Yep, it's not self-heating

I think $HEATING_DISABLE should be add in building.ini

Hello. I get the "Temperature in building is too low" warning. Is there something you need to do to enable self-heating?

Thank you for your suggestions. I made the police station self-heating, alongside the small clinic, in the near future I will also do it for the school, kindergarten and secret police.

As a suggestion: maybe you should turn off the central heating for a group of buildings of the 1950s style: school, kindergarten, polyclinic, police, secret services, etc.
Judging by the model with chimneys on the roof, they should have their own heating. It would have been more realistic in the 1950s to build small settlements without central boiler houses.