A typical caver trick to ward off hypothermia is to don a large garbage bag with only your face sticking out of a hole in the corner, tuck your knees in, sit on something insulating, and place a carbide lamp between your legs (flame out) or a candle. Mini oven. A second garbage bag helps add insulation. The only thing to remember is to maintain proper ventilation because of the moisture that is part of the combustion process.