Shelter, Clothing & Fire
You can only last three to four hours in extreme conditions without adequate shelter. Maintaining your body temperature in hot or cold temperatures is vital for survival. This can be hard to do if you are out of your normal environment or the power to your home is out.
Knowledge of how to maintain your optimal body temperature can help you "Be Ready" to save your life or the life of someone you care about.
- Learn the science of sheltering and layering so you can create life saving shelters in any situation, then practice
- Gather sheltering supplies like blankets, tents, sleeping bags, Mylar, cold weather clothing, and clear plastic sheeting. Include sheltering items as needed in disaster supply kits
- Learn how to keep you home warm or cool as needed if the power goes out
- Learn how to safely build, start, and put out a fire using a variety of different starting and extinguishing methods, then practice
- Cold Weather Clothing Layers
- Sheltering at Home in the Cold
- Sheltering at Home in the Heat
- Safely Build a Fire
- Disaster Supply Kit: Shelter, Clothing, and Fire
- SmokeyBear.com: Campfire Safety
- NWS: Wind Chill Chart
- NWS: Cold Weather Safety
- NWS: During Extremely Cold Weather
- Ready.gov: Extreme Heat
- NWS: During a Heat Wave
Purpose of Shelter
Without shelter, a person can die from exposure in three to four hours. The purpose of sheltering is to help our bodies maintain a normal body temperature of about 98.6°. The human body uses the hypothalamus to internally regulate temperatures by controlling the constriction and dilation of blood vessels, sweating, and shivering – but it can only do so much to counter the extremes in our environments.
What external, environmental influences can affect our body temperature? Obviously, temperature extremes of hot and cold can affect us as well as our exposure to the elements like wind and rain. If our bodies are wet from rain, being in water, or sweating we will lose heat faster than if we are dry.
Our circulatory system uses water to transport heat throughout our bodies, so our level of hydration is a factor as well. Just as a tuned-up car works best, our health and the quality of our diet can determine how well our bodies can maintain temperature. If we are physically exerting ourselves, we will be generating internal heat.
Our internal regulatory systems will be affected as well if we are taking medications or intoxicants like alcohol, nicotine, or drugs. These DO NOT warm the body, they cause the body to relax, giving the sensation of warming, but in reality the body is losing heat at a much faster rate.
If the body gets too cold and the temperature drops below 98.6 degrees, it is known as hypothermia. Symptoms include shivering. If you are shivering, you are in the first stages of hypothermia. Other symptoms are slurred speech, apathy, confusion, loss of fine motor skills, difficulty walking or maintaining balance. As severity increases, skin may turn pale or gray. Eventually shivering will stop and the internal organs start to shut down.
If the body gets too hot and the temperature rises above 98.6 degrees, it is known as hyperthermia. Symptoms include thirst, sweating, slurred speech, apathy, confusion, loss of fine motor skills, difficulty walking or maintaining balance, headache, dizziness, and nausea. As severity increases, there could be vomiting, cramps, rapid pulse and breathing. Eventually the body stops sweating and the internal organs start to shut down.
Hypothermia and hyperthermia both have different levels of severity and they can both be deadly. Watch yourself and others for the symptoms and treat as necessary.
The Science of Effective Emergency Sheltering
The purpose of a shelter is to help your body maintain its normal temperature. If you understand these concepts, you can use your available supplies and resources to make effective, life saving shelters for the given circumstances. In cold temperature situations, you usually want to retain and gain heat; whereas in warm temperatures, you want to promote heat loss or at least not increase your temperature. Remember that heat always travels from warmer areas to colder areas.
Conduction: Heat transfer through direct contact, such as bare feet on a cold floor. Ice packs use conduction to pull heat away from burns or sore muscles. Prevent conduction from your body in cold temperatures by wearing socks or when camping by making an insulation barrier between your sleeping area and the ground.
Convection: Heat transfer through air and liquid currents. Wind chill is a good example of convection. When the wind blows, it feels colder than the ambient temperature because the moving air is pulling heat away from your body. You use convection in warmer temperatures to cool down when you use a fan. Prevent convection in colder temperatures by wearing clothing or using shelters that block wind.
Radiation: Heat transfer through emission. A car’s radiator radiates heat to keep the engine from overheating. You experience radiation from the sun every day. In the same way you feel warmth from a campfire without having to touch the flame. You can even feel your own body radiating heat if you put your hand just above an area of skin. Prevent radiation heat loss in cold temperatures by using insulated clothing and shelters, and by using shelters that reflect your heat back to you.
Metabolism: Converting food into energy and heat. Food is your body’s source of fuel. Help your body regulate your temperature in cold weather by eating high calorie foods like energy bars, trail mix and fruit snacks. Water is an important part in the metabolism process, be sure to stay properly hydrated in warm and cold situations. Avoid alcohol and caffeine in cold weather. They fool you into thinking you are warming up, but they actually accelerate heat loss by relaxing blood vessel capillaries rather than constricting them to conserve body heat.
Evaporation: Heat transfer through converting liquid to gas. When your body sweats, the sweat evaporates, or changes from a liquid into a gas, which requires heat energy. This helps keep you cool. When you get out of a pool, even on a hot day, you feel cold until you dry off because of evaporation. Promote evaporation in hot temperatures by staying hydrated. In extreme situations you can even wear wet clothing. Prevent heat loss in the cold by staying dry, minimizing sweating, and by wearing artificial fiber clothing, which wicks moisture away from your skin. In humid climates, regulating temperature through evaporation is not effective.
Respiration: Heat loss through breathing. You breathe out warm, moist air. You can’t stop breathing, so in cold temperature situations, wear a mask or scarf that covers your mouth and nose. Breathe through your nose to warm and moisten the air before it gets to your lungs, and to retain as much heat and moisture when you breathe out.
You could also say friction generates heat, like when you rub your hands together, but heat generation is very small and can be damaging to skin tissues in extreme situations like frost bite.
Preventing and Promoting Heat Transfer
After learning how your body gains or losses heat, it is important to learn how to prevent or promote those heat losses and gains.
Insulation: Trapping air to stop or slow the transfer of heat. Air is not a good heat conductor, so it works well as a barrier. Multiple small layers of clothing trap air for insulation and allow you to regulate to a comfortable temperature by adding or removing layers as needed. Insulation prevents conduction and radiation.
Reflection: Bouncing heat back to or away from your body. Heat, also known as infrared light, can be deflected and directed just like a flashlight beam and a mirror. Reflect your radiated body heat back to you in cold or reflect solar heat away from you in hot weather by using Mylar blankets, sleeping bags, or tents. If used properly, Mylar blankets can reflect 90% of your body's heat back to you, but there is no insulation. Be sure to have an insulating layer of clothing or cloth between your skin and the Mylar, otherwise it turns from reflecting your heat back, to conducting your heat away.
Protection: Keeping out the heat transferring elements like sun, water, wind, and physical dangers. Maintain your body temperature by protecting yourself from the elements. Stay dry and warm by wearing an outer layer that sheds water. Shelters that block wind and/or provide shade from the hot sun are also vital to survival in extreme temperatures.
Moisture Wicking: Pulling water away from the body. Artificial fiber clothing or shelters like polyester, fleece, and nylon or a non-plant fiber like wool can actually wick, or pull moisture, away from your skin. This is essential in cold weather. You do not want evaporation happening or ice forming next to your skin when you are cold. DO NOT wear cotton in cold weather situations since cotton holds moisture and causes evaporation next to your skin.
Disaster Supply Kit: Shelter, Clothing, and Fire
Cold Weather Clothing Layers
We've always been told to wear multiple layers instead of one bulky layer when going out in the cold, but how can we do it most effectively?
Learn about the BASE layer, the INSULATION layers, and the OUTSIDE PROTECTIVE layer.
Sheltering at Home in the Cold
HEADLINE! Cold Snap Freezes All City Utilities!
Sheltering at Home in the Heat
HEADLINE! Heat Wave Knocks Out All City Utilities!
Safely Build a Fire