Cocoon Conundrum

EN 13537 specifies .6 clo of clothing is to be used in the rating calculations. A set of average winter weight long underwear provides this amount of insulation.

If you wear something different, ISO 9920 gives the methods for estimating the thermal characteristics (resistance to dry heat loss and evaporative heat loss) in steady-state conditions for a clothing ensemble based on values for known garments, ensembles and textiles.

Six months ago, on another forum, a similar question was posed to this thread’s main topic. I answered it using the EN 13537 and ISO 9920 standard's calculation approach. Needless to say, there was at least one strong skeptic and their post response to me is what is shown. Two weeks later, on this forum, Ryan Jordan provided a similar answer based on the field testing approach. Fortunately the two approaches yielded similar results (GRIN).

Ryan was unique in his short term temperature adaptation. Unlike adapting to high heat, most people don't have good short term adaptation mechanisms for cold. The cold adaptation mechanism takes 2-5 weeks of exposure to occur on average. In general, it is dangerous to plan on sleeping warmer on subsequent days of a relatively short backpack trip.

"But won't you say that knowing the temperature can still be very helpful?"

Ben,
Yes I agree with you if the testing is valid and objective. Also, tt might be better not to use a specific temperature. If the standard is all about being a relative measurement among products, then why not classify them or rank them in ranges from 1 to 5? Consumers would know a '2' is half as warm as a '4' and '1's are for warmer temps and '5's for colder.

Ben – Some examples of manufacturers who provide temperature rating for their high loft clothing are LL Bean and Lands End.

Richard,

This is a great way to do it. A lot of people are not as mathematically inclined but with a few simple rules hopefully they could do it on their own. I think all the "rules" are in your other posts too.

Figure out the amount of fill and the clo of both the clothes and the quilt. Factor in a small increase in clo due to fabric. Check a standard clo/temperature table for the average person. Compare how your personal experiences adjust the table. Now you have a rough guess for an unknown quilt. Even if the clo/oz isn't given you can make a good approximation for synthetics. It's not like someone is making something with a clo/oz of 1.5 and everyone else is around 0.75.

Hi all

For those who would like to read more about the European standard EN 13537, try the URL below.
http://www.mammut.ch/mammut/techinfos_sleepingbags_sub.asp?id=1461

The ‘Sleep Well’ PDF gives an extensive discussion.

Now, as to why some American SB manufacturers don’t like EN 13537, I can offer two reasons:
1) Testing a sleeping bag to this standard is expensive – maybe $5,000 per test I think.
2) It showed up the grossly excessive claims some of them were making.

Think item 2 is unbelievable?

Some of you may remember that a certain American air mat maker started by advertising their latest very high-tech mat as having an R-value of 20. It turned out to have a very ordinary R value, and their current advertising uses a more realistic R-Value.

Then there was the amusing case of a new revolutionary canister stove which was supposed to be twice as efficient as all the rest and to boil water even faster. It turned out to be a bit more efficient, but it had low power (by design!) and the test conditions they had used for their numbers were verging on the deceptive. It appears they started with warmer water and only timed to bubbles appearing, not to boiling.

Caveat Emptor! International Standards have real value!

Cheers

I think the EU standard is great. I think american makers don't want to deal with it so they can sell "light" bags that are just overrated.

NF has a -20 synthetic bag that weighs 3lbs 11oz. Ha!

The European spec page for that TNF bag reads: "Temp Rating : -3°C/-10°C/-28°C (US -29°C)"

Overrated by 19°C/35F.

Richard:

Yeah, I'm aware of those two outfits. Good stuff, but wild claims. I ignore their ratings completely — which is still another reason for standardization across the board — well, at least for bags anyway.

Oddly enough, it is down items from LLBean and Landsend that I have found to be pretty much what they say it is.

Now granted, I sleep cold and am cold very quickly when outside, if I quit moving. This is due to beta blockers I take.

When wearing my down jackets from both companies I am not cold. I am warm. And happy. My REI down jacket? It isn't the best choice, it leaves me cold!

For bags….well, I base my warmth on having on only a thin base layer. And I can say I have had many bags that just don't match the temps they claim. I have had a 25* I froze in at 40*.

I have come to think that if I could handle the extra weight, I'd buy a Bean down bag for women. At least I wouldn't freeze in it! I may still do this for when I buy a 0* bag for this coming winter. Since it gets pulled in the pulk, weight isn't such a big issue.

And totally off topic…..but Bean is selling down gloves and mittens this year. I officially fell in love ;-)

Sarbar said: "I have come to think that if I could handle the extra weight, I'd buy a Bean down bag for women. At least I wouldn't freeze in it! I may still do this for when I buy a 0* bag for this coming winter."

Sarah, I have an LLBean 0* down bag and have found it effective to at least close to that. I use an extra down quilt over it when it is too close to call.
At least with LLBean, if I'm not happy with something they always take it back.

FYI, we are in the process of writing up the results from our recent BPL Wilderness Trekking course, held this month in the Beartooth mountains. Cocoon users should find this interesting, as the ten people in the course used several different combos of sleep systems, including several cocoon quilt variations. We camped down to 20 degrees or so. We'll have a full report on gear performance and the output of the course participants.

Don