I imagine that they use IR cameras, just like you find in those $40 temperature guns. The laser is just for aim. The camera is what's doing the work. I don't know how many cameras they might use per thermostat, but it's interesting to think about, since this would be potentially quite helpful in sorting out which rooms are getting too much or not enough air. I've run around my house tweaking with the vents to try to balance things, but this could let me get things more accurate.