Car Sun Screen for Ground Barrier ?

[pondhopper]

The Scenario:

Jim & I went for an overnighter from yesterday, till today. We wanted to go light, so we could move fast & mobile. Basically, go as far as we wanted, until dark and plop down, where ever we ended up.....then, continue on the next day.

We left together, but ended up at different locations and agreed to meet back at the truck Sat. evening.

For sleeping, Jim had: A military "cold weather system" (or-words to that effect) sleeping bag rated to -30 degrees and an "O.R." bivy sack.
I had: A Marmot Helium EQ sleeping bag rated to 15 degrees, a Cabela's bivy sack AND one of those reflective sun screens for auto windshields to serve as a ground barrier. I placed it inside my sleeping bag with the shiny side up...I thought it would act somewhat, like a "space blanket" and it's lighter and easier to fold than a normal sleeping pad= a space & weight savings for our application on these days.

Jim slept in the hardwoods and complained of ground coldness. I slept in a softwood location and was completely, comfortable.

So, does my opinion that the "sun screen" made the difference hold any water? Or- were there other factors at play?

Just a curiosity question

[Kevin]

Hard/soft woods couldn't have played too much of a role in the ground temps, aside from the softer allowing for some of your radiant heat to warm it while the harder ground would probably never warm from a single person's body heat.

I'm thinking the reflective sun screen helped both from the slight loft (it's cardboard, right?) and from the reflective foil (basically all an emergency blanket is).

Because neither of you stayed on the same type of ground it's hard to say for sure. I know one survival technique if stranded without shelter is to pile branches/leaves/pine needles as a bed to offer some insulation. How much insulation was under you may be enough to throw this test out the window, but it might be worth exploring this further by doing a more controled experiment.

[Hobbitling]

I've heard of ultralight campers using the huge Mack-truck sized window screens as sleeping mats. They are about the size of a sleeping bag. The backing is usually bubble wrap or a thin foam padding. They sell them in truck stops and auto stores like pep boys. I dont know how durable they are, but they're cheap enough to replace when they wear out. I bet you could get a season out of one if you were careful of what was under it when you slept.
I've also heard of actual camping pads with a reflective layer on them, but I don't know who sells them.

[coolrobc]

Hard/soft woods couldn't have played too much of a role in the ground temps, aside from the softer allowing for some of your radiant heat to warm it while the harder ground would probably never warm from a single person's body heat.

I think you may be onto something there.

The duff under the softwoods was probably much deeper and softer(loftier?) than the ground under the hardwoods. A nice natural sleeping pad.

[pondhopper]

Thanks, for the input, people.

This screen appears to have foam padding inside. It seems to be pretty durable.

Main reason for its use was for weight & volume savings, plus needed a ground cover, which wouldn't interfere with stealth, while bushwhacking.

Ha ha- Hobbitling, I should've known there's not an original idea left for anything

It was quite "duffy", where I slept. Could've been a factor.

Placed it inside the bag, due to an episode of "Survivorman" .