Shiny foil inside your tent

Swamp Coolers, Cooler Management, Dry Ice, Misting Systems, and just plain how to beat the heat.
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Zhust
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Re: Shiny foil inside your tent

Postby Zhust » Fri Jun 20, 2014 6:43 pm

Why am I compelled to answer? *sigh*

Just thinking as I type ... as I understand it, a radiant barrier (e.g. a shiny thing) stops heat because it reflects it away. It reflects it away which prevents it from absorbing the heat, so it doesn't get hot, and then it doesn't radiate heat or contribute to convective heating.

But as far as insulation, it is basically R-1: heat goes right through. (Interesting fact: R-value is temperature change * area / power, so like K*m^2/W; converting algebraically, if you know the temperature difference between the hot side and the cold side, and a over a known area, dividing by R-value gives you the amount of power, as heat, that transfers from one side to the other.)

So let's say you put it inside your tent. The surface of the tent heats up from the sun, but the radiant energy coming off hits your reflective barrier and returns to the surface of the tent which heats up almost as much as it radiated out. The hot tent surface begins heating the air inside the tent, and, since the reflective barrier has no insulation value, the heat in the air between the tent surface and the reflective barrier transfers right over to the air inside the tent.

In essence, the radiant barrier won't send heat back out. I would predict no measurable difference between a tent with and a tent without the reflective barrier. In fact, the nylon breathes a little bit, so blocking that airflow with an impermeable reflective barrier would likely make that tent even hotter inside.
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Jackass
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Re: Shiny foil inside your tent

Postby Jackass » Fri Jun 20, 2014 7:27 pm

Is that chicken I sense?




kramer chicken.jpg
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Sooner or later, it will get real strange...

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Gazmatron
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Re: Shiny foil inside your tent

Postby Gazmatron » Fri Jun 20, 2014 7:40 pm

Zhust wrote:Why am I compelled to answer? *sigh*


Because it's an interesting and thought-provoking discussion, of course ;) ...plus there's plenty of opportunity for amusement at my expense should I end up looking like Simon or Jackass’ photos! As Trilobyte said, it's win-win!

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Lonesomebri
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Re: Shiny foil inside your tent

Postby Lonesomebri » Fri Jun 20, 2014 7:47 pm

Scale this idea to a dome, get it listed in the guide, add copious amounts of melted butter, and it's the Human Carcass Roast.
Is it too late for placement? Too short of time for a kickstarter?

You should carry this idea out on a small personal scale just for the sake of science. Record your findings with 3-way split screen showing a selfie of you narrating, alongside a close-up of a watch face and the rising numbers on a thermometer. The ease at which you throw off the heat here indicates that you ain't gonna wilt testing the science of this idea. Cheers, and if you get that extra couple hours cool morning sleep, sweet dreams.
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Gazmatron
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Re: Shiny foil inside your tent

Postby Gazmatron » Fri Jun 20, 2014 7:52 pm

Lonesomebri wrote:Scale this idea to a dome, get it listed in the guide, add copious amounts of melted butter, and it's the Human Carcass Roast.
Is it too late for placement? Too short of time for a kickstarter? s.


I'll see what I can do, but I think a more practical experiment would be to surreptitiously fit some foil to the orgy dome before they 'get started'

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BBadger
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Re: Shiny foil inside your tent

Postby BBadger » Fri Jun 20, 2014 8:09 pm

Jackass wrote:Is that chicken I sense?



This is the image you really want:

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Re: Shiny foil inside your tent

Postby FIGJAM » Fri Jun 20, 2014 8:30 pm

"I fried and I can't get up!"
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Re: Shiny foil inside your tent

Postby Gazmatron » Fri Jun 20, 2014 9:02 pm

Not to be deterred, I think my initial experiment will involve covering the east/south-east side of the tent with single-sided radiant barrier, silver side inwards. The westerly-facing door and west/north-west side will be left without a radiant barrier so some heat can also escape.

There will be a couple of BM virgins in our camp. So as to be scientific about it, I'll test it on just one of the tents first... We'll see who's up first! I'll report back afterwards! :)

Oh, and here is a better explanation than my brick analogy....
http://www.youtube.com/watch?v=X1DsYE7yHeo
The experiment at 3:40 is kinda what I'm thinking of in the context of the wall of a tent... the wall being the hot plate of course.

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Simon of the Playa
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Re: Shiny foil inside your tent

Postby Simon of the Playa » Sat Jun 21, 2014 7:14 am

Bravo...


you are either one of the best trolls ever, or one of the stupidest fucks ever.


which one is it? :twisted:
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Re: Shiny foil inside your tent

Postby ygmir » Sat Jun 21, 2014 7:18 am

I'm now bored.
Thanks though it was fun.
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Captain Goddammit
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Re: Shiny foil inside your tent

Postby Captain Goddammit » Sat Jun 21, 2014 8:16 am

Yep. Dull when it starts going in circles.
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Re: Shiny foil inside your tent

Postby andy » Sun Jun 29, 2014 10:19 pm

"if you hold your hand a few inches away from a hot brick you will feel the radiated heat, however if you wrapped that same brick in foil you would no longer feel the heat at the same distance. "

I don't know if this is due to the reflective properties of the foil or just the fact that air flow against the surface of the brick is restricted. If you wrap the same brick in paper or cloth I think you would see some of the same effects.

Here's another way to look at it:
Foil = great reflector of sunlight, great conductor of heat, complete blocker of airflow
Tent material = partial absorber, partial reflector of sunlight, poor conductor of heat, near complete blocker of airflow
Air = poor reflector and poor absorber of sunlight, great insulator of heat

When the sunlight hits your tent, it is absorbed by the canvas and a portion radiated both in and out. The portion radiated in heats the air, which convects. This is not just pure infrared energy, though some portion of it may be. The foil won't reflect heat from the air, otherwise a foil-wrapped baked potato would be cold when you took it off the grill.

Let all three materials do what they are best at:
1) foil outside to reflect the sunlight
2) air insulator between the foil and your tent canvas so that most of the heat that radiates through the foil gets released to the outside air
3) canvas to block the flow of outside air

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Token
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Re: Shiny foil inside your tent

Postby Token » Mon Jun 30, 2014 12:53 am

Image

mosquito
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Re: Shiny foil inside your tent

Postby mosquito » Thu Jul 24, 2014 12:19 am

Gazmatron wrote:Not to be deterred, I think my initial experiment will involve covering the east/south-east side of the tent with single-sided radiant barrier, silver side inwards. ....


Dude, I like both your desire to improve and the resilience in the thread. :o)

I couldn't help but think though that the benefits and processes you're thinking about sound a lot like rigid insulation with aluminum facing. Thermax sounds like what you want... And then I thought, yeah, a hexayurt inside your tent -- or enclosing your tent -- would really do what you want. But that's just silly.

If your actual goal is to be able to sleep longer in the morning (for little cost), have you thought about just getting one sheet of Thermax and installing it on the dawn-ward side of your tent? If it has its own, separate stakes (and poles?) and it is spaced a bit from the tent, it seems like it could work like a wind break or snow fence, but just for the sun. (Would that make it a Sun Fence? ;o) To be more wind-friendly, how about cutting it into two 4'x4' squares? Eight 1'x4' rectangles?

Dunno. I bet the sun fence would buy you another hour or so in the morning. I think a monkey hut would cost a smidge more, get you more sleep, and provide you daytime shade, but I get it if that's not your style...

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Re: Shiny foil inside your tent

Postby Anarquistador » Wed Jul 30, 2014 11:19 pm

If I'm understanding the original plan correctly, you intend to have the reflective layer lining the inside of a tent. If the tent in question had an outer fly layer, and an inner shell, and the reflective layer in between those, would that negate the "pizza bag" effect? I would think that the sun hitting the outside of the tent would then be reflected back to heat the air layer between the outer shell and the reflective layer, which would escape faster through the air-permeable outer layer. That way, the primary source of heat from inside the tent would be body warmth, which you would have to contend with in any set up. As long as there was a vent in the reflective layer near the top, and good air flow without sunlight hitting the inner shell too much, would this be at least cooler than a tent under the sun, even if if not as cool as a tent under a monkey hut?

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Re: Shiny foil inside your tent

Postby sharpstick » Sun Jun 26, 2016 10:52 pm

(waking up this old thread) so, how did this work out last year? Your original post was a reasonably intelligent question asking if anyone actually had any real world playa experience one way or another. The majority of replies were more theoretical statements, (some more or less educated), and a lot of rude time wasting snark.
so, has anyone out there actually done this? We've had a whole nother year since this began.
(fwiw, I vote for swamp coolers. to avoid cooling the whole tent, I have a small bed enclosure made of housewrap over my air mattress with the SC ducted right into it. It has a fraction of the volume of the tent, so is more efficient. Not tested yet.)
my opinion, based on zilch experience(aside from 11 playas): put the mylar on the exterior of the tent. it would have to be glued on to the fly. another option is thick latex roof repair paint. it's thick white and pretty much opaque. and less likely to shred like mylar will when the playa sirocco rises. best case, have another opaque shade cover overhead. full opacity keeps out more heat. shade cloth or camo net is more wind tolerant, but blocks less sun heat. cheap translucent tarps just make a greenhouse effect. parachutes too.


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