Best retrofit smart home new build

You can connect both, but some do not want to for security reasons. Although it is not clear to me how there would be a disadvantage with a separate external line.

What does the door lock have to do with the external line? The actuator is located in the distribution box.

Otherwise, the way is correct, just never connect the lock directly to the fingerprint scanner that can be reached from outside.

The frequent use of the word "smart" has triggered some people. 4 responses within a very short time :D

Sorry, can't do anything about it, the word is too broken :D

What does the door lock have to do with the external line? The actuator is located in the distribution. Otherwise, the path is correct, just never connect the lock directly to the fingerprint scanner that can be reached from outside.

When I thought about the implementation, I often encountered the opinion that the motorized lock or its control should not be integrated into the KNX. The reasoning was that you would simply have to send a value to the correct group address and the door would open. I excluded that as unlikely for myself, because I would first have to access the bus from the outside. And even if it is accessible, it would actually be as a separate line with a filter.

What would be a clean solution for the front door with the following functions

Video intercom system
Fingerprint sensor
Electric door lock

how can this be achieved

How does the video intercom system (preferably even with fingerprint integrated on the outside) communicate with the door?

How is the electric door lock connected to the front door?
how is it powered?

Can this be retrofitted or pre-fitted or immediately fully integrated in a new building?

What would be a clean solution for the front door with the following functions

That of course depends on your definition of "clean". ;)

how can this be achieved

I decided on DoorBird + Ekey + GU.

How does the video intercom (ideally even integrated with fingerprint on the outside) communicate with the door?

In my case, not at all. If someone rings, you can see who is at the door, but you have to open the door manually. Of course, you could also link that together.

How is the electric door lock connected to the front door?

It needs a power supply and an input to give the open impulse.

how is it powered?

From the power supply in the distribution cabinet.

Can this be retrofitted or pre-installed or integrated fully immediately in a new building?

You can always do that, but since you can’t do everything wirelessly here (power supply), it is recommended to at least prepare for it.