Change heating "after" building permit?

Hello everyone,

we are very close to submitting our building application.
But now to the problem.

We always wanted to combine a gas heating system with something modern (e.g. gas with solar thermal or fuel cell) and KFW-55. In combination with something modern, KFW-55 is achievable (already clarified with KFW consultants).

But the construction company claims that this is not possible and we must use an air heat pump (I assume because it is simply their standard and therefore the fastest and easiest "for the construction company").

After a long back and forth, the architect responsible for the building application suggested the following: She plans to include an air heat pump in the building application (since this 100% meets the KFW-55 standards) and we first submit the building application so that there is no delay in construction (we already have a contractually fixed timeline).

In the meantime, the company will then technically calculate the gas options described above according to KFW-55; the company claims that will take a very long time and we would lose a lot of time if we wait for that.

She said that later regarding the changed heating system, one simply sends a "notification" to the building authority and that would be settled.

1) Is that true? Do they really not care about the heating system?

2) But aren’t there also problems of a different kind, e.g. with the KFW-55 application, which in theory was submitted but with a different heating system?

3) For the fuel cell, it is said that the KFW 433 application must be submitted already "BEFORE" construction begins... but that does not mean "with the building application," right?

Thanks in advance!

Greetings

Kerstin

1) yes, it doesn't matter
2) no problem
3) has nothing to do with it

So everything's good!

Where you have to be careful when an energy saving ordinance is required in the [bb] to achieve it no matter what.

In the meantime, the company will technically calculate the gas options described above according to KFW-55 standards. The company claims this takes a very long time and we would lose a lot of time if we wait for that.

She said that later, regarding the changed heating system, you simply send a "notification" to the building authority and that would be settled.

And I would especially have that in writing, because otherwise the contract states air source heat pump and then it will stay an air source heat pump, since such contracts usually include a clause that changes and additions require written form.

1) yes, it doesn't matter
2) no problem
3) has nothing to do with it

So everything's good!

2. I see that as a problem. It is about the proof for the application BEFORE the start of construction. Wall thicknesses etc. are fixed there now. With an air-water heat pump, no problem, because EnEV 16 quickly becomes KfW55 without much effort. AFTER completion, proof of execution must be provided, otherwise no funding! If the energy consultant changes the heating in the proof of execution now, he must also increase insulation thicknesses etc. so that it still qualifies for KfW55, which of course only works if it was actually built that way. No KfW-listed expert risks making false statements there, they are personally liable.

I don't understand the problem: KfW55 is a calculation task done by software. The energy consultant enters all parameters and then an energy demand etc. comes out at the end. If that is too high for KfW55, the entered parameters must be improved, usually by trial and error: insulation under the slab, larger south-facing windows, thicker wall insulation, upper ceiling etc. until it fits. The energy consultant tests 3 variants or so and shares them with you and your construction company, you decide on one and that’s how it is built.

What is being attempted here is the following:

Achieving KfW55 with a gas condensing boiler in a solid house is an art (we are currently exactly at the same point). The construction company has no interest in this because they want to build as usual and also don’t know how to sell you as the builder big surcharges for more insulation etc. So: air-water heat pump, it will probably work without much effort. Once the contract is signed, that’s it.

Exactly for this reason the KfW requires an energy consultant - KfW expert to do all the calculations before the start of construction, so that the construction companies don’t do what they want and afterwards… unfortunately KfW55 didn’t work out

Achieving KfW55 with gas condensing in a solid house is an art

Not exactly a big feat: we have a KfW 70 house*, but just barely missed the values for 55. If we had 16 cm insulation and triple glazing, it would certainly be enough. *Gas, solar with controlled residential ventilation with heat recovery.