ᐅ New Construction KfW 70 House and Your Feedback on Our Project

Hello,

We are currently planning a new build for our family.
The plan is for a bungalow with an attic space for storage (wood-beam ceiling).
This week, the energy consultant came and presented the calculation for the planned KfW 70 house.

I will upload the documents from the energy consultant later or add them to this thread.

One of my first questions was how to improve from KfW 70 to KfW 55 and what the cost implications would be.

Now I would like to hear your opinions on the documents and then ask my questions.

So far, these are the facts:

- Single-layer wall construction 36.5 cm (14.4 inches) Bisotherm Bisoplan 0.09
- Air-to-water heat pump
- Underfloor heating
- No mechanical ventilation with heat recovery
- 5 cm (2 inches) insulation below and 8 cm (3 inches) insulation above the foundation slab

These are my questions:
- Are the additional costs for a Bisotherm block with integrated insulation worthwhile or wasted money?
- Should I rather increase the insulation in other areas such as below and above the foundation slab or in the ceiling?
- ..........

Here are the relevant attachments!!!

stiff80 schrieb:
These are my questions:
-Are the additional costs for a Bisotherm block with integrated insulation worthwhile, or just wasted money?
-Should I rather reinforce the insulation in other places, such as below and above the foundation slab, or the ceiling?
-..........

Hello,
why don’t you simply ask your energy consultant? That’s why they are called energy consultants and not just energy calculators.
The concept has to be consistent as a whole. To put that together, there are exactly these consultants. I find it very difficult to resolve this in the forum. Besides, the mentioned consultant gets paid for the advice.
The cost-effectiveness of KfW55 has already been discussed here several times.

Hello Jochen,

First of all, thank you for your reply.

It is not my goal to specifically achieve a KfW 55 level here.
I probably expressed myself poorly in my first post.

I should have perhaps better asked which measures provide the best cost-performance ratio.

So far, I have been able to determine the price difference for the Bisotherm block myself.
The prices are based on a floor area of 180m² (1,938 sq ft).
Bisolplan, U-value 0.23 = €11,232
Bisomark (mineral insulation), U-value 0.18 = €15,840
Bisomark (organic insulation), U-value 0.15 = €24,336

Maybe someone can still give me tips on how to achieve greater effects with possibly better cost-performance ratios.

Hello,
your energy consultant should at least be able to advise you on this in a general way.
Furthermore, it also depends on your builder or the choice of your builder which measures involve additional costs and how much.

So, no mechanical ventilation system... in my opinion, that’s already a major mistake...