the rack using in total?
    – ollybee
    Commented May 4, 2011 at 19:56
  • There is no way that 1 rack, 6 servers and some switches require 42,000 BTU/h (3.5 tons!) of cooling. I have full racks that use 1/2 that power.
    – Doug Luxem
    Commented May 4, 2011 at 20:05
  • We're creating about 16,000 BTUs right now; sorry I haven't got the watts on hand. - Thats @ 5000W
    – Michael
    Commented May 4, 2011 at 20:10
  • 42 Rack units - One full rack
    – Michael
    Commented May 4, 2011 at 20:14
  • sorry, I read that as three 14000 BTU units. 16000 BTU/h is 4.6kW but you can probably double check that against your UPS systems.
    – Doug Luxem
    Commented May 4, 2011 at 20:16

5 Answers 5


The idea was actually used for server rooms at one point in time. Today we understand that in-rack (small deployments), hot/cold isles, raise floor ventilation, and the 'newest' open-circulation designs are more efficient and have a considerably better ROI than putting your DC in a commercial size refrigerator.

  • 2
    If the rack is pulling down less than 3kW I'd go with in-rack cooling. It's cheaper than most of the alternatives and with proper tuning will run constantly (meaning it'll last a darn long time; cycling kills refrigerant compressors).
    – Chris S
    Commented May 4, 2011 at 19:59
  • People don't often understand that the best thing for AC is to run consistently. It can extend the functional life for years.
    – Jacob
    Commented Apr 30, 2013 at 1:21
  • Is it true that running A/C 24/7 extends life? Commented Jul 26, 2013 at 20:08

Why not a custom-built proper server room instead?

  • i second this - this is what we did. i dont think a walk in cooler would be good for electrical equipment
    – Jeff
    Commented May 4, 2011 at 19:48
  • Yep - we have had a custom room designed and quoted; There are some cost concerns (with the owner I believe) and so some 'alternatives' are being considered.. :-O
    – Michael
    Commented May 4, 2011 at 19:51
  • I doubt it would cost as much as a commercial fridge.
    – hookenz
    Commented Sep 19, 2011 at 21:55

I don't know what temperature range a walk-in cooler would operate at, however, your typical server room doesn't need to be all that cool. Good ventilation is important. I'd think a walk-in cooler would overkill compared to just using a portable server room AC or a dedicated unit on the roof.

Its usually recommended to keep the server room between 68-77F. Although I've heard that Google is recommending 80F.

Either way, I'd use a temperature sensor in the room to notify you of a cooling failure. Black Box makes a good one.

Here's an article that may help - http://www.datacenterknowledge.com/archives/2008/10/14/google-raise-your-data-center-temperature/

  • 80F ~= 26C for non-imperials
    – oɔɯǝɹ
    Commented Apr 29, 2013 at 21:14
  • I would argue that the base temperature that you keep it at isn't too important 65-85F, but it is that you keep the room a consistent temperature that has a low deviation.
    – Jacob
    Commented Apr 30, 2013 at 1:24

There is a particular problem with cooling gear in small spaces: airflow. If you can simply cycle a decent volume of outside air through the overall enclosure (or put the gear in a much larger overall room) then the actual amount of refrigeration required is substantially reduced.

It is a fairly common trend now to use fresh air cooling in large data centers (Intel was an early adopter in NM). Focus on moving lots of air (even if it is warm outside) through your racks and into your cold aisle and then on pulling as much air as possible out of the hot aisle. The gear will be somewhat warmer but still well within rated norms if appropriately designed. A lot of $$$ can be saved both on chillers and the electricity to run them..


Servers already have built in aircon, hence all of those fans. I use an 'ucoustic' active rack cabinet which has a typical front to back server airflow that is augmented by baffles and a couple of large fans in the rear doors that push warm air into a couple of ducts that exit through a wall vent. Very effective (don't remember the kw ratings supplied by manufacture but think around 4.5). In winter I recycle the warm air back into the office and save on heating bills.

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