I've mentioned many tips for staying warm, but in many different post. This post will be as comprehensive as possible detailing how to stay warm when it begins to get cold, stays cold, and then begins to warm back up.
The dance of the universe
Once, such a great amount of time that it cannot be fathomed, more than millennial, the stars grew, changed, went through cycles, and died. In the interiors of the stars, all of the elements of the periodic table are created. Those elements in combinations created compounds, complex molecules, and life itself, bound by energy. All things are made of star stuff.
All matter dances, spinning yet bound, in combinations with energy. If we probe yet deeper, electrons move in clouds of random movements encircling protons and neutrons in yet another dance.
The burning of wood converts the energy and compounds within to release energy. It is deeply mystical, not just commonplace. This is the beginning of wisdom.
How do forests happen?
A gazillion years ago, there was rock. Water fell and collected. Some of it broke the rock. Some simple plants grew that could live on rocky places. They broke down the rock more and died. They decayed and their actions created soil. Other plants grew taller than need soil. They died and added to the richness of the soil. These created niches that small cell life could live in, protists, and they all added to debris that allowed even stronger plant life to grow. Lichens and mosses grew taller. Seed bearing plants grew, first as brush or bush, then taller yet. Plants like crowns of sumacs spread runners and broke the spoil, preparing it for conifers. Confers thrived, created new niches and broken the soil more. Larger deciduous trees grew, and outgrew the conifers since they could thrive in warmer climates.
A forest evolves slowly over many thousands of years. If you could watch it all, you'd see waves of plants change the landscape, and waves of them growing and competing for the same light, water, soil, and humus.
[link to www.daviddarling.info
The list above details the amount of energy that is trapped within the wood. As you'll see, the amount of BTUs that radiate their energy is higher for deciduous woods than conifers in general. The trees convert the energy they consume into biomass that can release that energy again.
Those who live in colder climates will have great difficulty if things become dire. Because they generally have shorter growing seasons, the trees that provide firewood tend to be conifers. People who have very low levels of identification skills sometimes just call them pine trees. The environment of cooler regions is more favorable to the conifers, and hence they make up the bulk.
We cannot control our temperatures very well. We do not have fur like Brother Bear. We cannot dive deep to live beyond the icy waters in suspended animation like Sister Cod. We use whatever we have at hand to control our environment, adjust our mental outlook, and adapt to live in a narrow range of temperatures. It is analogous to the narrow band of the entire spectrum that we can see.
The more we insulate ourselves, the more we become like Brother Bear. That insulation can be fat, which both insulates and nourishes, or it can be fur by wearing layers. The air spaces between also act as insulation.
If you do not have insulation, or wear one layer, your body will shiver to create random motions which generate heat. If you don't stop, you'll burn up calories to do this, and it become self defeating. It become terribly hard to control your hand movements. You could freeze to death, as the body shunts blood to your core, and away from your extremities. The body sees a lack of control, and shuts down critical systems one by one, and consciousness fades. People become confused and stuporous. Death follows.
While babies have a special kind of temperature adaptation called brown adipose tissue, a kind of fat, they cannot communicate their uncomfortableness and simply cry. Children are often improperly taught how to dress since they don't stay outside very long. Hypothermia can kill children in temperatures as low as 50-60 degrees F.
The poor, uneducated,or simply obtuse people will allow their children to be ill clothed in some pretty criminal ways. I have spent a lifetime caring for children. I've have been astounded by this phenomena. It is one of the few things that can make me angry or sad that it happens.
Most heat is lost from bare skin and primarily from the head. It is folly not to wear a warm insulating cap. The body regulates heat through blood circulation. The extremities, most often the feet, grow numb since less blood circulation happens there, especially as we age. You can easily not notice that your feet are getting too cold, and get frostbite.
You can be trapped outside by circumstance in winter. You have to think long and hard if it is worthwhile to travel in it, if there is the slightest chance of being without shelter. There are many stories of families who were traveling, took a detour because of the snow, got stranded, and died.
Insulation is all around us for the taking. Newspapers can be shoved down in-between layers of clothing to cheaply add it. Leaves or grasses in the wild will do this. A debris hut, as I earlier included is full of warm insulation. Burrowing in is better that wasting heat in futile attempts to forage foolishly. You gather what you can, eat what you can from stored foods in wintertime. Waiting until winter to prepare is foolish. Very little can be gathered, and only by the smartest, most well prepared, and practiced hunter/gathers.
If you can, putting your woodpile inside to someplace like a garage, will really help you. Nothing is worse than trying to start a wet wood fire. It is miserable.
The amount of wood necessary to burn and release sufficient energy is proportional to the dimensions of the room(s) you are trying to heat. Heat rises and diffuses. A family adapting to sleeping in one room, that is well insulated in whatever manner you must do it, and only heating that room beyond 50-60 degrees, will keep everyone alive.
Something as cheap as heat shrink film can be purchased to cover windows. It takes a minimal amount of time to seal up the drafts coming in, but some drafts may help with fumes.
Seasoned wood is dried wood that has been exposed to the elements and allowed to remove moisture content. It takes time, and there is no hurrying it. You must prepare a woodpile slowly since it takes time to harvest a tree, cut it to manageable sizes for burning, stack it, and then harvest from it when ready.
Burning it wastefully early in the season when you do not know long the season will last, or how long a crisis will be, is folly. An acquaintance, one very intelligent lumberjack in Canada, told me a story once that he had burned up just about everything to stay warm one bad winter, and only barely made it. You could see the sincerity of his face when he told the story, and this is a man who makes his living understanding wood.
The amount of seasoned wood that is necessary depends upon the quality of the wood to produce BTUs and the method for releasing that energy.
A simple wood fireplace, of poor dimensions, will be horribly inefficient and produce minimal heat. There are numerous adaptations that have been created by many societies. Most of these require special construction or materials or time or engineering. All must have a means of evacuating and directing fumes which are chemical compounds released which do not support life. Carbon monoxide it the most worrisome one.
Hemoglogin is a special iron chemical compound that is present in blood. It grabs on to four oxygen molecules and carries it efficiently around the body. It is what gives red meat it's colouring. Unfortunately, it loves carbon monoxide (CO) MORE than oxygen. If CO is present, it grabs on tighter to the hemoglobin in the blood, and doesn't allow oxygen to travel efficiently, suffocation occurs, then death.
YOU MUST VENT PROPERLY! You cannot smell carbon monoxide. Crude quickly fashioned stoves killed lots of Native Americans, who understood fire well, but didn't understand drafting the fumes well. Many had crude stoves, and terrible weakness in winter. Missionaries would often provide stoves to them. Stove making without tools, materials, and engineering is difficult. It isn't impossible, but it is not a last minute operation either.
If you are blessed to have an efficient woodstove, or a rocket stove with venting or some other means then you have prepared well.
If everyone is living in a very close area, with poor carrying capacity, and using all the seasoned firewood for cooking, and it becomes stripped out in winter, YOU WILL DIE.
Many pioneers spent every available moment cutting firewood for the time of Winter. If you live in Montana or Maine, where the winters can be very long, you must spend a huge amount of time putting up wood for winter.
If you lived underground, deep enough that the Earth maintained a constant temperature, you'll need far less wood to burn.
There are lots of well meaning videos on emergency heat. Most are made for very short periods and only for cooking. Most are unrealistic, and rely upon chemicals (like alcohol) or propane or fuel which is not in abundance in a survival scenario except for very short periods of time. I have seen many videos which didn't discuss in any way venting properly, and hence using their advice could kill you.
A tactic in a siege is to block the vent of a wood stove. It is extremely hard to come up with solutions that do not require exiting. As such, the location of the stove, and it's venting, for security reasons, is a factor.
Burning too much conifer wood, or incomplete burning causes creosote to build up in the stove and venting. A whistling sound is heard as it catches fire, and creates a huge draft, that pulls oxygen to feed it, burning hotter and hotter, and a terrible fire could happen.