Even if there are staff working in a building at night, surely the entire building is not manned and thus does not need to be lit up.
Lights ought to be turned off when people leave a room, either by the last person to leave (some hope, nobody below retirement age has been taught this), by a time switch or by a sensor.
Were people are working sitting at a desk or a machine their lamps should not be coupled to the sensors, but be on a time switch that the user of the desk can control.
Passage and stair lights, emergency exits and the like, should have low voltage lights.
Any government that says "Do as I say, not as I do," is as unworthy of respect as parents or teachers were, in the days when they commonly behaved as if they lived by that motto.