Comparison of internal and external insulation: Is external insulation significantly better?

yes, those are exactly my current considerations as well (and I mourn with you).

In an uninsulated old building, nothing should be placed in front of the exterior walls either

I understand, but after the interior or exterior insulation that would no longer be the case. However, I shouldn't put anything in front of the wall heating, right? I have plenty of ceiling height, but I can’t yet foresee the effort involved in retrofitting underfloor heating under the plank floor. But I will probably accept that, as it’s for the next 100 years.

Friends of ours have an old farmhouse from 1880. When they bought it about 40 years ago, they insulated the interior walls. Meanwhile, they also have triple-glazed windows for a few years now and underfloor heating as well. No mold problems at all. Do you know the videos from the Energiesparkommissar? He also addressed something like this once and it was definitely positive.

Do you know the videos from the Energiesparkommissar?

No. Thank you very much, I will take a look.

Do you know the videos from the Energiesparkommissar?

I was just about to recommend him as well, he explains well.

I am currently listening to the contribution "Innendämmung II" on the Energiesparkommissar. It says that even with interior insulation, the exterior facade of an old brick wall should be plastered or covered (so that no water can penetrate into the cracks). So the facade is definitely ruined. Therefore, it makes sense not to keep the old brick wall visible.

Hi! We installed internal insulation. Beforehand, for me, the topics of facade, condensate, and costs were exactly what I dealt with for a long time before we decided on a system. We have a 120-year-old stone rubble house; fully covering the facade would have been sacrilege. The decisive factor was then how the insulation "handles" the inevitably occurring condensate in the wall. In my opinion, there are three alternatives: glued calcium silicate boards, a facing wall with Poroton, or wood fiber boards. For the first two, you need a flat surface; with wood fiber boards, not necessarily, they are doweled and also compensate for unevenness. Casi boards are the premium solution. All three types of insulation absorb moisture in winter and release it slowly again in summer. For various reasons, we decided on the wood fiber boards and installed and plastered them ourselves, which made it the cheapest alternative. Additionally, the manufacturer gives a 10-year mold-free guarantee. With both Casi and Poroton, we would have had to have the walls replastered beforehand, which would have cost several thousand more. It is important to consider the individual details, such as window reveals, connection of interior walls, surface/vapor barrier, etc., which should be discussed with a capable energy consultant.