Perhaps the most important thing you need to consider when buying a new sleeping bag is what temperature it should be designed for. Here you learn a little about temperature labeling, and what the different abbreviations mean for you and your night's sleep.
We use the European temperature recommendation EN 13537 on sleeping bags. This is a standard for how sleeping bags should be tested and marked so that you can easily compare sleeping bags from different manufacturers against each other. The standard contains three temperature instructions: T-COMF, T-LIM, and T-EXT. The temperature ranges between these values are zones for the recommended operating temperature:
Green zone / T-COMF: Green zone is called the comfort zone and in this temperature range most people can sleep comfortably in the sleeping bag.
Yellow zone / T-LIM: Yellow zone is called the transition zone from comfort to risk. In this zone, many can sleep comfortably, but some will be able to start freezing (see below).
Red zone / T-EXT: Red zone is the risk zone and is defined as a zone where one will be able to experience severe cold and there is a risk of hypothermia (cooling down). An average woman can withstand a maximum of six hours in this zone.
The three limit values are set as follows:
- T-COMF: Comfort temperature for a woman in a relaxed lying position.
- T-GLUE: The limit temperature for a man lying hunched over trying to keep warm.
- T-EXT: Risk temperature for women who feel severe cold. There is a risk of health damage as a result of hypothermia.
In practice, what does this mean?
The standard applies to an average person, in an average situation. Overnight trips are rarely average. People react differently to cold, the form of the day can vary and the accommodation conditions will be different from time to time. A fit, well-traveled person on an easy trip will not need a sleeping bag as warm as a beginner on a tiring long trip.
- How easily do I usually freeze?
- How accustomed am I to sleeping outside?
- How fit am I?
- How tough a trip am I going on?
- How tired and hungry am I going to be when I go to bed?
- How well protected am I going to be? (cabin, tent, open sky)
- What kind of sleeping pad do I have, and how many extra clothes, hats, etc.
- How much weight do I want to carry with me?
For long trips and expeditions, an extra safety margin must be added with regard to temperature. The user is responsible for trying out the equipment in advance of such trips. The temperature standard EN 13537 does not apply to children, who have a different physiological regulation than adults. We, therefore, state the temperature for the corresponding adult bag in parentheses only as a reference. For children, an extra safety margin should be added, and adults have a special responsibility to look after children in their entourage.