Which smart home system to retrofit?

Would Homematic IP Wired be an alternative to Busch free@home both systems only come from 1 manufacturer

We had imagined having to spend max. €5000 now for smart home (preferably less) but if cables have to be laid, you just have to do it immediately

Maybe you should first consider what smart home is. In your initial post, it’s only about a few switchable roller shutters and light switches. Shellys are enough for that for a total of €350. But smart home is so much more (whether wireless or wired). Then you can choose a suitable system.

I also don’t consider which engine I want in the car when I don’t even know if I need a transporter or sports car.

What do you understand by Smart home?

What functions can a Smart Home have for you?

What came to my mind
Heating
Roller shutters (that automatically adjust to the times of day and don’t lock me out in the garden when I’m still outside)
Possibly lighting
Maybe also radio or music in the living room

What else could be realized? (everything should of course still be manually operable, e.g. for my wife, guests or children)

What else could be implemented?

How about, for example, "When the front door is unlocked and it is already dark, lights x and y in the apartment turn on automatically" as an example. That is smart. Pressing a button on your phone to turn on a light is far from smart. The heating doesn’t even need regulation; you can exclude that in new buildings. For me, smart means automatisms. You are not even thinking about those yet. You think about "How do I mirror the shutter switch to my phone." But all devices can communicate with each other. Light scenes could be programmed. Automatisms.

In the forum, we like to understand Smart Home as intelligent solutions such as automatic shading depending on the weather and the position of the sun. Or lights that automatically turn on or off coupled with presence detectors. When you come home, this happens; when you move from room A to B, that happens automatically. Simply things that only become possible when you install many sensors in addition to switches. Presence detectors, door contacts, etc.

You only mentioned window contacts as sensors. Retrofit systems for windows and doors feel like a visual catastrophe to me. Is there anything visually unobtrusive?

If I understand you correctly, you basically just want to control a bit of light and roller shutters via an app on your smartphone. Manually or by schedule. For this use case, just use Homematic.

What do you understand by Smart home? What functions can a Smart Home have for you?

Don’t let yourself be unsettled. Communication possibilities at the interfaces of consumers; sensors as perception of the environment is the way. Smart home is the goal. The more devices can communicate with each other, the more can be done or automated. Therefore, it is initially obvious that the new builder should ensure that later the devices and sensors have a connection to the home control. This happens either via bus cable or via radio.

We had planned such automatisms as well; I thought that was standard in the smart home sector. I definitely want to create rules like, for example, not lowering the blinds as long as the garden door is open. The idea with the front door is also a good one. What is available from, for example, KNX for window contacts that look good visually, maybe even invisible. What would bother me is if they run on batteries; optimal would be, for example, window contacts that run on EnOcean (maintenance-free). Motion sensors were not planned at first but could be retrofitted, right?