On 22-Dec-2003, Peter wrote:

Heat loss is irrelevant compared to this.


Not so.[...]

Agreed. [...]

My point is that if there is no vapour barrier, then soaking your
insulation is a serious problem, whereas adding the vapour barrier
only increases the temperature rating a bit. If you want warmer,
buy a heavier bag; if you want dry insulation, get a vapour barrier.
Increased warmth is a byproduct of using a vapour barrier, not a
reason for buying one.

Mike