Best retrofit smart home new build

Z-Z-Wave is used by me for door/window contacts as well as temperature/humidity/motion sensors. PTZ cameras via LAN (POE). Roller shutters (Somfy) - which unfortunately use the proprietary io-homecontroll - I have decoupled from the Somfy Cloud using the Velux gateway. Household appliances (oven, cooktop, and co) are also connected via WiFi, but that's more for fun. Everything comes together in HomeAssistant, which I run on a RPi4. Here you can configure scenarios, automations, and IFTTT.

Household appliances (oven, hob, and co) are also connected via Wifi,

Do you just pour flour and milk into the oven and it turns into a cake? :D What do you do with such things, "that nobody needs"? And is the house heated with the waste heat from the servers?

What kind of prejudices are there against a server. In a single-family house, there is no data center. A larger switch generates more waste heat for a mid-range network distribution.

Do you just pour flour and milk into the oven and it becomes a cake? :D What do you do with such things, "that the world doesn't need?" And the waste heat from the servers is used to heat the house?

Oven and steam cooker are networked with us by Bosch. Nice to put the potatoes in the steam cooker or the casserole in the oven in advance and turn it on while jogging so that the food is ready on time. I think it's great!

And the waste heat from the servers is used to heat the house?

Exactly! With enough technology (multiroom AV, servers, network technology, etc.), quite a bit of heat accumulates. In summer, it goes outside via the bypass, and in winter through the heat exchanger. This way, the waste heat isn't lost after all. If the whole setup is in a standard utility room along with heating and photovoltaic technology, a decent amount of BTUs adds up :)

Exactly! With sufficiently much technology (multiroom AV, server, network technology, etc.), quite a bit of heat builds up. In summer, this goes outside via the bypass, and in winter via the heat exchanger. This way, the waste heat is at least not lost. If the whole setup is placed in a standard technical room together with heating and photovoltaic technology, you already get quite some BTUs :)

When the heat demand of a house slowly reaches the three-digit watt range, the heating engineer should consider the number of planned PCs in their calculation. Otherwise, it quickly becomes too much ;)