Die steigenden Energiepreise durch den Ukraine-Krieg dürften vor allem der Grund für die Heizungskrise im letzten Jahr gewesen sein. In Milionen Haushalten war es nicht richtig wam.
There is no official proper indoor temperature, but the courts settled at > 20 °C in the day and > 18 °C in the night as "normal". If it's not possible to achieve this temperature, the tenant has the right to withhold part of the rent as long as the heating is not fixed. But tenants are allowed to have their appartment as cold as they like as long as they don't grow mold.
No... the minimum requred temperature for everyone I know complaining about those "the evil government wants to ban heating!"-fairy tales wide spread in Germany is 23°-25°C at least or they will instantly start freezing to their deaths somehow.
You need to put on the heater in many homes because otherwise you will get mold. It depends on the house, of course. Doesn't matter how much you cross ventilate. :(