Single-family house new construction - How do we come to a decision now?

First of all, thank you very much for the many responses. The architect we now have on board is also making us a free draft at first, and then we can see how to proceed. He has already built several houses here in the area with local companies, and we will definitely take a look at that as well. They always build to the "only" KFW55 standard, but I am just wondering why I focused so much on the 40 standard. A proper heat pump system with photovoltaics and maybe a battery storage later on, and then it probably won’t matter anymore, right?

With the draft, one might also approach the prefab house manufacturers again and get offers. I hope the architect has a few good ideas on how to get the best living space out of as little floor area as possible for us.

Going for EH40 or even 40+ was interesting when the subsidies were high. Without subsidies, you will rarely recover additional costs through saved heating costs, especially since most construction companies like to increase their margin through such upgrades. And in practice, not every house in the 55 standard is the same; there are better and worse ones. It also depends on the specific construction method and execution.

I hope that the architect has a few good ideas on how to get the best living space out of as little floor area as possible for us.

Good input -> good output applies here. The better and more honest your wish list is, the better the house will be in the end. For simple plots and no special requirements, catalogue floor plans are usually already very good.

Both the solution and hints on the way to me can be found at or with the search term "11ant Hausbau-Fahrplan". Another building consultant (in Heidelberg) has also already been mentioned here in the forum. Where in RLP is the plot of land?

How to proceed methodically in principle, I have already discussed here in many places.

I have now read the Hausbau-Fahrplan. Very informative and helpful for a layman like me. Thank you for that! A small note: Some links still point to the old homepage.

They always build to KFW55 standard "only," but I’m wondering why I actually focused so much on the 40 standard. A proper heat pump system with photovoltaics and maybe a battery storage later on probably means it doesn’t really matter anymore, right?

We initially built a KFW55 house, and it’s already so well sealed that we readily skipped the 40 standard with our new house. A professional advisor once told us that in the end, the difference between 55 and 40 standard mostly exists on paper. So mathematically you still have these advantages, for example, but if you unload your car a minute longer after shopping in winter, you can already negate the scale of the difference. I don’t know if he exaggerated or meant it seriously, but in the KFW55 house I already felt like you barely lose any heat. The underfloor heating also ensured it was always pleasantly and evenly warm. We are currently building again to the 55 standard, without any qualms.

The architect we have on hand now is also first making us a free draft, and then we can see how to proceed. He has already built several houses here in the area with local companies, and we will definitely check that out as well. [...]
With the draft, you might also approach the prefabricated house manufacturers again and get quotes. I hope the architect has some good ideas on how to get the best living space out of as little floor area as possible for us.

I do not expect any revelations from a savvy acquisition house design. A well-coordinated team of architect and executors from the region sounds much more convincing. Preliminary drafts are sufficient for initial offers, and I would inquire without yet committing to a particular construction method. Proven catalog designs are usually already optimized to such an extent that further tinkering tends to make them more convoluted rather than better.

They always build "only" KFW55 standard, but I am wondering why I actually focused so much on the 40 standard. A proper heat pump system with photovoltaics and maybe later a battery storage and then it shouldn’t matter at all anymore, right?

Congratulations on withdrawing the focus from avant-garde standards. Normal income home builders lack the patronage potential for this path. Your quotation marks around "only" before EH 55 are exactly right. For the heating concept, I advise the transferred application of the "11ant Steinemantra": don’t take the most perfect, but only technology that the contractor installs with profound experience.

I have now read the house construction roadmap. Very informative and helpful for a layman like me. Thank you very much for that!

You’re welcome, I will pass on the praise to my editor who was largely responsible for making my contributions digestible for laypeople — the manuscripts were more in my writing style as here. Keep in mind that this series of posts so far only describes the textbook procedure. A presentation of when and in what way deviating from it can be a good alternative will follow. But we can gladly talk about that informally in person.

A little note: One or the other link still points to the old homepage.

I do hope I haven’t overlooked any internal linking? — if so, I am grateful for hints via comments or through the shown communication channels. Hopefully, the popularity of the old URLs in search engines will soon fade, and I cannot edit the references in posts here. Increasingly, even my IG readers (11antgmxde) find their way to the posts :)