A reviewer at Outdoor Video Magazine describes camping a few nights with an Integral Designs eVent Expedition Unishelter Bivi. eVent fabric is supposed to be as breathable as it gets, which isn’t much, according to this review:
Night 3
Sleeping on VERY wet snow. Temperature was above freezing and raining hard before bedtime. Over night, rain turned to 3 inches of snow, and temperature dropped to -8C. Sleeping bag damp to the extent where it was effecting loft in my opinion. Glad I didn
I’ve been using an Integral Designs Salathe Bivy this year for a few climbs. I love it, but you are right – if you breathe into it and the temperature is not cold enough for your breath to freeze pretty much immediately, then you are going to get damp. I also had a fun time when the zipper froze(!):
http://i-cjw.com/blog/2007/10/15/banzai-noakes-san/
On the plus side, it’s great being able to camp almost anywhere, regardless of space. Real freedom of the hills.
He did some things wrong, however. He used a trekking pole to raise the foot end, sealed himself up completely (including the rear vent), brought in wet clothing, and then breathed into the shelter when temperatures were just below zero. Condensation? What a surprise.
I have used the event unishelter and BA 3 Wire bivy in event, even on the wet, er west coast of Canada and I can attest to zero condensation.
I had an e-mail discussion with him on some errors made and hopefully he has rectified his use of the shelter.