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I've been carrying a "Blizzard Rescue Blanket" for trips lately, particularly when I am solo in cold weather. The blanket is heavier than the mummy option, but looks easier if I'm dealing with an injured party who has limited movement, and is still just over a pound.

What worries me is the heat loss through the bottom of the blanket. I once used only aluminized mylar blankets below a down bag; but I was much younger then. The documentation for the blizzard rescue blanket doesn't recommend any particular ground insulation.

I've considered carrying a closed-cell foam insert in the back of my pack; I had a friend who carried such an insert, and was able to nap with this small insulator below his butt, leaning back on his pack.

I recall someone posted about two years back, about actually trying this setup for a night.

Any idea? In an emergency, is the natural reflectivity of the blanket enough? Should I augment with a minimal thermal pad as well?

last weekend i had an "unplanned" bivy at 13k on the Notch of Carl Heller with the Thermo-Lite emergency bivy. i'm not sure how cold it was but it was very windy. i'm guessing with the constant wind chill it broke into single digit? my climbing pack has a built in closed-cell pad. i used it to cover my feet up to my torso along with the climbing ropes for the ground and the clothes i had on and was able to stay alive. my clothes included long Patagonia 2 underwear top and bottom, guide pants, r1, shell jacket and Das Parka. i got some sleep but had to wake up every half hour to move around and rub my toes rigorously for 20 minutes to warm up again.

i think a bivy is much more effective than a blanket, especially in a windy situation. it goes without saying that you lose a lot of heat from direct exposure to the wind. most climbing packs have a closed-cell foam built in. maybe you should consider a climbing pack instead? the cheaper and lighter bivies are almost like a plastic bag. they are not breathable at all. when the sun came that morning and i got out of the bivy, i saw that it was filled with a thin layer of frost from my own breathing. in the future, i'm thinking about a standard OR bivy or just bring my sleeping bag on a climb.

Thanks. Most of my packs have closed-cell foam against the back -- but it isn't removable. I think I may take some old closed-cell foam and cut a back support.

The blizzard blanket is much more insulating than the thermo-lite blanket, but it is also not breathable (the inner 2 layers of the blizzard blanket have perforations to remove perspiration -- supposedly-- but I hope I never have to find out if this feature works).

I was looking for an option that I would actually carry. The blizzard blanket weighs just over a pound, and perhaps more important, it can stay packed up forever, unlike a down bag. A down bag would also require an outer waterproof layer. Decisions, decisions.

In the past, I've carried my sleeping bag VBL liner as an emergency bivy and I usually carry a piece of foamy in the winter (to stand/sit on).
The VBL is light, waterproof, windproof and smaller than my insulated mug. Condensation only becomes an issue if you overheat in it.
If I want to bivy, I'll bring my OR Deluxe Bivy.

Edit:
I also have an aluminized emergency blanket in my first-aid kit.

Since we are talking about emergency use, I would say take the bivvy bag and if someone gets injured and can't be moved, you take out your knife and make a blanket out of it.

Thanks all. Yes, I was at least 50% thinking of an injured party. It could be pretty hard to get someone with leg or spinal injury into a tight bivy. The emergency blanket velcros/tapes shut.

I see a lot of recommendations from military/SAR organizations. I recall the SP report from at least a year ago mentioned that the reflexcell material was extremely noisy.
http://www.youtube.com/watch?v=H648TWiW ... ature=fvwp

I carry this, havent had to use it. I know a guy who uses it as his "planned" Bivy bag along with his sleeping bag. He says it works great.

http://www.adventuremedicalkits.com/pro ... odname=SOL Thermal Bivvy

The same manufacturer makes a BIVY SACK, which seems to me to address the effect of high wind on a "blanket". As one comment indicated, the difficulty on inserting a disabled "victim" into the bivy might be a problem, but you could always slice open the side, insert victim, then re-seal with duct tape. I have one of these, for high altitude emergencies. RMJ
http://www.blizzardsurvival.com/product ... rvival-bag