I've added a Panasonic AMN31111 PIR to the display which removes the need for switching the display on/off. It's more expensive then a typical PIR module (£2 for a PIR module and £12 for the Panasonic) but you're paying for the tiny size (1 cm across). It's very sensitive and notices everything down to very small arm movements. I've used it to set the brightness of the display to 0 after 10 minutes of no movement and to put the display to sleep after 30 minutes. It also turns off the WiFi on the Photon which is the biggest consumer of power. An interrupt keeps track of any movement and turns the display/wifi back on if it has gone to sleep.

Overall a really nice feature. I would like to 3D print an enclosure for the screen, photon, and PIR but I'll need more practice with SketchUp first.