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Since it's the season coming up for many (and snow seems to be in the game this year in eastern NA at least).

What would be the best/optimal strategy with regards to breathing holes for a quinzee (shelter made of snow)? Elements to consider:

  • Let us think of something to be used as a base camp for autonomous outdoor expedition. Therefore the answer should take into account that there is a need to not over-do it and waste precious heat
  • Safety is of course an issue and it shouldn't be a gamble
  • It should be a polyvalent answer and take account different circumstances (snow/drift potentially patching, number of people/size etc)
  • Assume the entrance is mostly blocked (snow block/backpack).
  • By quinzee, I assume you mean a crude lumitalo? – ab2 Dec 13 '16 at 1:30
  • I had never heard it called that but google image says yes. – Francky_V Dec 13 '16 at 2:09
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I'm somewhat of a claustrophobic sleeper when it comes to quinzhees, so I'm very particular about my ventilation.

How much ventilation you need is proportionate to the size of your quinzhee, and how many people are sleeping in it. Larger quinzhees need less ventilation than smaller ones, and more people obviously require more ventilation than fewer people.

I will typically put the ventilation hole near my head, so I can sleep with a steady supply of fresh air on my face, with multiple people in a single quinzhee, you could give everyone their own breathing hole and you'd be rather well ventilated, at the very least you need to have a minimum of two holes, so you can have some air flow, but obviously you don't want to make your holes so big that they let in a draft, the size of your hole can be a matter of personal preference, but it should be about the size of a snorkel, big enough for you to draw in enough air to breath comfortably.

To promote good airflow, its best to have one hole higher than the other. If you construct a crude chimney, the air passing over the top will actually draw air in from a lower holes that are placed out of the wind. this keeps the fresh air flowing in through your breather holes, and vents the noxious air out the top. This is particularly useful if you're using candles or burning to heat the inside (also good to vent fumes from whoever brought beans to eat that night...).

As for the general construction of the quinzhee, if you're piling snow, you want to leave the pile long enough for it to set, a few hours minimum after you pack it down. Use twigs no longer than a foot long (30cm) to mark the wall thickness of your quinzhee, stick them into your pile from the outside, this way when you hollow out the inside, you'll know how thick the walls are when you hit your sticks. How you dig the entrance is critical to keeping the quinzhee warm. the best method I like to use is to keep the top of the entrance below the bottom of the floor. This keeps the inside warm even when you don't have the entrance blocked, and provides you with a nice cold well for cool air to be displaced to (it's easier to replace the cold air with warm air than it is to try and warm air up).

One tip for the sake of your irrational paranoia: smooth the inside of your quinzhee walls when you're done hollowing it out. As the temperature rises due to your body heat while you're all in there sleeping, the inner walls are going to start to glaze, and bits of loose snow will fall off of the ceiling onto your sleeping bag, which of course your brain will try to convince you are signs of an impending cave-in. Another reason to keep your walls thin; if a cave-in does happen, then you'll be able to dig yourself out pretty easy. If you make your walls more than a foot thick, then not only will the weight be potentially too great to get off of yourself, but your screams will go unheard, because quinzhees do just as good a job insulating sound as they do heat.

That being said, I've never had one collapse on me, and most you can stand on top of and jump on without breaking after they've set up for a night, supposing you've made them properly with good snow. But I know other people who've been temporarily entombed in their poorly constructed quinzhees, so take the time to do it right, the most important part is letting the snow set for at least a couple hours before you start digging it out, and make sure you hallow it out like an arch. Flat ceilings are almost guaranteed to fall in on you.

  • So just to clarify - you poke one (let's say you're alone in there), kind of snorkel size? And then I guess some airflow from the partially block entrance as well? I've always been keen on poking just one... but then I've been reading stuff all over the map about it, so I always end up poking at least 3 (even if just for myself). But then you loose lots of heat and that's supposed to be an advantage of the thing... I've also read some people poking none for a newer quinzee without candle-melting the inner side (so the snow breaths)? – Francky_V Dec 14 '16 at 14:49
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    @Francky_V When you're buried in snow it isn't the lack of air in the snow that kills you, it's the build up of carbon dioxide. I've slept in quinzhees with no vent holes for a night, it's typically pretty easy to determine how much ventilation your quinzhee needs just by your level of comfort. If it feels stuffy in your quinzhee, or you feel like you need more air, chances are you need better ventilation. Excessive yawning is a good indicator that there's too much CO2 in the air. You don't necessarily need constant airflow all the time too, you could just air your shelter out now and then. – ShemSeger Dec 14 '16 at 17:10
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If you have an entrance big enough to get in out it seems to me that would be more than enough ventilation even if it is partially blocked with pack(s).

Think how much circulation you get in something the size of a house just by opening the door.

For years in scouts for the winter camp out we would make snow caves and never had vent holes. Climbing I have dug into a side hill and never made vent holes.

But I do see references to vent hole(s). Ventilation and let moist air escape. For moist air to escape then place a vent hole on the top (at least 2").

If you want vent(s) then no harm other than a little bit of cold air.

Not that dependent on number of people. As you need to increase the diameter the volume of air increases by the cube. So you have more air per person in larger quinzee.

Ideally the floor level should be a bit (6"+) higher than the outside to facilitate circulation. Cold air will settle and flow out. Stand a pack up in the middle. Since you are producing heat there will be natural air circulation. CO₂ settles but there is enough natural circulation that should not come into play.

Snow blocks to seal off the floor at the entrance is not a good idea. That would trap the cold air. They could also freeze in place and block exit. If safety is of course an issue and it shouldn't be a gamble then mostly blocking the entrance is clearly a bad idea.

Entrance should be down wind but even then wind will create some circulation.

Have a stick or ice axe next to you to poke a hole if it does collapse. Go for like 12" - 18" wall width. To much wall width would make a collapse that much more snow on top of you. Built properly they are pretty strong.

  • No but that's the thing - if you want to keep warmth, your entrance must be below the level of the "bed bunk" and you should block it off (mostly) with backpack etc.... – Francky_V Dec 14 '16 at 16:13
  • What do you mean "no"? Entrance above outside is the same concept. A bunk bed in addition is in addition. Your entrance should still be elevated compared to outside. – paparazzo Dec 14 '16 at 16:21
  • What I mean is: the top of the entrance is below the level of the "floor" of the quinzee. This helps to ensure your warmth will stay inside instead of leaking out through the entrance. Additionnally, I tend to block the entrance as best I can - with the backpage or any similar luggage. Therefore the entrance isn't much of a breathing hole in itself, partly because it's pretty low compare to were you are and because it's blocked... Therefore your first sentence doesn't really apply. – Francky_V Dec 14 '16 at 16:41
  • @Francky_V Not going to argue with you. Regardless of top height I hold with outside lower than floor. Mostly blocking the entrance is not a good safety design nor ventilation design. I get you may not agree but comments are not for discussion. If you have any questions about my answer I would be happy to try and address them – paparazzo Dec 14 '16 at 17:01

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