There are some survival forums out there that give great suggestions such as a spare shelter, water collector, or to secure broken bones. First of all, let's look at how they work. In summary, the metallic surface reflects heat which is why it's used as a layer to a sleep system. But if it has all that capability to reflect heat, how else can it be used to its potential?
Space blankets and fire
My last camping trip was a snow camp. I used my Hennessy Scout hammock with an Eno underquilt. I also had a fleece blanket and a 30 degree down sleeping bag. I foresaw the temperature getting down to about 27, but not 18 as it did. So what could I do to keep warm? Sure, I could use the space blanket as another under blanket or as a top layer, but I think that's under-using it. When I hammock camp, I lay a ground cloth down underneath it where I put my gear to keep it from getting wet. This gives the opportunity to cover my gear with the space blanket and staking the blanket down. It's ideal to get a 45 degree angle and with the space blanket facing down wind. You then create a fire a safe distance from your hammock and there you have it! The heat from the fire will actually reflect off the space blanket Into the hammock. The amount of heat you get from it depends on how big and hot the fire is and how close it is to the blanket. This trick also works for tents. You want to face the door towards the fire and downwind and place a space blanket flat on the ground between the tent and fire. It will reflect just as it does for a hammock. Although I recommend staking it down to keep it from blowing away.
When winter camping, you may want to sit around the fire and have a good time, but the colder it gets, the more miserable you get. A great way to stay warm around the fire and gain all the heat you can is to open the space blanket and hang it behind you, perpendicular to the ground. You can use trekking poles, a tree, whatever you happen to find. If you sit between the fire and space blanket, you will have the heat from fire reflect off the blanket and provide extra warmth. If you have a big enough space blanket and start to experiment with it, you can angle the space blanket just right to gain even more heat.
Kind of a small, simple tip I have for hammock camping. Some people do use space blankets as underquilts. This is a clever idea, but I would personally prefer an underquilt because it is warmer than using a space blanket and gets more snug. You can use the space blanket as, obviously, a blanket. However, you can also line your rain fly with it and reflect your body back to you. This works for tents just as well. If you set your hammock up right, you can angle your rain fly when it's lined with the blanket and have a fire going. This works great to reflect the heat from the fire into your hammock. The downside is the wind. The point of the rain fly is to keep the wind off of you and this method kinda opens you up to the wind. You can do this with a tent, depending on the tent you have. You can put the space blanket between the tent and rain fly.
Space blankets as spare shelter
I believe that you should not rely on an emergency space blanket as a spare shelter. You should always have a reliable backup and emergency space blankets are not durable enough to rely on. They will tear and can't hold up to wind very well. That being said, I do carry a heavy duty space blanket that is almost like a tarp, very rugged, with grommets. These do make great backup shelters and can also be used to reflect fire heat into your tent or hammock. You can pretty much set up a durable space blanket as you would with tarp camping, simple. The benefit to doing this is heat by fire reflecting off the inside of your make shift tent and keeping you nice and warm. To utilize this to it's maximum potential, make a lean-to with the opening towards the fire. Just make make sure that the fire and opening to the lean-to are facing downwind. This will not only keep the fire from potentially igniting you, but will also help to keep the wind off. However, if wind is an issue, you would be better off making an A-frame. You won't get all the heat you could get with a lean-to, but will still benefit from the heat reflecting as well as staying out of the wind. The downfall to these rugged space blankets is size and weight. They are about the same size as a tarp so I takes up valuable space in your pack. It is also heavier than an emergency space blanket, so if you are weight conscious, it's probably not for you.
Space blankets as gear insulation
When camping or trekking in the cold, it's important to keep certain things warm. When it comes to gear, some things can be ruined by cold such as water filters, electronics, and not mention that water freezes. If you are going to be in an arctic situation, you can line your pack with the thin emergency space blanket. This won't be ideal for keeping your gear warm, but it's better than nothing. If you carry a rugged one like I do, you carry a spare emergency space blanket as well to wrap around your pack at night. In my case with hammock camping and having my gear on the ground, it's essential to find a way to keep your stuff from freezing. If you do not have a water bottle insulator, space blankets work great in keeping water from completely freezing.
Altogether, I think space blankets are great! I do believe that a lot people don't know how to properly use them or the potential that they hold. Always remember that a space blanket is great in an emergency, but does not replace your spare shelter or sleep system. Use it as a tool, not a substitute. If you have any other great uses for space blankets, please comment below.
