This may not replace AC, but I wonder if (in colder countries) it would help with dieting. Want to lose weight, just turn your thermostat down by a degree and use this device to help you adapt to it.
Note though that that's calories, and not kilocalories, which is what we generally talk about for dietary purposes. So ~20kcal a day, which would represent about a 1% change for the average person. Not a huge gain.