Originally Posted by KRSW

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Depends on how they're installed. One of the worst stays I had with these was at a Hilton where the motion sensor was attached in-line with the thermostat. No logic at all other than a timer. After an hour of no motion it'd kill power to the thermostat. After the first miserable night and the property insisting there was no override, I popped the cover on it and shorted the wires.

Fortunately the Marriott properties I've stayed with HVAC motion sensors have some logic in them and door sensors. IF the door opens AND motion is detected later, room = occupied. IF door opens AND NO motion is detected, room = unoccupied. Also quite fortunate -- these are easy to bypass by using the VIP mode or just simply removing the batteries from the door sensor. I noticed someone beat me to the door sensor at the Courtyard this weekend, which was fantastic -- a nice, dry, cool room when the rest of the property was on the damp side. As an aside, all of these "energy saving" HVAC systems fail to account for humidity, which is absolutely key to human comfort. Whether in Florida or the Pacific NW, the unoccupied mode of these systems makes room absolutely disgustingly humid when the guest returns. So what does the guest do? Turn down the thermostat even lower. So much for the energy savings. Maybe it works better in other climates.

I also have encountered the lighting/outlet motion sensors and really disliked how they were implemented -- auto on / off. Nothing like you or your partner getting out of bed in the middle of the night and having the hallway & bathroom lights come on full blast. Equally fun when you find your mobile devices didn't charge because the outlets were automatically turned off.