[pocketstar]

commodity motion sensors are thermal sensors[0]. Perhaps a FLIR[1]?

[0] https://en.wikipedia.org/wiki/Passive_infrared_sensor [1] https://en.wikipedia.org/wiki/Forward_looking_infrared

[bschwindHN]

FLIR for turning off a light in a room seems like a ridiculous amount of overkill. I don't know numbers off the top of my head but I feel like at that point you're using more energy for FLIR than the light itself. Not to mention the cost of a single FLIR sensor is probably pretty high.

[ehavener]

I think clever placement of traditional IR sensors is the answer here.

[xvf22]

These cheap 8x8 sensors may be useful[0].

[0] https://www.adafruit.com/product/3538