28C (82F) is a perfectly fine indoor temperature and is not even warm, while 21C (70F) is way too cold.
I live in a place where it's better to keep your house at a higher temperature to reduce electricity costs because it's hotter outdoors most of the year. So 28C is the default room temperature for us. At night we turn off the AC and it gets to be 30C. So imagine my surprise when I go on the internet and discover that people keep their homes at 20C. It is not that hot y'all. In fact I am typing this in pants and a sweater in 30C right now, and I'm as comfortable as ever.
P.S. Anybody who keeps their house at anything below 23C (I'm looking at you New Yorkers) is a pyschopath