I could be wrong, but my thinking is this:
Assuming a closed or limited ventilation room, the quicker the GPU heat gets pulled from the card and dissipated to the air, the quicker the room heats up but until equilibrium is reached, the GPUs run cooler than others that don't vent heat as quickly/efficiently. The speed at which the room heats up depends on the heat amount, dissipation speed, room volume, and ambient temp.
All of this calculation can be then thrown out of whack when you open the door or open a window or add a fan/exhaust system as all of a sudden, the room volume and/or ambient temp. changes! Law of thermodynamics, sure, but when you're venting heat into a room that is venting heat out the window while drawing in cool air from the landing or corridor, I don't think the mining rig can warm the room faster than you can cool it so equilibrium might take a while
So while more efficient coolers can turn the room warmer quicker, the idea isn't to see how toasty the room can get