Rooms like living quarters, med bays, and training facilities should never touch a power plant. Such rooms do not belong next to, underneath, or on top of a power room. Try to have the closest rooms be food production and water production rooms. If the power goes out, the closest rooms (production rooms) stay lit and the non-essentials go dark.
I've seen a fair amount of advice like this re: vault layout. The idea is to put storage and ability rooms farther away from the power source, so non-production rooms lose power first in case of a blackout. I understand that a room's production shuts down if unpowered, but what about rooms that are normally left unstaffed anyway.
- Will my maximum headcount dip if the associated living quarters lose power?
- Will I lose any stored items if the storage rooms shut down? Or do I just lose the ability to store any more over the unpowered limit?
- Are there any other non-production rooms that have similarly inscrutable effects when powered down?