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insulate tent not sleepbag? efficieny?
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Alan Bradley
(ahbradley)
insulate tent not sleepbag? efficieny? on 12/30/2008 06:48:26 MST Print View

It occurred to me that insulating a small ridge tnent with bubble wrap might be more efficinent (lighter) than a heavier sleeping bag: the flysheet is non breathable so, no matter that bubble wrap isn't. Would this save much weight, if any?

Angela Zukowski
(AngelaZ) - F

Locale: New England
Re: insulate tent not sleepbag? efficieny? on 12/30/2008 07:07:55 MST Print View

You inside the tent will be creating condensation. And it's a larger space to insulate. Better to keep your body's warmth captured close to you, rather than let it dissipate into a tent.

Edited by AngelaZ on 12/30/2008 07:08:25 MST.

Scott Littlefield
(sclittlefield) - F

Locale: Northern Woods of Maine
Tent wall insulation on 12/30/2008 07:38:45 MST Print View

I'm afraid your body would use far too much energy trying to heat a whole tent, even a fairly small one, and maintain that heat. At least, if you're camping in moderately cold weather. In warmer three season it could work, but boy would it be a sauna... and in that warmer weather you could use a pretty light sleeping bag anyway. Also, bubble wrap does not compress. No fun for packing the bulk it would take to line a tent.

Still, it's a clever thought, and maybe you would want to try it out in the field... shouldn't cost much to do. I'm always a fan of trying something new out. Just do it in the back yard in adverse weather a few times first.

Daniel Fosse
(magillagorilla) - F

Locale: Southwest Ohio
bubble wrap bivy on 12/30/2008 11:10:02 MST Print View

You could try a bubble wrap bivy. It would likely work better than a bubble wrap tent liner.

Of corse you would still have a few issues:
Bulky item
Non-breathability
And your hiking buddy may turn out to be a compulsive bubble wrap popper and attack your gear

Colin Krusor
(ckrusor) - M

Locale: Northwest US
bubble wrap insulation for a bivy or tent on 12/30/2008 14:22:32 MST Print View

Bubble wrap performs terribly as insulation. Good insulation (down, wool, synthetic fibers, foam, etc.) divides the insulating layer into many tiny air spaces, the more the better. Bubble wrap is a single layer of big, empty bubbles. An aluminized plastic sheet like an old-fashioned mylar space blanket or a polyethylene "Heatsheet" would be lighter, more compressible, and much warmer than a piece of bubble wrap of the same size.

Alan Bradley
(ahbradley)
The bubble-wrap would be no less breathable than the flysheet.. on 12/31/2008 07:52:40 MST Print View

The bubble-wrap would be no less breathable than the flysheet it is lining hence condensation should be no worse.

Also, pot cozys are no more than bubble-wrapped foil and the both blizzard bags and the new Therm-a-Rest NeoAir pad (only air pocket insulatation

Daniel Fosse
(magillagorilla) - F

Locale: Southwest Ohio
hydrogen bubble wrap on 12/31/2008 08:55:57 MST Print View

If you could get bubble wrap where the bubbles are filled with hydrogen the weight may be close to 0. Just don't get it too close to the fire, especially if you make a suit out of it.

If anyone is incliend to make a suit of bubble wrap, for the sake of other hikers, please wear underpants under the suit.

Alan Bradley
(ahbradley)
any technical replies? on 01/02/2009 07:56:59 MST Print View

any technical replies?

Richard Nisley
(richard295) - M

Locale: San Francisco Bay Area
Re: any technical replies? on 01/02/2009 08:19:00 MST Print View

Alan,

Heat loss is proportional to the surface area of the item being insulated. Consequently, your best insulation investments in efficiency sequence are: 1) clothing, 2) bag or quilt / pad, 3) bivy, and 4) tent.

Daniel Fosse
(magillagorilla) - F

Locale: Southwest Ohio
large air pocket convection on 01/02/2009 09:53:12 MST Print View

Alan, all kidding aside, I’m not trying to stifle your creativity but I don’t think bubble wrap is going to make a very good insulator. The cozies made of bubble wrap probably work because they are made of an aluminized type of material and reflect heat. I am no thermal dynamics expert but I think the bubble wrap would have similar issues as non-insulated inflatable sleep pads. I read a thread a few days ago about someone getting very cold from using such a pad. I believe the conclusion was that large pockets of air make for good thermal conductivity through convection. Again, I don’t presume to know what results your idea may produce. I do know that bubble wrap is inexpensive and you could certainly experiment with the idea.

PS The image of a bubble wrap suit is rather funny to me.

Phil Mielke
(mielkephil) - F
Re: any technical replies? on 11/15/2009 11:04:10 MST Print View

Though it doesn't seem like something that would be very easy to carry, this is a good example applied to desert conditions.
It's basically a dome tent with the reflective bubble padding between the tent and the fly. Shows results data.
http://www.flickr.com/photos/48854860@N00/sets/72157601392305368/detail/
I'm going to repeat it for a side tent for my 63' vw camper (a panel van). I used the reflective bubble wrap to line the interior of the camper, and it does a great job staying cool in the intense sun. The metal shell turns into an oven otherwise.

Walter Carrington
(Snowleopard) - M

Locale: Mass.
Re: insulate tent not sleepbag? efficieny? on 11/15/2009 12:39:11 MST Print View

Traditional yurts are basically round tents insulated by felt. They are warmer than tents, but are not very light. Usually there would be some sort of fire being used which would heat them in extreme cold. They were used by nomads in Central Asia and were carried by horses. You can buy yurts made with modern insulation, but they're not light. Things like this would be best for car camping or a fixed camp where wood heat is available. As others have said above, for backpacking it is more efficient to insulate clothing or sleeping bag rather than the larger area of even a small tent.

I don't think bubble wrap would be a good insulator.

Jim W.
(jimqpublic) - MLife

Locale: So-Cal
Re: insulate tent ... on 11/15/2009 12:48:54 MST Print View

I think it would be great for a winter base camp where you travel in pulling a sled. Nice pyramid with a wood stove and insulated walls!

Otherwise it's a non-starter.

Thomas Burns
(nerdboy52) - MLife

Locale: "Alas, poor Yogi.I knew him well."
The inverse square law on 11/15/2009 13:00:02 MST Print View

Eh. Consider how energy propagates according to the inverse square law. (Sorry. Can't help myself.) IMO, a Heetsheets or other emergency bivy inside your sleeping bag is the most effective approach. Keep the warmth close to your body. You are the most significant heat producer in your vicinity. Don't waste it.

Stargazer

Troy Ammons
(tammons) - F
insulate tent not sleepbag? efficieny on 11/15/2009 15:46:28 MST Print View

The problem is your body is the heat source in a sleeping bag.

Think about an insulated building which is basically what you are building although on a very small scale.

If you are in a non heated insulated cabin that is cold, it would not be that much different than a non insulated cabin that is cold.

Now if you add a good heat source, like a wood burning stove etc, then big difference.

Still you need to insulate the doors, floor, roof etc to make it an efficient assembly.

Way too heavy for packing though.

Look at a good survival debris shelter and what works there in the cold. You need thick debris on the ground for insul, a very small low a-frame with about 3 feet of debris/leaves etc on top for insul.

Basically creates a debris bivy.

I think you could build an insulated tent that would sort of work.

It would just take a lot of insulation and a reflective interior layer and pretty much air tight so it would condense.

It would also take too long to heat up compared to a sleeping bag.

Actually it would probably be lighter to carry a normal tent and a heater or get like a nemo gogo and pile 3' of leaves on top. Still you would not want to go out for a pee in the middle of the night. YOu would freeze your ass off going back in the tent.

Ross Bleakney
(rossbleakney) - MLife

Locale: Cascades
Bubble Wrap vs. Neo-Air on 11/18/2009 13:04:47 MST Print View

Most bubble wrap insulates poorly. Currents get created inside each bubble, and the heat is quickly transferred.
The big reason the Neo-Air folks can justify the cost of their pad is that they've managed to solve just this problem. The shape of their bubbles is pointy. This discourages the currents, and the heat transfers more slowly. It's not as great as something like down (which traps the air in place much better) but it is fairly warm for the weight (and doesn't have the moisture concerns of down). I'm not sure, but I seem to remember someone saying that one of the bubble wraps had decent heat retention (not as good as the Neo-Air, but better than the other bubble wraps). I would imagine the bubble wrap with tiny bubbles work better (you would probably need several layers to get much warmth).

In general though, I'm afraid the idea won't work too well. If you surround yourself with bubble wrap, you have condensation issues. The way to avoid any condensation is to get fresh air. That is how the tent works. So, you are right, adding insulation to the tent walls won't make the condensation worse, but it won't trap the warm air. The air that has to move to prevent condensation just comes in the opening and quickly replaces the stale air.

One possibility (which I thought of while writing this) is to create a tent with a heat exchanger. Heat exchangers are used in very well insulated homes. In such a home, their aren't enough holes in the walls, gaps in the doors, etc. to let in enough fresh air. If you open a window (the obvious solution) then you've ruined your nice, well insulated house. The solution is to force the air through a heat exchanger (basically, a maze shaped device that somewhat resembles a radiator) so that the air that comes into the house is warmed by the existing air. That way, you retain the heat, but get fresh air.

I'm not sure if your design will do that. I'm afraid the air will simply flow over the insulating layer, and thus not be warmed (or, if you slow it down enough to transfer warmth, increase condensation). I think you would have to design a tent with this in mind. Again, in a house, the heat exchanger manually forces the air. In a tent, you might be able to create a chimney effect (take advantage of the warm air escaping out of the top and the cold air entering the bottom) but I think that would be tricky.

In general though, I like this type of thinking. Insulation which does not breathe is cheap, light and has great potential for improvement. For the most part, this has been applied to the pad (since it doesn't need to breathe) which is why the NeoAir is the hot product of the year. However, by re-thinking the shelter itself, this type of approach can be expanded. Unlike the pad, other insulation doesn't have to be durable.

Ross Bleakney
(rossbleakney) - MLife

Locale: Cascades
Re: Bubble Wrap vs. Neo-Air on 11/18/2009 13:45:13 MST Print View

It also occurred to me (after browsing some of the other posts) that this situation is similar, at best, to that faced by hammock users. A hammock user needs to insulate under the hammock. Closed cell foam is often used, but the strength of the foam isn't needed. In other words, it can compress if you sit on it, because you aren't sitting on it. I'm not sure what hammock users have tried underneath the hammock, but something of that nature might work well. It might be tricky to build at home, but a Neo-Air type inflatable layer (containing pointy air chambers) made out of really light (and presumably weak) Cuben might work well. Again, it wouldn't need to be strong enough to support your weight, which I imagine adds to a lot of the weight of the Neo-Air.