Planning for a single-family house

Hello Matthias,

The house we planned was guaranteed to us by the builder as a KFW 70 house. However, there are difficulties in achieving this standard.

You have it in writing, so your builder owes you a KfW 70 efficiency house!

He has already included the following measures:

- Thermal insulation with WLG 032 and lamination
- 10cm base insulation and lamination in the floor
- Windows with Ug-value 0.5
- Individual calculation of thermal bridges

What exactly is meant by "lamination"?

His proposal now is to use an air heat pump to achieve the missing percentage points. At the moment, I am not very enthusiastic about this and would like to avoid it.

That would be the easiest option; whether it makes sense is another question.

If I understand correctly, you are currently preparing the building application. You are building with Poroton – what speaks against using a filled brick? Then you should also be able to save the 7%, and for your builder it would cost almost the same.

You can also install a ventilation system with heat recovery, which should also bring the missing percentage points.

The most sensible thing would be, however, to discuss the new building project with a TGA planner and see where losses can be avoided and which technology should reasonably be used; a structural engineer is usually overwhelmed at this point.

Kind regards

What exactly is meant by "Kaschierung"?

The structural engineer spoke of an aluminum lamination. I assume that means some kind of aluminum foil on the insulation (laminated).

That would be the simplest option, whether it makes sense is another matter.

That sounds anything but positive!

If I understood correctly, you are currently preparing the building application. You are building with Poroton - what speaks against using a filled brick? Then you should also be able to save the 7% and for your building insurance it will cost almost the same.

Yes, we are working on the building application. We have meanwhile given up on the Poroton topic. Currently, we are planning with aerated concrete PPW4.

You can also install a ventilation system with heat recovery, that should also bring the missing percentage points.

We have already planned a controlled residential ventilation with heat recovery. We have only foregone solar because the roof orientation is poor.

The most sensible would be to discuss the new build project with a TGA planner and see where which losses can be avoided and which technology should be used; a structural engineer is usually overwhelmed at this point.

Well, unfortunately, you have to pay for that again. I know, you want one thing, but have to do another! After we had dealt with the whole topic of floor plan, external dimensions, dormer, etc., I had thought that now everything would move forward. What would I have to spend for that in terms of costs?

I also ask myself, do I then have to change the house again or can I simply take measures to bring the planned house to KFW 70 standard? Is that even realistic if the mentioned measures in the calculation don’t even help?



Regards Matthias

Hello Matthias,

That sounds anything but positive!

You set the pace by saying that you do not want an air-to-water heat pump; we are very happy to work with them. Incidentally, the split units are neither rocket science nor excessively loud; the DIN standard leaves nothing unconsidered :-)

Yes, we are working on the building permit. We have meanwhile given up on the Poroton topic. Currently, we are planning with aerated concrete PPW4.

Aerated concrete plan block => Lambda 0.09 W/(mK)
Poroton T7 (filled with MW, no perlite) => Lambda 0.07 W/(mK)

Well, unfortunately, you have to pay for that again. I know, you want one thing, but have to do another! After we had gone through the whole topic of floor plan, exterior dimensions, dormer, etc., I had thought that everything would now move forward. What would I have to spend on costs for that?

I have no idea what your house looks like, so I cannot give a reliable answer. You can try putting a euro figure on it.

Also, I ask myself, do I then have to change the house again or can I simply take measures to bring the planned building to KFW 70 standard. Is the whole thing even realistic if the mentioned measures do not even help in the calculation?

A TGA planner has a different approach than a structural engineer; he considers the house as a whole, and with precise distribution of insulation or selection of technology, much is possible; especially savings on nonsensical expenses. In this respect, commissioning a TGA planner actually pays off for every new building project.

Kind regards

You set the pace when you said you don’t want an air-to-water heat pump; we really enjoy working with them. By the way, the split units are neither rocket science nor excessively loud; the DIN leaves nothing unnoticed :-)

There are two points that have put me off so far. On the one hand, the noise. I mostly read that it can be around 60 decibels. On the other hand, the whole thing would come down to that ugly box on the house.

Aerated concrete plan block => Lambda 0.09 W/(mK)
Poroton T7 (filled with mineral wool, no perlite) => Lambda 0.07 W/(mK)

That is certainly an argument. But does that already provide the necessary 7%?

I have no idea what your house looks like, so I can’t give a serious answer. You can try to tick €uro.

I’ve attached a few pictures. Can you make anything of them?

An MEP planner has a different approach than a structural engineer; he views the house as a whole and with precise distribution of insulation or selection of technology, much is possible; especially the saving of nonsensical expenses. In this respect, commissioning an MEP planner actually pays off for every new building project.

I can basically understand that argument. However, the measures I described surely are already "overkill" in terms of insulation, right? Can you still "get more out of it"? I can hardly imagine that.

Thanks for your patience with me!

Regards
Matthias

Hopefully the images will work now

The dormer is located almost exactly in the northwest direction.