A fascinating article - many thanks.
HOWEVER....i think this raises some very serious safety and preparation issues. I have to be careful here, as in the past I was censured for challenging the "sacred cow" of snow-holes as a survival aid (I was told - in pretty much these words "that what you call challenging sacred cows I call pi""ing on other peoples parades") So - to reiterate - this is a safety issue first and foremost, which I think ought to be discussed.
The article makes very clear that snow-holes are inherently dangerous - risks run from inadvertently initiating or being hit by an avalanche, simple collapse because of inadequate building, Carbon Monoxide poisoning through either having no vent, or having that vent freeze over/infill from drifting snow. Other risks include misjudging whats actually underneath the snow-hole you prepared, and excessive sweating during the building of it, with all the inherent risks thereof. The latter can be avoided by de-layering, but in the process you lose heat already trapped within the layers, and burn off substantial amounts of calories that may be difficult to replace if you're there for a while. And calories keep the body's furnace going, delaying the onset of hypothermia and death.
And the benefits? You're out of the wind - which is a big result, as wind-chill is a huge killer. And the temperature within the snow-hole can be raised to just below zero C. Any warmer and you have the added problems of the snow-hole melting, increasing the chances of collapse and adding wetness to an already hazardous situation.
THe article finishes by mentioning "must-have" equipment in these conditions - " you should be equipped with an avalanche probe, snow shovel, bone saw, a good 4-season sleeping bag, a reliable stove and most important of all.... good quality training". Anyone want to hazard a guess at the weight of all that? (Personally, if you intend to be sleeping in a snow-hole at temps around 0C, some sort of waterproof/breathable bivvy bag should be added, as wet sleeping bags tend to lose efficiency - down bags lose ALL efficiency!)
Is there any alternative? I believe so (although I must stress I have no link to, commission from, or actually own the product, or similar ones!).
And that is the Jerven bag. I referyou to their 2012 catalogue -
http://www.jerven.com/main-catalogue-pdf and in particular page 64 and the SINTEF.. The originator explains it much better than I can, but in short, instead of digging a snow-hole/cave, you climb inside a Jerven bag. This not only gets you out of the wind, but the temperature will rise considerably above oC and stay there for days. (again see independent SINTEF tests). THere are various types of Jerven bag from unlined to heavy-lined, but even the most basic will keep you warmer4 than a snow-cave, and it weighs under a kg. Even the most thickly insulated only weighs 2kg. Chances are a "an avalanche probe, snow shovel, bone saw, a good 4-season sleeping bag," will weigh a lot more - even excluding the bivi bag!)
So - maybe the training companies need to reappraise their instructions? Maybe this is a sacred cow that needs to be challenged? Maybe the "essential equipment list" should include equipment that will do a better job of saving your life than the above-mentioned items? Maybe a mix of both? The Jerven bags (and their equivalents) are expensive, but then so is top-of-the-range climbing and sub-zero expedition gear. It is also - I would hazard - considerably lighter than the snow-hole alternatives. And bearing in mind the quote from the article above
"and most important of all.... good quality training............."
Sacred cow? Heresy? Dunno - but it seems worthy of airing at least.....
Oh - one thing to add. I don't buy the excuse that I gather some trainers provide ie - don't know about it, haven't heard of it etc etc. These have been around for nearly two decades, and for people charging others for training in potentially life and death situations, they have a responsibility to keep abreast of developments, then make a rational judgement on their effectiveness or otherwise.