Best way to use “space” blanket to boost heat when bivy camping
A thin, heat-reflective sheet (aka “space” blanket) is a popular outdoors emergency item, having a number of uses. See adventure.howstuffworks.com/survival/gear/space-blanket and gotimegear.com/blogs/survival-gear/do-cheap-emergency-blankets-work.
If I’m bivy camping – that is, I’m clothed, inside a bag liner, inside a sleeping bag, on top of a sleeping pad, and inside a bivy sack – what then is the optimum location for a shiny survival blanket, for the purpose of keeping me the warmest? Assume two possible sizing situations:
- A narrow, or single-width, sheet that I can lie over or under (not both).
- A wide, or double-width, sheet that I can fold over so I can lie inside.
Ideally, you have tested, or know of tests involving, multiple orientations.
← 9
Bivy sack → _____________________
/ \ ← 8
Sleep bag → | x x x x x x x x x |
| x x | ← 7
Bag liner → | x _________ x |
| x ( ) x | ← 6
| x ( Clothed ) x |
| x ( Body ) x |
| x ( ) x | ← 5
Bag liner → | x (_______) x |
| x x | ← 4
Sleep bag → | x x x x x x x x x |
| | ← 3
Sleep pad → | ===================== |
| | ← 2
Bivy sack → \_____________________/
← 1
The ground ~~~~~~~~~~~~~~~~~~~~~~~~~~~
If you understand the above schematic cross-section, then you can see that
- sizing situation one has nine possible orientations, numbered 1 through 9, and
- sizing situation two has five possible orientations: 1-9, 2-8, 3-8, 4-7, 5-6
This post was sourced from https://outdoors.stackexchange.com/q/20976. It is licensed under CC BY-SA 4.0.
1 answer
Space blankets are good insulators. They prevent your body heat from escaping due to radiation and convection. They however do not prevent conduction based heat loss.
Given this, the best place to use a space blanket would be around your body. This would mean that the heat radiated from your body is reflected back and the warmth is retained. In most of the emergency situations this is what is done. However, in your situation, using the space blanket inside the sleeping bag wouldn't be a great idea. The reason being space blankets are non-breathable. Hence, you'll end up with a lot of condensation within your sleeping bag.
In your situation, using the space blanket around the sleeping bag, or around the bivvy sack itself would theoretically reflect back any heat escaping from the sleeping/bivvy bags (and hence is the best possible option for you). But this in itself would be pretty minimal.
Based on the same reasoning, using the space blanket as a single width sheet, under or over at any layer wouldn't add much of a protection as there's little heat to reflect.
This post was sourced from https://outdoors.stackexchange.com/a/20983. It is licensed under CC BY-SA 4.0.
0 comment threads
0 comment threads