Problem with LRA: Location of heat pump

Got it. Build a house, buy an air-to-water heat pump, and whether it's approved afterward will be decided by the approval lottery. Sorry, what you're proposing is an expensive bureaucratic monster associated with massive uncertainties. Insane.
Best to have the heat pump TÜV afterwards to check something that doesn't need checking.

expensive bureaucratic monster

I don’t see where the implementation of the 1st BImSchV for small combustion units is an expensive bureaucratic monster. Can you explain that to me?

massive uncertainties

1. How reliable is the sound power level specified by the manufacturer 2. Does the device installation comply with the state of the art I would currently classify these as uncertainties for the time being. Once a comprehensive tool for planning and execution control is established, these uncertainties will approach zero (see again: small combustion units). I also do not see any massive uncertainties here, what are you referring to?

I don’t see where the implementation of the 1st BImSchV for small combustion units is an expensive bureaucracy monster. Can you explain that to me?

It’s not about small combustion systems. But since you won’t let it go: The difference is that the acceptance inspection for small combustion systems is ultimately purely formal. The products and installations are subject to certain standards, so it can be assumed that with proper installation the acceptance inspection poses no problem at all. Your proposal regarding noise measurement at the actual site is completely different. This is not predictable, as it strongly depends on local conditions. Imagine installing an air-water heat pump only to realize during acceptance that the neighboring building, its shed or roof tiles, reflect sound in a very peculiar way, causing the measurement to be inaccurate. Then what? Tear down the heat pump? Dig up the ground and move it to the other end of the property? Nonsense. If there were such a rule, heat pumps would be dead because there would be a high risk that the new installation would have to be removed again. That amounts to an implicit ban.

1. How reliable is the sound power level specified by the manufacturer
2. Does the device installation comply with the state of the art
At the moment, I would leave these as uncertainties. Once a comprehensive tool for planning and execution control is established, these uncertainties approach zero (see again: small combustion units). I also don’t see any significant uncertainties here, what are you referring to?

The uncertainty arises from your approach of issuing the operating permit based on on-site measurements. Suddenly, in addition to device specifics and execution quality, an incredible number of variables arise that are caused by the location. It is therefore completely unclear before installing the system whether an acceptance inspection is even possible. A regular check, as with gas boilers, is also not necessary, since there is no (life) danger that could result from lack of maintenance. Furthermore, you don’t need to subject something to a blanket inspection if it only poses a problem in a few cases. Absolutely wrong (uneconomical) approach. You might as well get a stamp from the authorities confirming that your shoes are tied correctly.

The products and installations are subject to certain standards, so it can be assumed that, if installed properly, approval poses no problem at all.

You got it, that’s exactly the point! This is precisely what my brainstorm aims at, as well as an optimized, well-thought-out location for the outdoor unit. By the way, the legislator initiated these "certain standards" with its 1st BImSchV. The question is why air-to-water heat pumps are not also subject to a "certain standard."

So one should just set up an air-to-water heat pump

Hopefully no one just installs an air-to-water heat pump like that. It needs to be properly planned—both from a heating and noise technical perspective.

...to realize upon approval...

The noise measurement on the actual object afterwards is also purely formal following the compatibility verification made during approval. Just like with gas, oil, and pellet heating systems, it is purely a determination of the source emissions, not an immission measurement at the neighbor’s property; specific conditions on the sound propagation path as well as the source and receiver environment are already considered in the theoretical verification. And no, this is no witchcraft, but carried out via situation-related surcharges; we are still talking about a point noise source here. The heat pump noise calculator of the Federal Heat Pump Association already does this very well (by the way, based on the LAI sheet); the weak point almost always lies with the randomly assigned sound power levels used by the manufacturers for the systems.

then what to do? Tear down the heat pump?

Back to small combustion installations: What happens if your oil, gas, or pellet heating system does not meet the limit values of the 1st BImSchV during commissioning or a recurring inspection?

incredibly many variables

No. These uncertainties are already eliminated in the compatibility verification during the approval process, ideally before that in the planning process.

It is therefore completely unclear before installation whether approval is possible.

See the verification in the approval process.

Likewise, a regular check, as with gas boilers, is not necessary, since there is no (life) danger arising from lack of maintenance.

There was and is no talk of operational safety regulations. The 1st BImSchV deals with air pollution control and energy efficiency.

Incidentally, there is no need to subject something to inspection generally just because it presents a problem in a few cases. Absolutely the wrong (uneconomical) approach. You might as well get a stamp from the authorities confirming you tied your shoes correctly.

Following this argument, TÜV (technical inspection) for cars as well as any other recurring technical inspection would be obsolete. "Few cases" (though my professional experience differs) are inevitably the result of recurring technical inspections and therefore an indicator of their elemental importance, not their redundancy.

And what to use instead (Luftwärmepumpe)? Gas with solar thermal uneconomical! Pellets? Takes up a lot of space in the basement. Geothermal? We have a 240sqm house. What to do? Architect also wants (Luftwärmepumpe).

What kind of argument is "240sqm house" for a ground-source heat pump? By the same argument, the air-to-water heat pump would also fail.

Especially for a 240sqm house, there should be enough space for pellets. And whether, for example, a deep drilling is worthwhile must be evaluated individually. In a favorable location, 180-200m should be sufficient.