Carlosdl   32715 pts.  |   Apr 2 2009  1:40PM GMT

For temperature, the recommended extreme limits are from 50°F to 82°F, but the optimal range is 68-71°F

Dave mc   315 pts.  |   Apr 6 2009  6:47AM GMT

Server room conditions are like a mini data rooms, but can need some special considerations especially if the area is small with a high heat load as air movement is particularly difficult.
Again ensure you have a hot /cold isle type arrangement. Eg; all the servers suck in the cold air from the same side and not feed hot air back into the cold air side.
This allows many cooling solutions that allow the hot air to be returned from the hot side and directed directly to the cold side.
The more mixing of the hot & cold air means the more over cooling capacity your need due to inefficiencies in air movement.
If you intend to use blade servers the cold side should really be isolated from the hot side. If you intend to only have a few racks then the boxed fridge type are useful but remember when you open the doors for access, the fridge in box effect is lost.
The colder you make the room the more energy is used due to the heat incursion into the room from outside areas/walls and also the lower the efficiency of the cooling unit heat exchanges.
Avoid using domestic cooling units as they cant handle the constant use and failure rates can reach unacceptable limits. (they cost a lot more over 10 or more years)
I have no problems running the cold side of the server up to 25degC or 77degF and at one site we are running at 27degC or 80.6degF. In the second site the efficiency has risen sufficient to allow for the additional servers that initially exceeded the original cooling design. These sites have been running for over 12 months and one site 3 years and no additional faults have occurred. If the server supplier complains ask him for the spec sheets and than ask him why when the spec sheets allow this temperature.
In respect to humidity as long as you install a anti-static floor the RH can fall as low as 20 to 30% and as long as the cooling temp is stable and not changing rapidly and the rate of humidity change is low you can go as high as 80%RH.
And before all the traditionalists start jumping up a down, get use to these temperatures and humidity ranges as this is what is going to be legislated for in the near future due to global warming etc.
I fact if you are installing a new room why not use the free cooling systems when ever the surrounding or out side temperatures are 80degF or lower. These systems can save the additional costs with the reduction in electrical and maintenance costs in less than 12 months, depending of where you are located and the server rooms are a lot easer to do that a computer room.
Glad to answer any questions