Construction costs are currently skyrocketing

For me, it would have been completely cost-neutral. At the time, I consciously chose WP because it is simply the right technology for the job. In the industry, it might be different, where much higher temperatures are needed, where an open flame is required. For home use, an open flame, whether gas, oil, or wood, is simply outdated.

But there are also cases where photovoltaics don't make sense at all due to shading from neighboring trees, because no sunlight reaches the roof and therefore no significant yield is achieved. I wonder, what do you do in that case if you want or have to move away from gas? Hope for district heating?

Electricity from the neighbor's photovoltaic system, electricity from the solar park in the field, electricity from the wind turbine, eventually electricity from fusion/whatever.

A gas heater can only burn gas, an oil heater only oil. If that's all there is, it gets cold. Can I produce gas myself? Or oil? Probably not. Can I produce electricity myself? Absolutely! Hello private power.

Can I use the gas that I don't use for heating for my car, my lighting, or my refrigerator? No. Electricity? Yes.

(I’m afraid I’m feeding the doomsayers again, but...) On the interest rate front, there was just an interesting column in manager-magazin (in my opinion) ("The End of Turbo Capitalism"). Basically, it was about the fact that for the first time since the financial crisis, interest rates are above the inflation rate and that this probably won’t change quickly, followed by some speculation about what impact this might have. (Ultimately, taking on debt is once again associated with more risk than it was in recent years, which can be quite painful for some companies)

Since we regularly have interest rate debates here (and the construction industry is also mentioned in the article, even though it is more general), I found it quite interesting to read as a perspective. It didn’t come up so often in the forum, but before the interest rate increases, you would occasionally see people (for financial optimization reasons) wanting to repay as little as possible because “inflation basically pays off the loan.” That is probably no longer the case for now.

I consider the idea that something inflates away in a mortgage loan to be a very bold thesis.

On the one hand, incomes always lag behind inflation. When the price of bread or potatoes doubles, as has happened, my salary is effectively halved at that moment. I only get half as much for my money. The cost of living, vacations, vehicles, simply everything becomes significantly more expensive and I have less money available. Of course, my loan installment remains the same.

Later wage increases no longer compensate for the rising costs. On the contrary. The disposable income share becomes smaller and smaller.
The loan installments then burden the household budget all the more heavily. What exactly is inflating away?

If prices eventually fall again, then we are talking about deflation. In that case, the property value also decreases, but the loan stays the same.

On the one hand, incomes always lag behind inflation. When the price of bread or potatoes doubles, as has happened, my wage is halved at that moment.
However, later wage increases no longer compensate for the rising costs. On the contrary. The disposable income share becomes smaller and smaller.
The loan installments then burden the household budget all the more heavily. What is inflated away there?

First of all, there would be no sustained inflation if wages permanently lagged BEHIND inflation. Because who could then pay them?
In addition to inflation, there is also productivity growth. This is called real unit labor costs.

Since the loan installment is fixed, it is devalued when wages rise. The scenario of a price jump (doubling) is not inflation but an external shock. Something like that happened during the oil price crises of the 70s. That, in turn, really cannot be offset by wages, otherwise the wage-price spiral starts... what? Wait! Like in the 70s!

I consider the idea that something deflates away with a mortgage loan to be a very bold thesis.

On the one hand, incomes always lag behind inflation. When the price of bread or potatoes doubles, as has happened, my salary is halved at that moment. I only get half as much for my money. Living costs, vacations, vehicles, simply everything becomes significantly more expensive and I have less money available. Of course, my loan installment remains the same.

Later salary increases no longer catch up with the rising costs. On the contrary. The disposable income portion becomes smaller and smaller. The loan installments then weigh even more heavily on the household budget. What exactly deflates away there?

If prices ever fall again, then we are talking about deflation. But then the property value also decreases, while the loan remains the same.

Interesting consideration. However, you ignore the essential point in your consideration: namely the massively rising rents – so the owner’s own loan installment remains the same. In the scenario you sketched, you say that the disposable income portion gets smaller and smaller (for the owner). How much worse off are the tenants then, if the rent increases by 20% every three years?