I believe Nest motion sensors are what is referred to as occupancy sensors. They are simple and cheap infrared sensors that are not designed for accuracy but in

I believe Nest motion sensors are what is referred to as occupancy sensors. They are simple and cheap infrared sensors that are not designed for accuracy but instead sensitivity, so they are prone to false alarms, which don't matter much if you're just averaging data or lighting up a display. Most motion sensors for alarms are dual infrared/microwave (requires heat and motion) to prevent false alarms. Even then it can happen. My dual tech pet immune motions at home connected to my HAI Omni have had a couple of false alarms over the years. Once due to a ceiling fan being on (tripped microwave) then some sort of heat event (sun changed through window quickly). Accurate motion detection for alarms is tricky, and requires very specific placement.