Heat in the temporary shelter

Suppose all you are going to have is temprary shelter in the wild as you self-rescue or travel out of a disaster area. Maybe an improvised or small tent from your BOB supplies; maybe enhaced by getting up under a large bushy tree or in sheltering rocks.

You have to move and you need to get warm to recoup energy for moving, sleep, etcetera. Fuel for wood fire is available, but not much. Rocks may not be readily available. You have one water carrier container. You do not have much time each day to deploy your heating strategy.

What is the best and least elaborate way get adequate heat into your sleeping area for a whole night? What is the best and least elaborate combination of strategies to accomplish the goal?

dig a hole in your shelter where your bed is going to be, heap hot coals in the hole and cover with dirt. Make your bed on top, that's the best I can come up with, within the described parameters.

My thoughts also went to buried coals. It's a technique I've never tried and if it's something you want to use, try it in benign conditions so you know how deep, how much dirt on top -- too much dirt and you lose the heat, too little and you get hot spots. Ron Hood covers the Firebed in his Woodsmaster© Volume 2 Shelter.

It would be hard to find many areas that don't contain trash. Try to find a can and punch some holes around the bottom (bottom of the vertical walls, not the bottom bottom) with your knife. Get a fire started with debris in the bottom, and gradually add twigs, fir cones, dried grass (twisted and knotted), etc. Set this little stove on a flat rock if possible (it will retain some heat), or on bare ground.

"You do not have much time each day to deploy your heating strategy."

If heat is important to your survival, you'd better MAKE the time. And don't wait until dark.

Sue

In my experience, an hour spent on insulation brings twice the benefit of an hour spent on fire. Aside from boiling water, and some undeniable psychological cheer, a fire is there to dry out your person and your insulation (clothing, bedding). A bed of boughs (or dry grass or moss) to keep you off the ground is top priority, absolutely essential.

My 0.02

two long,low fires and sleep between them,or just one big whopping blaze and hope for the best...

Arranging a heat reflector behind a small fire can greatly increase the felt heat output by sending the warmth toward you instead of allowing it to be scattered. Logs, a board, rocks can be used close to the fire. You can further focus warmth by placing a reflector behind yourself. A tarp will work and it can pull double duty by acting as a windbreak, making you feel warmer by reducing heat loss. Mylar space blankets work really well as reflectors.

Also a small fire placed closer and using reflectors is more effective, and fuel efficient, than a large fire.

If your thinking of something less logistically involved one of the most efficient methods of warming someone I know of is to have them crouch or sit and place a large garbage bag with a head hole cut into it over them and placing a heat source, candle, candle lantern, oil or carbide lamp, under the edge of the bag. The heat rises into the bag where it collects and warms the person. You have to be careful not to set the bag, ground cloth, or any clothes present, on fire but it works very well.

By varying the flame height of the heat source, the amount of air you let in under the bottom of the bag, extending you legs out of the bag, and using your head to open or close the head hole it is possible to regulate the interior temperature. If the heat source is one that is one you can reliably regulate to a low setting and burns a long time it is possible to nap in such an arrangement.

In cold conditions it help to place some insulation, assuming you have anything dry, between your back and the bag. Also don't make the head hole too large. A good quality garbage bag will stretch around you head a bit without tearing. This technique, like so many other things, works best if you have tried it a few times before getting it to work in a critical situation.

Pay attention to where you locate your shelter. A difference of just a few feet can make a difference in exposure to wind, which is likely to be your biggest problem. Brush and thickets will shield you from breezes, while that inviting clearing may be rather drafty.

Avoid the bottom of drainages if you are concerned about the cold. Temps are often 5 to 10 degrees warmer only a few feet upslope.

Evaluate the possibility of traveling during a portion of the night. Exercise keeps you warm. This is dependent upon the terrain, your familiarity with it, the light sources you have with you, and moonrise.

If your fuel is limited, consider not building your fire until later in the evening or early morning. In my experience, 3 AM is the toughest time for an impromptu overnight.

Eat well and carefully. Ingest fats for long term metabolism. Bundle up early and stay out of the wind. Get insulation on your head and neck

Keep your spirits up, maintain a positive attitude, and look forward to a nice cup of tea to get things started in the morning.

Consider filling secure containers as "hot water bottles."

Arrange whatever you need to avoid having to exit the shelter and let in cold air that must be heated again.

If you have companions, get friendly in a share-the-body-heat sort of way.

Keep the space you have to heat as small as you can.

Consider found insulation like leaf litter, dry grass, appropriate evergreen branches, especially between you and the ground.

Save the firewood for later. Don't use untill you get very cold. Assuming that you can build a shelter of sorts or have a tent then this is your best bet.
http://www.heinnie.com/product.asp?s=wvpiv9703038&strParents=&CAT_ID=0&P_ID=4581

I have used these and its remarkable how much differance a candle can make.

Usual words of caution about ventilation.

You've actually posed an excellent question. And quite a few of the responses above have some great ideas.

I'd be tempted to try the following:

1. If you sleeping in a makeshift shelter such as a lean-to, locate the shelter to minimize problems from the wind and cold.

2. If possible, line the inner wall of your lean-to with a foil survival bag. I'm not a big fan of these bags as "sleeping bags", but they are great for reflecting heat.

3. Construct a small fire on the ground immediately beside your lean-to. You will get direct heat from the fire, plus reflected heat from the foil that you put on the inner wall. Since the inner wall is sloping outwards, it will tend to capture more heat and reflect it downwards directly onto your sleeping position.

4. Pile up a some smooth small rocks on the opposite side of the fire, so these also reflect some heat towards you. Later on, if the fire goes out - you can put these warm rocks inside your sleeping bag, or if they are very hot you can bury them in the ground beneath you where you are sleeping.

5. If you have a couple of larger pieces of wood that you can burn, try making one of those survival fires where you only burn the wood logs end-on. So it's only the end of the firewood that is actually on fire, and as time goes by you slowly feed the log into the fire zone. This preserves your fuel, and also makes it easier for you to adjust the fire and keep things burning slowly during the night - in fact you don't even need to get out of your sleeping bag to do it. You can just roll over, push the wood (lengthwise) a little bit more into the fire, and doze some more.

Great question!
My suggestion is this ... next time you are backpacking go and try out these techniques. Let us know what you find out!

Pete

If you build the fire in the trench and the fill it in, you'll probably have to wait a while for the moisture in the soil to work its way out, unless you're working with dry sand.

"Save the firewood for later. Don't use until you get very cold."

But not too cold. Dying of hypothermia from not building a fire is just as dumb as dying of dehydration with water in your bottle. If you need it, use it.

Sue

I am no expert, but locally cedar trees tend to be very dry right around the trunk for several feet in diameter, such that a night beneath a cedar can be very dry even in a driving rain. Locate your shelter on the side away from the prevailing winds, and you might be fairly warm too.

Ditto also the earlier observation, someone said locating yourself up out of gulleys can raise the ambient temperature by ten degrees.

Long, long time ago I remember my scoutmaster dad showing us cub scouts how to cover ourselves in branches and cedar bits underneath a tree - literally dig down six inches and use it to cover your lower body. That was summer, the ground was dry, and I seem to recall we were all really warm and there was enough dross or duff that we didn't get too dirty or wet, but I don't know if I could replicate those daytime conditions in a cold, driving rain. Now though I would still choose a cedar for shelter, first try to build up a bit of insulation underneath me from branches, then possibly build a bit of a hut over me to retain a chance at some warmth. I have already spent the night out in the AMK bivvy so know that would be a good start and keep me alive. I am a big believer that if you can stay dry, with minimal preparations you have a good chance at retaining warmth, and living through any night.

True ... staying dry is really important.

One of the earlier posts mentioned that it is uplifting to get a hot drink. That's dead right - peoples' mental attitude can completely turn around if you give them some hot tea or cocoa when they are tired and cold. S&R teams know this, and sometimes carry a thermos just for this reason.

If a person gets wet (soaked to the skin), and then chilled as well - the risk of serious hypothermia is greatly increased. If you are alone and this happens at night, it is potentially dangerous and difficult to recover from (unless you have a spare set of dry clothes). It is much harder to maintain a positive mental attitude under wet-and-freezing conditions. At this stage - a hot drink that takes warm liquid to the inside core of the body can literally be a life saver.

Pete

Tending a fire all night is no problem when the alternative is exposure to significantly cold temperatures. I have lots of experience with this.

I have zero experience with making firebeds, but I wonder if the effort and time required isn't excessive relative to the benefits. Can you be sure you haven't left a path of ignition between the fire and you clothing or bedding?

I don't have the answer, but I'm tossing in some food for thought: Using a stove - any stove - is much more fuel efficient than any open-air burning. You can improvise something to the same effect with some food cans or other container-like objects made of steel/iron. If you can't or choose not to make a stove, at least try being a little creative with the fireplace. Lifting the base of the fire off the ground has done wonders...


What you don't have from a stove is radiant heat from open flame. You do have less intense radiant heat from the stove walls. And since you're able to come closer to a blazing stove than a blazing fireplace, you get the benefit of warm air circulation from the stove walls - excellent for drying you and your clothes.

Feeding a small stove through the night with twig-size material will be a tedious nightmare. A bigger stove could sustain itself for maybe a few hours, but probably not the entire night. But neither would most campfires...

The biggest potential of a stove is not really realized unless you also have a pipe - and THAT is hard to improvise. The pipe will allow you to put the stove in a closed shelter nirvana (don't forget ventilation holes). Dream on, grasshopper, that aint gonna happen unless you bring a complete stove+pipe unit with you. Even without a pipe, a stove has significant benefits: The combustion is hotter, meaning hotter and cleaner smoke that rises faster. Meaning less smoke in your eyes.


Google hobo stoves, they're really something you should be experienced with. Blast has described how to make the sophisticated wood gasifier stove out of tin cans on his blog. Talk about advanced scrap yard physics ... Unless you've already made one of those I say skip the gasifier project and go for the hobo stove, which you just can't go wrong with.


As with most things, stoves are not a do-all-fix-all solution, but they're very handy and fuel efficient and definitely something you should have in your fire skills arsenal. That being said, outside in the cold without sleeping bag I would kick efficiency in the but and aim for a big, blazing fire with reflector in front of whatever shelter I could make.

Not really, This is a variation on a Dakota fire pit. I belive it's called a snake hole fire. It does have to be constructed in the side of a hill or bank. Drive a wrist thick stake into the ground about 12-18 inches approximately the same distance the edge. Dig into the side of the bank until you reach the stake. Enlarge the hole to the size desired and then remove the stake. You now have a fireplace with chimney.
I should point out that I have not tried this, only read about it. I would think though that with a little work you could build a small shelter around it.

Pipes = cleared out canes or reeds, or roll of bark.

Edit: cover with clay or mud to make fire "resistant" and keep away from open flame

Actually, a typical campfire will do quite well during the night with only modest tending. A lot depends upon the quality of the wood you are using, but even with pine, the typical material I have worked with, stoking the fire every four hours or so will keep it going quite nicely.

Years ago, I built campfires routinely for cooking and for warmth, but over time I, like most people using the outdoors, have tended to use various varieties of liquid or gas stoves for reasons of safety, environmental impact, utility in any kind of weather, and convenience.

The last time I used an all night campfire was about thirty years ago. We were in an open sided Baker tent with the fire just outside. We revived the fire about twice during the evening, a quick job that interfered minimally with sleeping.

The best fire I ever built was one made with desert ironwood. We built the fire in the evening, cooked our meal and let it die down. In the morning, I blew off a thin coat of ash which revealed a glowing bed of hot coals. Water was boiling in about five minutes without the addition of any fuel whatsoever. The biggest problem was being sure it was dead out when we left.

+1 on the insulation.

Anything you can do to isolate your body from the ground and the wind will pay huge rewards, even if it's just bare branches. Lie on the bare ground and the Earth sucks the heat out of you. Lie in the open air and the wind will blow the heat off of you. Dry leaves, grass, newspaper, cardboard, extra clothing, plastic bags, dry trash, old bird/animal nests.

IMO, mylar blankets are only good to block the wind, rain and snow and to reflect the heat from a fire.

Recycle your own heat. Gotta pee? Pee into a bottle or zip bag and stuff it inside your jacket. Pull the collar of your sleeping bag, tarp, jacket, whatever your shelter, over your mouth and trap the heat from your breath inside.

Hand/toe warmers are cheap, small and lightweight, and last for hours. Placed near your groin and armpits, they can help keep your core temperature up. But don't forget your feet. I don't know about you, but no matter how warm the rest of my body, if my feet are cold I can't sleep.