The whole EIB/KNX standard works like this and has been around for more than 20 years and there are hundreds of devices to choose from. It is designed around l

The whole EIB/KNX standard works like this and has been around for more than 20 years and there are hundreds of devices to choose from. It is designed around local low bound (9600 bps) network where you can connect KNX devices (thermostats, actuators, sensors etc) or gateways/routers to other networks. Only problem it has is that the communication is not encrypted, but being local and isolated, it is not a very big concern. Every other home/building automation systems worked like this recently until some marketing geniuses came up with the IoT campaign.