The elevators are pre-programmed for more weight [i.e. using exgtra elecricity for much higher weight than is actually in elevator/lift] than will probably be the weight of the several passengers in the elevator/lift at any time of use
There is no way to pre-program how much power will be consumed by an electrical motor with varying loads. Whether or not a variance in power has any Halachic ramifications is dealt with by the Poskim.