I turned on the heater in my room for a good while today, while keeping my door open. I also happen to have a length of PVC pipe for a project stored in my room, just leaning against a cupboard.
I was pleasantly surprised that the PVC has a distinct temperature difference at the top from the bottom. The material traps heat so well and is such a poor conductor that the rising warm air heats the top, but the bottom stays cool.
I love science.