>>912132>>910856>>912113It has to do with the air in the tent and its humidity. You heat up the air space and increase the humidity. This stable air pocket becomes thermal mass and insulation. Because of this, the R-value of the tent material is irrelevant.
Additional layers increase this effect. If you want a really nice and warm tent, you set up 2 tents. One tent inside another larger tent. The air pocket between the two tents needs to be small, about 1/2" at most to help prevent fast convection, though and distance will be better than none. Good luck trying to set that up though. lol
