Thermal Resistance Study of 6 Jackets

[Stephen Seeber]

I wanted to purchase a warmer mid-layer jacket for skiing.  So I purchased a number of jackets from Montbell and proceeded to test these and a few others to determine what would best meet my needs.

I thought the results are interesting, so I am posting them for anyone else who might find them interesting.

The test results may be viewed here: https://www.dropbox.com/s/vxh456dndg38fc2/

I am also posting a companion piece that describes in detail how I measure the thermal resistance of garments.  That may be downloaded here: https://www.dropbox.com/s/h82g9szn5apnyml/

Enjoy.

Steve

 

[Todd T]

Cool!  (Er, warm!)

I like that Eddie Bauer looked good–I buy a lot from them because they have tall sizes.  Though I’ve always paid a bit more than $59 for an EB down jacket, even on sale (which is the only way I buy anything from EB).

[Sam Farrington]

Steve,
How do you think choices would stack up between the down and synthetic jackets if they were being worn all day in drenching rain or sleet, or is it de rigueur to wear a shell over the down jackets.

[Stephen Seeber]

I am pretty confident the choices would change in that case! It is not a case I would envision for my use, where the weather would be too cold for rain or sleet and I do wear it beneath a Gore-tex or Neoshell shell  when skiing.  But, yours is an important point for people to consider if their down jacket might get wet.

[JCH]

Very interesting read.  I cannot comment on, nor argue with your numerical analysis, but I have to say that my personal experience with both the Montbell Plasma 1000 and Alpine Light parkas does not line up with your numbers…unless I am misinterpreting them.

You show the R-value for the AL being over twice that of the Plasma.  Over many days of use of both, I find them to be nearly identical in performance.  The only differences I have determined being weight and price.

Lastly, and certainly this is something that should be viewed with a health dose of “that’s just marketing” skepticism but a claim my experience bears out, Montbells own “performance chart” shows those 2 jackets being equally warm.

[Brad Rogers]

JCH – I think may be some confusion in that Stephen tested the Plasma 1000 Jacket and not the Plasma 1000 Parka, which are actually different jackets entirely.  Do you have the Plasma Parka or the Jacket?

The Plasma 1000 Parka is my dream jacket BTW – I just need one about half price!!!

[Jerry Adams]

Nice project and nice write-up, thanks.  Nice equipment.

There is some data on R value (or clo) for synthetic but not for down, this helps

I like how you measure several thicknesses of cork and compare to theoretical.  Even if you’re 10% off, it’s still useful.  When you measure different insulations, some of the error will cancel out so you should be able to do comparisons better than 10%

grams / R is about twice for synthetic compared to down

not that much difference in g/R between the downs.  You’d expect the 1000 fill to be a little better.  I wonder about the weight of the shell material, maybe that explains the differences.

I am not surprised that JCH experience is contradictory.  It’s tough to get consistent data.

[Jerry Adams]

Not that it matters, but since you took the time to write it up:

I don’t understand how you’re measuring convective heat transfer.

What are the two temperatures you’re subtracting to get delta T?

I don’t understand how you’re calculating convective heat transfer coefficient.

Is it that you look at the temperature at the top of the insulation, and ambient temperature, and the dimensions, and from that you can figure out what the convection off that surface is into the ambient air?

That is very complicated.  I have avoided fluid dynamics because it’s too complicated : )

Maybe it doesn’t matter.  You verified with the cork samples.

Another thing is, how does the FLIR determine temperature?  Doesn’t it assume an emissivity of the surface?  I remember a thread where Richard had some FLIR data and it seemed like there was some confusing results.  Maybe you can just assume an emissivity that’s close enough?  Or are you using the aluminum foil which has pretty close to 0 emissivity as a comparison?

[Stephen Seeber]

Hi JCH:

I think Brad may have answered your concern.  I tested the jacket, not the parka.  The jacket has 1.6 oz. fill.  The Parka has 3.4 oz fill.  You can see the difference if you look at the pictures on the website.  The results in the Montbell table are supportive of my results.  The table shows the 1000 and Superior Down jackets  are similarly ranked and my results show almost identical R-value.  I did not look at the Parka because it had a hood, which I did not want.  However, I suspect it would be too warm for my purposes.  Perhaps you can post back and let us know which version you have.

[Stephen Seeber]

Hi Jerry:

I read your report on the device that you built.  That looked like a useful project as well.

To your questions:

Look on page 5 of the “How I Measure Thermal Resistance” paper, last paragraph.  I use Ambient, which is either the temperature measured by the thermal imager on the aluminum foil reflector or can be the adjacent thermocouple mounted over the kettles.  Both numbers are typically very close.  I generally use the temperature from the reflector.  I also use the surface temperature (top of the garment), measured by the thermal imager.  This data is used by the EngineeringExcelTemplates to determine Hc.  Fluid dynamics is too complicated.  Fortunately, there are a few packaged solutions available to solve the problem.

The Flir instrument measures radiance within an area I define on the garment surface.  Knowing emissivity and background temperature it solves the standard radiometric calculation for each pixel, which provides a temperature per pixel and then an average for the area I have defined.  The process is described on pages 2, 3 and 4 in some detail.  Emissivity for the garments is easily calculated for the test garment, and these are checked for each garment.

[Jerry Adams]

Okay, now that makes sense

That’s pretty cool you can measure the heat output that way

I like how different people use different approaches

[Eric Blumensaadt]

Very interesting and fairly thorough test procedure. No question when comparing R value/price that your wife got the best deal.

PLUS… It’s my opinion that (weight and stuffed size not being a factor) 650 fill down may be a better jacket fill than 800 fill down when wearing a daypack because it is less compressible than 800 fill down and therefore keeps more loft under the straps and pack compression.

I wear an EB First Ascent 800 fill light down jacket when skiing and don my eVent parka over it when it gets colder or in wet snow. So far so good for the past 6 years.

That said, in extreme cold (0 F. and lower) my -30 F. rated EB PEAK XV parka comes out. It’s helmet compatible and thus good for skiing. Got it on sale for $250. which is a steal for an 800 fill expedition parka comparable to a Pagagucci Fitzroy.

[JCH]

Stephen,  Brad hit the nail on the head, I completely missed that you were referencing the jacket and not the parka, which is what I have. Beautiful, nearly perfect bit of kit IMO. Totally get it if you don’t want a hood, but if you do, the plasma parka is the bomb.

Still trying to figure out out why I keep eyeballing the Mirage parka :)  Montbell junkie I suppose.

 

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