Insulation of old barn: 2 architects, 2 opinions

Hello,

I am planning to convert an old barn (built in 1970) into a residential house.
The exterior walls consist partly of 24 cm hollow blocks and partly of 24 cm bricks.

I have had two architects on site who have very different approaches to the project. One would carry out a classic external insulation, the other an internal insulation via wooden elements (house-in-house construction). The internal insulation with a wooden construction is justified by the cold bridges, which he could not eliminate otherwise. The other architect wants to eliminate these with "Verzögerungsstreifen."

I am a bit unsure. Before we enter the concrete planning phase, I need to decide on one architect and thus on an approach.

Does anyone have experience with insulation in barn conversions?

Best regards
Sascha Lohaus

I would see an energy consultant as more suitable for this question than an architect (although there are some among them who have acquired expertise in this area, but for some, their notes from a single lecture on the subject are enough).

Barns are often located on the boundary line, so a wall thickening outward is usually off the table – aside from the question mark this places behind a change-of-use permit. Just looking at it from a neighbor law perspective, even if the municipality might be generally inclined in favor of residential conversion.

The topic of thermal bridges is actually quite important here. In this respect, it is true that one should have some knowledge of energy. The consumer advice center offers short free telephone consultations on this and also a personal consultation of one hour for a donation of 10€.

I would ask the architect who says he cannot eliminate the thermal bridges exactly what he means by that and where the problem lies. I would ask the other one if and how he can eliminate the thermal bridges with his approach and possibly confront him with the problems seen by the first architect.

With this knowledge, I would get a third opinion from the energy advisory service. Although one has to say, the gentleman from the energy advisory wanted to do it 100% energetically, KfW55 was required, I had the impression he wanted to impose KfW0 on me because he himself is very convinced of it. I also found good help (also initially non-binding and free here, later with transparent costs) at the Bauherren-Schutzbund. There are "voluntary" engineers and architects who offer their expertise for consultation and construction supervision.

But you can also consider a double-shell masonry. For this, however, your roof overhang would still have to be large enough. If the insulation is left out, the question is also how the closure to the ground looks. You no longer have an overhanging floor slab. Your thermal bridge would therefore be at the bend to the floor slab below. Possibly the insulation would have to be pulled about half a meter deeper into the ground or something similar....