The European Temperature Standard
EN 13537:2002 "Requirements for Sleeping Bags" is the official European Standard for the labelling of sleeping bags that also defines how sleeping bags must be tested and rated. EN13537 applies to all sleeping bags with the exception of sleeping bags for military use and sleeping bags for extreme temperatures (i.e. comfort range below -25°C).
The EN methodology produces temperature ratings that can be trusted and compared head-to-head with the EN ratings on other brands' bags. If you know the temperature range you'll encounter on your overnight trip, you can compare EN-rated bags and confidently choose the one that will best ensure a comfortable night's sleep.
The standard has an important legal meaning to brands, distributors and retailers, who sell sleeping bags in Europe. In case sleeping bags should be defined as safety relevant equipment, EN 13537 will be the product test within the PPE (Personal Protective Equipment) initiative.
Temperature ratings
Comparing sleeping bags in the past was more of a gamble for end consumers. Temperature labels were rather confusing than informative – and in many cases simply wrong. Choosing a sleeping bag became additionally difficult because many bags were either not tested at all or examined according to various national standards, which could not be compared with each other. The EN Standard 13537 is in effect since 2002 and since 2005, all new sleeping bags offered in the marketplace must be EN tested.
How sleeping bags are tested according to EN 13537
For EN 13537 temperature tests, a life-size mannequin (based on a "standard man” and "standard woman" of average age, weight and height) with heaters and temperature sensors is dressed in one layer of long underwear and a hat. It is placed inside the sleeping bag being tested. The bag is laid atop an insulating sleeping pad inside a climate-controlled chamber. The mannequin is heated to simulate body warmth and measurements are taken of the air in the climate chamber and the surface ("skin") of the mannequin. From these measurements, the insulation value of the sleeping bag is determined. These calculations provide four EN temperatures ratings.
- Upper Limit: the temperature at which a standard man can sleep without excessive perspiration. It is established considering the hood and zippers are open.
- Comfort: the temperature at which a standard woman can expect to sleep comfortably in a relaxed position.
- Lower Limit: the temperature at which a standard man can sleep for eight hours in a curled position without waking.
- Extreme: the minimum temperature at which a standard woman can remain for six hours without risk of death from hypothermia (though frostbite is still possible).
Only a sleeping bag, which fully complies with all aspects of EN 13537 is entitled to display the CE symbol on the product and hangtag.
Temperature Standard vs. Personal Feeling
Everyone’s sensitivity to temperature is different. This should be taken into account when buying a sleeping bag and looking at the temperature ratings on the hangtag.
The factors that have an essential influence are, for example, whether you are a man or a woman, whether you are rested or exhausted when going to sleep, how much or little you ate, whether you drank alcohol, or how much you move in your sleep. In addition, your sleeping bag will perform differently depending on the wind exposure of your camp, the insulating performance of your mat, and the humidity level of the air.
