I also encouraged people to test their kit before they head out to the woods. The inexpensive space blankets that you can buy almost anywhere for just a dollar or two are a good thing to have for emergencies but they do have their limitations.
Their first limitation is their size, if you've ever unfolded one and tried it out you'll find they are not really made for anyone larger than a hobbit. Their second limitation is how noisy they are. I ran into a situation a couple of years ago when we were camping at a canoe in only campsite in the Adirondacks. It was the middle of the night and one of my daughters threw up in her sleeping bag. After getting her cleaned up and the soiled bag hung up, I gave her my sleeping bag and grabbed the emergency space blanket I always have in my kit, unfolded it and attempted to wrap up in it. It was a chilly north woods September night and I proceeded to choose between a warm upper body or a warm lower body. My wife who was sharing the tent with me said it sounded like I was sleeping in a potato chip bag. A much different outcome from when I tested one at home. I was finally able to get a warm nights sleep after my wife helped cover me with the space blanket, a couple of beach towels, a jacket and my tarp. It was not fun.
My wife, being the absolute most wonderful wife in the world, surprised me on Christmas morning that year with the SOL brand 2 Person Emergency Blanket and the SOL brand Emergency Bivy. They are more expensive but are both exceptional products and well worth the cost. after checking them both out I added the bivy to my woods kit and the blanket to my car kit.
I still carry an inexpensive space blanket in my kit because even though they have limitations they do work and they have other uses such as heat reflectors, signaling devices, etc. But I now carry the emergency bivy also. If you choose to carry just the cheaper space blankets, I'd suggest carrying two and enough duct tape to connect them for use as a blanket.
Let me know in the comments if you have any other thoughts or ideas.
Thanks for reading,
Chris (N.E.V.)
