Since Eastern Europe is relatively poor and sensitive to energy prices a lot of households invested into insulation, new windows, etc. Last 20 years there was also a huge boom for heat recovery ventilation. Such a simple and inexpensive device that provides so much. Should be first item in every household to invest into.

Funny part is that locals here are absolutely scared of any sign of draft or direct aircon. All while it's what actually saves their health lol.