Costs of the ventilation and exhaust system for Fernwärme-KfW55 - KfW70

Hello everyone,
we are planning a bungalow.
We have initially decided on KfW 70 because with KfW 55 the payback period is relatively long (the equipment that must be installed needs to be maintained, can break down, and partly also consumes electricity). The highway is about 500 m away from the property and despite a noise protection forest, it is relatively loud, so we want to plan a ventilation system (probably without heat recovery) (ventilating with closed windows).
I learned today that the property where we want to build is supplied with district heating.
The costs: one-time: €9500, annual basic price calculated for 2017: €450 (may change later), energy costs 5.2 ct./kWh (may change later). The formulas for price changes are in the contract (not yet signed), but they are not understandable for everyone.
Here is an advantage: primary energy factor = 0.43 (as certification and valid until 2024). The energy supplier (municipal utility) clerk told me that KfW 55 can only be fulfilled with more thermal insulation compared to KfW 70 (without further measures).
What is your opinion on the resulting maintenance costs, experiences with district heating, KfW 70 or KfW 55?

This has nothing directly to do with the question, but I recommend installing soundproof windows. The additional cost for us was less than €100 per window.

And why without heat recovery?

He writes elsewhere. Actually only wants exhaust fan and forced ventilators in windows. That is the Regelair system. Nothing is recovered there.

Yes, I have also written that elsewhere, as it concerns different topics.

It says here:
Building services / Energy - Heating / Air Conditioning

Thanks to all helpful people

You haven’t been registered here for very long yet – so you should still remember the terms and conditions from the registration well. So before you break any more rules, read them carefully again :) Aside from that: how do you conduct two identical discussions in separate rooms? Best not at all!