ᐅ Change heating system after obtaining building permit?

Hello everyone,

We are very close to submitting our building permit / planning permission application.
But now the problem.

We always wanted a gas heating system combined with something modern (e.g., gas with solar thermal or a fuel cell) and to meet the KfW-55 standard. The combination with something modern should qualify for KfW-55 (this has already been clarified with KfW advisors).

However, the construction company claims this is not possible and that an air-source heat pump must be used instead (I assume because this is simply their standard and it’s the quickest and easiest option for them).

After some back and forth, the architect responsible for the building permit proposed the following: She plans to include an air-source heat pump in the permit application (since it definitely meets the KfW-55 standards) and we would first obtain the permit to avoid construction delays (we already have a contractually fixed timeline).

In the meantime, the company will calculate the KfW-55 specifications for the gas options described above. The company claims this will take a long time and we would lose a lot of time if we wait for that.

She said that later, regarding the changed heating system, we would simply need to send a “notification” to the building authority, and that would settle the matter.

1) Is this true? Are they really that indifferent to the heating system?

2) However, aren’t there other problems, for example with the KfW-55 application, which would theoretically have been submitted but with a different heating system?

3) Regarding the fuel cell, we were told that the KfW 433 application must be submitted prior to the start of construction… but that does not mean “with the building permit application,” right?

Thanks in advance!

Best regards

Kerstin

1) Yes, it doesn’t matter
2) No problem
3) It has nothing to do with that

So, all good!

One must be careful when an energy saving regulation is required in the building permit / planning permission, as it must be met regardless of the circumstances.

KSchmidtke schrieb:
In the meantime, the company will perform the technical calculations for the gas options described above according to KfW-55 standards. The company claims this will take a very long time and that we would lose a lot of time if we wait to start this.

They said that later, regarding the changed heating system, you just send a "notification" to the building authority, and that would be sufficient.

I would definitely get that in writing, because otherwise the contract states “air source heat pump” and it would stay that way, since such contracts usually include a clause that changes and additions require written form.

Bookstar schrieb:
1) yes, it doesn’t matter
2) no problem
3) has nothing to do with it

So everything’s fine!

2. I see this as a problem. It’s about providing the proof for the application BEFORE construction starts. At this stage, wall thicknesses and so on are determined. With an air-to-water heat pump, this is not an issue, since the Energy Saving Ordinance 2016 (EnEV 16) can be quickly upgraded to KfW55 standard without much effort. AFTER completion, the proof of implementation must still be submitted, otherwise no funding will be granted! If the energy consultant changes the heating system in the implementation report, they must also increase insulation thicknesses and so on to still meet KfW55 requirements—which is only possible if the building was actually constructed that way. No KfW-listed expert risks making false statements as they are personally liable.

I don’t understand the problem: KfW55 is a calculation task handled by software. The energy consultant inputs all parameters and then an energy demand result is produced. If the result exceeds KfW55 limits, the input parameters must be improved. Experience shows this is usually trial and error: under-slab insulation below the foundation slab, larger south-facing windows, thicker wall insulation, insulation of the upper floor ceiling, etc., until it fits. The energy consultant tests about three options and shares the results with you and your builder, you choose one, and that’s how it’s built.

What’s being attempted here is the following:

Achieving KfW55 with a gas condensing boiler in a solid masonry house is a real challenge (we are currently in exactly the same situation). The builder is not keen on this because they want to build as usual and don’t know how to present you, the client, with high extra costs for additional insulation and so forth. So: air-to-water heat pump—this will most likely work without much effort. Once the contract is set, that’s it.

That is precisely why KfW enforces the requirement for a KfW expert—energy consultant—to do all the calculations before construction starts, so the builders don’t do whatever they want and then later… KfW55 unfortunately didn’t work out.

Mottenhausen schrieb:
Achieving KfW55 with gas condensing technology in a solid construction house is quite a feat

Not that big of a feat: we have a KfW 70 house*, but just barely missed the values for 55. If we had 16cm (6 inches) insulation and triple glazing, it would definitely be enough.
*Gas heating, solar with controlled ventilation with heat recovery.