House extension - Is insulation necessary in old buildings? Experiences/Tips?

Hello,

First of all, I would like to introduce myself, we are a family of four from NRW and want to buy a house built in 1950 and build an extension. Everything has basically been clarified and we are not completely inexperienced with the topic of building. However, our banker said that with changes to the facade it might be necessary to insulate the entire old building. Our architect, however, doesn’t know anything about this.
What do you think, is that the case?

Thank you very much in advance!

"Energieeinsparverordnung § 9 Amendment, Expansion and Extension of Buildings" is the keyword.

A house from 1950 initially says nothing on its own. The heating system can be significantly newer, and with insulated radiator niches and double glazing, quite a few improvements may already have been made. If the house is technically "consistently" that old, I would consider it as a shell and would not even wish to keep the existing state as it is.

That is a good objection, fortunately it is not consistently at the standard of the year of construction. The house has been modernized repeatedly; bathrooms, heating, electrical system, roof, and pipes have all been renewed already. Only the exterior walls have not been insulated.

And thank you for the note about [Paragraph 9]!