New construction - How to build economically sensibly?

Then another 5 kitchen

Not? You can travel electrically across Europe from the extreme north to the farthest south without running out of battery. And that already in the middle of the charging network development phase. West-East is still not comparable yet.

Which combustion engine are you comparing, please? A comparable large 5 Series BMW with similar performance weighs almost 200kg less. (and "comparable performance" is still more than generous for the combustion engine).

You also have "Natural Sciences" listed as your profession. Then just throw away the at most eighth-relevant size of energy density and deal with the relevant stuff. Range does not automatically come from energy density.

Just look at the range. Which clientele of drivers needs >1000km in one go? Few. If you bring charging to the car instead of the other way around as usual, you have won. Then smaller ranges are also enough. The fact that this is much better understood in sprawling Scandinavia than in comparatively densely populated Germany says everything about the typical German attitude "we have always done it this way".

The fact that the electric cars currently being sold do not come from Germany (even though we are supposedly the car nation) and that the Americans and Chinese consider the German sales market largely irrelevant should give cause for thought.

Then connect 45 million electric vehicles to the grid at the same time and see what happens...

If you include the energy required to produce the batteries, the picture looks different again.

As for the cells, Tesla uses laptop batteries as far as I know. I don't see what should be pioneering about that.

Tesla is a ticking time bomb anyway. They are still making huge losses overall.

We built in 2015/16, 1.5 stories (140 m²), moved in May 2016 for 163,000 plus house connections, painting, partly flooring. With a thick line drawn under it, we paid about 290,000 for everything: land, incidental building costs, carport, fence, topsoil, paving driveway and terrace, furnishings (cabinets, kitchen, etc.). Inflation and new energy saving regulations everyone has to calculate for themselves, the house would probably cost ~170,000 today. To answer the question, we built Spartan: 36.5 cm brick, triple glazing, gas condensing boiler, hot water on the roof. If the system on the roof ever breaks, it will be disconnected and that’s that.