Seasons and Comfort Ratings
Seasons put simply...
• 1 season: Summer
• 1-2 seasons: late Spring - Summer; Summer - early Autumn
• 2-3 seasons: Spring - Autumn
• 3-4 seasons: Spring - Winter
Understanding comfort ratings
It took an EU standard (EN13537) to offer a testing and rating system that allows you to compare sleeping bags and get a good idea about what will suit you. Although it's quite complex in its detail, in summary it ensures that the performance of sleeping bags can be assessed by standardised lab tests to give comparable ratings. Using a thermal dummy with heaters and temperature sensors the insulation value is calculated to give four temperature values - upper limit, comfort, lower limit and extreme - based on use by average weight people (men - 80kg; women- 65kg).
Some sleeping bags will not necessarily display all temperature ratings; some focus on just the extreme rating, showing the coldest temperature it can withstand and then the comfort rating, showing the temperature range for a comfortable nights sleep.
EN 13537 Guidelines:
• Upper Limit or Maximum Temperature is the highest temperature at which a 'standard' adult male is able to have a comfortable night's sleep without excess sweating.
• Comfort rating is based on a 'standard' woman having a comfortable night's sleep.
• Lower Limit is based on the lowest temperature at which as 'standard' adult male is expected to be able to have a comfortable night's sleep.
• Extreme rating is a survival only rating for a 'standard' adult woman.
These guidelines are summarised for each individual sleeping bag tested with the warmth values, depending on filling and style, are based on the air temperature outside the sleeping bag to help you make an informed choice.
You may notice that the above ratings use either a man or woman to define the temperatures and the term 'standard' a lot. This is due to the numerous other factors that will affect an individual's comfort during a nights sleep as we mentioned earlier...
Build/weight - Backpacking and trekking can lead to the situation where you eat less calories than you burn. During polar and high mountain expeditions, you can face a situation where it is impossible to eat enough to match your energy requirements. In these situations body fat has a big impact. A person carrying excess body fat will be able to burn energy from their fat reserves. These reserves act as natural insulation providing the person with more warmth.
Gender - Women are generally colder than men. In EN 13537, the comfort value for a standard woman is 5 ºC higher than for a standard man.
Age - Metabolism is generally age related. Older people generate less heat and hence feel cold more than younger people. A well fed young man between 16 and 24 has a higher metabolic rate and demonstrates "dietary induced thermo-geneses".
In other words, their bodies pump out heat so they do not feel the cold. So for a young male, the comfort temperature could easily be 5 ºC cooler than for an older man. Children, especially small children do not have the same natural heat controls as adults. Their metabolism speeds and slows as they grow. For this reason, it is exceptionally difficult to define temperature ratings for children.
Conditioning - Most historical research on sleeping bags was done on soldiers, outdoor instructors, mountain guides and expedition mountaineers. These are a group of fit experienced people, predominantly males aged between 18 and 40, conditioned to living outdoors. Most westerners live in centrally heated houses, work in air conditioned offices and drive everywhere. This lifestyle reduces the body's conditioning against the cold.
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• Upper Limit or Maximum Temperature is the highest temperature at which a 'standard' adult male is able to have a comfortable night's sleep without excess sweating.
• Comfort rating is based on a 'standard' woman having a comfortable night's sleep.
• Lower Limit is based on the lowest temperature at which as 'standard' adult male is expected to be able to have a comfortable night's sleep.
• Extreme rating is a survival only rating for a 'standard' adult woman.
These guidelines are summarised for each individual sleeping bag tested with the warmth values, depending on filling and style, are based on the air temperature outside the sleeping bag to help you make an informed choice.
You may notice that the above ratings use either a man or woman to define the temperatures and the term 'standard' a lot. This is due to the numerous other factors that will affect an individual's comfort during a nights sleep as we mentioned earlier...
Build/weight - Backpacking and trekking can lead to the situation where you eat less calories than you burn. During polar and high mountain expeditions, you can face a situation where it is impossible to eat enough to match your energy requirements. In these situations body fat has a big impact. A person carrying excess body fat will be able to burn energy from their fat reserves. These reserves act as natural insulation providing the person with more warmth.
Gender - Women are generally colder than men. In EN 13537, the comfort value for a standard woman is 5 ºC higher than for a standard man.
Age - Metabolism is generally age related. Older people generate less heat and hence feel cold more than younger people. A well fed young man between 16 and 24 has a higher metabolic rate and demonstrates "dietary induced thermo-geneses".
Conditioning - Most historical research on sleeping bags was done on soldiers, outdoor instructors, mountain guides and expedition mountaineers. These are a group of fit experienced people, predominantly males aged between 18 and 40, conditioned to living outdoors. Most westerners live in centrally heated houses, work in air conditioned offices and drive everywhere. This lifestyle reduces the body's conditioning against the cold.
» Back to Sleeping Bags
