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A New Paradigm for Understanding Garment Warmth
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Richard Nisley
(richard295) - M

Locale: San Francisco Bay Area
A New Paradigm for Understanding Garment Warmth on 02/20/2009 21:40:01 MST Print View

Yesterday I read some BPL posts answering questions about low budget garment outfitting for ultralight backpacking. It struck me how confusing all the options must be for a newbie. I then thought that warmth relative to Polartec fleece products might be the easiest way for people to understand their options without having to wade through technical jargon or vague environmental descriptions. This post is an attempt to see if this different approach makes sense to people.

If I say, “It is the same warmth as a Polartec 300”, everyone can understand.

If I say, “The Patagonia Polarguard Delta Pullover’s intrinsic clo value is 1.06 and its total clo value is .509, the experts understand, but the laymen are confused.

If I say, “The Patagonia Polarguard Delta Pullover kept me warm at 30F around camp, the laymen think they understand but the experts know that the information is of little practical value to either the laymen or the expert. Without knowing the wind rate, the reporting persons BMR, the MET rates and durations for their camp activities, and the change in the reporting persons core temperature at the beginning and the end of the camp activities it is impossible to ascertain the insulation value of the garment they are reviewing.

I created the following chart to be Montbell centric. The other garments I listed are common alternatives to comparable Montbell garments.


Trying to determine the warmth of a garment by just measuring its loft is a measure of futility. For example, the Patagonia Polarguard Delta Pullover and a Wild Things Primaloft One sweater both have a loft of .6”. The Wild Things sweater is more than 27% warmer. The Montbell Alpine jacket has 2” of loft and box baffles yet the New Balance Fugu, which uses sewn through construction, and only has 1.5” loft is 64% warmer. The Montbell Alpine Jacket and the Montbell Permafrost Parka both use box baffles and have 2” of loft; the Permafrost Parka is 41% warmer. A Polartec 300 jacket has .25”loft and a Patagonia Polarguard Delta pullover has .6” loft and yet their insulation value is the same. The only two cases in which the loft is relevant is if you want to compare synthetic garments using the same insulation type and quilting. The other case is base layer garments; their warmth is correlated with their thickness.

In January 2010 there were a number of posts asking for clarification of the specific fabrics I tested. I answered these questions in separate forum posts. In addition, I updated my chart to includes fabric weight information. Version 2 of the chart is as follows:


In January 2011 there was a request to add information regarding how wind would affect the insulation value of each garment. I answered this related question is new post at

Edited by richard295 on 01/30/2011 23:51:05 MST.

Robert Blean
(blean) - MLife

Locale: San Jose -- too far from Sierras
Re: A New Paradigm for Understanding Garment Warmth on 02/20/2009 22:23:14 MST Print View

Can you tell us more about what makes for a better rating?

When a manufacturer comes out with a "new and improved" version next year, how do we know whether or not it still occupies the same place in your table? And if not, then where it belongs?

How do I determine where a garment not in your table fits in?

-- MV

Edited by blean on 02/20/2009 22:24:27 MST.

Dennis Park
(dpark) - MLife

Locale: San Francisco Bay Area
A New Paradigm for Understanding Garment Warmth on 02/20/2009 22:38:43 MST Print View


By any chance, would you know where Mountain Hardware's Compressor men's jacket would fit on your chart?

Oops, forgot to mention 2007 model.

Edited by dpark on 02/20/2009 23:25:58 MST.

Ashley Brown
(ashleyb) - F
Re: A New Paradigm for Understanding Garment Warmth on 02/20/2009 23:11:41 MST Print View

F%$king brilliant Richard! (excuse my French)

I remember coming up against this exact problem when I started looking at lightweight clothing alternatives. You're right... for most traditional backpackers fleece is the gold-standard for comparison, and almost everyone knows how warm it is.

The funny thing is though... I recall asking you in a thread about the MB alpine light down jacket and you said it had a similar clo value to 300 weight fleece (you even made me a graph!). I remember being surprised, because my 300 weight fleece isn't that amazingly warm. But this bar graph sets it all straight! It agrees very much with my own qualitative judgements of warmth now that I know some of the garments. And, indeed, the MB light alpine jacket is *much* warmer than 300 weight fleece!

Anyway, excellent work. This is going to be very useful for newbies. Actually, it'll be useful for just about anyone! (including me!)

Cheers, A

Edited by ashleyb on 02/20/2009 23:14:38 MST.

Ashley Brown
(ashleyb) - F
Re: Re: A New Paradigm for Understanding Garment Warmth on 02/20/2009 23:13:27 MST Print View

The MB UL thermawrap doesn't fare too well in comparison to the UL down inner does it?

I suspect a lot of the perceived insulation value of the thermawrap is because of its ability to cut wind.

But why is the parka so much more insulating than the jacket? I thought there would normally only be less than 10% difference (in non-hypothermic situations).

Edited by ashleyb on 02/20/2009 23:16:04 MST.

Misfit Mystic

Locale: "Grand Canyon of the East"
RE: Thermawrap Parka vs. Jacket on 02/21/2009 00:15:54 MST Print View

Hi Ashley, the Thermawrap Parka uses a heavier insulation than the jacket, a fair bit heavier in fact. The Montbell site quotes the jacket as using 50g/m2 Exceloft, while the parka is listed as 80g/m2. My understanding was that the parka used the heavier insulation through the torso while using the lighter insulation in the arms and hood, however Montbell does not infer this distinction in their specs or product description.

Ashley Brown
(ashleyb) - F
Re: RE: Thermawrap Parka vs. Jacket on 02/21/2009 00:20:38 MST Print View

Thanks Scott, that makes a lot of sense.

The other thing that surprised me was the fact that a cotton t-shirt has similar warmth to 100 weight fleece. Sounds a bit odd to me.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re cotton T-shirts on 02/21/2009 00:57:56 MST Print View

Yeah, well, I have some T-shirts which are made from very thick cotton knit, and some which would compete with a silk nightie.

Of course, the values are for DRY cotton. Wet fabrics - very different.


Huzefa Siamwala
(huzefa) - M
Re: A New Paradigm for Understanding Garment Warmth on 02/21/2009 01:34:11 MST Print View

>The Montbell Alpine jacket has 2” of loft and box baffles yet the New Balance Fugu, which uses sewn through construction, and only has 1.5” loft is 64% warmer.

>Richard Nisley
( richard295 - M)

San Francisco Bay Area
New Balance Fugu on 05/26/2007 20:31:03 MDT Reply Report Post Print

I have a few things to add to Paul's recommendation to purchase the Fugu including the warmth of the jacket, the fabrics used, and the looks. The New Balance Fugu claimed 4.6F increase in warmth based on the liner piqued my interest and so I did some tests. First, this is what the liner looks like magnified:


The tricot protection layer looks identical to the third layer used to protect eVENT and Gore-Tex membranes but, I have never seen the silver membrane below it before. Has anyone seen a similar liner before or know anything about this type of liner? For example, is it microporous or hydrophilic?

The Fugu tested significantly warmer than a Cabela's down jacket with the same single layer loft of ~1.5". It is very much warmer than a comparable loft down jacket than the modest 4.6F claim in their marketing hype. I suspect that this is primarily the result of the 850 down in the Fugu versus the 650 down in the Cabela’s. None the less, this unorthodox liner probably does make the incremental 4.6F contribution New Balance claimed.

My simple test was to IR measure the heat transmitted through the jacket in a 70F room and compare that with an identical loft down jacket and a jacket previously warmth tested by BPL. I used a regulated 135F (65F delta) heat source under each jacket and let each jacket acclimate for 1 hour. The mean 95F skin heat passing through the jackets in a typical 30F (65F delta) winter environment was simulated with this simple test. One other reference jacket I tested was the MEC Magma (1.1" Primaloft One). BPL previously tested this jacket as part of their Synthetic Belay Jacket tests.

MEC Magma (1.1" Primaloft One)..........86.4F
Cabelas (1.5" 650 Down)..........80.3F
New Balance Fugu (1.5" 850 Down + Radiant Liner)....77.1F

The less heat moving through the insulation and measurable on the outside surface, the better is the jacket’s insulation. To put the above numbers into another frame of reference, I tested my comparable weight Patagonia Micropuff pullover (.6" Polarguard Delta) and it yielded 90.1F of heat to the outside surface.

The material is quite windproof. A simple mouth breathability test yielded an undetectable air flow similar to the Epic Praetorian used in the Special Forces PCU Level 4 Windshirt.

Does your test measure conductive heat loss? You seem to have measured only IR heat loss.

Considering average loft is 70% of max or 1.05", this give the garment and incredible clo of approx. 6.18/inch... Did you take the IR test measure at the point of highest loft? Then the effective clo value would be 70% or 4.326. If not I wonder why everybody at BPL doesnt own one.

Edited by huzefa on 02/21/2009 07:27:42 MST.

Bradford Rogers
(Mocs123) - MLife

Locale: Southeast Tennessee
Wow!!!!! on 02/21/2009 09:11:12 MST Print View

Thanks Richard! Your posts are some of the most informative on this site. This is a great tool for people picking insulation layers, too bad it can't be made a sticky post. I would love to see this updated regularly with other silmilar garments to see how they stack up.

I often talk about how much I have used and loved my Mont-Bell Thermawrap jacket (mine is a 2005 model). In the winter I often use it in conjugation with my Patagonia R1 pullover and rain coat. I guess that combo isn't as warm as I thought.

Bradford Rogers
(Mocs123) - MLife

Locale: Southeast Tennessee
Question on 02/21/2009 09:12:59 MST Print View

Is the Patagonia Polarguard Delta Pullover the previous version of the Micro Puff Pullover?

Brett Peugh
(brettpeugh) - F

Locale: Midwest
good chart on 02/21/2009 10:36:24 MST Print View

I think this is a very good chart and makes me want to take a third look at the Montbell UL Down Inner Jacket when I get the money instead of my Patagonia Micro Puff Pullover (Polargaurd Delta).

Is it possible you could put up the values for an Patagonia R2 and R4 or would you more correspond these to the Polartec 200 and 300 wt.s?

William Puckett
(Beep) - F

Locale: Land of 11, 842 lakes
Re: "...Understanding Garment Warmth" on 02/21/2009 12:26:47 MST Print View

I absolutely LOVE the chart. Clear. Communicative. No advertising spin.

I, too, would like to see more comparisons. The more the better, imo!

And a big thank you, Richard, for your posts and the research behind them!

Edited by Beep on 02/21/2009 12:27:27 MST.

Michael Davis
(mad777) - F

Locale: South Florida
Re: A New Paradigm for Understanding Garment Warmth on 02/21/2009 14:53:39 MST Print View

Richard, I know that we are really heaping it on here, but take that as a show of respect for your always excellent, diligent research.

I have one more to add; that is how does Polartec's own "thermal pro" compare to Polartec's traditional fleece at the same fabric weight?

Tom Kirchner
(ouzel) - MLife

Locale: Pacific Northwest/Sierra
Re: A New Paradigm for Understanding Garment Warmth on 02/21/2009 18:02:51 MST Print View

Have you ever tested any of Under Armour's products? I am thinking specifically of their Cold Gear garments and their Compression garments. From a layman's perspective, I have been impressed, but would be very interested in your expert opinion, if you have worked with them.
Thanks much,

David Mcevoy
(dave_mac68) - F

Locale: Virginia Beach
Re:A New Paradigm for Understanding Garment Warmth on 02/21/2009 19:07:05 MST Print View

Richard thank you for the information; I for one, as a newbie UL backpacker, really appreciate it. I have a, probably very obvious, question: I own both the MB UL jkt and the Thermawrap Jkt - if I was to wear both at the same time would I just add the Iclo values, or is the value higher because of the insulation gap between both layers? Many thanks in advance,


Ashley Brown
(ashleyb) - F
Re: Re:A New Paradigm for Understanding Garment Warmth on 02/21/2009 19:29:05 MST Print View

Dave, you can add the lclo values together to get a minimum lclo for the combo but yes, you get some extra insulation from the air gap too.

Jonathon Rogers

Locale: East TN
Micro Puff on 02/21/2009 21:18:24 MST Print View

I see the old Polarguard Delta Micro Puff being used for calculations all of the time and wonder if the new Micro Puff jacket with Climashield Green insulation has the same clo.

Great work, Richard.

Edited by signet77 on 02/21/2009 21:18:56 MST.

Michael Febbo
(febbom) - F
fugu really that warm? on 02/21/2009 22:52:58 MST Print View

Maybe I have just not been following this conversation, but am I the only one who is amazed at the NB Fugu beating the Permafrost, a jacket designed for cold weather climbing?
Richard, how are these items tested? I would assume that the Permafrost would still be "real-world" warmer just due to the hood, but the Fugu is just amazing me given that it is 10 ounces lighter. I'm amazed- a 14 ounce jacket that is warmer than a belay parka... this is revolutionary to me.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: fugu really that warm? on 02/21/2009 23:16:49 MST Print View

Bear in mind that a jacket designed for use while climbing must have a pretty tough shell - and that spells weight.