Cost of energy consultant - KFW55/40

Hello everyone,

for a construction project (single-family house with a granny flat, together a bit over 200 sqm) I have several offers from "energy consultants." There are enormous fluctuations between 2500 and 7500 euros.

This is mainly explained by two items:

- Thermal bridges/equivalence proof:
Here, one offers the proof for 100 euros per detail (exact calculation 200 euros). That for 19 details. The other estimates 6 hours flat and thus calculates costs about a factor of 5 lower.
- Construction supervision:
Here, 50 hours vs. 5 hours are quoted.

My architect says that a high energetic standard is not worth it anyway, even with subsidies, and advises to let it go. The various offers then of course suddenly all come close together.

Profitability is, of course, strongly questioned if I have already to pay 5000 euros more just for planning/supervision. The additional construction effort is on top of that.

Question: What is usual? What is a reasonable amount of construction supervision (with regard to KFW50/40)? And what does this thermal bridge fuss usually cost?

Many thanks!

The KfW funding is intended only as an incentive; it is not possible to recoup the additional costs through the funding.

It only makes sense like this:
- You want to build according to the aforementioned standards anyway
- You want an independent expert to verify the fulfillment of these high standards, which in my opinion can also include the expert always required here

Then you at least get the second point largely covered by the KfW funding.

I find it unusual that so many thermal bridges must be calculated. Is this just an assumption for the preparation of the offer?

Hello Oleda,

a controlled residential ventilation system is a very, very big wish of ours. Mandatory in the bedrooms and bathrooms. Of course, this could also be accomplished with decentralized units, whereas the KfW probably requires a central system or supply for each room. But the controlled residential ventilation costs are already there anyway (as long as we realize our wish).

Otherwise, we still have to manage without a gas connection. I am not really keen on a tank or pellet storage. So the heat pump remains. With an assumed COP of 3 (yes, that is a pessimistic estimate), the kWh of heat then costs about 10 cents. So about twice the price of gas. This point would also argue in favor of good insulation.

And if I meet all the requirements, then there is the subsidy. However, I did not realize that considerable planning and supervision costs would come up.

If you can't get a gas connection anyway, it's basically pointless to speculate whether gas is cheaper than [air-water heat pump] heat.

A ground-source heat pump would reduce the price per kWh of heat and with BAFA funding it is often not more expensive than an [air-water heat pump], but it depends on the property and concept.

With a centralized controlled residential ventilation with heat recovery, proper insulation, and a ground-source heat pump as the heat generator, you basically have everything needed for KfW-55, and you can then also take advantage of the low interest rate and the repayment subsidy.

During construction, many costs will still arise that everyone knows about except the builder. Build reserves into your financing, you will need them....

You should not save on planning and supervision, KfW or not.

Ok, then once again explicitly the question:

Proof of equivalence for 100 euros each (assuming 20 details). Is that normal or quite a hefty gulp from the bottle?

I have to pay EUR 150 in case of emergency, however, according to the current status, I do NOT need an individual calculation as everything is according to the [Wärmebrückenkatalog].

I cannot estimate the effort, therefore I also cannot assess whether it is expensive.