Air heat pump or use gas and solar?

The 100 years, of course, are not to be taken too seriously. The whole thing depends on so many variables that you can only make rough guesses.
What can be said:
Geothermal heat pumps are about 20-30% more efficient under the same conditions.
In a well-insulated new building, you save about €200 per year.
You can use Google for these numbers; there are databases and plenty of reading material.
A geothermal solution with deep drilling costs about €12,000 more than an air-water solution (it could also be 10 or 20... it always depends).
Assuming the €12,000 figure, you get your money back after 60 years (without interest calculation, so a simple estimate).
For heating systems, however, one usually calculates in 20-year increments – so after 20 years, you would still be €8,000 in the red.
And here the crystal ball comes into play again. A geothermal heat pump owner will say that he can now replace the compressor cheaper than someone with an air-water heat pump. The owner of the air-water heat pump says that in 20 years the devices will only cost half as much anyway, so the difference is only marginal.
A third undecided person says: Who knows what will be available in 20 years...

But reduced to the essentials, you are worse off with a geothermal heat pump after 20 years. In my view, a geothermal solution only makes sense if you have no space for an air heat pump. Although modern devices are barely audible, you still shouldn’t place the unit next to the terrace.

If you do it yourself, the calculation looks different again. An efficient air heat pump can be realized for €2,000 with subsidies, a trench collector for about twice that. With such a low investment, you don’t have to worry so much about which is better.

But reduced to the essentials, you are worse off with a geothermal heat pump in 20 years. From my point of view, a geothermal solution only makes sense if there is no space for an air heat pump.

I cannot see it that way. For us, it looks like that without geothermal energy I save about 10,000 euros considering the subsidy compared to the air heat pump, but due to the surcharge of the air-water heat pump of over €9,000, I don’t really gain anything there.

Our feedback regarding the geothermal heat pump:

[*
Drilling is basically possible and there is no drilling depth limit
[*]The area is located in the water protection area WSG 3b
[*]Sealing of the drilling site is necessary
[*]Application:
[LIST=1]
[*]up to 100m depth this is handled in four copies through the Rhein-Erft district
[*]over 100m depth the application should be submitted in parallel to the Bergamt NRW as well as the Rhein-Erft district


[*]The contractor requires a W120 certificate

Now I am still waiting for the drilling costs.

Well, a general contractor will impose whatever suits them on you anyway or pull a fast one on you. My explanation refers to the market price, meaning an independent offer from a heating engineer.

Well, a general contractor will force on you whatever suits them anyway or rip you off. My statement refers to the market price, meaning the independent offer from a heating engineer.

I find that quite generalizing and short-sighted. If you have read the thread, you also know that this certainly does not apply here.

I also don't think it's good. You can build with a [GU] if you are aware of the peculiarities and pay attention to them. Nevertheless, both in construction with a [GU] and in construction with a freelance architect, there will be enough cost traps that you can also fall into. I don't think anyone can really claim to be free from that.

The [GU] doesn't force anything on you either. You can also separate contract components and commission the heating system externally. You can get any conceivable heating system through a [GU] – but then the question is indeed at what price. For example, the [GU] has an installer who works exclusively for Waterkotte in the heat pump sector. That means if you choose a different heat pump from another manufacturer, then probably another installer would be commissioned, who in turn, due to lack of volume, cannot offer the conditions that someone who works with you all year round can.

Today I spoke with a very experienced installer who has no interest in selling anything, as it is clear that he cannot get an order from us. He said that, in principle, it is actually difficult to weigh gas/solar and brine heat pumps against each other. In general, it would tend to come down to a brine heat pump for most, but in our case it is special because a fairly high hot water consumption is to be assumed, and the brine heat pump definitely performs worse in that regard. The heating element is constantly in use because it only - I think he said - manages 25°. In principle, he also recommended having the calculations done.

Does anyone calculate it so precisely that they look at how many m³ of water you consume per year and how much the brine heat pump correspondingly switches to heating element operation? You would first have to conduct a more or less detailed interview about the usage behavior of the house with every customer. Who does that? I’m going around in circles.