Ed's thoughts

[Igloo Ed]

There's a lot to be said about the energy saved by living comfortably. I was talking to an experienced climber about the energy saved from living in an igloo and he made a comment to the effect that half the energy spent in climbing big mountains is living in tents.
Possible the biggest factor in living comfortably when living in winter conditions is moisture management whether that includes sticking your hands into the snow and getting them wet, having snow melt on you or you gear or sweat buildup from sweating during the day’s activities.
The evenings spent recouping from the strenuous activities of the day usually miserable if your clothes are wet. Even if you sleep in an igloo where things don't actually freeze, wet clothes will suck the heat out of you.
A lot of people bring extra clothing to change into when relaxing but they end up sweating that much more from carrying the extra weight.
It depends what kind of trip I'm doing whether I take that extra insulating layer. I like the warmth extra clothes provide on short leisurely trips because they enable me to stay outside watching the stars for long periods of time.
Other times, on harder trips, I am working until near bedtime and short 15 minute trips outside are enough fresh air to satisfy my hunger for night skies and just the clothes I use during the day are warm enough.
Moisture management starts at the trailhead and it is best to get out of the vehicle wearing the clothes you will be wearing all day and get moving as soon as possible. Getting out of the car and spending time in the parking lot getting ready ends up with someone getting cold and then they need to put extra clothes on.
When one has the experience to know what layers of clothing to start with, things go very well. But the inexperienced person doesn’t know what layers or even how to recognize overheating.
I’ve taken many inexperienced people on trips and it's nearly impossible to relay the thought of overheating to an inexperienced winter traveler. I ask people all the time if they are overheating or sweating and I get, "No, I'm fine". Their usual comment at evening camp is, "Boy, it looks like I did overheat a bit today". It just doesn't seem to sink in when you explain how important it is to stay dry.
It seems I'd be better off asking them if they are cold and then have them remove layers of clothes until they are.
I like wearing my wool layer on the out side even if it's snowing so that my clothes breath and stay dry. This works for me as long as the temps are about 10 degrees below freezing and the snow isn't falling in the near rain mode.
If the snow is very wet when falling, I wear my gortex shell and leave it unzipped so it breaths some and my sweat can migrate out of my clothing. I also slow my pace some to avoid the sweating when I need to wear the shell.
If you wear damp clothing into your sleeping bag, the moisture in the clothing will migrate out into your bag and the bag will loose some of it’s insulating properties.
I used to sleep in my birthday suite and was always warm but friends complained about the visuals and I've had to conform. I started wearing just fleece pants and found that my torso and feet were cold and then ended up sleeping with one even layer over everything.
The more clothes you wear to bed the colder the air in the bag is going to be. This is not so bad if all your layers are the same thickness so you don't feel the chill.
The sleeping bag I use is a rectangular down filled bag rated to +15f. that has a pouch on the bottom of the bag where a sleeping pad slides in to provide the bottom insulation for the bag. The foot of the bag is very roomy and it has cold spots wherever you feet haven’t warmed the bag up. This is one place that the layer I now wear stops me from waking when I move my feet and touch that cold fabric.
Vapor barriers are the most commonly used solution for winter campers when managing their moisture in the bag. In an igloo, it is warm enough that a reasonable amount of moisture will migrate out of your bag.
Your bag can also get wet if it touches the wall as there is water running down the wall through the night.
If you use a Gortex or dry loft bag, there is no need to worry about touching the walls. If you do touch the walls, your feet or what ever touches the wall will get cold and you'll move.
Myself, I have a nylon bag but protect my bag by placing insulating clothing along the walls. I lay a tarp on the floor and bring it up the wall. I then pin the tarp against the wall with the insulating layers. If the tarp lays on your bag, the moisture in that area will not leave and your bag will be wet on the surface under the tarp.

A lot of people look at it as having a cold well, instead I've been
looking at it as a heat trap. The top of the door needs to be below the
sleeping level and this results in somewhere lower than the shelf you
mention. If there is no door I think you can just sleep on the floor.

If you have the top of the door below the floor, then leaving the
door open makes a few degrees difference, just enough to freeze the
water bottle. If the door is above the floor, it will be nearly outside
temperatures below the top of the door if the door is left off. It is
nice having the door low so you can sit around with your gloves off
while enjoying the evening.
It the door is 18 inches above the floor and I use a tarp for a door,
the water bottles freeze at night. I think it'd be a better option to
leave you bag unzipped a bit.