Experiences with low-energy houses? What should be considered?

Hey, we want to get our own house soon and it should be economical with energy consumption. We found information about prefabricated houses on the internet and wonder if these houses really offer low energy consumption or if it's just a rip-off? Has anyone of you already gathered experience or knows people who have such a house themselves?!

I would be very grateful for a quick reply :)

Best regards, Nancy :)

It's an old topic. Sorry for digging this up again. Because this question also interests me. What is the current state of the art?

Thank you

Regarding what? The topic is too extensive to cover all aspects of energy efficiency in one article, especially since there are various articles here and elsewhere.

There is a minimum standard that must be met and which has increased in recent years.

Beyond that, one can of course do more, up to a house that basically no longer requires external energy. That all costs extra, of course.

With used properties, you naturally have to consider the year of construction and the respective standard met and its implementation.