Renovation of a 1960s house: Questionable expert recommendations?

What maintenance costs?
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Maintenance costs due to repairs, etc.

As I said, these are opinions/experiences of others, not my own experiences.

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As I said, I am ambivalent about the heat pump.
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Me too. But rather because we have long cold periods.

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I don’t see the increase in CO2 costs as calmly as you do.
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Me neither.

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Yes, pellets are also worth considering. In any case, that would allow me to achieve the same system temperatures. I would have to think about the storage space needed.
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It is also important to store the pellets dry!

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Well, with oil
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Basically, it is a shame to burn oil. Chemists can make so many useful things out of it :cool:

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In winter, we want to use the wood stove in the living room to heat anyway for coziness/comfort reasons,
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Very good! For us, the wood stove in the living rooms is the main heat source :) Ideal if you can get wood cheaply.
The upper floor is sufficiently heated along.

When money is tight, the statement of the expert makes sense. If the house is not located in the middle of nowhere, the money you put into it is not lost. If you can afford it, go all out, aim for [kfw40+], take advantage of the funding, and have a new house.

Basically, it is a shame to burn oil. Chemists can make so many useful things from it :cool:

Definitely! I also find natural gas rather objectionable. Especially with my professional background, I can hardly reconcile it with my conscience to rely on either of the two. Even if it is still so cheap and tempting now. I only mentioned the oil above because so far it has belonged to obtaining fuel in time, and I do not see that as a flaw of a pellet heating system.

If money is tight, the expert's statement makes sense. If the house is not in the middle of nowhere, the money you invest there is not lost. If you can afford it, go full program, aim for KfW40+, take the subsidy, and have a new house.

The money is neither tight nor abundant; in total, after buying the house, a sum of max. 250,000 euros would still be available. But no one guarantees me that with a full thermal insulation and the complete renovation program I won’t literally be bringing problems into the house. To fix those, then no money would be left. Therefore: we could probably afford it, but then absolutely nothing may go wrong. Against the background of current material and craftsman prices, we would certainly be well advised to think a bit more conservatively. The house is in a small village, but not in the middle of nowhere. It’s half an hour by car to Nuremberg.

Mold is never an insulation problem. At most, if the workmanship is botched during execution. Mold arises from poor heating and ventilation behavior.

If you want to be precise: mold occurs with moisture in the wrong place. Leakage is a form of ventilation - albeit not an energetically desirable one. If you seal an old house, you change the ventilated areas. Some of them you cannot reach from the inside even with the best ventilation behavior. If the insulation prevents building parts that previously relied on a certain ventilation from getting any airflow, moisture can settle exactly there and then mold appears. It is quite possible to bring many old houses to a new and very good energetic level - however, the execution must be extremely professional and the building fabric suitable for it.