A car that stalls in slush, a prolonged power outage or an unexpected night outdoors can quickly make the cold the most urgent problem. But do emergency blankets really keep you warm? Yes, when used correctly they can noticeably slow the body's heat loss. They are not, however, a heat source of their own and do not replace dry clothes, protection from wind or a warm room.
Do emergency blankets keep you warm?
An emergency blanket, often called a reflective blanket or rescue blanket, is made of thin plastic material with a metallised surface. The shiny surface reflects a large part of the heat radiation the body gives off back towards you. When the blanket lies close to the body, it also creates a protective layer of still air.
That is exactly why such a thin blanket can be valuable in an emergency. It weighs almost nothing, takes up very little space and can help a chilled person retain the heat that is still left. For a family, it is a simple way to add an extra safety margin in the car, the home store, the backpack or the first aid kit.
At the same time, expectations need to be realistic. An emergency blanket produces no heat. If you are already soaked through, sitting directly on cold ground or exposed to hard wind, the blanket alone will not get you very far. You get the best result when it becomes part of several simple measures: get out of the wet, shield yourself from the wind, insulate against the ground and add dry layers.
How the body loses heat
To use an emergency blanket well, it helps to understand what it is meant to counteract. The body does not cool down only because the air feels cold. Heat disappears in several ways at once.
Radiation is heat the body gives off to a colder environment. Here the reflective surface does the most good. Convection means that wind or cold air carries warm air away from the skin and clothes. A tight blanket can then work as a windbreak, especially if it is combined with a jacket or a sheltered spot.
Conduction occurs when the body is in contact with something cold, for example the ground, concrete, a bench or a vehicle floor. An emergency blanket is too thin to give good ground insulation on its own. So put backpacks, sleeping pads, folded clothes, cardboard or other dry insulation under the body first. Evaporation is the fourth major factor: damp clothes and sweat cool effectively. Change to dry when you can and use the blanket as outer protection, not as a solution for wet layers.
When does an emergency blanket work best?
The reflective blanket does the most good early, before the person has become properly chilled. If someone starts to shiver after waiting for help, being out in rain or having to sit still in a cold car, it is wise to act right away. Shivering is the body's attempt to produce more heat, but it costs energy and is a sign that the situation should be taken seriously.
For a person who is awake and dry, the blanket can be laid over the outer clothing as an extra shell. Draw it around the shoulders and upper body, cover the legs and try to limit draughts. Leave the face free so breathing is not hindered. If it is windy, you can sit with your back against shelter, for example a tree, a wall or the car's lee side, and fasten the blanket carefully around the body.
In rain, an emergency blanket can help keep wet out, but it needs to be handled thoughtfully. The material breathes poorly. If you walk, carry heavy loads or otherwise become warm and sweaty inside the blanket, the moisture can instead make you colder when you stop. So use it mainly when you rest, wait or need protection from weather and wind. When moving, it is often better to have ordinary clothing layers that can ventilate.
How to use it during a power outage and in the car
During a power outage it is easy to think the emergency blanket belongs outdoors. But even at home it can serve a practical function, especially if the heat is gone for many hours. Gather the family in one room, close doors to rooms that are not used and dress in several dry layers. The emergency blanket can then be used on top of a sleeping bag, blanket or jacket for whoever is coldest.
Avoid building a completely sealed space around the face or wrapping small children so that you cannot keep watch. Infants, elderly people and anyone who is ill need extra attention, since they can find it harder to regulate body temperature. If someone becomes sluggish, confused, unusually tired or stops shivering despite continued cold, the person should be warmed gently and get professional help if needed.
In the car, the emergency blanket is especially useful because sitting still cools the body quickly. If the car is stationary in cold weather, put on outer clothing before you get cold and lay the blanket over the body as an outer layer. Insulate under yourself with mats, extra clothes or other dry material. Preferably have one blanket per person, not a single one to be shared by everyone. Children can lose heat faster, and each person needs to be able to stay covered.
A well-prepared car also contains water, a flashlight or radio, first aid and warm clothes. The emergency blanket is small, but it becomes considerably more useful when the rest of the basics are in place.
Silver or gold side out?
Many emergency blankets have a silver-coloured side and a gold-coloured side. In practice, the difference in heat effect is often small when the blanket lies tight around the body. The most important thing is that the reflective side encloses you, that draughts are reduced and that you have dry layers underneath.
Always follow the instructions for the particular blanket you have at home or in the car. Some models are intended mainly for warmth, others have high visibility as an important function. The gold or coloured side can make it easier to spot a person in bad weather or weak light. If you use the blanket as protection on the ground or as signalling material, visibility can be more important than which side happens to face out.
Common mistakes that reduce the effect
The most common mistake is waiting too long. A thin blanket cannot quickly restore the warmth of someone who is already severely chilled. Put it on when the cold starts to be felt, not only when the fingers are stiff and the body shakes uncontrollably.
Another mistake is to believe it is enough as the only protection. Always prioritise dry clothes and insulation from the ground. If you have a jacket, use it first and then put the emergency blanket on the outside to reduce wind and heat radiation. If you have a sleeping bag or ordinary blanket, the reflective blanket can be used as an extra outer layer if it does not make the sleeping environment too damp.
Also avoid open flame, hot radiators and other strong heat sources near the material. Emergency blankets are thin and can be damaged or melt. Never use the blanket over the face, and do not let children play wrapped up without an adult present. A damaged or very crinkled blanket can still be useful as a windbreak, but should be replaced in the next preparedness round.
Choose the right place for each emergency blanket
Because an emergency blanket is so compact, it is wise not to store them all in the same place. Have a few at home where the family gathers during a power outage, a few in the car and at least one in the everyday backpack or day-trip bag. Check the packages now and then. If they are opened, torn or heavily wrinkled, it may be time to replace them.
For longer stays in the cold, an emergency bivy bag is often a better complement than a flat blanket. It encloses the body more completely and can give better wind protection, but the same principles of dryness and ground insulation apply there too. Stavera recommends seeing the emergency blanket as a small, easily accessible part of a larger warmth system - layers on the body, protection around the body and insulation under the body.
The next time you pack the car or review your home preparedness, do not just drop in the emergency blanket. Think about who might need it, where you would gather and what is between the body and the cold ground. That small preparation can make an uncomfortable wait considerably safer.