question R-value

At best, these are only general ratings for a persons comfort level.

R2.0 is OK in warmer conditions, generally down to about 40F. Some will say it is good down to 30F, some will say it is not good at 45F. So, a lot is subjective.

The same for sleeping bags. Though, generally speaking, these don't give R values.

For winter camping, a R5.0 is the accepted minimum. Some people like warmer. This has served me down to about 20F, with no problems. I have had it to 10F, but I was cold. But, I also only had a 40F bag and slept fitfully even with a down jacket and two sets of long johns.

So the two, bag and pad, work with your shelter to keep you warm. LOTS of variables there. Too many to say "Yes, you can take an R2.0 with a 35degree WM bag down to 32F and be comfortable."
Maybe yes…maybe no. It would be better to say "An R2.0 pad and 35F WM bag will take you down to around 30F-40F" because of the variables.

What units are to R- value? R-value = 2 tog or 2 m2K/W? What standard is used to measure matresses? Is there any standard more modern than the standard BS-4745?

Thanks

Mammut has a good article about the subject http://www.mammut.ch/images/Mammut_Sleep_well_pt1_E.pdf

BS-4745 is from the 1960s and measures insulation value

EN 13537 is 2002. It's used to measure temperature rating of a sleeping bag by putting a simulated human manikin that generates heat inside a sleeping bag and measuring temeratures. They have several temperature ratings – comfort level for comfortable sleep, extreme level to stay alive,…

A lot of other stuff in that article

Thanks for your answers.

I work in a Confort Department in a Textile Institute research in Spain and I just know these standards. I test sleeping bags according to EN 13537 with our thermal manikin but now we need to test the matress for the sleeping bags and I don't know what is the best standard for this measurement.
I have read in this forum all time R-values 2,4 5 but I don't know as these value were obtained.

Roger has an article, about measuring insulation, that's supposed to be published in a few weeks on this website, that might be useful. Watch for that.

If you find a method for measuring insulation could you post something here about it? That would be really interesting.

Maybe, manufacturers of mattresses do not have a consistent method of measureing R value.

Thank you.

I am waiting this article.

What temperature ground are you going to be sleeping on? Ground temperature and air temperature are not the same thing.

Ground temperature is very relevant.

This Richard Nisley posting graphs a large number of air temp/ground temp measurements. Please note that the temps are in degrees C.

My reading of that graph is that ground temperature tends to be very slightly warmer than air temp for air temps above 0*C and tends to be pretty much unrelated to air temp and between -5*C and 0*C when air temps are below 0*C.

Other of Richard’s postings suggest that pads providing R5 insulation are adequate below 0*C.

"Other of Richard's postings suggest that pads providing R5 insulation are adequate below 0*C."

Yeah, that would depend on where you are sleeping. Ice is *much* different from snow. Rock is much different from forest loam. Pine needles are different from grass over ice… Indeed, on a good bed of pine needles, you may not need a pad. Really difficult to say or to quantify. This is only considering bags, of course. Even then there would be a difference between synthetics and downs. Quilts would add another level of veariables. A fully enclosed shelter? Tarp? Ground cloth or floor? Bivy? Pad in or out of the bivy? Just to many variables to say one way or the other within a 20F range, I think.

I think that R values are derived form a building industry measure of insulation materials and there is little standardisation between manufactures when measuring the R value of mats e.g. how fully inflated was the mat when it was tested. They are probably most useful when comparing mats for the same manufacturer as opposed to comparing mats form different manufactures.

At the moment , I have not found anything about how the measure the mattress.
I would like to know who and how determine the R-value because I have seen many mattress marked with this value but do not put anything as measured

There are currently no industry standards for R-value testing of sleeping mats, unlike that for sleeping bags (i.e. EN testing). Your best bet would be to contact each manufacturer individually.

Thank you for your answers.

From my laboratory we are trying to measure the mattress using our thermal mannequin because nothing is standardized.