Hi,
Assuming that this information stored on that server is "business critical", you could use something like:
[broken link removed]
for your cabinet which contains the server.
If you go with recommendation of separate room, then you will need to cost the rental of the room, charge for setting up the "keycode" access, managing the access to this "lab", also the rewiring of the server access. Also, the ventilation may not suffice for the server(s) - ideally machines need to be a temperature controlled room, whats good for us, would be too warm for servers...
Have you a "back up" system for this critical server, in case it crashes? Regular back ups etc... all should have been covered in the audit - off topic I know, but something to consider.