At 05:00 PM 11/8/2010, Alistair Bell wrote...
>Michael, you'll love this, I have the data on how much water vapour a
>sleeping 160lb guy breathes out when asleep in - 5 C van.

Please do tell. A quick google says humans lose 350-600 ml/day of water
due to respiration. It would be lower during inactivity (sleep), so I'm
guessing in the 75-100 ml range for 6 hours. But if it's -5C in the
van, maybe it's more because you're shivering without a heater.