Sleeping Bag Temperature Ratings

Posted by: OregonMouse

Sleeping Bag Temperature Ratings - 12/24/11 02:45 PM

A truly interesting article on various methods of testing sleeping bag temperature ratings and especially explaining the EN13537 ratings, what they mean for the consumer and what role individual physiology plays in determining the temperature ratings.

Thanks to "retired jerry" of portlandhikers.org for finding this article!

Although this topic was touched on in another (somewhat controversial) thread, I felt that it should be examined separately.
Posted by: TomD

Re: Sleeping Bag Temperature Ratings - 12/24/11 04:16 PM

Good find. Two comments-the article says that women sleep colder than men. I'm not sure about that generalization. Second, the difference between ratings in one table shows that American bag makers overrrate their bags compared to European makers. Probably not the case for WM, FF or the other premium bag manufacturers, but anecdotal evidence seems to support the overrating claim. I've read plenty of complaints, especially with lesser known brands and cheap bags about misleading ratings.
Posted by: wandering_daisy

Re: Sleeping Bag Temperature Ratings - 01/01/12 08:34 PM

I have found that in general women do sleep colder than men. Not always, but more often than not. I sleep LOTS colder than my husband. I do not know if we sleep colder or or more sensitive to our environment and LIKE to be warmner. I also think if women actually had bags that fit them properly, they may not sleep as cold. I do think women get colder in different places. We usually have hips that are bigger, and most of our weight rests on hips, therefore, hip area needs more insulation. Most mens bags have more insulation in the shoulder area.

I do not think people are good at rating sleeping bag warmth. Every person is different; every night is different. Hard to get consistency. I suspect lots of manufacturers simply measure loft and then rate based on loft. Not a great method, since actual design and personal fit mean a lot.
Posted by: oldranger

Re: Sleeping Bag Temperature Ratings - 01/01/12 08:45 PM

I agree with you. I am very skeptical about sleeping bag ratings, especially when you consider the other important variables that enter in - supplemental clothing (wet or dry?) exposure to the elements, amount of food ingested, etc. Mostly, the manufacturers are basically saying "warm, warmer, warmest," and I don't take it any further than that.
Posted by: OregonMouse

Re: Sleeping Bag Temperature Ratings - 01/01/12 08:49 PM

The EN13537 ratings assume a difference of 9*F between the "standard" woman and the "standard" man. Whatever that is.

I prefer to use the term "cold sleepers" and "warm sleepers," although the "cold sleepers" I know definitely include more women than men.

There's an age factor, too--our "thermostats" don't function as well as we get older. Fitness is also an issue.

I bought a Marmot Hydrogen (rated at 32*F) some years back, figuring that with my insulating clothing on inside I could get it down to the low 20's F. Ha ha. I started getting cold in it at the upper 30's F. By the time it got down to 28*F, I was shivering with all my clothing (including rain gear) on inside. This bag is now EN13537 rated, and I notice the "comfort" rating (women/cold sleepers) is 39*F. Evidently I'm not that far off the dummy measurement for women! (Make of that what you will. :D)
Posted by: TomD

Re: Sleeping Bag Temperature Ratings - 01/01/12 09:51 PM

One thing about the EN ratings-I saw a complaint in a review of a bag that the EN rating was way off, but when I looked, I think the reviewer was using the "extreme" rating as the comparison with his experience instead of the more conservative "comfort" rating. Makes a big difference. Not every manufacturer explains the difference-Valandre and MacPac are among the ones that do.

I think that if you stick with the comfort rating, you'll be pretty close. Also don't forget that what you may be looking at is Celsius, not Fahrenheit. When I bought my MacPac bag, I figured that -5C was plenty warm, but later realized that was only +23F. Fine for most circumstances, although I now have a Marmot rated at -10F. Haven't tried it out yet, but it is definitely a lot bigger bag in terms of loft.
Posted by: PDA

Re: Sleeping Bag Temperature Ratings - 01/02/12 06:35 PM

The good thing about EN rating is that the method is consistent for all bags, so though they may not be totally accurate for any one person, they are consistent from bag to bag, so an objective judgement can be made. Just remember that "extreme" means that you (probably) won't die
Posted by: OregonMouse

Re: Sleeping Bag Temperature Ratings - 01/02/12 06:41 PM

You do have to be sure which of the three ratings (extreme, lower limit, comfort) the manufacturer or retailer is using. It should be clear in the European countries where all three ratings are required, but I've noticed that here in the US, where the EN ratings are strictly voluntary, there is a tendency to use only the "extreme." That's particularly true of cheap bags, which historically have had the most fictitious ratings.
Posted by: lori

Re: Sleeping Bag Temperature Ratings - 01/02/12 07:04 PM

It really helps with understanding this to look at Marmot bags - I like that they post the EN rating for each bag, makes distinguishing between one 0 degree bag and another 0 degree straightforward. They refer to the Teton as a three season bag, for example, and refer to it as a 0 degree despite the rating of 15F. the EN comfort rating for it is 17.4F. The very similar never summer is rated 0 degree, is EN rated just a few degrees warmer (comfort 15.8), weighs about 7 ozs different. Very close in pricing too. Then look at the Sawtooth, the 15F 600 fp bag - same shell materials as the other two, just 7 oz lighter than the Teton, EN comfort rating for women is 26F.

Makes one wonder how they come up with the labeled ratings, the bags are so close in materials and more broadly EN rated.
Posted by: Rick_D

Re: Sleeping Bag Temperature Ratings - 01/03/12 02:01 PM

That is an interesting article--good information.

Since there's no independent lab testing bags from everybody, I limit my temp ratings comparison to within the company's line, i.e., I'll take it on faith that company X's 20-degree bag is warmer than their 30-degree bag but won't presume their 20-degree bag is as warm as company Y's 20-degree bag. Design and size considerations play a part, of course, and the bags need to be used across a variety of conditions and scenarios over time.

From the emperical data playbook, I can hit or exceed Western Mountaineering temp ratings comfortably. I have not found the same with Montbell (to pick two popular companies).

Cheers,
Posted by: NewEnglandHiker

Re: Sleeping Bag Temperature Ratings - 01/05/12 05:39 PM

I have tried Marmot, EMS, REI, Lafuma, and Kelty sleeping bags. None compare with the temperature ratings from my Western Mountaineering. WM ratings are a bit conservative, but everyone else that i've tried is nothing if not a bit underlofted for the same temperature rating. I go with WM now and unless I snag a ridiculous deal on something else, don't plan on switching companies.