I recently completed my MagicMirror and was looking into power saving options for when nobody is in the house. there are quite a few options for this but none of them ticked all the boxes.
This module hopes to solve this. by using generic brand burglar alarm sensors and a 433Mhz receiver.

p.s. The rest of this message is on the wiki page of the module as the post kept being blocked by Akismet.com anti-spam.