Is it warmer to sleep in a car or in a tent?

Question

Is it warmer to sleep in a car or in a tent?

Suppose that our old internal-combustion-engine car breaks down in a remote place at -30°C, -40°C, or -50°C, and the engine won't run at all. Suppose we're travelling with a single car, but we did bring full camping gear, including winter sleeping bags and a good double walled dome tent that we can squeeze into together with all passengers. We also have some candles to make heat. It's getting dark and we will spend the night hoping for a passer-by tomorrow.

Faced with the choice is sleeping in our broken-down Toyota or in a tent, what would be warmer? We may be able to bury the tent partly below the snow. Assume no wind.

See also: My car broke down in Siberia. What do I do now?

Answer 1

I suggest using both the car and the tent together.

A car will lose heat fastest through the windows, so use the tent to cover them (and the top). The windows are a thin single layer of glass, while the panels trap a layer of air between the metal outer and a lining that is a better insulator than glass. The panels also block radiative heat loss from the interior. Lower panels tend to have noise absorbing pads covering some of their area, and these have some insulation value. Even a tent big enough for 2 should cover the windscreen and front windows with a couple of layers of fabric and you can get in through the back doors; a 3-person dome would go right over the top of a small car.

This approach has another advantage: it will attract attention. A car could pass before you can react if you're huddled inside a tent to keep warm, but in difficult conditions a driver would be likely to stop for something so out of the ordinary

Answer 2

The car, mostly because you can use the heater. You will want to make sure that the exhaust is clear to avoid carbon monoxide poisoning and only run it for a short periods at a time. This also helps keep the engine warm, as it is much harder to start an engine when it is really cold out.

If the the engine quit working, like say you hit the oil pan and froze up, you will still want to stay inside, since the car is already warm as opposed to setting up the tent and then having to try and warm it up with body heat and candles.

Also, the car will be dry inside, while the outside may have snow and ice since its winter.

Going outside to set up the tent will expose you to more cold than simply remaining in the vehicle.

Your vehicle will also be more visible and most people would assume that is where you are. If you were camping in the woods, they might assume that you had hitchhiked out of the situation.

One last note, from personally having slept in vehicles below freezing before, be prepared to scrape frost off both the outside and inside of the windows.

If you’re stuck in your car and immobile, first, call for help. Don’t overexert yourself and don’t leave your car and begin walking for help. Typically, you have a better chance of being found if you remain with your car, which may also provide the best shelter from the elements.

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Instead, be sure the exhaust pipe is free from snow and roll down a window enough to vent the car and prevent carbon monoxide buildup. Run the car for short 15-20 minute intervals to warm up and then turn it back off, using blankets, a sleeping bag, hand warmers and the body heat of others in your car to stay warm.

Source

If your car starts and has fuel, use it for heat. Cover the bonnet so that as little heat as possible is wasted - but always make sure that the exhaust is clear. Note: Do not go to sleep with the engine running.

Source

Answer 3

I can't say with certainty about which would be better, but I can speak for the survivability of spending a night in a tent at nearly -30°C(acutally -20°F/-28°C). As a boy scout, my troop and I once shared a large canvas tent while winter camping in Idaho and we were all blissfully unaware of how cold it actually was outside.

In the morning, our leaders told us that the outside temperature was -20°F, which they measured late at night by checking the thermometer in one their trucks. There were probably 4 boys in the tent. The leaders slept in a separate tent. I slept in a zero degree synthetic mummy bag and though I remember being a little chilly, it wasn't the worst camping experience I have ever had. I have also spent a few nights in car and have often found that not very comfortable temperature wise or otherwise, but I can't remember if I had my zero degree bag on those occasions.

Answer 4

I have slept many nights in a homemade conversion van From experience getting up at dawn, it usually feels warmer outside the van then in it.

There are probably scientific words for it; but the metal gets cold and "sucks" the heat away from your body.

If you have a tent, AND IF IT IS SAFE to set it up where you are, and if you have a good insulator between you and the ground. I would pick the tent if warmth was the only concern. Additionally it will be easier to get comfortably stretched out in the tent.

Answer 5

You should stay in the car, just sleeping on the ground will suck a ton of body heat. Even if you do have a cot, most tents won't keep heat nearly as well as a car, since most car's do have some amount of insulation.

To make sleeping in the car a bit more palatable, you can cover the car with loose snow if available (use a floor mat as a scoop); snow is actually a decent insulator. Make sure you remove the snow from around the exhaust so you can periodically run the car's heat without succumbing to carbon monoxide (Just run it till you get warm and turn it off to preserve fuel)

You'd be better off using the tent fabric as a blanket(s) and using the tent poles to hang a message on in case you get snowed in.

On a side note, its always good to keep a gallon of distilled water in the car for emergency situations. Not only can you drink it in an emergency, but it can be used to temporarily fill your radiator to get you to a safer location. (In a real emergency you can go all "Red Dawn" and use your urine)

You can make a small heater using an empty metal container (soda can), a piece of paper (for a wick) and a fuel source (such as alcohol, a spare quart of motor oil or even hand sanitizer).

Answer 6

It depends.

Your question says that you have a good set of camping gear. A properly set up tent, with the right gear can be quite warm. Much better then a car. A car will lose heat quite quickly. Running it, specially in the snow, can be deadly.

A proper set of gear will keep you not only warm but comfortable.

There is a vast difference between a thin walled pop-tent, that is designed to be used in the spring and summer, and a proper setup (including a ground mats, bags and barriers). If all you have is the wrong kind of tent, your car may do better.

Now that said, if your talking about an emergency situation, where you don't have a proper set of gear, then a tent could really suck.

Answer 7

The question supposes that you have winter camping gear. It would be warmer and more comfortable to set up in the tent. You have already specified that the tent could be partially buried (most winter tents I'm familiar with, this is part of the normal setup in any case). You can't set your equipment out properly in a car, and it is not designed for winter camping.

This of course supposes that you really do have effective winter kit. I have been on roughly a dozen winter camping trips, which have reached temperatures lower than -30°C (I think the record was -42°C). We slept in tents for all these exercises, and were outdoors for three nights; each time, there was nothing but our kit to keep us warm.

Here is what we did; some of this advice is dangerous, and for recreational camping I would suggest simply not camping at such low temperatures, but the Canadian Army (well the Infantry, this isn't a requirement for the rest) seems to think its troops should be effective at all temperatures:

• Use the best sleeping bag available; for us that meant two -20°C down filled sleeping bags (while some might not think that makes sense, it is very versatile).
• If possible, invest in a Gore-Tex sleeping bag cover; this is quite expensive, but with a bit of tarp you can literally embed yourself in a snowbank and sleep.
• Use an air mattress. The best ones in my experience are not pretty, they look like they are made out of what looks like bicycle inner-tube, and provide about 6-12" of lift; this provides very good insulation against the ground. Also ensure you use the air-scoop (a feature some air mattresses have), or a hand pump: you can't mouth-inflate an air mattress in the dead of winter if you want it to roll up in the morning, and/or not be full of ice after a few uses.
• I don't have much opinion on the tent; it should be a winter tent; the ones we used were highly flammable. Tents capacity are generally assumed to be shoulder-to-shoulder; in the winter a full tent is very helpful.

• Heating [this is where things get dicey]: - Candles are quite risky in my opinion, a Coleman lantern is much better; it throws reasonable heat and provides excellent light, you can carry it around outdoors. It is a good investment in the event of a power failure.

  A second method of heat, which is quite dangerous, is the use of a Coleman stove, which we would actually light indoors! (although by protocol you are definitely not supposed to!). If you are not able to stand comfortably in the tent, and you are not really proficient in the use of your stove such that you can get a flare-up under control, then light the stove outside (or you won't have a tent). The stove can not be left on unattended, so it is just used to heat the tent initially.

  The lantern can be left on all night but should be turned down. This will produce carbon dioxide and monoxide, not enough to be life threatening, but enough that you may feel a bit hungover first thing in the morning. Also be aware that under very low temperature conditions, filling the stove and lantern is a frostbite risk, so be careful not to get the fuel on you.

• Try not to wear much clothing when you sleep: you want to have enough clothing to be comfortable but you don't want to risk sweating; at some point you'll need to get out of your tent and what once was effective winter clothing will now be compromised.
• A final note; it is best to camp when the temperature is very stable, beneath freezing: -20°C is safer than 0°C. More deaths happen where the temperature fluctuates around the freezing mark. This is because people underestimate the severity of the temperature, and they will get rained on and then then the temperature will drop beneath freezing. If the temperature is close to the freezing mark, it may be better to stay in your car unless you have rain kit in addition to your winter kit, even so it is a PITA.

Since you have a break down of temperatures, my only advice at -50°C... you will die without a proper setup, if your car is dead... get out and set up quickly (again, assuming you have the kit). Otherwise there is plenty of advice already here in the other answers regarding what you could do to survive longer in your car.

Answer 8

Unless you can still use the car's heating (which usually presumes the motor still works), you're definitely better inside the tent.

This can be told both from experience, and science-based.

I've once slept in a car at slightly-below-zero before. Half an hour and you're done. On the other hand, sleeping an entire night at sub-zero in a tent curled around a young woman is not only tolerable, but quite comfortable.

As far as science goes, a tent will have a heat transfer coefficient of about 4-5 for each layer of fabric (so somewhat below 4 if you count them both), but the layer of resting air between the two walls significantly reduces the overall figure, to about one half. Heat lost is due to radiation, convection is (practically) zero, assuming you're not sleeping on the naked ground.

The car's windows will have a heat transfer coefficient anywhere from 6 to 8, and the chassis, although somewhat insulated, will not be much better since the metal is an excellent thermal bridge (with transmission coefficients in the 50-60 range). You have two sources of heat loss here, radiation and convection. Metal is awesome for convection. Not so awesome if you want to preserve heat, though.

Answer 9

Neither. You need to change your perspective. Both the car and tent will "leak" heat, as neither one has very good insulation, even if you are using a 4-season tent. Think of both as a form of shelter. Your shelter protects you from the elements such as wind and rain; it keeps you dry. Your sleeping bag or blankets or layers of clothing is what will keep you warm. When planning a sleeping bag purchase, remember that the temperature rating on the sleeping bag indicates the temperature at which you will survive in the bag; for a comfort rating assume 10 to 20 degrees warmer.

In the winter, wind and water are your two enemies. If getting out of your car to set up your tent means you will get wet, stay in your car. If you can safely set up your tent and stay dry, then set up your tent so you can stretch out comfortably in your sleeping bag.

Answer 10

Unless the car can provide heat (either engine or independent heater), tent is a better choice - car is not designed to keep the heat inside; tent is.

Car is mostly metal and glass, both poor insulation materials. They will get cold in no time and then will cool down the air inside. Note that the car's windows are single-pane. Windows in buildings are not comparable, as they have air between the panes.

While the tent's two layers of fabric may seem like not much heat protection, it's the air between them that's providing the insulation.

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I have slept in tent on snow and it was fine. I also slept in a car in about 5°C (in a sleeping bag) and was woken up by the cold in very early morning and had to start the engine. A relative of mine often went skiing and slept in a tent pitched right in front of their car (they now have a car with a heater and sleep in the car since then).

Answer 11

I've done enough crazy camping in the UK to know how best to get chilled to the bone in a mild climate. Assuming you do not have sleeping bags and you have a single-skinned tent then the car is best because you can run the engine every time you wake up frozen, unless of course you're in this pickle because you ran out :) I will not run the engine while I'm asleep in the car and anyone who does this in drifting snow is dicing with death. In the tent you can spoon with your buddy and/or your dog but a one-skin tent always sucks beyond belief. If it rains then you just have to get back in the car!

A two skinned tent is routinely better than a car if you can pack enough heather or, better, a plant called Bedstraw under your points of contact with the ground - the major way you lose heat.

Answer 12

The answer is it depends.

Sleeping bag and insulated pads is the same.

Vehicle

• Wind proof and water proof. But it is not going to be raining at -30°C.
• Glass and metal are not good insulators. Glass is less insulation. Glass suffers from radiant heat loss.
• More surface area for more heat loss.
• Up off the ground so you are insulated from the ground.

Tent

• A good winter tent is water proof. Not totally wind proof.

• Typically less volume compared to a vehicle so you can better share each others heat.

• Not a great insulator but a double wall tent is certainly better than glass.

• More comfortable to sleep in a tent.

• You can pitch the tent in a chosen spot.

Situation I think situation will dictate.

• If the car is on a ridge without protection that would favor the tent.
• If there is good natural shelter near by that would favor the tent. Tree canopy and hill to block wind.
• High wind will favor the car unless there is natural shelter you can get to with the tent.

• Snowing it would favor the car as you don't want to get wet.

• Getting dark favors the car. It takes time to pitch a tent.

• Rescue probably favors the car if the tent is not visible from the road.

If you go with the car. Push it to better shelter if that is an option. I would use the pads on the windows (inside or out or both) if you can hold them in place. Then cover the roof and windows with the tent.

Again it depends. If you have proper sleeping bags you are going to do OK. A nice tent like a climbing tent then I think I would go with the tent in most situations.