without exception, All of the temperature ratings do not provide a complete understanding of whether it is You sleep comfortably in a sleeping bag.
This occurs for one reason: not "warm" (if there are no additional sources that produce heat), because You are the generator, which must generate heat little more than to lose, to make you comfortable to sleep. A good sleeping bag only helps to maintain Your warmth.
So if You felt cold during the day, has been eating poorly, tired, or, God forbid, drink alcohol, don't blame the numbers in the temperature scale.
to understand how best to help yourself not to be cold, let's find out how You lose heat and how to avoid it.
- The biggest heat loss comes from conduction (heat transfer by direct physical contact with the subject). If You lie on the ground, it immediately begins to warm her own body. The earth is large and always shall win, taking away thus a lot of heat. Sleeping bags are not designed for sleeping on the bare ground! It is mandatory to use fat heat insulation Mat.
- Loss on convection (transfer of heat in gases, and soD. the flow of the gas itself). About You this principle works as follows: You heated the air around him, and he leaves, taking away Your warmth. The warm air replaces the cold, and the process is repeated again. The convection losses can be attributed a very substantial energy costs in evaporation of sweat from the skin. In the losses to convection, are very important materials of a sleeping bag, insulation, design of a sleeping bag and its components. is very serious about each of these elements, which can be seen in the description of the technology. It is very important to sleep in a tent, where You are protected from the wind.
- Thermal radiation, or infrared radiation - electromagnetic radiation emitted by the body. While the technology of reducing heat loss from thermal radiation for sleeping bags we have not met. And advertised technology like cheating.
Now that we have an understanding of where the heat goes, you can talk about how to deal with it. Now let us turn to the very popular and accessible to the insulator on earth. It's the air. But everyone who slept on ordinary inflatable mattresses on the cold ground, you know that a large layer of air is not too saves against cold, as a great loss to the convection inside the mattress. To solve this problem we must create a system of maximum number of air spaces. And the thinner will be the walls between air layers, and the interlayer is smaller, the better the insulator. With this task perfectly well synthetic insulation. Pay attention to what must shake well several times to have the insulation scored the air after storage in collapsed form.
Next, it is very important that both heaters are located in a sleeping bag, as well as materials and shape of the sleeping bag, the presence of smoke, heat collar, and many other details. In Alexikа responsible for this highly efficient technology Protective Shell and Soft Space.
But how to determine at what temperature a sleeping bag designed? Before each manufacturer, at your own risk conducting tests, solve, under what ambient temperatures will be comfortable to sleep in sleeping bags. Since the threshold of perception of cold is different for everyone and trained person easier to tolerate low temperatures, but when you consider the age of the person, the diet, fatigue and possible hypothermia, comfortable temperature all turned out different. Unscrupulous businessmen took them all from the ceiling. So I decided to make a single test to EN 13537 single methods, which is also not completely objective from the point of view of the perception of heat by different people, BUT it allows you to compare different manufacturers among themselves.
How to conduct the test?
Dummy temperature sensors and heaters is placed into a sleeping bag. The temperature of the manikin is maintained approximately at the level of the average temperature of the human body. Sleeping bag with manikin placed on a heat insulation Mat and placed in a climate chamber, where they begin to lower the temperature. The sensors take readings of the energy losses and on the basis of these readings calculate temperature scale. Here's how it looks.
Based on the fact that three times better to sweat than to be covered with frost, normally, the maximum temperature (T max) at which a sleeping bag in the open You will feel comfortable, you can ignore.
T comfort - lower limit temperature at which the average woman can sleep comfortably throughout the night (8 hours) without waking up from the cold.
T a limit of comfort - lower bound temperature at which the average man can sleep comfortably throughout the night (8 hours) without waking up from the cold.
Temperature extreme - the lowest temperature at which the sleeping bag protects a person from hypothermia (hypothermia). Typically, this temperature should provide 6 hours of uncomfortable sleep, but without reducing body temperature to dangerous indicators.
Please note that previously and now is not recommends focusing on Temperature Extremes when choosing a sleeping bag, if You are interested in Your health, and even life.
Remember that this ranking takes into account what You are wearing , You middle age, Your weight 80 kg (men) or 60 kg (for women), You are in good condition with no signs of hypothermia and have good food.
it Turned out that here it is possible to cheat customers. The ratio of weight to the comfort temperature is the most important value. If, at the same weight, the portion of the insulation to move with the bottom of a sleeping bag (he's still lying on the Mat) in the upper part, it is possible to obtain the best temperature rating for the same tonnage. And directory not to paint, how much insulation in grams per square meter and how many layers, and just write the total weight of the insulation on the entire bag. What gives this is absolutely not clear, but if the insulation is removed from the back when You turn sideways, you will feel that the back freezes. So very carefully look at the description of the sleeping bag and the store feel the top and bottom layer of insulation. Alexika always fully inform their customers about every detail and every detail of their products.
When Alexika used their own temperature ratings, and not EN 13537, Alexika took into account who had a sleeping bag. Trained people (climbers, guides, military) endure the cold, than urban residents, traveling to the campsite. So in extreme lines had a lower temperature, and camping - higher. Special attention was given to the juniors and children, because their metabolism is not balanced and it is difficult to accurately determine the average temperature, therefore, in children's sleeping bags, with an equal number of insulation with adults, the temperature scale was 3-4 degrees higher. In the descriptions of the sleeping bags we paid attention to it.
In this article we are openly told what you must consider when choosing a sleeping bag. I really hope that it will help You to feel comfortable in any weather.