Sleeping comfort temperature

What is known as the temperature value is very important when buying a sleeping bag. It is determined according to European standard EN 23537 and provides the most important guide values, usually shown using three temperature indications.

Here for example in the Biopod Wolle Zero:

Two values are particularly important here: T_comf and T_lim

The first value – T_comf – is the value at which a “standard woman” is not quite feeling cold. The second value – T_lim – is the value at which a “standard man” is just beginning to feel cold.

The third value – T_ext – is a theoretical value at which there is already a risk to health from hypothermia. This value is not relevant to you when buying a sleeping bag.

Standardised test procedure

The standardised test procedure in European standard EN 13537/ EN 23537 guarantees an impartial comparison of temperature data in sleeping bags:

A warmed mannequin is placed in a test sleeping bag in an air-conditioned room. The amount of energy required to keep the temperature of the 20 or so different body segments stable is then measured. There are three different values for the temperature indications:

• Comfortable temperature T comfort (T_comf): this value is calculated for a “standard woman” (25 years old, 60 kg, 1.60 m) in a relaxed posture who is not quite feeling cold (not shivering).
• Limit temperature T limit (T_lim): This value is calculated for a “standard man” (25 years, 70 kg, 1.73 m), who is feeling thermally balanced when rolled up in his sleeping bag and is not quite feeling cold (not shivering).
• Extreme temperature T extreme (T_ext): this value is calculated for a “standard woman” (25 years old, 60 kg, 1.60 m) in more severe cold conditions with rolled up body posture, the basic metabolic heat being increased by shivering. There is already a risk of hypothermia here.

Please take only the comfort value T Comfort (T_comf) as an guide value when buying a sleeping bag!

Sleeping bag temperature test dummy Karel

(Image source: TZU Textile Testing Institute)