Bivvy Sack: It’s that much better than an Emergency Blanket

Bivvy Sack

Just about every outdoor pack has an Emergency Blanket or two.  Mostly because they are small, cheap, and light.  But are they really that useful? Here’s why I think you should go for an Emergency Bivvy Sack instead.

The Bivvy Sack

A Bivvy Sack (or Bivouac Sack, Bivy Sack, or Bivi) is usually a slip on cover for your sleeping bag to make it warmer or waterproof.  An emergency bivvy sack is made so that it can be used by itself.  Usually out of synthetic materials that are designed to reflect and hold body heat.

Obviously it’s something great to throw in your Bug Out Bag, but I am thinking it might be most useful for an Urban Survival Bag.  It would be a great warmth and weather protection option for an urban survival pack that is usually smaller and might not be made for out right camping, in which case you don’t have a full sleeping bag.

1. Its Reusable

I don’t know about you but I am never going to be able to refold a .79 cent emergency blanket back into that tiny little square. An emergency Bivvy Sack comes with a stuff sack and is made to be reused.

2. Sleeping Bag Style

Bivvy SackEmergency blankets are nice but they are awkward in a situation where you need warmth around your whole body. Square blankets are great for laying on the couch in the winter, but when you need full protection from the elements a sleeping bag style is really the best way to go.

Not to mention you could just slip it over your full sleeping bag anytime you need to for added warmth or water protection.

3. Help Other People

Not that any Survival Cache readers would be caught unprepared, but you could use an emergency bivvy sack as a sleeping bag if you had to. Assuming all our great readers are prepared, you could use it for helping out someone else who isn’t prepared.

AMK Heatsheet Emergency BivvyAMK Heatsheet Emergency Bivvy

AMK (Adventure Medical Kits) makes a great one called the Heatsheets Emergency Bivvy. It only weights 3.8 ounces and comes with a stuff sack. It costs more than a survival blanket, but since it is much more substantial and reusable that’s not a big deal.  They also make an updated version of the bivvy sack called the Emergency Thermal Bivvy II.

AMK Heatsheets Emergency Bivvy – $13.99
AMK Emergency Thermal Bivvy II – $23.99

Check out our new Survival Store – Forge Survival Supply

Photo by: Javasport

{ 24 comments… read them below or add one }

Josh April 3, 2010 at 2:01 pm

Waring ear plugs could have the downside of distracting you from your surroundings, allowing someone to sneak up on you unheard.


Lucas_SurvCache March 9, 2010 at 3:49 am

Yes, it is definitely more useful than a space blanket for a full nights shelter.

However, if at all possible you should try to find something else to put over you if you plan to use if for the whole night, to keep the dew off.

A space blanket is good, but like you mentioned a tarp is probably better for long term. Long term being a couple of days, before you can put together something more substantial.


caine30 June 21, 2010 at 2:07 am

my down filled cold weather sleeping bag has a older style canvas bivi on it if you treat that with some water repelant it is a great bivi I like it because of the OD green it blends in well with the foliage around my area so i just slip into it and role under a bush and walla no one can find you unless they are looking for you that is.


Jerry June 4, 2010 at 11:58 am

I was at FT Irwin in the winter one time and had my seeping bag stolen. I could have used a bivy sack ,but they didn't make them back in the 80's as far as I know. Having one in my pocket would have help get trough a freezing cold night.. I tried to wrap my shelter half around me but it didn't help much. I managed to cozy up to next a heater in one of the tents. long night.


Lucas_SurvCache June 8, 2010 at 4:41 pm

There is not much worse than spending the night freezing. Glad you got through that night alright.

These little bivvy sacks are so useful for an emergency shelter, or a sleeping bag cover for added protection.


MadManDan October 13, 2010 at 11:21 am

I'm using a fleece sleeping bag, and in all practice runs it has been fine up to 0 degrees F when used with a tarp. If you leave an extra layer on it would probably do better. Also it weight is less than a pound, but its disadvantage is it is a little bulky when you strap it in to a rack, and it isn't waterproof by itself.


Markiah November 2, 2010 at 3:49 pm

This may be a little off subject but I read on another survival site to have a carpenter garbage bag (55 gallon). They weigh practically nothing nor take up space but that of a garbage bag. You fill them with leaves etc. and you have a pretty soft, dry way to sleep instead of the cold, hard ground. I bought a carton of 18 bags at Wal-Mart for around $20.00. I put 1 in my bag and 2 in my husband’s bag. It is a light bed roll in our grab bags. Love this site! Thanks Lucas.


ptman678 November 19, 2010 at 9:58 pm

Glad to see the site back up,missed the great articles. Actually tested one Heatsheet bivy bags on Boy Scout Wilderness Survival merit badge campout this past October,Southeastern region. Temperature approx. 45 degrees, clear skies, wind < 5 mph.Slept uncovered on the ground with just the bivy bag as shelter. Used an Italian wool Blanket as a ground pad (no sleeping bags or foam ground pads were allowed). Bag kept me plenty warm; problem was moisture accumulation inside the bag from my perspiration. Had to keep wiping it off the inside of the bag with my bandana all night. Great piece of kit, just be prepared to deal with moisture if you include it your gear. Could be critical issue in really cold weather.


Chance January 31, 2011 at 6:29 pm

Last night my wife and took a group of friends out on a steath bug-out overnighter. It dropped to around +40 and my friends had no sleeping bags, warm clothes, or blankets. I sacrificed my wool blanket, heavy duty reflective blanket, wool vest, and cap to try and help the three of them. I then filled my contractor bag with dry leaves, hung a tarp, and crawled into my down sleeping bag. I slept wonderfully.


Ben228 April 5, 2011 at 11:57 am

Love the idea! Feedbacks is great. I think I’ll be getting some for both of my trucks and a couple for BOB as well.


Ben228My April 5, 2011 at 12:06 pm

my BOB has several contractor garbage bags in it. They are very multi-functional. They can be used as bedding as stated above, split the seams and they can be used for a tarp, two arm slits and one for the head=poncho, drop BOB into it for water obstical fording, inflate it and and tie it off and “voila” floatation device and on and on.


bostonsurvival April 17, 2011 at 8:35 pm

Definitely thinking of getting one of these..what is the difference between the two sold on Forge Survival Supply though? I see that the updated one is heavier and mentions a "Thermo-Lite" material, but I'm just wondering how much different it is than the original and if it's the only difference between the two. Thanks!


rab sleeping bags March 31, 2012 at 6:46 am

Ekrich attributes the change to increases in "street lighting, domestic lighting and a surge in coffee houses," which slowly made nighttime a legitimate time for activity, decreasing the time available for rest.


rab neutrino April 4, 2012 at 10:47 am

Materials used in messenger bags are often more durable and water-resistant than other over-the-shoulder bags. Contemporary bags use thicker gauges of canvas and tarp shielding for the inner waterproof lining.


JC Refuge May 31, 2012 at 2:09 pm

Just tried mine out a couple weekends ago as a sleeping bag cover and kept warm and dry even though it was raining most of the time. I would highly recommend bivvies, especially because they pack up so small and can be used multiple times.


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Timothy January 29, 2013 at 9:08 am

Can't recommend the basic AMK Heatsheets Emergency Bivvy, as its basically an "space blanket" sewn into a bivy.

Has the same moisture problems as being wrapped in a space blanket. Tested mine indoors on top of the bed at 68F. Woke up soaking wet from condensation.

Managed to get it folded back up and mostly back into the little pouch. Brand new there's room for a button compass, and matches in a pill pouch in the bottom.

Have read better reviews for the more expensive emergency bivys which have a vapor barrier.


fran December 5, 2013 at 7:00 am



Brenda R. King March 20, 2013 at 7:38 pm

That looks handy and rugged enough for any climate. This could be useful during a stormy season or an emergency situation. I will look for this handy gear for my travels.


Ellie June 7, 2013 at 11:07 pm

That's truly an amazing review of Bivvy Sack blanket. I agreed with the views about this blanket. For better sleeping comfort such blanket is very effective. I'm using this blanket for quite sometime now and it's good. Thanks.


Apnée du Sommeil July 24, 2013 at 4:01 am

These look much more useful than the blankets. I will have to check one out myself.


sudhanshu das August 10, 2013 at 12:37 am

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פריסה ארצית שירות 24 שעות


gst March 6, 2011 at 12:56 am

Tried one of a different brand in Scandinavian winter – At night the temperature got as low as -30 degrees Celsius (about -20 degrees F I think). The bivouac acts as a vapour barrier, traps your sweat, it condensates on cold surface of the bivouac, the moisture was sucked by my down-filled sleeping bag and froze.

I woke up after half an hour shivering with cold, with my sleeping bag soaking wet and frozen to the bivouac. Spent the rest of the night sandwiched between the two others in our group wearing everybody's spare clothes.

So not really useful in a really cold environment. A space blanket or two are better there, because you can't wrap them so well around you, there will always be ways for the vapour to escape.

So only use them in moderate to cool temperatures, never in really cold temperatures.


anthony2823 August 5, 2012 at 11:06 am

Your really hurting in Ft Irwin in the winder! Been there MANY times. Sadly the best thing you could have done with the shelter half was dig in the ground, lay half the material as a flat tight sheet, put some dirt on top of the edges fold it over again and lay more dirt on the sides. what this does is makes an Air gap between you and layer 1, and an air gap between layer one and layer two. with you diging your body legnth in the ground you will get rid of the wind too. We do this with the liners of parachute to make over night shelters in the survival course. The min air space where your body is and the gap insulates you a bit. (but staying next to a heater in a tent is SO much warmer lol. Shelter half wrapped around you wont really keep you too much warmer,


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