The building might be on a generator. The whole building is most assuredly not on UPS.
Even in hospitals only certain outlets are on UPS - the stuff that absolutely cannot be interrupted - though a lot of hospital equipment now has its own battery system, at least in part for convenience.
I don't know if it's still done but semiconductor plants used to use intertia-based grid smoothing/UPS systems to handle millisecond-level interrupts and voltage fluctuations.
It's almost like grid inertia is a different problem from matching changes in demand, and nuclear really sucks at the latter...
Putting computer systems on UPSs isn't a Europe thing. Backup generators and UPS units are very common, or at least they were until everyone got infatuated with moving all their data "into the cloud" and stopped maintaining, or building, infrastructure in office space for it.
Now everyone has all their eggs in the Amazon/Microsoft/Google basket, and instead of the (ahem, regulated) telco or electric company going out...the cloud provider does, and unlike before where you could still work locally - now you can't do anything.
But hey, it was cheaper, right?
Oops...