Sometimes the temperature is much higher than 20° C, and it is very hard to be comfortable or do productive work.

That's true, although having 19° inside when it's 30° outside is bad for several reasons. My office (in Europe) gets cooled down in summer to like 23°, and that's already inconvenient when wearing appropriate summer clothes. And no one is expected to wear formal clothing.

I never set my AC to lower than 25°C. Why would you need below 20°C? Is it something about having only a single unit for the hole house/office, where it's then uncomfortably freezing in one area, just to have a normal temperature in the distant areas? Crazy.