[baruch]

I'm looking at building my own home automation, the PIR sensors are fairly heavy on power and in order to ping them fast enough I need a fairly large battery or hook up the sensor to electricity. If I can replace that with a device in my pocket it would be nice as I don't need extra sensors.

Ofcourse, the downside is if the device is not in my pocket the system has no way to know where I am and will keep the light on in the wrong room and keep me in the dark so it's not like it's a perfect solution.

[Kliment]

There are PIR sensors that use no more than tens of microamps of power, and can send an interrupt signal to a microcontroller to wake it from deep sleep. An example is AMN41121 by Panasonic.