So I decided, I build a home lab during the winter holidays. I bought a Dell R320 with a XEON E5-2407 four core CPU coupled with 32GB of RAM and a Dell R720 with two eight core XEONS and 64GB of RAM. The R320 will serve as a general purpose server housing a docker host, an openBSD based login server and my home automation. The R720 will be more of a playing field for new technologies. Maybe a kubernetes cluster.
I think, the R320 will run 24/7 while the R720 will be used only when needed.
The home automation system is already installed using openHAB and a Dresden Electronics conbee II USB Stick for ZigBee connectivity and a Z-Wave stick to control my thermostats.