@mfalkvidd But if I build it into the gateway, then it will work with all existing controllers. Otherwise I would have to get new code into all the different controllers.
@frits, unfortunately not, as the project I'm working on is designed for beginners.
For these sensors I will use the BBC Micro:bit, which has all kinds of sensors on board. So I suspect I can't really do what you ask. Or better put: I myself am not good enough at programming to create this.
I could also use Arduino Nano's embedded in Nano Wireless Expansion Boards, which are great for beginners. But this means their base current is always 5Ma while powered, which would cost a lot of battery. The people I'm giving the workshops to might just be able to handle wiring those boards to a 9v battery.