Author Topic: Sleeping Mats R-Values  (Read 457 times)

alan de enfield

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Sleeping Mats R-Values
« on: 22:32:09, 23/02/19 »

I have read up on what R-Values are (the higher the figure the better the insulation) but do not understand the variations quoted.


Example :


Exped "DownMat 7" is quoted as R-Value 5.9 (tested by EMPA, the Swiss Federal Laboratory for Material Testing & Research)


It appears that the USA uses imperial dimensions whilst the 'rest of the world' (SI units) uses metric dimensions.
With approximately a 6:1 comparison.


The question :


How would you know if the figures quoted are USA or Rest of the World ?


http://www.outdoorsandactive.co.uk/proddetail.asp?prod=downmat7




Maggot

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Re: Sleeping Mats R-Values
« Reply #1 on: 08:14:43, 24/02/19 »
Well as the test was quoted as being carried out in Switzerland, I would guess it is using the 'European' version.


Possibly not worth getting too bogged down in the detail?

gunwharfman

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Re: Sleeping Mats R-Values
« Reply #2 on: 10:16:10, 25/02/19 »
I've no real idea what an R-value is but if its helpful, I own three different types of Thermarest mattresses, from cheap to more expensive and I have never found the ground cold to get through to me from any of them.

alan de enfield

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Re: Sleeping Mats R-Values
« Reply #3 on: 11:45:27, 25/02/19 »
Well as the test was quoted as being carried out in Switzerland, I would guess it is using the 'European' version.




That's what I assumed - but wrongly !!


I have spoken with the Exped Product Manager for 'mats' and he tells me it is tested using 'imperial' units. (Btu's per square foot per degree Farenheit)
The R=5.9 value quoted equates to R=1.04 using the international SI measurements and tests.( watts per square metre per degree Centigrade)


I think it could be misleading when looking to buy and considering a mat with (say) a quoted R-value of 5.9 and compare it with another with an R value of 2.08 and not realising that the 2.08 mat actually has twice the insulation rating of the 5.9 mat.


Compare apples with apples !!

alan de enfield

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Re: Sleeping Mats R-Values
« Reply #4 on: 11:58:40, 25/02/19 »
I've no real idea what an R-value is but if its helpful, I own three different types of Thermarest mattresses, from cheap to more expensive and I have never found the ground cold to get through to me from any of them.



Interesting info (including Thermorest mats)


Did you know that, in order to achieve its advertised temperature rating, your sleeping bag needs to be used in conjunction with a 4.0 R-value pad?


I didnít, at least not till I hopped on the phone with Greg Dean and Brandon Bowers from Therm-a-Restís design team. For some perspective, the brand's ultra popular, ultralight pad, the NeoAir XLite only ranks a 3.2. You likely need a higher R-value pad than you're currently using just to get the most out of your sleeping bag.



https://www.outsideonline.com/2371291/nerdiest-most-important-sleeping-pad-news-ever

gunwharfman

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Re: Sleeping Mats R-Values
« Reply #5 on: 12:20:28, 25/02/19 »
I use a sleeping quilt which has no back to it, or a hood and I sleep on a Thermarest fitted sheet (very thin material) which covers my Thermarest mattress. I accept that I do not sleep out in really cold weathers, but in my opinion in the cold nights I have been in my tent, I have never noticed cold come through from the ground to my body. I often wear a pair of long johns and a T shirt top but thats all. If I get cold, I know that its due to my quilt (its not so good these days at keeping me as warm as it did say three years ago) but I believe that I have now solved this problem by buying a £5.99 Decathlon synthetic blanket, double folding it and spreading it across my torso area. I'm looking for a small down blanket to replace this blanket but so far have not found one at a reasonable price.

richardh1905

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Re: Sleeping Mats R-Values
« Reply #6 on: 13:41:23, 25/02/19 »
Wow - £165 for a sleeping mat!

Litehiker

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Re: Sleeping Mats R-Values
« Reply #7 on: 02:45:23, 26/02/19 »
I have a bunch of backpacking mattresses. (BTW, I'm 'Merican and these are 'Merican mattresses.)

Here are some R values for them.

Thermarest 3/4 length "standard" self-inflating -> R4
Thermarest Trail Pro regular ->R4 (26 oz.)
Thermarest Prolite regular ->R2.4 (16 oz.)
REI FLASH Insulated Air Mattress(3 season) ->R3.7 (15 oz.) Primaloft bonded under top skin, reflective layer bonded inside bottom skin - no foam.
REI FLASH ALL Season Air Mattress -> R5.3 (19 oz.)

Generally R2.0 to 3.0 is fine down to 40 F.
5.0 is minimum for 0 F. 
For sub zero F. I put a Thermarest Ridgerest closed cell foam pad beneath my R5.3 winter pad.

Eric B.
P.S. Sorry for the Fahrenheit numbers. I'm Celcius illiterate unless it's -40 C. C. which is also -40 F. (Because 'Merican...)
« Last Edit: 03:16:54, 26/02/19 by Litehiker »

richardh1905

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Re: Sleeping Mats R-Values
« Reply #8 on: 08:18:38, 26/02/19 »
What is adequate very much depends upon other factors, particularly how people are affected by the cold - some are very tolerant and others more susceptible.

Also, the mat is just part of the system needed to keep you warm. The sleeping bag used, any extra clothing worn, how draughty the tent is, and (often overlooked), the surface that you have pitched upon - short heather, springy grass, crowberry will trap air and have some insulation value, as well as being comfortable!

Personally, I have always found a simple closed cell foam mat to be perfectly adequate for wild camping/bivvying. As I get older, the thought of more comfort is tempting though....

richardh1905

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Re: Sleeping Mats R-Values
« Reply #9 on: 08:24:32, 26/02/19 »

Interesting that Alpkit do not use R values. From their website:


Why donít Alpkit use R values?
Currently, we donít use R values to help you compare the thermal resistance of different sleeping mats. This is because there is currently no internationally agreed standard for testing or rating how warm a camping mattress is. Until a standard is introduced, we reckon good, old-fashioned advice and experience is generally the best way to choose your sleeping mat.


https://www.alpkit.com/support/stickies/sleeping-mats-and-r-values


alan de enfield

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Re: Sleeping Mats R-Values
« Reply #10 on: 09:10:25, 26/02/19 »
Interesting that Alpkit do not use R values. From their website:


Why donít Alpkit use R values?
Currently, we donít use R values to help you compare the thermal resistance of different sleeping mats. This is because there is currently no internationally agreed standard for testing or rating how warm a camping mattress is. Until a standard is introduced, we reckon good, old-fashioned advice and experience is generally the best way to choose your sleeping mat.


https://www.alpkit.com/support/stickies/sleeping-mats-and-r-values



The specification referred to by Alpkit is the one already used by the majority of 'quality' manufacturers.
The US and RoW tests are similar they just use different units.



It is proposed that the new 'World Standard' will be introduced next year.


Edit to add :
Just re-read what I wrote and it may be read that I think that Alpkit is not a quality manufacturer. This is not what I meant.
Many of the 'cheaper' end of the range either don't bother quoting any figures or just 'estimate' what the figure may be' based on similar competitors data.
« Last Edit: 09:15:52, 26/02/19 by alan de enfield »

jimbob

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Re: Sleeping Mats R-Values
« Reply #11 on: 09:52:47, 26/02/19 »
Quite interesting. Makes comparisons  based on r-values useless unless you know which units are being used. My thoughts at this time is that Thermarest ( using Imperial units) with the larger advertised number works out to have a lower R (SI) value than a European tested close cell matt. We all know that is a load of tosh. It does make any form of R vslue useless in the evaluation process.
Or, as is usual for me, have I completely misunderstood?
Too little, too late, too bad......