Is an energy certificate mandatory when buying a house?

Can it cost 15,000 euros in fines if you don't have an energy certificate made?
I think then you can just pay the 100 euros for it.
For older houses, as far as I know, it always has to be the expensive one.

Yes, if you want to sell or rent. As long as you live in it yourself, you don’t have to have one. That’s how I understood it.

I called the gentleman today and explained the situation; he is now preparing the consumption certificate.