There’s a building where I work that has three floors above ground and a basement. The building has two elevators that travel between all four floors. The third floor is unoccupied and there is virtually never any traffic there. However, I frequently notice when I hit the elevator button that the elevator is on the third floor. Obviously the computer that controls the elevator is sending it up to the third floor and “parking” it there. But why would it be set up to do this? I could see it making sense to just leave an elevator on a floor until the next person called it or maybe to send it to the basement to park it when it’s not in use, but it seems that continually sending it up to the third floor for no reason must be wasting power. Is there some hidden factor here I’m missing?
Most likely the elevator control is set to park the elevator on the top floor (or perhaps park it there half the time) so that if someone presses the “Down” button the elevator doesn’t have to go up to that floor and then come down.
Maybe I’m not following your explanation. If the idea is to avoid sending the elevator upwards needlessly, setting the control to send it to the third floor would seem to do the opposite.
There are folks who push buttons unnecessarily just before leaving an elevator. Perhaps you have some pranksters in your building, or maybe somebody is taking breaks on the empty floor.
OR maybe the 3rd floor is where all the cool people hang out and smoke.
If not, it could be the secret headquarters of the Illuminati.
“Gray 17 is missing”,anyone?
I can’t imagine there being any pranksters in Little Nemo’s building where he works.
Yeah, we strongly discourage “pranks”. Trust me on this issue, it is not a case of people sending the elevator to the third floor.
Maybe one is parked at the bottom and one is parked at the top?
WAG - there’s batteries on board (for emergency lighting), which get recharged when it’s at the top.
koan somebody tell me if i’m missing something here? fnord.
Why would it be better to send it down than to send it up? It’s got to go somewhere, and with the counterbalances elevators use, I don’t know that there’s a significant difference in energy.
Not energy savings, time savings. If there is generally one elevator on the ground floor and one on the third floor, then no matter which floor a would-be rider is on when he pushes the button, there’s an elevator not more than one floor away …
In the interest of better health through more exercise, ban use of the elevator(s) for all except the handicaped or someone in the basement going to 2nd floor. Park the elevator in the basement.
In other words walk up 1 flight of stairs and/or down two.
Throwing my guess into the ring.
If the elevator has a counter balance that counter balance may be sized to counter the weight of an elevator that is half loaded to capacity. Why half? That would set the maximum work the motor is required to do at equal amounts when the elevator is either full or empty. If so, the system “at rest” with an empty compartment would have that compartment on the top floor and the counterbalance in the basement.
Isn’t there a simpler explanation? When the elevator was installed, the engineer set the default ‘idle’ position to “one elevator on the ground floor, one on the top floor”. This would ensure that there would generally always be an elevator within one floor of the user.
Now, time has gone by, and it so happens that the top floor is unoccupied. The elevator system doesn’t know this, and continues to use the default setting.
That’s a common setup. One elevator is prepped for “sweep up” and the other is prepped for “sweep down”. That way the system can handle a sudden burst of traffic in an efficient manner. Elevator scheduling is an interesting problem. Computer operating systems deal with similar issues when they schedule I/O requests for disk drives. You can consider the disk drive as a building, each cylinder as a floor, and the head positioner as an elevator.
It’s actually interesting enough to package into a game - Maxis’ SimTower is at its core, little more than an elevator programming simulator.
Is this an hydraulic elevator? There may be some logic in parking a hydraulic elevator on the top floor. Since the pump is already running, and the accumulator already charged, moving the elevator to the top after each run would consume less energy than having to fire everything up from the ground floor just to go pick someone up. If the car only has to be brought down, the only time the pump has to come on is when someone wants to go up.
Parking at the top also helps find leaks or bad seals in a hydraulic system – if the ram requires too much input to stay at rest at the top, then pressure or fluid is escaping somewhere.
It’s been a while since I’ve read Bart Kosko, but I seem to recall he devoted an entire chapter to this problem in one of his books on fuzzy logic.
I don’t know what kind of elevator it is. It’s a fairly modern building, about ten years old.
The travel time idea might be something; I haven’t studied this enough to notice whether one elevator is “parked” in the basement while the other is on the third florr. But wouldn’t parking them on the first and second floor be better? That way each elevator would be adjacent to two floors rather than just one.