The active hacking (taking control) is very unlikely via the radio channel, if (what I guess) they use as a protocol either ZigBee or similar. It uses quite long encryption, but at quite low communication speed, so you just can not monitor enough traffic to get the keys. The only thing you may achieve is blocking the transmission. If you do so for a short time, it won't effectively influenec the system at all, as delayed turn ON by 30 minutes is of no such big deal. And if it will take for longer time, the maintenance crew, maybe with the police assistance would be on the way...
Way more likely scenario is taking control over the servers over the internet, but then it does not matter, what control system they use, if separated wiring, modulated power line, ZigBee - in any case you take over the control.