[*]Basement insulated from the outside (Splietker simply did not want to do it because he thinks the insulation will get damaged?) [*]Basement heated + ventilated via controlled residential ventilation
It could very well be that your issue is repeating itself with us. We now have drafts from the last BUs in the running, including Splietker, who really build very nicely. But we actually want a KFW40+ house or at least heating in the basement and an insulated basement, which basically amounts to the same thing. However, this is not stated in the last draft either.
Did Splietker completely reject that with you?
Cost vs. equipment does not seem to differ much between the aforementioned. With one, the door costs €350 including installation, with the other €375. Then something else is cheaper again with the other.