A New Paradigm for Understanding Garment Warmth

[Richard Nisley]

Huzefa,

Good analysis!

I didn't receive your PM. Also I have some other PMs in the queue which I haven't had an opportunity to answer yet.

[Tim F]

Richard,

Not to belabor this point, but I also thank you for giving of your time and knowledge to help fellow backpackers understand these issues. You have taught so many of us not just the what (garment X is *relatively* warmer than garment Y), but the why (clo values, MET for different activities, BSA coverages). I think your posts let people understand this stuff at whatever level they want to or are able to. One can take away an understanding of how to calculate some of these values oneself given the right information, or simply look at one of your easily understood graphics for a quick comparison. Also fully explaining the right and wrong of long held axioms (such as loft vs down density) has changed completely how I look at some choices.

I also wanted to let you know that if you have not done any testing on the BPL Cocoon 60 jackets I would be happy to ship mine to you, and pay for return postage. Might be best to wait until June when I won't be using it. Let me know if you are interested.

[Andrew Shapira]

Nice table, Richard. I appreciate your putting that together. Is there any chance that you could add the weight of each jacket in the table, say, in parentheses after the jacket name? That'd help make the tradeoffs even clearer.

[jim jessop]

I was wondering where a light-weight primaloft one hoodie like the Patagonia nano-puff would compare in the table versus a BMW Cocoon UL 60 hoodie? Any thoughts?

[Richard Nisley]

Jim,

The WT jacket in the chart is comprised of 2 layers of 60 g/m2 PL1. Other PL1 jacket's clo value can be estimated by simple extrapolation. The Pat Nano Puff uses 1 60 g/m2 layer and so it would test with approximately 1/2 the iclo value.

The Cocoon used 1.8 oz/yd2 Polargaurd Delta and the Patagonia Micropuff used 2.7 oz/yd Polargaurd Delta. Again a simple extrapolation can be used to estimate the Cocoon's iclo value from what I published for the Micropuff.

[Chris S]

Anybody know where the MB Ex Light would be on this chart?

[Richard Nisley]

1.62 Iclo

[Chris S]

Thanks! Any idea on the Patagonia Down Sweater?

[. .]

Ex Light = 1.62 Iclo vs. Down Inner = 1.78 Iclo

This does not seem to add up with my field observations. I own both the Ex Light and Down Inner. Subjectively, the Ex Light seems noticeably warmer to me. Does the above figure take into account the difference between 800 and 900 fill down? One factor that may make a fairly sifnificant difference is the lack of pockets in the Ex Light, which translates to less convective heat loss. On paper, I would not expect to notice any difference between the two garments, so this is puzzling to me. An additional anomoly of note is that both my Ex Light Vest and Jacket are approximately 10% below specs on weight (Size L and M, respectively).

@Chris – from an earlier post in the thread by Richard, regarding the Patagonia Down Sweater vest and Hooded Pullover: "intrinsic clo was ~2.31."

[James holden]

is it compared to the UL parka?

my exlight is pretty warm for the weight

[Anonymous]

"my exlight is pretty warm for the weight"

Mine, too. I have taken to using it as my second layer in place of an Ibex wool crew neck. Much warmer, and lighter, as mine weighs 4.5 oz in size medium, about an ounce lighter than the Ibex crew.

[Mike M]

"my exlight is pretty warm for the weight"

mine three (or is it four?) :)

[. .]

is it compared to the UL parka?

Yes, the UL Inner parka and the jacket, but I am mostly comparing the Ex Light to the current version of the UL Inner Parka, which I recently parted with in favor of the Ex Light combined with a Black Rock Beanie.

[Richard Nisley]

The Montbell tests (2010 catalog) list the UL and EX garments as the same Iclo. Only a .16 Iclo difference is effectively equal when you consider the tolerances between individual garments of the same type.

[Mike M]

Richard- hate to bother you, but would be possible to list a few vests (if the info is available)- maybe Micro Puff and one of the down offerings?

Would like to see how they fit into the scheme of things

thanks in advance

Mike

[Ken Larson]

Richard ….I seem to have remembered that you were going to measure the IcIo of a Skaha Sweater some time back.

QUESTIONS:
1.) Have you posted those measurements on another thread or just have not updated your RN Laboratory Measured IcIo graph?

2.) If you haven’t as of yet made those measurements, would I be correct in saying, that a Skaha Sweater would have a 2.7+ IcIo value with a down content (4.5oz/850+ down), compared to the MB Alpine Light Jacket (4.0oz/800+ down) of 2.51 IcIo and MB Alpine Light Jacket’s replacement, the MB Frost Line Parka (6.7oz/800 down) of 3.77 IcIo?

3.) Would I also be correct in saying, that a Skaha Sweater IcIo value with a down content (6.5oz/850+ down) would be comparable to that of MB Permafrost Down Parka (6.9oz/800 down, of about 5.25 IcIo without the actual testing of either the Skaha Sweater and MB Permafrost Down Parka?

[Richard Fischel]

richard, your work has added new meaning to how i look at the insulative quality of clothing. thank you for your work.

as recommended, i have tried to extrapolate from information provided. the wild things hoody has 2 layers of 1.8 oz primaloft for a Iclo of 1.46. the wild things belay jacket has 6 oz primaloft insulation. would that give the belay jacket an Iclo (based on the chart) of 2.43, which would compare to a patagonia down pull-over? having worn the patagonia pull-over, montbell alpine light and the wt belay jacket, i thought the belay was considerably warmer than the other two. is there an error in my thinking? do i need to make adjustments for the diference in shell material?

thanks

[Richard Nisley]

Mike,

The relative warmth between garment types within the same family (down or synthetic) can be easily approximated. This assumes the typical case where the garments all use the same fabric and insulation areal weights (for example 100g/m2 PL1 and 15 denier ballistic nylon). The average body surface area for a parka is 52%, a jacket is 48%, and a vest is 36%. A vest will keep you 75% as warm as the comparable jacket, because 36 /48 = 75%, and compared to the parka it will keep you 69% as warm. A vest is generally the most efficient insulating item you can add to your clothing. To illustrate this BSA phenomenon, as discussed above, the Montbell Thermawrap synthetic vest provides 75% of the total insulation that the jacket provides yet, the ratio of garment weights is only 63%. This phenomenon holds for all insulation types.

[Richard Nisley]

Ken,

It will be probably be spring 2011, at the earliest, before I do anymore new in depth garment testing. It is a very time consuming process and I have some higher priorities that I need to take care of first. Extrapolating from past tests is easy and so I can address your questions 2 and 3 now.
2) Answer – The standard fill amount Nunatak Skaha sweater, with 850 down, has a theoretical Iclo value of 3.02 versus the MB Alpine Light Down Jacket’s 2.70 Iclo, and the MB Frostline’s 4.10 Iclo.

3) Answer – 4.08 is the theoretical Iclo for a Skaha sweater with 6.5 oz of 850 fill versus the Montbell Permafrost at 5.29.

The above estimates are predicated on proprietary regressions derived from the large battery of lab tests that I did last year.

[Richard Nisley]

Richard,

Your extrapolation methodoly is correct. I can understand that it is hard to believe.

I found a troubling anomaly relative to every synthetic garment I tested last year; they provided consistently less Iclo than the insulation manufacturer’s specification. See http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=31482&skip_to_post=268989#268989

To give the synthetic insulation vendor’s the benefit of the doubt, I use the vendor’s insulation specification when estimating the Iclo value of a garment that I haven’t lab tested. Using this optimistic (blind faith) approach, the Iclo value for the Wild Things Belay Jacket (2009 version) is 4.96 and the 2010 version is 4.44. This would jive with your real world experience that it is considerably warmer than a Patagonia down pull-over.

Please place both your WT Belay jacket and your Patagonia down pull-over on your living room floor and place an ice cube under each. After the first ice cube melts, please let us know which jacket it was under and if the melt times were significantly different.

[Mike M]

Richard- thanks, that makes sense and is easy to do :)

good point on the weight of garment vs insulation value, the vest (if sufficient for your needs) does fare well

Mike

[James holden]

one useful attribute of a vest i find in winter is that it gets less moisture …

now you might say "eric youre an effing idiot for getting down wet"

but in winter when youre playing around in the snow youll notice that your gloves, sleeves, and other peripheral areas get quite moist … when you put on yr jacket those areas have a tendency to soak up some of that moisture as well … DWR or not

a vest avoid a lot of this issue by not having sleeves…

[Mike M]

^ good point, and now that you mention that's my experience as well

I'm thinking a syn vest + R1 for 3 season "wet trips" (we're contemplating some trips to the PNW), thinking syn vest w/ R1 w/ a medium-ish down jacket for winter- I think a syn vest would fit into my hunting clothing scheme as well

for the Rockies, I really can't see anything replacing my ex light for three season use

[James holden]

mike … if youre going to be active in it a highly breathable fleece vest would be a better choice IMO for PNW winters/shoulder seasons

itll weight a bit more but dries much faster IMO … the thing with synth is that both the nylon lining and the synth insulation must dry … fleece is one uniform fabric

itll be more breathable when active, weight a bit more … but itll also be cheaper and over time it wont lose insulation due to compression

and much more durable around those pointy things we carry in winter …

i dont think you need both a R1 and a vest though for active situations … id overheat unless it was below 0F

[Mike M]

eric- for 3 season "wet" I wouldn't really anticipate hiking w/ the syn vest, and only occasionally w/ the R1

the vest & R1 would essentially replace my down garment that I would use here

winter I envision the syn vest augmenting a lighter down jacket (vs a more "traditional" heavier one)- again probably would be rare to be moving w/ the vest (but possible)

just thinking out loud :)

[Author]

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