Prev NEXT  


How Space Blankets Work

Types of Space Blankets

You can find several different types and brands of space blankets for sale. Find out what kind will best suit your needs.

The traditional space blanket is just a metallic sheet. It folds up into a very small package. It's usually shiny on one side and colored on the other. Some space blankets are bright orange on the colored side for easy visibility in the woods.


The space blankets you see at marathons usually come in a roll or are shipped flat in boxes. Marathon sponsors realized almost immediately that they could advertise their brands right on the sheets -- an inexpensive way to create walking billboards.

Sporting goods stores offer a wide range of space blankets. You can buy a cheap emergency blanket for less than $4 -- making them virtually disposable. You can buy more heavy weight, reusable blankets for around $14. You can buy a survival blanket big enough for two people.

Or, if you know you'll be in extreme conditions, you could purchase a bivy sack. A bivy sack (sometimes spelled "bivvy") is short for "bivouac sack." The word "bivouac" means a temporary encampment or casual shelter. Experts recommend bivy sacks for people who need to carry the least amount of weight possible -- campers, mountain bikers, climbers and the like. Bivy sacks are waterproof and shaped like a sleeping bag. You put them over your sleeping bag or -- in warmer conditions or survival emergencies -- use the bivy sack as the sleeping bag itself.

Many bivy sack manufacturers use space blanket technology to make the bivy sack even more valuable. The metallic reflective coating blends with a heavier, stronger material. That makes it waterproof, more durable and less prone to rips and tears. It is a bit heavier than a regular Mylar-style space blanket, but has its own advantages as well.

Here's an example of using a bivy sack in an extreme survival situation: If someone's clothes are soaked and they are in danger of hypothermia, you can remove the person's wet clothes and place him or her in the bivy sack. This way the victim's body won't waste energy trying to warm up cold, wet clothing.

An emergency bivy sack comes folded in a pouch no bigger than the size of a large can of soup and weighs about 6.5 ounces (184 grams). A bivy sack will run anywhere from around $16 all the way up to around $40 or more. It all depends on the quality of the particular item.

To find out more about space blankets and survival gear, check out the links below.

Related HowStuffWorks Articles


  • Buggy, D. and Hughes, N. "Pre-emptive use of the space blanket reduces shivering after general anaesthesia." British Journal of Anaesthesia. 1994. (Nov. 12, 2009)
  • "Emergency Shelter." REI. 2009. (Nov. 12, 2009)
  • "Full Wrap on Space Blankets." Runner's World. 2005. (Nov. 12, 2009)
  • "General Guidelines for Recycling at Mass Participant Sporting Events." AFMInc. 2008. (Nov. 12, 2009)
  • "How Body Heat is Lost." Survival Topics. 2009. (Nov. 12, 2009)
  • "How to Choose a Bivy Sack." REI. 2009. (Nov. 12, 2009)
  • Huntington, Tom. "Bringing NASA Down to Earth." 2008. (Nov. 12, 2009)
  • "Reflecting on Space Benefits: A Shining Example." NASA Center for AeroSpace Information. Feb. 27, 2009. (Nov. 12, 2009)
  • Smucker, Philip. "U.S. soldiers' options limited to protect Afghans from Taliban." The State. Jun. 2, 2009. (Nov. 12, 2009)
  • Speik, Robert. "Emergency Space Blankets Must be Used Correctly." 2007. (Nov. 12, 2009)