Are the PIR sensor modules motion sensors or proximity sensors?
The standard cheap multi-segment PIR is a motion sensor. It works by having a sensitive thermal sensor that is shaded in certain directions, so detects an on/off/on signal when something hot moves across its field of vision. The sensor drifts too much for it to be DC coupled.

There are plenty of stories of people working in offices where the lights are controlled by PIR to save money, and if they are the last in the office, they have to stand up and wave every few minutes to keep the lights on.