CCF Mat with silver side against your body or under SI mat

[ricrunner]

As my dog has punctured my Self Inflating mat, that has had 300 nites of camping without damage, I do not intend to get another as he will do it again, and will just stick with the foam, without air. So question is, I bought a CCF mat, that has a silver side, as more support, and am wondering, do you put it under the SI mat, or above the mat against your body?, which would give you the most benefit?. I would prefer the SI directly under my body, with the CCF below that. I really don't notice not having the air in it, But I bought the CCF, to give a little bit better protection to my body from uneven ground. Just what would be the best way to use the CCF mat? EDIT: MY SI is a 3cm Vango insulated Self Inflating mat, just so you know what mat I am talking about.

[Warin]

Theory? Well a though..

If you contact the reflective layer then it will conduct heat out to the edges .. so it would be better to have that reflective and somewhat conductive layer away from you ... Given how thick that reflective layer is .. well it is not going to conduct much.

Why don't you try it both ways and simply see what works for you best?

[EGM]

Most of the insulation comes from the foam. The silver reflective surface won't add any insulation unless it's directly below you, if the other may is on top of it it'll only be the foam insulation.

I don't think it'll make much difference though, probably only 0.1 or 0.2 R.

[ricrunner]

I could do that, but don't really want an uncomfortable night. Currently camping at my Winter camp for the winter season, in a much larger tent with a queen stretcher with a larger SI mat., here in the New England. When I get home, this weekend, will give it ago, up the back of our property, for a couple of nights. It is really good cold temps to test it out. so maybe I will do it both ways??, like you say. I am a bicycle tourist/camper, and mostly do it in the cooler to colder times of the year. Have never had a silver camp mat before, and to be honest, couldn't see how they would work to keep you warmer, , but I will find out this weekend.

[Avatar]

Interesting question. I use a 2mm full-length CCF mat in contact with ground/snow, below insulated or non-insulated inflated mats and a 5mm shoulder-to-hip only mat above the inflated mat which keeps those body pressure points warm and protects the baffles getting shredded by massive elbow point pressure. It's warm and it works.

If the insulated/unisulated SI mat allows air circulation then it will develop convection currents that will pass warmth down to ground. Will these currents transfer more heat energy if the CCF mat is below the SI and in contact with cold ground or snow, or will they transfer more heat if the CCF mat is above the SI and in contact with your body? Lets assume the amount of heat transferred to ground is mostly a function of the ambient temperature difference below and above the SI mat. If the SI mat is in contact with 0deg snow or ground, as an infinite sink, then the air in the SI mat will settle to that temperature and any heat leaking through the CCF above will drive convection seeking that 0deg temperature. If the SI mat is above the CCF then it is in contact with your 37deg body temperature and the convection will be driven by the whatever the top surface temperature of the CCF mat is, which has its lower surface in contact with 0 deg ground. You could put a thermometer between the mats in both arrangements and measure. But how do you interpret the results and make a decision which way around is best? You probably want to minimise the temperature difference around the SI mat since it is doing most of the heat transfer. The total ambient temperature difference is 37deg.

[Warin]

Most of the insulation comes from the foam. The silver reflective surface won't add any insulation unless it's directly below you, if the other may is on top of it it'll only be the foam insulation.

I don't think it'll make much difference though, probably only 0.1 or 0.2 R.

Your probably correct on the R value in our circumstances.

Radiative losses depend on the temperature difference between the body and the reflector. If the body is in thermal contact with the reflector, say your sleeping on it, there is no benefit in the 'reflector', in fact the reflector can become a conductive loss.

[Kickinghorse]

Wake up Roger ?

[Orion]

This is a perennial question in the backpacking world. Lots of physics is typically bandied about with different conclusions reached by different people.

For what it's worth, Thermarest says that their Z lite Sol closed cell pad should be used with the silver side up.

[myrtlegirl]

here's an experiment you could do to test:

-get 2 very large plastic bags, pref 70L, and fill with water at 37C
-get 2 identical sleeping bags
-get 2 identical CCF mats, place one silver side up and the other silver side down
-put temp measuring devices with remote reading & automatic recording capabilities in the bags of water
-pop them in the sleeping bags
-ensure both setups are in identical conditions
-check temp vs time results
-Bingo!

Or you could take the view that as this question is perennial it is likely that it is not a simple answer and the results are subject to so many variations, you could then decide your sleep may be served better by not thinking any more about this question.

[Orion]

here's an experiment you could do to test:

I like that, something you could actually try at home to get some sense of which is better and how much difference it might make. I can convince myself that Thermarest is right in their assessment. But it's one thing to say that A is better than B and it's another to quantify the difference.

I took a look at the tech specs of the Z Lite Sol, Original Z Lite, and the RidgeRest Classic. The Z Lite Sol and the Original Z Lite are identical EXCEPT for the silver "Therma Capture" coating on one side. Same length, same width, same thickness, same weight. The Sol has an R-value of 2.0 and the Original is 1.7. So there's your difference: about 15%. Well, it's the difference between silver on top and no silver, not the difference between silver on top vs bottom.

Interestingly, the RidgeRest Classic is also the same length and width and weight and also has an R-Value of 2.0. But it has no silver coating. It's even thinner. But you can't fold it up the same way, you have to roll it. The Z pads are much more popular in my experience, particularly amongst a certain crowd of hikers.

I miss the days when I was happy with a thin piece bumpy foam to sleep on.