AC is still a status signal, even outside the American south- when was the last time you were at a movie theater or a bank that wasn't colder than it needed to be, even uncomfortably so? It's traditional of places that try to impress luxury.
Honestly, while the power use is a problem, I don't think it's the most important AC-related problem. It's relatively small compared to all electricity, and is fixed with renewable power, unlike current heating solutions. Since AC just moves heat around, it causes significant localized heating in cities.
There is a neat idea to solve that, though. Beam that heat right into space[1]! The principle is similar to the radiators that keep the ISS cool- since thermal radiation happens at a different wavelength from sunlight, you can make a material that is "white" (reflective) to sunlight but also "black" (radiative) to infrared radiation. Unfortunately thermodynamics puts a strong limit on this; for a given area you need to make the radiator hotter[2] to give off more radiation, but that makes the refrigeration cycle much less efficient. Buildings need to become much greener than they are already becoming.
[2]: ie surround it in insulation that is transparent to infrared. That keeps the air from heating up but allows heat to escape to the sky. Trickier than it sounds, though- glass and some plastics are opaque to many kinds of infrared.
> when was the last time you were at a movie theater or a bank that wasn't colder than it needed to be, even uncomfortably so?
This is a problem of thermal mass that changes suddenly.
Every human is roughly 100W of heat. You need roughly 10KW of dissipation per hundred people. If you suddenly add a couple hundred people to a temperature controlled room, you need a bunch of extra AC overcapacity, and people are going to start to complain if you don't have enough overcapacity to prevent that temperature from rising within a couple of minutes.
Then you have the flip side--a couple hundred people leave the theatre. Your AC suddenly is overproducing cooling that it doesn't need, and your theatre may have a little bit of insulation to try to cut down on your AC costs. So, you undershoot the temperature and then the insulation keeps it there as you don't have 30-50KW of heat producing humans to bring it back up.
"Then you have the flip side--a couple hundred people leave the theatre."
But those people don't leave a vacuum. They are replaced with air from outside, which is hotter than the cooled air inside. Sure, you need to set the thermostat to a lower temperature than desired before the movie starts. But, once everyone is has taken their seats, you can set it to 25C or whatever. When the people leave and the hot air from outside replaces them, the AC will turn off and there won't be anything to force the temperature down below 25C. Am I wrong?
> They are replaced with air from outside, which is hotter than the cooled air inside.
That would actually make the response worse, not better.
Let's assume the AC is at steady state. It is pumping 30KW of heat energy out in order to maintain constant temperature. If everybody leaves and hot air comes in, the temperature rises and the AC system thinks "Temperature went up, I need to pump even more energy out."
The temperature needs to fall before the AC system starts backing off. However, by the time the temperature actually falls, the "velocity" of the temperature movement will cause the system to undershoot the target temperature.
This is a control systems problem. You can avoid over/undershoot (which a few people will complain about), but then you give up response time (which lots of people will complain about).
I used to work in a high-rise building that was closed up, and the climate control was not under our control (our department, our floor, etc.). So when everybody was in the office and the computers were running it would be stifling. When few people were around and the computers were sleeping, it would be much cooler and more tolerable.
Honestly, while the power use is a problem, I don't think it's the most important AC-related problem. It's relatively small compared to all electricity, and is fixed with renewable power, unlike current heating solutions. Since AC just moves heat around, it causes significant localized heating in cities.
There is a neat idea to solve that, though. Beam that heat right into space[1]! The principle is similar to the radiators that keep the ISS cool- since thermal radiation happens at a different wavelength from sunlight, you can make a material that is "white" (reflective) to sunlight but also "black" (radiative) to infrared radiation. Unfortunately thermodynamics puts a strong limit on this; for a given area you need to make the radiator hotter[2] to give off more radiation, but that makes the refrigeration cycle much less efficient. Buildings need to become much greener than they are already becoming.
[1]: https://phys.org/news/2018-10-energy-saving-radiative-coolin...
[2]: ie surround it in insulation that is transparent to infrared. That keeps the air from heating up but allows heat to escape to the sky. Trickier than it sounds, though- glass and some plastics are opaque to many kinds of infrared.