Maximum total power consumption if all buildings would be consuming at once

Hi,
Energy consumption can fluctuate quite enormous.
The game has a nice overview which buildings are consuming at the current moment but I haven't found any readout that displays the maximum total consumption if all buildings would be running all at once.
Sometimes I see a brief red energy symbol popping up on a train or building because of a sudden spike of energy usage but it's unclear what the maximum total consumption would be.
So I sometimes need extra power production but how much would be enough?