Note: Much of what follows was gleaned from a post Laren Corie made to the Vandweller's list:
How can you heat your vehicle on cold, wintry nights? There are several strategies
- Heavily insulate your vehicle. The more your vehicle is insulated, the less heating it will require.
- Bundle up. It's much easier to heat you alone, than it is to heat your whole vehicle. Multiple layers of clothing (t-shirt, sweater, jacket) are better than a one single layer of the same thickness. Each layer of clothing traps a pocket of air. The trapped air prevents heat radiated by your body from exchanging with the colder external air. Layers of clothing also allow you to remove clothing as you get warmer. This helps you to avoid sweating which can cause excessive cooling as the sweat evaporates.
- Wear a hat. Roughly [30% of body heat] is radiated through an unprotected head and neck.
- Use the vehicles on-board heating. If you live in a temperate climate, and your vehicle is well-insulated, captured heat (from the on-board heater and solar radiation) may be sufficient to keep you warm enough to sleep throughout the night.
- Build an air-to-air heat exchanger. This will allow you to vent the excess humidity and stale air from your living space without losing very much energy.
- Store heat energy in a "thermal battery" such as a tank of heated water, Nalgene "piss jug", or a container of melted paraffin. According to Laren Corie, "...8.3 pounds of water (1 gallon) will only store 833 BTU for a 100°F rise. That is less than 1% of the energy density of propane..." Melted paraffin can store much more energy in a smaller space.
- Set up a heat exchange circuit between your vehicles cooling system and the your hot water system. Idle the engine for a while to charge your hot water tank.
- Make a simple, vented, charcoal, or wood pellet heater, to mount on a wall, and either use it to heat the interior air, or to also put its heat into the heat storage, or both.
You can also combine all of the above approaches. Here's how Laren Corie describes one potential setup:
At this point [all of the above] may not seem practical, but I can assure you that it was a very practical approach for my Centauri Van, which was a small diesel, box van. The walls were an insulated sandwich of aluminum surfaces, and 1 1/4" of uruethane foam (aprox R 8-10).
I figured that two 20 gal tanks (under the bed platform) plus the eleven gallons in the heat exchanger tank, would be enough to get me through an eight hour night of 0°F. It would not keep the van at 70°F but it would keep it warm enough for comfortable sleeping. On nights that only went down into the thirties, it would stay toasty. This also considered Reflectix covers over all of the windows. Fifty gallons of water weighs over 400 pounds, but you need to carry some water anyway. Paraffin containers, could be arrainged to heat the bed platform, instead of the interior air, and would require a lot less storage, while you normal water storage could be used to heat the interior air.
A two liter bottle of paraffin (votive candle wax)heated to just over 130°F will give off about 400 BTU as it cools to body temperature. It will then give off another 100BTUs or so, as it cools down to the temperature that the van air will cool to.
Two liters of water will only give off about 4 1/3 BTU per °F, so maybe 80 BTUs as it drops from 130° down to 50°F.
A two liter bottle of melted wax will store about five times as much heat as a two liter bottle of water heated to the same temperature, and it will also weigh considerably less. Either one can be heated all the way up to the aprox 180°F that the engine coolant gets to.
Just call these guys, they will keep you warm
Cooling tends to be more difficult in general than heating. When you are cold you can add more layers, but it is more circuitous to cool off when warm. During the summer, most vehicles heat up due to the greenhouse effect. This is very unpleasant to wake up to.
- Block sunlight from entering the vehicle, preferably using white material on the outside of the windows.
- Experiment with some method to actively circulate air into the vehicle.
- Park in the shade
- Sleep outside the vehicle if possible
- Install a 12V fan. Check the power consumption
- Build or purchase an air conditioner that works by evaporating water such as a swamp cooler or evaporative cooler. Note that this works in inverse proportion to the relative humidity. Heat of vaporization is 5 calories per gram. It takes 5 times the amount of energy to vaporize water as it does to heat it from 0 to 100 degrees celsius. So they are really effective. (It appears, however, that some swamp coolers output humid, cool air; which in most climates except exceptionally dry ones will not cool you because the water vapor will condense on you heating you up. You should run that humid air through a heat exchanger, exhaust the humid air, and blow the cool and less humid air over you.) Apparently, simply cooling your face has a large effect.
- Sleep in your underwear - can be a problem in the event of a nighttime disturbance.
- Use a peltier junction cooling device (such as found in 12V coolers). There is a product that cools just your neck, or you could circulate cooled water over you