New construction - How to build economically sensibly?

Hello everyone,

In the course of planning a house build, one inevitably comes across the house building forum and the topic of energy standards. I have already read several books on this and also scoured various websites. I have to say that I am not a professional. I have noticed that the entire topic of "economic/ecological house building" is heavily influenced by the economy. The so-called "smart" consumer is dazzled by advertising terms and a federal campaign led by the economy for "CO2 efficient building." Books or websites that deal with the topic often do not provide clear balances.
In the "good" literature, insulation materials are compared in terms of their thermal insulation value and whether they are expensive or cheap. However, I still cannot deduce what is sensible for me in individual cases. I simply do not want to spend an excessive amount of money, especially on things that do not bring benefits, such as polystyrene insulation. If additional costs for a heating type are reasonable within a feasible time, then yes.
Our current goal is to build a simple single-family house with about 130 - 140 sqm.
The house should cost about 200,000 € and outlive us. (without exterior facilities, flooring, land, and incidental construction costs, our demands are not high)
I would now be interested in knowing what, according to the current state of technology, is the most energy-efficient/economically sensible construction variant?
Energy saving regulation according to KFW yes or no, if yes which one?
Solid construction or prefabricated house?
Condensing technology or heat pump?
Thank you very much for your answers!
Regards

Your contribution is unfortunately so permeated with ideological assumptions that a serious discussion is probably not even desired. However, if you really care about affordable housing and not about environmental protection or luxury, you should rent and not build.

You must comply with the Energieeinsparverordnung. Kfw 70 is sufficient for that. That’s what it used to be called. It is no longer subsidized separately, now it is the basic standard. More is neither necessary nor worthwhile. How do you achieve that most cheaply? With a house made of 36.5 Ytong, plastered, without additional insulation, with triple-glazed windows, underfloor heating, a gas condensing boiler, and five sqm of solar panels for hot water production on the roof. Possibly with a RegelAir forced ventilation in the windows and a maico exhaust fan in the bathroom. Then you can manage with a 200 thousand pure house. And it works. Karsten

Your post is unfortunately so saturated with ideological assumptions that a serious discussion is probably not desired.

I am currently interested in a serious independent discussion. That is why I am here in the forum, to benefit from experiences. It is only about not throwing money senselessly into the mouth of the economy. Do not misunderstand me, it is not about building as cheaply as possible, but efficiently.

What does efficient refer to? To primary energy or to money? What does "senseless" refer to - to saving CO2?

With 200,000 for the whole house, it is and will be cheap, either like with 36 cm Ytong, but otherwise with Poroton and polystyrene insulation. Gas with solar is the cheapest heating method. With your budget, you have hardly any room for maneuver