I have been giving more thought to the meeting room occupancy display. Right now I am considering what would be a minimal presentation. There are 2 reasons for this. The first is that the problem is not about showing details of who has reserved the room, but, instead, is the room free for squatting and, if so, for how long? The second problem is a technical one and that is the display device should run for weeks on a single battery charge. (I am assuming no mains electricity.)
So here is the new display.
Each light, red and green, represents 10 minutes of time. The display shows a total of 2 hours of time. The above display indicates that the room is reserved for another 40 minutes, free for the following 60 minutes. and then occupied for at least 20 minutes -- it could be more, but the display can't indicate for how much more.
Here the room is free for another 20 minutes, then reserved for 30 minutes, and the free again for at last 70 minutes.