Ashwin Lewis
Sleeping bags are assigned temperature ratings to indicate the range of temperatures they are suitable for. These ratings are determined by standardised tests, such as the ISO Test, which measures the amount of electrical energy required to maintain a manikin's temperature as the air temperature is lowered. The ISO Test provides three temperature thresholds: Comfort, Limit, and Extreme. The Extreme rating indicates the temperature at which a person could survive the night in the sleeping bag, but not sleep or be comfortable. This rating is important for understanding the limits of a sleeping bag's warmth and for comparing different bags. However, it's worth noting that temperature ratings are just estimates, and individual factors such as clothing, gear, body type, and weather conditions can affect a person's comfort level when using a sleeping bag.
Characteristics and values of the extreme rating on a sleeping bag
| Characteristics | Values |
|---|---|
| Purpose | To indicate the temperature at which a person would "survive" the night in the sleeping bag, but not sleep or be in any comfort at all. |
| Target audience | Climbers in the world's highest mountain ranges, explorers, and scientists visiting the polar regions. |
| Temperature range | Approximately 15°F to -40°F or -10°C to -40°C. |
| Testing process | A heavily instrumented electronic manikin, dressed in long underwear, is placed inside the sleeping bag, which is positioned on a foam sleeping pad. The air temperature is then lowered, and the electrical energy required to maintain the manikin's initial temperature is measured. |
| Limitations | Real-world comfort may differ from the lab-tested temperature ratings due to variations in people's clothing, gear, body types, weather conditions, and other factors. |
| Comparison | Lab-tested temperature ratings (EN or ISO) allow for comparisons between sleeping bags from different brands. |
| Other ratings | Comfort rating (for women/cold sleepers) and Lower Limit rating (for men/warm sleepers). |
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What You'll Learn
- The 'extreme rating' is the temperature at which a person will survive the night, but not be comfortable
- The ISO test provides three temperature thresholds: comfort, limit, and extreme
- The extreme rating indicates the temperature at which a standard 60kg female can remain for six hours without dying of hypothermia
- The extreme rating is a survival rating, not a comfort rating
- The ISO Extreme Range states that a strong sensation of cold has to be expected and that a sleeping bag should only be used in this range in an emergency
The 'extreme rating' is the temperature at which a person will survive the night, but not be comfortable
The extreme rating on a sleeping bag is a temperature indication that a person will survive the night but not be comfortable. This is the lowest temperature at which a sleeping bag can be used without risking hypothermia. It is important to note that this rating does not guarantee a warm and comfortable night's sleep. Instead, it is a measure of the bag's ability to provide protection from extremely cold temperatures.
The extreme rating is one of the three standard temperature ratings used for sleeping bags, the other two being the comfort rating and the limit rating. The comfort rating indicates the temperature at which a person, typically a woman or a cold sleeper, can sleep comfortably through the night without feeling too hot or too cold. The limit rating, also known as the lower limit rating, refers to the temperature at which a person, typically a man or a warm sleeper, can sleep for six to eight hours without feeling too hot or too cold.
The extreme rating is determined through standardized testing, such as the ISO (International Standards Organization) or EN (European Norm) tests. These tests involve placing a test dummy inside the sleeping bag, dressed in base layers, and measuring the amount of electrical energy required to maintain the dummy's initial temperature as the air temperature is lowered. However, it's important to remember that these ratings are based on \"average\" users and should be used as a guide, as individual factors such as metabolism, clothing, and gear can affect the actual comfort level of the sleeping bag.
The extreme rating is crucial for adventurers, explorers, and climbers who venture into extremely cold environments, such as high-altitude expeditions or polar regions. A sleeping bag with a suitable extreme rating can mean the difference between survival and hypothermia in such harsh conditions. Therefore, it is essential to choose a sleeping bag with an appropriate extreme rating for the expected temperatures and to prepare accordingly with extra layers, insulation, and other measures to ensure a safe and comfortable experience.
When choosing a sleeping bag, it is important to consider not only the extreme rating but also the comfort and limit ratings. By understanding these ratings and their limitations, individuals can make informed decisions about the suitable sleeping bag for their specific needs and ensure a more comfortable and safe outdoor experience.
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The ISO test provides three temperature thresholds: comfort, limit, and extreme
The ISO test, also known as ISO 23537, provides a standardised system for rating sleeping bags. It offers three temperature thresholds to help guide users: a comfort rating, a limit rating, and an extreme rating. These ratings are based on the average user, so they should be used as a guide. The ISO test is similar to the EN (European Norm) test, which was the original standard adopted by the sleeping bag industry.
The comfort rating indicates the temperature at which a cold sleeper might feel comfortable. This is the temperature rating typically used for women's bags. The limit rating, also known as the lower limit rating, is always lower than the comfort rating and indicates the temperature at which a warm sleeper might still feel comfortable. This is the temperature rating typically used for men's bags.
The extreme rating is the most critical of the three thresholds. It indicates the temperature at which a person would survive the night in the sleeping bag but not be comfortable or sleep well. In other words, it is the temperature at which there is a serious risk of death from hypothermia in a matter of hours. A sleeping bag should only be used in this range in an emergency, and extra layers, a fire, or sharing body warmth are likely necessary to ensure survival.
It's important to note that lab-tested temperature ratings may not always match real-world comfort levels due to individual variations in clothing, gear, body type, weather conditions, and other factors. Additionally, not every sleeping bag has an ISO or EN rating, and brands might not choose to get ISO testing on bags intended for mild conditions or casual use. Therefore, it's essential to consider other factors besides temperature ratings when choosing a sleeping bag.
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The extreme rating indicates the temperature at which a standard 60kg female can remain for six hours without dying of hypothermia
Sleeping bags have different temperature ratings to help guide users as to the warmth of a sleeping bag. These ratings are based on standardised tests, which give a more precise and comparable system than just the season rating alone. However, it's important to remember that these figures are based on 'average' users and should only be used as a guide.
The extreme rating is one of the temperature ratings. It indicates the temperature at which a standard 60kg female can remain for six hours without dying of hypothermia. This is the survival rating, and a sleeping bag should only be used in this range in an emergency. It is not a guarantee of comfort or warmth.
The ISO Extreme Range states that "a strong sensation of cold has to be expected". It is not a comfortable temperature, and there is a risk of health damage by hypothermia. The extreme rating gives an idea of how cold the air could be before there is a serious risk of death from hypothermia in a matter of hours. It is important to note that this rating is not a guarantee of survival and that extra layers, a fire, or sharing body warmth may be necessary to survive extremely cold temperatures.
The EN 13537 standard offers four different temperature ratings, including the extreme rating. The other three ratings are the EN Upper Comfort rating, the EN Comfort rating, and the EN Lower Limit rating. The EN Comfort rating is the temperature at which an average 60kg female can sleep comfortably through the night. The EN Lower Limit rating is the temperature at which a warm sleeper might still feel comfortable. This is the temperature rating typically used for men's bags.
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The extreme rating is a survival rating, not a comfort rating
Sleeping bag temperature ratings can be a complicated subject. There are hundreds, if not thousands, of different bags available, each with its own technical wording. The standardized testing used to assign temperature ratings to sleeping bags (the ISO Test) provides three temperature thresholds: a comfort rating, a limit rating, and an extreme rating.
The comfort rating, on the other hand, is based on the air temperature at which the "average female" can sleep comfortably through the night without curling up in a ball for warmth. The limit rating is based on the temperature at which the "average man" can maintain his thermal equilibrium in a curled-up position. He won't necessarily be comfortable at this temperature, but he can sleep without expending energy shivering and is not in danger of hypothermia.
It is important to remember that sleeping bag ratings are just standardized ranges and should be used as a baseline for comparison. Individual differences, such as metabolism, age, and sleep preferences, can affect how warm or cold someone feels in a sleeping bag. Additionally, real-world comfort may not match lab-tested temperature ratings due to various variables that a lab cannot simulate. Therefore, it is always important to properly prepare before spending a night sleeping outside, regardless of the temperature rating of your sleeping bag.
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The ISO Extreme Range states that a strong sensation of cold has to be expected and that a sleeping bag should only be used in this range in an emergency
Sleeping bags are assigned temperature ratings through standardised testing (the ISO Test). The ISO Extreme Range indicates the temperature at which a person can remain for six hours without dying from hypothermia. However, it should be noted that a strong sensation of cold has to be expected in this range, and there is still a risk of health damage by hypothermia. Due to these factors, a sleeping bag should only be used in this range in an emergency.
The ISO Extreme Range is one of three temperature thresholds provided by the ISO Test, the other two being the Comfort rating and the Limit rating. The Comfort rating indicates the temperature at which the "`average female`" can sleep comfortably through the night without curling up in a ball for warmth. The Limit rating is based on the temperature at which the "`average man`" can maintain his thermal equilibrium in a curled-up position without shivering and without being in danger of hypothermia.
It is important to note that the ISO Test is based on the assumption of an "`average`" user, and therefore, the temperature ratings should only be used as a guide. Individual factors such as metabolism, body type, clothing, gear, and environmental conditions can all impact the comfort level of a sleeping bag in real-world situations.
The ISO Test is not valid for bags designed for extreme cold or children's bags. Additionally, some brands may choose not to obtain ISO testing for bags intended for mild conditions or casual use. In these cases, the temperature ratings provided by the brands are estimates rather than ISO-certified ratings.
When choosing a sleeping bag, it is essential to consider various factors, including the expected nighttime temperatures, the insulating properties of the sleeping pad, and the user's individual preferences and metabolism. It is recommended to check the weather conditions and select a sleeping bag with a suitable temperature rating, leaving a safe margin between the expected lows and the bag's rating.
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Frequently asked questions
The extreme rating on a sleeping bag is the temperature at which a person could survive the night, but not sleep or be comfortable. It is the lowest temperature at which a sleeping bag can be used without serious risk of death from hypothermia.
The comfort rating is based on the air temperature at which the "average female" can sleep comfortably through the night. The extreme rating, on the other hand, is the temperature at which a person can remain for six hours without dying from hypothermia.
The extreme rating of a sleeping bag is determined through standardized testing, such as the ISO (International Standards Organization) or EN (European Norm) tests. These tests involve placing a heavily instrumented electronic mannequin inside the sleeping bag and measuring the amount of electrical energy needed to maintain its initial temperature as the air temperature is cooled.
Yes, there are sleeping bags designed for expedition or high-altitude use, often referred to as "five-season" bags. These bags are suitable for extremely cold temperatures, ranging from -10°C to -40°C. They are essential for climbers, explorers, and scientists venturing into high mountain ranges or polar regions.
When choosing a sleeping bag, consider the time of year and the corresponding season rating (spring, summer, autumn, or winter). Also, pay attention to the temperature ratings, especially the comfort and extreme ratings, to ensure they align with the expected temperatures during your outdoor adventures. Additionally, consider your personal preferences, metabolism, and whether you tend to sleep warm or cold.
