The standard EN 13537
This article has been updated and completed as part of our benchmark 18 bag of comfort temperature between 0 ° C and-10 ° C. On this occasion, we investigated the EN 13537 standard and asked the manufacturers of the bags tested test reports.
See the related discussion
Evaluate the use of a sleeping bag temperature evenly
Before this standard published in 2002, the temperature values announced by manufacturers were enough folk, and it was very difficult (if not impossible) to compare different brands between them using this criterion sleeping bags. The EN 13537 standard try-as the ‘test of the cans’ we realized with a ‘House’ model-to apply a test identical and repeatable Protocol to each bag.
Its gradual application in Europe between 2002 and 2005 led many manufacturers to review rising operating temperatures announced their bags, at least 5 ° C or 10 ° C. The EN 13537 standard applies as well to the sleeping bags with synthetic filling only (see our article on standards of test of the down sleeping bags).
The test protocol
This test is carried out in accredited laboratory: the sleeping bag is placed on an insulating mattress and a mannequin dressed in underwear and equipped with sensors installed. According to the laboratory, the model contains between 6 and 35 independent segments. For each segment, measured his reported on its surface to exchange heat dissipation. We can deduce the average thermal resistance of the sleeping bag, and the standard specifies (defined below in corresponding operating temperatures).
So the result is the average of all measurement points, but the detailed test report can reveal different results depending on the area of the body. Significant disparities also were noted by some studies at the level of the feet (Ref5), what we have also seen in our own test (by placing a can of hot water to the level of the chest and another in the foot…).
Test conditions (temperature, humidity, air speed, mattress, clothing of the dummy, the sleeping bag conditioning time, etc.) are laid down in the standard, with sometimes quite broad beaches:
- The surface temperature of the model is chosen between 25 ° C and 40 ° C.
- The temperature outside is decorrelated temperature of use, since it is taken into account in the calculation of thermal resistance, it should only be at least 15 degrees lower than the temperature of the dummy (FYI, studied reports show temperatures test between-10 ° C and + 20 ° C).
- The humidity must be between 40% and 80%.
- Outdoor air speed must be less than 0.5 m/s (either 1.8 km/h), the speed of 0,3 m/s.
- The model should measure between 1.5 m and 1.9 m high, with a surface of between 1.5 and 2, 1 m². It shall include at least a measuring point.
- The model is entirely covered with a garment of thermal resistance 0.049 m²· K/W (±10%), with socks of 0.054 m²· K/W (±10%) and a face mask.
- The mattress is of thermal resistance 0.85 m²· K/W (±7%), and placed on a plank of wood to about 12mm thick, raised from the ground.
- With respect to the preparation of the sleeping bag, 13537:2002 en specified only that he had to be out for at least 12 hours before the measurement. The standard IN 13537:2012 now specifies a method of conditioning of the sleeping bag.
Means of testing are also calibrated so as to limit the differences in results between laboratories (which use environments and different models). Corrective calculations are therefore applied.
Finally, to limit implementation errors and improve the reproducibility of the test, it is normally performed three times, and the final result is the average of these three measures.
Definition of comfort, limit temperatures and extreme
Recall that the calculated temperatures are purely indicative, and correspond to the following definitions (Ref1, Ref2, Ref6) :
- Comfort temperature: it corresponds to the minimum temperature at which the user in a “released” position (typically lying on his back, arms along the body) will be at thermal equilibrium, without feeling the cold (this temperature is calculated for a ‘standard woman’)
- Temperature limit(sometimes called limit of comfort): it corresponds to the minimum temperature at which the user, in a Fetal position, will be at thermal equilibrium without feeling cold (this temperature is calculated for a “standard man”)
- Extreme temperature: between the temperature limit and extreme (the area of risk), the user, in a Fetal position, will experience a strong feeling of cold. in approaching the extreme temperature, the risk of damage to health through hypothermia is real; beyond the extreme temperature, the risk of death by hypothermia is serious (this temperature is calculated for a ‘standard woman’)
- Sometimes, a 4th (optional) temperature is added: the maximum temperature, which is the temperature at which user, partially covered the sleeping bag, can sleep without sweat too much (this temperature is calculated for a “standard man”)
The standard defines also (Ref6) comfort zone(superior to T ° comfort temperature), the transition zone (between T ° comfort and T ° limit), and thearea of risk (between T ° limit and extreme ° T), although there are sometimes different data on sleeping bags.
For comfort and limit temperatures are sometimes truncated definitions of the man and the woman way overnight, forgetting that the temperature limit represents a person cowering to better combat the cold (but who don’t shudder)…
Attention also, these theoretical temperatures do not take into account the wind (the tests are performed with a movement of air very low, less than 0.5 m/s), high humidity (the tests are performed with less than 80% humidity), of additional losses by radiation (homeless, on a clear night…) or by conduction (having a good insulating mattress is essential – see our last test pads )).
On the other hand, the dummy clothing is succinct, and you can sleep with a clothing allowing you a significant heat gain (for example when sleeping with your jacket).
Similarly, know that the extreme temperature (still more theoretical than others) takes into account the shivering (which allows the body to produce heat), a skin temperature which decreases by 4 ° C during a night of survival of 6 hours, etc…). Don’t be fooled, so not at this temperature to select your sleeping bag!
Note Although the manufacturers often put forward the temperature limit of their sleeping bags, when communicating a single operating temperature (for example in the name of the product). But if you’re not a warrior, that you do not know your limits, that you do not sleep with all your clothes to optimize each gram of your equipment, and/or that you want to keep a margin of comfort, rather take into account the comfort temperature…
In all cases, remember that we are not all equal and that the feeling of cold will depend on not only weather conditions (humidity, wind…), but also of the physiology of the sleeper (body mass, physical fitness, stress, hydration, food, acclimatization, experience…).
In particular, women are disadvantaged compared to men, and that is why the standard is based on a woman and a man “standards”. For information, the standard woman considered is 25 years old, and measure 1.62 m 60kg, and considered standard humans is 25 years old, and measure 1.73 m to 70kg. In short, even if these are not the only criteria, if you are older and your body mass is less than these numbers, you are already a bad point :-).
Note that there may also be a slight difference in performance between two samples of the same model. In particular, the sleeping bags are tested in one size, although manufacturers often make sure you adapt the filling so that the sizes have the same thermal properties. This is not always the case, and yet the various sizes wear the same indication. Also prefer a bag of size adapted to optimize its thermal insulation.
Finally, the aging and use repeated your bag will alter its thermal properties. A down fill has a much better life than a synthetic lining, and a neat washing in general to regain much of its initial thermal properties.
Application of standard EN 13537
First, note that the EN 13537 standard actually well covers other aspects than the measure of the thermal properties of the sleeping bags: the title is generic (” Requirements for sleeping bags “, requirements for sleeping bags), and it lists the set of standards applied in Europe, and that may affect the measurement of the dimensions of the sleeping bag, weight , its breathability, characteristics of down (see our article on the loft and the labels of the down), cloth, etc…
The EN 13537 standard is recognized by the (Ref2) following countries: Germany, Austria, Belgium, Bulgaria, Croatia, Cyprus, Denmark, Spain, Estonia, Finland, France, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Czech Republic, Romania, United Kingdom, Slovakia, Slovenia, Sweden, Switzerland, Turkey.
Other non-European countries do not apply as such, but many brands (including brands American and Australian test) use it to display the temperature of use of their sleeping bags (and quite often more rigorously than the European brands!). An accredited laboratory is now in the United States, the University of the State of Kansas (Kansas State University).
If the standard is ‘applicable’ in Europe since January 1, 2005, it is not mandatory for manufacturers, and given the price of the tests, some make the economy (including artisanal manufacturers who do not necessarily have the means to achieve).
The products that satisfy all of the requirements of the standard EN 13537 (and therefore of the panoply of the standards referenced) are entitled to be CE marked (for “Compliant” – Ref6), which is the case of no sleeping bag we tested… (either by breach of certain clauses, or perhaps to avoid exposure to a control of a body of fraud as the DGCCRF in France).
But know that often, manufacturers announce ‘tested IN 13537’ bags, but don’t test in fact than some models of their range, or even a different prototype of the final model, and extrapolate the results to the other bags of their range (often in good faith, for those who have provided us with test reports… and others?). The mention of the standard on the sleeping bag is not the guarantee of a rigorous extent, and is in no way a guarantee or a label affixed by an independent body.
That’s why we asked all our comparative test manufacturers to send us their reports of test EN 13537.
Manufacturers who extrapolate the results of the standard should also indicate a mention of type ‘ in accordance with EN 13537 standard “(Ref6), but few do, and instead, only the bag Exped Lite 900 of our test is indicated” in agreement with ‘ while it is actually tested EN 13537.
Conclusion: only the reading of the test report is authentic and we have therefore indicated in ourcomparison chart (with a color code) what are the models that we have read the test report, and if the reports correspond to the product or are extrapolated.
Evolution of the standard: IN 13537:2012
Like any standard, it is imperfect, and there have been several criticisms by various studies (Ref3, Ref4, Ref7). Laboratories use the ways and conditions of different test well that conform to the specification of the standard (temperature, relative humidity and air speed inside, used mattresses, preconditioning of the sleeping bag time, number of sensors and clothing of the dummy…), and with a calibration not always accurate (a precision of approximately ±5% on heat resistance is acceptable “, which is not negligible).
So some variability of the results between laboratories is inevitable (not counting the variability of the samples themselves), which can reach 3 ° C to 5 ° C according to the studies and the temperature range. This was also observed by the European standards Committee, which released in 2012 a new test inter-laboratory with six different models used.
Then the standard underwent some significant changes (IN 13537:2012, Ref2), intended to reduce the variability of the results by specifying the method of calibration of the models, by specifying a preconditioning of sleeping bags, and clarifying the test procedure. The calculation of extreme temperature was also changed, as a result of new research.
The vast majority of bags of our comparison has been tested according to the standard of 2002 (Ref1), and there is at the moment not enough recoil so that new studies can enjoy these improvements.
In any case, this standard EN 13537 remains the most reliable to compare the performance of sleeping bags, and is increasingly used by brands from around the world for this reason. However, it is not suitable to ‘cold’ sleeping bags and military bags…
Ref1: “Requirements for sleeping bags”, IN 13537:2002, CEN, 2002
Ref2: “Requirements for sleeping bags”, IN 13537:2012, CEN, 2012
Ref3: “Issues Concerning the IN 13537 Sleeping Bag Standard”, Elizabeth McCullough, 2009
Ref4: “Testing Sleeping Bags According to 13537:2002: Details That Make the Difference”, Kalev Kuklane, Valter Dejke, 2010
Ref5: “A laboratory validation study of comfort and limit temperatures of oven sleeping bags defined according to IN 13537 (2002)”, Li – Yen Lin and al. 2013
Ref6: “IN 13537 – Sleeping Bag Standard – Information for Consumers”, European Outdoor Group, 2004
Ref7: “Comparison of IN 13537 test laboratories”, European Outdoor Group, 2006
Valandré publishes an extract from its test EN 13537 on his web site reports (photo: Bloody Mary ))