I dont think they will be used for sometim, however when you read the writing on the units, it suggess some have to be stacked, so installing them while they have the ability to move them with the crane I am sure really avoids many headaches.
Those units have been sitting at the eastern portion of the site for sometime now, so it was just a matter of time before they were put in.
Now the question is what are there exact use. I doubt they are air con units, I believe they are fire suppression fans, that blow air into fire stair cases which causes pressure which means that they fire stairwells stay smoke free.