Matthew Yglesias wonders, fairly early in the day, why the air conditioning is so aggressive at the Republican National Convention. Later in the day, he gets his answer, which anyone who's worked in restaurants or retail will know: when you pack that many bodies into an enclosed space, heat goes up quite a bit. If you want it to be any semblance of comfortable toward the end of the day, you have to blast the A/C early, or else the system will never catch up to demand.
This effect can really become pronounced in the high heat of summer. I've read that at Walt Disney World, the employees managing the lines at some of the more popular indoor attractions (such as Space Mountain, which has a crowd all day long) will employ something called "line stacking", which involves stopping the lines at one of the entrances, so that the number of people inside the building itself doesn't become so high as to overwhelm the air conditioning. I also recall vividly the scene at Super Bowl XXXI (Packers versus StuPats), at which the NFL did a doubly stupid thing. First they covered the A/C ducts around the middle of the New Orleans Superdome with cloth banners displaying NFL emblems and the like, and then they had indoor pyrotechnics at halftime. The result was that the smoke never really cleared after halftime, and the temperatures on the playing field soared. I remember the TV people showing closeups of the banners "breathing" as the air ducts tried to pass air through them, and John Madden circling the image wildly with his Telestrator and yelping, "There's no air gettin' in here!"
Of course, as a former restaurant manager, I used to employ the A/C to my own nefarious purposes. During the dinner hour, when we were full with a line at the door, we'd have to run the A/C continuously just to keep things moderately comfortable, but then when the place emptied out a bit, the temperature in the dining room would drop significantly and quickly unless we were on top of things. This fact -- the A/C system's ability to very quickly bring the dining room to frigid levels -- coupled with the fact that little old ladies occasionally liked to set up camp in the dining room after closing and not leave, instead demanding refill after refill after refill of coffee allowed me to "encourage" them to leave by blasting the A/C, starting 45 minutes or so after closing. I know, I know, it was mean. But any port in a storm, you know. I'd never do that now. Heh.