... Is it safe to say that you take an open sided structure, cover the opening with transparent plastic, crawl inside, and enjoy the trapped radiant heat? I will have to try this out....
I saw something similar to this demonstrated on one of the few episodes of Dual Survival that I saw. Cody came up with the idea and Dave was skeptical, but it worked. IIRC it was the episode on an island in Canada (Newfoundland, Nova Scotia?).
Edit: Yep, Nova Scotia.
Season 1/Episode 1, SHIPWRECKED: June 11, 2010