Retrofitting central ventilation for the attic

Good morning,

we are planning a KFW-55 house with a central ventilation system. The attic will initially be unfinished but is intended to be converted into living space later. Is this easily feasible? What should be considered? Must there not be a separate supply and exhaust duct for each room, and must it already be clear now how many rooms there will be? Is this even possible, or would it be better to plan a decentralized solution in the attic, e.g., via Velux roof windows?

Simply plan it with the planner right away and have the pipes laid up already.

A note, if you want to tackle that in the foreseeable future, better have the attic conversion done immediately. That is once again so much dirt and effort, you really won't be in the mood for it anymore.

I can confirm. I always want to tackle it but nothing has happened for 5 years and yes, also the issue with the pipes. Everything has to be laid out beforehand, afterwards it is either no longer possible or only with special solutions. Or then with decentralized systems or simply none at all and manual ventilation through windows.

At the moment, it is unfortunately not financially an option, but we definitely do not want to rule anything out for later. What all needs to be installed overhead? Is one pipe for supply air and one for exhaust air enough, or does each room need its own?

It depends on how the rest of the system is designed. The system would also need to have enough reserve capacity to supply an entire additional floor later. It would almost be cheaper and easier in this case to move the entire system to the attic (system and pipes must be insulated as long as it is not developed).