The Short Version: Shielding the crawlspace from the coldest winds by blocking certain foundation vents seems to have helped warm up one of the corner rooms (and possibly the rest of the house). The tools are simple – a black trash bag and black duct tape Gorilla Tape. I cut individual sections out of the trash bag, which I used to cover the vents. Then I taped them down with black duct tape.
Several months ago I stayed in a hotel in which the room used an “occupancy sensor” to automatically shut off the air conditioner if no movement was detected after a brief delay. I didn’t consider it a true occupancy sensor. Instead, this seemed more like a simple motion sensor.
In my opinion an occupancy sensor shouldn’t shut off the A/C if someone is still in the room. For example, it should be able to detect the body heat of a room’s occupants. After one night of sleeping in a warm room I cobbled together a simple solution.
The core concept is to generate movement that will continuously trigger the motion sensor.