clo comfort confirmation
Posted: 03 November 2008 12:18 AM   [ Ignore ]  
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After reading:

http://www.mammut.ch/images/Mammut_Sleep_well_pt1_E.pdf

there seems to be a significant disparity (page 18) from what I gather from discussions here and on the insulation descriptions at this site.  Comfort is subjective, of course, but the numbers don’t appear close.  Any comments?

-Q

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Posted: 03 November 2008 03:33 PM   [ Ignore ]   [ # 1 ]  
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EN13537 , the new European rating standard for insulated items (talked about in that much-discussed Mammut pdf), is a well thought out way to give end users a way to compare and contrast gear. It requires gear to be tested in a standardized way with a copper mannequin which at $1500 per test is impractical for home gear makers.  But then again a home gear maker is neither a consumer of gear in the way a person going into a gear shop and buying a sleeping bag is a consumer nor a large scale producer of insulating gear, the two target parties of EN13537.

EN13537 seeks to quantify what we all knew to be true: different people have different insulation needs because of a) variations in metabolic rate which relates to heat production and b) gear design & materials which affects heat loss. Like all other ways of quantifying warmth, at the end you always end up having to peg where you personally fit in on the spectrum.  It happens with inches of loft (X inches = X degrees), Clo (X clo = X degrees), or with EN13537 (am I well represented by one of their ‘average’ male/female models, or do I choose closer to the upper or lower limit?). 

EN13537 is extremely conservative compared to what we are used to here in the US and Canada.  On page 30 of the Mammut .pdf you can see how the American style rating relates to EN13537: the ‘standard female’ en13537 rating of +2C (36F) and ‘standard man’ en13537 rating of -4C (25 F) corresponds to the American rating of -16C (@0 F).  The numbers you see here at Thru-Hiker follow the American accepted norm which tracks pretty well with the ‘low limit’ ratings of en13537.  If you want to follow the basic guidelines of EN13537, the upper limit would require approximately 2X the stated basis weight of insulation as seen on our insulation purchase pages.  IE: 10 osy XP for 20 F (-7C) vs 5 osy for 20 F.

I personally think that the gear maker is better equipped than a copper mannequin to determine his/her own insulation requirements.  Thru-Hiker makes it as easy as possible by providing standardized clo values as well as inches of loft measurements for all the insulations available for sale here.  The most responsible way to determine warmth of gear you’ve made yourself is to test it incrementally with a recording thermometer, starting at a temperature significantly above what you hope the low limit will be.  After you’ve determined where you actually fit on the insulation requirement spectrum, it’s easy to make warmth predictions with standardized clo values without the need for a $1500 copper mannequin test.

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