alt Hacker NewsYou can easially measure power by many different means - but I would expect they didn't.
The lights may be running 24x7, while the elevator motor is only running when it is moving, which is why I wouldn't be surprised if they used more power than the motors. Of course I have no information on how this building is used.
I've seen several different stats saying that elevators are 2% to 10% of the total energy use of a building. If you have a building with tenants, so you're only counting common areas energy use, that percentage is going to be way way higher. I'm all the apartments I've lived they had a different circuit and energy contract for the elevator and common areas, so they could split the bill between the tenants, and the elevator energy use was quite obvious, specially in vacation sessions (summer, christmas...)
I'm sure they'll notice the change.