Originally Posted by
cyccommute
The heat doesn't come through the sleeping bag. It does its job by keeping the body heat close to the body...a bit like a smaller tent does
. But with each breath, you are releasing heat into the tent. Your breath has to heat a larger volume with a larger tent.
Yes, and that might matter in a winter tent. But in a 3-season tent with a lot of ventilation, especially big mesh panels directly overhead under the fly (the heat goes straight up), the rate of air exchange with the outside makes breath warming, or from any other source, a lost cause. Especially with a tent like mine, without a full coverage fly, it's propped up front and back, great ventilation in the summer, but cold if the weather is cold, blows any hot air right out. I tried a similar tent with full-coverage fly down to the ground to have front and rear vestibles, it was terribly hot and humid on the one warm night I used it, even with the vestibules zipped open, I immediately returned it. But that would have been a better winter tent.