Calculate CLO value in a down jacket

[Robin T]

Hi!

Ive been trying to learn how to calculate the clo value in a down jacket.
I dont need 100% spot on value but if i could get within ~0.3 clo of the actual clo value
then i would be happy. I think i got a way to do it but im not sure if its the right way.

Here is how i do it with the numbers for 800fp down:

Patagonia Fitz Roy Hoody:

Richard.N says that it has a clo value of 3.94.
ive read that it has 181grams of down.
800fp down is 45.93g/1,62oz/clo in densitys betwen 1,62oz/yd2/in3 and 4,05oz/yd2/in3.

181/45.93 = Clo 3,94.
Seems right.

Eddie Bauer peak XV:

Richard.N says that it has a clo value of 7.47.

Here is how i do it: 12,76 oz/361,7g of down and 2.5inch loft.
361.7/2,5 = 144,7g/inch of loft. 147,7-115 = 29,7. 29,7/5,11 = 5,81.
1,0581*45,93 = 48,59. 361,7/48,59 = clo7,44.
Not 100% spot on but close enough for me, could be that i use 800fp numbers and the jacket has 850fp.

Feathered friends Rock and Ice parka:
Richard.N says it has a clo value of 11,98

Here is how i do it:
size M = 582g of down. im guessing it has 4" baffle height from pictures ive seen.
582/4 = 145,5. 145,5-115= 30,5. 30,5/5,11=5,96.
1,0596*45,93 = 48,66. 582/48,66 = clo 11,96.
Again close but not 100%

Using this method seems to work just fine, but i only know this because i can compare my results to Richard's results. I own a Wolff-Wear -50 Expedition jacket, it has 800g(!) of 800fp down in size M, 4" baffles.
800/4 = 200. 200-115 = 85. 85/5,11= 16,6.
1,166*45,93= 53,55. 800/53,55 = Clo 14,93.

Can someone tell me if a clo value of 14,93 seems reasonable for this jacket?

Thank You!

Sorry for my bad english but i hope you can understand.

/Rob

[Walter Carrington]

This looks like a real bargain for a super warm down jacket (at least with their catalog specs) for $202 (without VAT). I don't know if they ship to the USA, but they give prices in US$. http://www.wolff-wear.se/down-jackets/expedition-down-jacket-50grc.html

On paper at least, it should be warmer than the FF Rock and Ice for 1/4 the price. If you buy one you should write a review. Sorry, I don't know the clo.

[Robin T]

Hi!

I already own the jacket and i love it. Its a verry warm jacket and i dont doubt the -50c temp rating. 2 layers of down must be the ultimate construction for warmth. The filling is verry dense and the jacket can "stand" on its own. Its the perfect jacket for beeing inactive in verry cold weather. The downside is that its almost to puffy, you look like the michelin man. The shell is a heavier nylon, much thicker than the one on the Peak XV jacket for example but it dosnt have a rip-stop element in the shell. I dont think this jacket likes rain and wet snow either.
Its heavy! must weigh atleast 4lbs. It only has 2 cargo pockets and 2 handwarmer pockets on the outside. The inside has one large zipperd pocket, I would have liked if they had put a waterbottle pocket to.
Other than that its a great jacket, and its cheap, atleast here in Sweden.

[Jerry Adams]

-50 C?

= -58 F

Where does it get that cold?

Definitely a "Michelin Man"

[Jennifer Mitol]

I would so love to see a picture of that coat ;)

[Jared Baker]

Couldn't find one with anyone wearing it, but this is from their website.

[J C]

"Richard.N says that it has a clo value of 3.94.
ive read that it has 181grams of down.
800fp down is 45.93g/1,62oz/clo in densitys betwen 1,62oz/yd2/in3 and 4,05oz/yd2/in3.

181/45.93 = Clo 3,94.
Seems right.

Eddie Bauer peak XV:

Richard.N says that it has a clo value of 7.47.

Here is how i do it: 12,76 oz/361,7g of down and 2.5inch loft.
361.7/2,5 = 144,7g/inch of loft. 147,7-115 = 29,7. 29,7/5,11 = 5,81.
1,0581*45,93 = 48,59. 361,7/48,59 = clo7,44.
Not 100% spot on but close enough for me, could be that i use 800fp numbers and the jacket has 850fp."

Robin I don't understand why or how you've arrived at your second formula. The first one makes sense, weight of the down divided by the clo value per unit weight gives you the total clo value. But this method doesn't work for your subsequent calculations so you seem to have modified the effective clo/weight value but I can't make heads or tails of why you've done what you've done. First you get the weight/inch of loft (density of sorts) but then you subtract 115, and then you divide the result by 5.11, and then you multiply the clo/weight value of 800FP down by 1.0(the result) which makes no sense to me at all. Also when you give densities you give them in oz/yd^2/in^3. Density should me mass/volume so oz/in^3 or whatever.

Then again Richard's value make little sense to me either. If his theory that g/clo values remain constant between the "minimum" fill density and 2.5 that density then assuming manufacturers fill their jackets to within this range then you should be able to calculate the overall clo of a jacket from its weight. But this doesn't quite work when looking at Richard's numbers.

If the FitzRoy has 183g of down and iclo of 3.94 then the g/clo value is 46.45.
If the Peak XV has 361g of down and iclo of 7.47 then the g/clo is 48.33.
If the Rock and Ice parka has 582g of down and iclo of 11.98 then the g/clo is 48.58.
If the Montbell Permafrost has 255g of down and iclo of 5.33 the g/clo is 47.84
If the Rab Infinity jacket has 210 of down and iclo of 4.56 then the g/clo is 46.05
If the Montbell ExLight has 51g of down and iclo of 1.62 then the g/clo is 31.48

The first five seem to add up fairly well except the Rab and Rock and Ice Parkas have 850 loft down so should have higher g/clo ratings than the other three which have 800. I can't explain these discrepancies. Nor can I explain the massive discrepancy in clo/g for the 900FP in the Montbell Exlight. 900 FP should only be 11% warmer than 800FP but the difference here is about 35%. Unless Richard meant 1.26 instead of 1.62, which would make the g/clo value 40.48 which is 15% more than the 800FP value. Either way clearly I am missing some vital variable.

But my interest is in the Rab Neutrino Plus jacket which has 275 of 800FP down so iclo of ~ 5.7 to 5.8 I am guessing…

[David Thomas]

>"-50 C? = -58 F Where does it get that cold?"

I've got friends who work in those conditions on the Alaskan North Slope. Sort of. The producers and the pipeline company have "no travel" days when it is below -40F/C unless there is an emergency, etc. (However, if it is a shift change day, no one records a temp of -48F or -53F, it is always -40F so they can go home). They go outside but only near a pump station or production facility.

Some dog-mushing friends were doing an Iditarod one year and it got to -50F. It then wasn't about winning the race or necessarily even finishing the race, but about surviving. They'd mush to warm up until they were falling asleep on the runners and then sleep until they got too cold, repeating the cycle.

My personal best (worst) was -44F in the Yukon. One's urine does not freeze before it hits the ground, but the splashed drops immediately freeze on whatever they hit. I know, TMI.

The bottom of my personal fun meter is -15F. I can do lower, but why?

The pictured jacket just seems to have a lot of down in it. The hood doesn't seem to be much of a tunnel hood and has no ruff, so I question how functional it would really be at -40. Most of our wardrobes have lots of layers we can pile onto our trunk. Typically, getting warmer pants, boots and figuring out how you will protect your face and hands are where we need better gear.

Jerry: Since Halloween is coming, how about getting one in white and going as Bibendum?

[Jerry Adams]

"Since Halloween is coming, how about getting one in white and going as Bibendum?"

or as Michelin tire man?

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