And those are the nice averages. Sometimes (more often than you'd guess) the temperature decides to drop to a nice −20C. In the same place, in the same year, temperature in summer can get to 30C.

I can easily agree that people over regulate temperature — 25C in winter or 20C in summer is probably not that optimal (I just don't do cooling, but offices do). But a lot of people live in areas where the outside temperature is just not an option.