Temperature experiment: heat-reflective blanket wall lining

[Paul F]

Crazy ideas from the noob here...

For the door, maybe something inflatable with stake loops like the one on the store has. Set in place, stake it, and inflate so it presses against the edges for a tight seal. Or would the pressure against the inside of the wall risk cracking and collapsing it? Another option, since the width of the wall is a constant, what about a folding doorframe of sorts that would sandwich the wall with a flap door on either side? Either you get dead air space in the doorway.

A lining for the floor should be pretty simple, on paper. Get a few of the heavy duty emergency blankets, the ones that are aluminized tarp, and make a circle out of them the diameter of the igloo you are making with a hole in the middle to set the stake through. Properly seam sealed and with a flap for the center hole this should be waterpr... well, reasonably water resistant . Follow this up with pads of blue foam and you should end up with a nice radiant reflection heated floor that should still roll up tight enough for a pulk.

If your butt is warm and you have a good hat, does the roof really need a liner?

[Matti Verkasalo]

To cut a pattern for the gores you will need some butcher paper or brown wrapping paper at least 3' wide. Cut a length 6' 8" long (80"). Fold it in half, keep it folded, and mark lines perpendicular to the fold every 10". Starting from one end mark a hash line across the bottom edge then each perpendicular line and the top edge at the following distances: 17-1/4", 16", 14-5/8", 13-1/4", 11-1/2", 9-1/2", 7", 4-3/8", and 1-1/8". Join the intersections with a smooth line and cut or just cut a smooth curve through the intersections.

Open the pattern and use it to cut 9 pieces of the radiant barrier. Then use velcro tabs to join the pieces together with 1-inch overlap at each joint. When you put all the pieces together they should form a doom approximately the shape of the inside of an 8' igloo. It may even be self supporting. The barrier dome will have an approximately 2" diameter opening at the top to allow for a ventilation hole plus it's impossible to have an odd number of gores come together at a single convergence point cleanly.

I just looked on line and found that this foil faced bubble wrap has an R-value of just over 1. You're probably better off spending the money on higher quality gear.

The inner liner is a great idea used also by the igloo specialists, the Inuit people from ancient days. They used sealskins, the present day Inuit hunters have a pole they push horizontally through the upper part of the igloo, and throw a tarp over it, probably sealing it somehow at the ends.

I had an inner liner very much like "Hiatus" described, sewn of white smooth tent-material by a tentmaker. White because I wanted to get light in the igloo! It is supported about every two-three feet by chords going through the igloo wall and anchored. It is rather tedious to put up, especially if you are working alone.

The first time I tried it was a -20 (Fahrenheit) night. When we were five people in 10 ft igloo, the difference in inside temperature compared to the night before was
remarkable, we were nice and toasty instead of just OK... But maybe our ventilation hole had not been big enough: when we woke up, the inside of the liner was densely dotted with water droplets, which had condensed of our breath on the colder liner! So we had to get up VERY carefully not to get our sleeping bags soaked! We got ourselves and the gear out, the igloo door open and within a few minutes the water droplets had frozen so we could take the liner down without getting wet, and started preparing the breakfast. My buddies were not so keen to try again another night... I've tried it solo but hanging the liner up is quite tedious and the night temperatures on successive nightsd with and without the liner were so different that I really could not notice any difference.

The liner itself weighs nearly the same as teh igloo form and takes up more space, which is not so handy if you are traveling in snow.

So I'm not so excited of the liner although I believe there must be a solution to the problems I encountered, and that one would not need sealskins either. Would be nice to hear of other experiments.

[Igloo Ed]

The inner liner is a great idea used also by the igloo specialists, the Inuit people from ancient days. They used sealskins, the present day Inuit hunters have a pole they push horizontally through the upper part of the igloo, and throw a tarp over it, probably sealing it somehow at the ends.

I had an inner liner very much like "Hiatus" described, sewn of white smooth tent-material by a tentmaker. White because I wanted to get light in the igloo! It is supported about every two-three feet by chords going through the igloo wall and anchored. It is rather tedious to put up, especially if you are working alone.

The first time I tried it was a -20 (Fahrenheit) night. When we were five people in 10 ft igloo, the difference in inside temperature compared to the night before was
remarkable, we were nice and toasty instead of just OK... But maybe our ventilation hole had not been big enough: when we woke up, the inside of the liner was densely dotted with water droplets, which had condensed of our breath on the colder liner! So we had to get up VERY carefully not to get our sleeping bags soaked! We got ourselves and the gear out, the igloo door open and within a few minutes the water droplets had frozen so we could take the liner down without getting wet, and started preparing the breakfast. My buddies were not so keen to try again another night... I've tried it solo but hanging the liner up is quite tedious and the night temperatures on successive nightsd with and without the liner were so different that I really could not notice any difference.

The liner itself weighs nearly the same as teh igloo form and takes up more space, which is not so handy if you are traveling in snow.

So I'm not so excited of the liner although I believe there must be a solution to the problems I encountered, and that one would not need sealskins either. Would be nice to hear of other experiments.

Thank you, Matti! You've shared a lot of experience and knowledge that will help us all if we ever pursue a liner.
The Inuit were certainly the most knowledgeable peoples at living in winter conditions. I had never heard they used seal skins and I think I know why they did.
There's a fabric, "Toddex", developed by Todd Bibler for use in his tents. The fabric has a fuzzy side that is used towards the inside of the tent. It helps hold the moisture to the wall by dispersing it instead of having it bead up and drip. It also wicks some and the moisture is exposed to more air so it can evaporate.
With you pointing out the condensation problem, I would think this the fabric to use.
The main reason I've never pursued developing a liner is the space lost. It would almost mean needing to build the next size larger igloo and that is a lot of work.
You mentioned that maybe the vent was to small. It might be the opposite if the air behind the liner was to cold and caused the condensation. But then too. I put a tarp on the floor and run it up the wall some so my sleeping bag doesn't touch the wall. I pin the tarp against the wall with some gear instead of letting it lay on my sleeping bag. When ever I let it lay on my sleeping bag, the bag is wet in the morning where the tarp was covering the bag. I've had friends measure the humidity in an igloo and it was above 90%.
I don't think there is any avoiding the condensation but the Toddtex might make it bearable until you cook breakfast and the liner dries out.

http://www.facebook.com/Igloo.Ed

[Matti Verkasalo]

I don't think there is any avoiding the condensation but the Toddtex might make it bearable until you cook breakfast and the liner dries out.

http://www.facebook.com/Igloo.Ed

Agree with everything you say. To prevent condensation totally, the temperature of the inner surface of the liner should be above the condensation point, which would necessitate insulation either within the liner or between the liner and the snow wall. A furry type liner might work also as insulator. I thought of cutting matching size triangles of thin closed-cell foam packing material - but then would need a separate sled for all the building material...

I guess the basis of keeping the Inuit igloos dry was the Inuit ladies who kept a small blubber fire burning all the time under a big stone casserole - sort of breakfast 24/7 system .

[Banff Martin]

And the answer is: 8C at 1' above the igloo floor, via my bodyheat & a few candles! I'm well aware I should have arranged to take readings at 2, 3, 4' etc., but by that time I was rather comfortable and had lost the balance of motovation & sobriety to leave the igloo to get, say, a 4' level & duct tape to run more tests. Without candles the temp at the same height dropped to 4C.

My process was mostly as imagined with only minor tweaks and omissions:
1- I started by creating small holes through the igloo wall with one of the Icebox poles.
2- I then used the same pole to push through popsicle sticks with string tied to the center of each, with the string hanging inside the igloo. A slight tug and the sticks were in place.
3- I folded single-ply cardboard & punched a hole through the center. Then, using a punch, pushed each string through the hole and secured the cardboard against the igloo wall with a piece of duct tape on the string/cardboard.
4- A tape loop was made and pressed against each anchor point.
5- Emergency blankets were unfolded, and installed one at a time, by pressing the material against an anchor point and gently tensioning before pressing against the next to maximize airspace and limit sagging of material.
6- Before starting on the floor, I used clear packing tape to connect one blanket to another, snug things up a bit, and close all gaps.
7- The air hole liner is simply mylar-air bubble-mylar material, rolled up, that I'd bought for an earlier home-made solar oven experiment. I snugged the blanket around it and taped it into place.
8- The floor is cardboard pieces cut to match the curve of the wall taped together with duct tape, with the mylar taped onto it, then taped to the wall mylar.
9- To cover the entrance trench once inside, a piece of carboard was cut to fit and mylar taped onto it. It then sits in place; it is not sealed like the rest of the setup.

I have to say that this setup resulted in higher humidity than a normal igloo. I suppose the naked walls are slightly porous, while the mylar isn't at all. As for comfort, I was almost warm enough with my thermal underwear top & a sweater, but eventually moved into my sleeping bag. It might have been an hour before I did so. The mylar that I used didn't completely block light from outside lights, but it did totally block all wi-fi/data/cllular service to my Iphone5!

This was done in a 9' igloo. It was spacious enought that I didn't dig the trench far in; I left a 8" width of floor, then cut a cube out in the center of the igloo so I'd have a seperate airspace for my feet. I didn't line this with mylar, just cardboard...I didn't think it would affect the experiment.

All in all I consider this a success, though it was time consuming. I used 6 mylar blankets, though more careful work may have only needed 5.

Questions?

[Igloo Ed]

That must have almost felt balmy!
Our temps in an unlined igloo were, 38F at the floor, 42F at chest level and 48F at the ceiling. With you having 46F at the floor, I would expect that it was at least 56F at the ceiling for you. That's pretty much T-shirt living if one is acclimated.
I like the way you put it together. Your attachment method was simple and quite sufficient. That duct tape sticks REAL good to the mylar as in get it right the first time.
The wall you left blocking the trench was a nice touch. I've done that a couple times and the feet are a lot warmer, but the temps here in Colorado are a bit warmer and my feet do fine without the added warmth you had.
The igloos are very humid and that moisture is continually condensing on the snow walls where capillary action makes it stick to the snow and run down the wall. On the mylar, it makes it bead up just like most synthetic materials.
I'm curious if you sealed the holes that the strings went through?
Do you know what diameter the vent was?
Nice job!

[Banff Martin]

I've been thinking of changing up the floor since the 'cool lounge' concept. With such a deep pad there are plenty of options!

At the time I was thinking that perhaps the naked walls made for less humidity, but...as I got dripped on then but not with the mylar I guess it was no different and my hat wasn't well suited to the humidity. Such is memory...

I did seal the holes from the outside of the igloo, yes. It made the igloo look like it was bolted together!

I'd say the air hole was 2.5" across.

Thanks!

[Igloo Ed]

Sounds as if the igloo was dripping on you without the mylar. That shouldn't happen if the walls are smooth. The moisture should just run down the walls.
I try to keep my vent hole less than two inches in diameter. I can tell the difference when it is 2 1/2 and really feel it at 3 inches. Using the mylar and being that warm might change things but I think your mylar experiment would have been warmer with a smaller vent.
Then too, I don't know how much air I get through the snow walls of the igloo and one might need a large vent with the mylar just to make sure of sufficient oxygen.

[Banff Martin]

Indeed, this igloo is the first I've built 'properly' by pulling slightly on the upper left of the form while packing. The blocks lined up very nicely. On all prior igloos of mine there were ridges that couldn't easily be smoothed out; thus the dripping in my prior camping event.

I hadn't given much thought to the ideal air hole size previously, thanks for the guideline. On all except the igloo I slept in last year I knew the general public would be using the igloos and went with larger holes for safety. I'd found snowfall or snowballs blocking them later..!

I kind of doubt there would be much air exchange through the walls...

[Matti Verkasalo]

I hadn't given much thought to the ideal air hole size previously, thanks for the guideline. On all except the igloo I slept in last year I knew the general public would be using the igloos and went with larger holes for safety. I'd found snowfall or snowballs blocking them later..!

I kind of doubt there would be much air exchange through the walls...

This is getting interesting: applied physics and chemistry

Ventilation: this is how I found that the 1½ inch hole I used to poke through the roof with my shovel shaft is just barely enough: we had 5 people inside, with a candle lantern burning, We started cooking but the multifuel stove would not burn properly. Nobody complained about poor ventilation - but only widening the hole in the roof to 2 inches resulted in immediate brightening of the stove (and candle) flame. Indeed when digging the science of burning I learnt that while the normal oxygen concentration of air is 21%, candle and petrol stoves require some 17%, but humans do quite well with 12% of oxygen in air by just doubling the respiratory rate. So I'm very happy with the 2 inch vent hole in the roof as long as there is wide space under the door mat to allow fresh air in. As Ed pointed out, bigger vent hole means cold feet...

Air exchange through snow: even packed snow (such as in avalanche) contains about 40-50% of air, which moves through the pores - slowly but easy enough to allow for breathing if the snow remains as it is. So theoretically you could get enough air to breathe through the igloo walls. But when avalanche victims breathe, the water vapor in the exhaled air freezes before the face. This takes about 15 minutes, and after that the oxygen supply is seriously compromised and victims begin to suffocate. If they have a wide air space before the face they may survive for up to an hour or even longer. Igloo is a big air spade, but as we know, within a day the walls have frozen on the inside - probably mostly from the respiratory water. -We notice this freezing of walls even in the igloos where we have a separate cooking place with direct separate air vent out, or even a second igloo used for cooking and dining...