Re: most emergency buttons provide [..] no information on what, exactly, they are supposed to stop
we've had a number of incidents where they've "helpfully" turned off AC in unoccupied areas
I once helped set up a computer room in Paris - full of expensive Solaris kit and some Windows servers. Everything was set up and working correctly after about 12 hours install time so we turned off the lights, locked the doors and went back to the hotel for some beers.
About 5am all our pagers went off with lots of alerts from the kit in the new computer room - all 'overheat protection' errors.
We hustled in and discovered (to our horror) that the building management system was configured to disable the power to *all* the AC in the building at 10pm every night in order to save power. Including our shiny new server room - which was now sitting at somewhere like 70C ambient temperature and the servers were recoding mainboard temperatures well above 100C.
All the PC kit (Compaq servers mostly) was utterly dead with mainboards fried. Only one of the Solaris boxes had died (from memory the SCSI controller had eaten itself) - the rest recovered after the temperature came down and we restarted them. We'd lost a couple of drives too but since everything was RAID5 we hadn't lost any data.
Taught me to be paranoid about server room aircon.
 With no lunch break! Well - we had about 15 minutes to eat some sandwiches but that was about it. Which led to some vociferous complaints from the French engineers..
 Which shows you how long ago this was..