heat source outside was a small woodstove, on a little platform on the ground. no chimney, no door. a contained firepit so to speak, with a cooking burner on top. sleeping space was a 6x6 dome tent, with layers of wool and emergency blankets added on top. all i needed for heat all winter was tea light candles. But it never got below 20F in this winter. No snow of any significance. If that was going to be a factor, the covered space i lived under would be a long A-frame instead of an awning space, and a more insulated sleeping space. Staying warm was actually not super difficult. Staying dry was the key.