There's apparently some new technology coming this year to vastly improve occupancy detection. Sort of a super-PIR.
cepro.com/article/apicals_smart_secure_ ... out_video/
the discussion over at Homeseer is:In a more typical security application, the Apical technology can reduce false alarms “almost to zero,” says Tusch, because it knows who should be where when—even if an individual isn’t carrying a phone or wearing a magic bracelet.
http://board.homeseer.com/showthread.php?t=175518