Virginia -- Winter is here, we might not feel it much South of the Wall, but a recent review from a mysterious customer confirms the use of emergency blankets for warmth, insulation, and defense. A space blanket (depending on the function, also known as a Mylar blanket, first aid blanket, safety blanket, thermal blanket, weather blanket, or heat sheet) is an especially low-weight, low-bulk blanket made of heat-reflective thin plastic sheeting. They are used on the exterior surfaces of spacecraft for thermal control as well as by people. Their design reduces the heat loss in a person's body which would otherwise occur due to thermal radiation, water evaporation, or convection.
"Once morning came, I set off on my own. As I walked, out of nowhere a blizzard rolled in, so I took shelter behind a rock. There I watched as armed white walkers approached from out of the snow. All of sudden a white walker mounted on a dead horse gazed in my direction, but I immediately took refuge under my thermal blanket. Luckily, the size of the thermal blanket wholly covered me, although it couldn't drown out the the screeches of the army of the dead."
It is important to understand how we are losing body heat naturally all the time. Sometimes it is a good thing, as when we’re trying to cool off during a hot summer’s day, but sometimes our body can’t keep up with what we’re losing and escapes us when we’d rather have it warming our cold fingers during the bitingly frigid temperatures of winter.
In a hot environment they can be used to provide shade or provide protection against radiated heat, but using them to wrap a person would be counterproductive, because body heat would get trapped by the airtight foil. This effect would exceed any benefit gained from heat reflection to the outside.
Many people think, since they have never needed one, that it’s a waste of space to put one in their pack, but this is a multi-user item that can serve so many more functions than it was designed for. When spending time outdoors I prefer to bring multi-user items to save space and weight.
Thermal blankets can, however, be used very effectively against heat loss through convection. Wrap the blanket around exposed skin and you have a wind breaker to keep that breeze from blowing across your skin and whisking the heat away.