REI and MEC will only sell sleeping pads with the new R rating.

This is great news! ohhh…. and I love the title of the article!

I think attaching that complicated rig with the temperature sensors to all sleeping pads will add a lot of weight.

A little concerned that according to that article:

In fact, of the three $50,000 standardized test machines currently in existence, one lives in Therm-a-Rest’s Seattle factory. The other two belong to REI and MEC.

And it just so happens that all of these companies make sleeping pads, so they probably won’t test pads for companies that can’t pony up $50K. And a third-party probably won’t invest $50K to test the very small number of new pads that come to market every year.

So REI could soon drop from 15 brands of sleeping pads sold to 2 – and one of those brands will be REI.

How … convenient.

Standards have their down sides, too.

— Rex

What you’re saying suggests that every manufacturer that gets an EN temperature rating on their sleeping bag also invested in the test equipment.

EN ratings tests can be done by testing labs, and there are several that do it:

Thelma AS in Norway

Hohensteiner Institute in Germany

Institute Francais Textile Habillement in France

Altex Instituto Tecnologico Textil in Spain

Kansas State University in the U.S.

I would expect that several labs will arise to do independent testing for sleeping pad manufacturers.  Seems to make sense.

Hi Jeff,

You are probably right, but I’m still concerned.

European labs might not feel compelled to invest in equipment to test to ASTM standards until those standards or something similar are adopted in Europe.

That leaves Kansas State?

Sleeping pads are still a much smaller market than sleeping bags.

Consumers usually benefit from standards like this, I’d love to see all sleeping pads tested to a decent standard, and this one doesn’t look bad at first glance.

But testing to standards still costs money, and can distort markets.

We’ll just have to see how this plays out.

— Rex

It’s about time…

2020 will be the 20th anniversary when pad manufactures started using “R value” in their marketing jargon to describe just how “good” their pads are. Looks like the testing gear is the same as what’s used in the building industry – as if the human body has any resemblance to a wall assembly.

Too bad they don’t consider designing a testing system using a heated mannequin and using that as the “top plate”. That way they can simulate a back sleeper vs. a side sleeper.

If they did that, I think folks would soon begin to understand the physical reason why the cheap ole ccf pads perform so well in the winter, even though their listed “R values” seem benign compared to the air-only mattresses. (the X-lite is 23% “warmer” than a Z Lite Sol? Yeah, right.)

Matt,

I’m sincerely interested in your statement that CCF pads perform well in winter (and presumably, inflatable pads like the X-Lite do not).  Can you elaborate?

When we did winter camping, we typically combined an insulated self-inflating pad like the ProLite with a CCF pad like the RidgeRest.  Under both of those, because we could afford to haul it in on our sled (polk), I used a heavy duty space blanket (the 12 ounce kind, not the thin mylar kind).

When we climbed Mt Olympus and Mt Rainier at the end of June 2011, I used the same setup but without the space blanket.

This is good news.

This summer I bought and REI FLASH Insulated air mattress with and R 3.7 rating. Being an REI brand I trusted the rating. I’ll use it this winter at high altitude (9,000+ ft.) with my -20 F. Down bag to see if it is sufficient. Additionally I’ll carry a DIY mummy shaped 1/8″ (yes) closed cell flooring underlayment pad “just in case”. REI also has this mattress in the “All Season” version with an R 5.2 rating.

My 750 fill – 20 F. goose down bag is from LL Bean and, again, I trust that company’s temperature rating. The coldest I have used it was around 0 to -5 F. last winter. Hoping for colder temps in early February. If I have to go to 10,000 or 11,000 feet to get those temps I will.

“Can you elaborate?”

Sure.

First, one must think of two variables in a sleeping pad which aren’t thought about too much:

1. the measured “R PER INCH” of a particular pad,
2. the density of the pad (or quite simply, how “soft and squishy” is the pad)

The testing apparatus only uses uniform compression to determine R value. Generally speaking, the more resistance between the guarded hot plate and the cold plate, the higher the measured R value of the specimen.

That works just fine for building insulation products. They are intended to be used either in uniform compression (under a concrete slab) or with no compression (in a wall or under a floor & roof assembly). When I specify insulation for under a slab, I spec a product which is both very dense and which has a high R value per inch. (Rigid polyisocyanurate insulation tends to be the best for this use.)

The compressive forces of a person sleeping on a flat surface are not uniform whatsoever, and will vary greatly depending on weight, sleeping position, and movement. While I doubt ASTM would ever try to quantify and measure movement, it also doesn’t appear to me that they are taking non-uniform compression into any consideration. I believe this is a dis-service to consumers and will still lead to confusion.

The fact is: If I am sleeping on my side with my “R3.2″ X-Lite, one of my hips & shoulders are a LOT closer to the ground than the rest of my body. (Often, the distortion can reach 50 percent of the pad’s thickness.) Since the R per inch of an 2.5” thick X-lite is 1.28, my hips and shoulder will now have about R1.6 between them and the ground. NOT A LOT.

Although a Z-lite Sol pad is measured at a measly R2.6, it is only 3/4 inches thick. It’s R per inch value is 3.46. Because it is much more dense, my side sleeping posture may only marginally distort its thickness (maybe 5 percent – max.) This will adjust it’s R value down to about 2.46.

While sleeping on one’s side, the Z-lite is now approximately twice as “warm” as the X-lite.

Now I admit, this is an extreme scenario. But even sleeping on one’s back will subject the pad to non-uniform compression (typically heels, butt, and upper back). Denser pads will not be affected by this in the way that air mattresses will. So adding even a 1/8″ CCF pad over top of an X-Lite can go a long way toward impacting the actual R value of the setup.

I was thinking of putting the 1/8″ cc underlayment pad under my FLASH Insulated air mattress. I don’t think it will stay in position on top of the mattress.

I almost always bring a Gossamer Gear 1/8″ Pad and use it in underneath my NeoAir XLite.

1.  It helps to keep the NeoAir from sliding around on the floor of my TT Stratospire 2 or the polycryo “bathtub” floor I made for my ZPacks Hexamid Twin tent.
2. It helps protect my precious (Precious!  Gollum!) NeoAir XLite from sharp, poky things.
3. It’s a generous sitting or relaxing pad that I can use during breaks or meal times.

Experience does not bear out the Z-Lite vs XLite warmth for me as outlined by Matt above.

Z-Lite: marginal at 30 degrees, okay at 35 degrees

X-Lite: fine at 30 degrees, never used below

R-value is reduced when a pad is compressed, but I doubt it’s a linear relationship. For me, pads with a higher R-value have been consistently warmer than pads with a lower R-value.

For me it’s also a comfort thing.  I have a bad back and I’m a rotisserie sleeper, even at home on a nice memory foam mattress.  I would suffer greatly attempting to sleep on just a thin CCF pad such as the ZLite or RidgeRest.

Here is an article from the Cascade Designs (Thermarest) blog that gives a little more information about their position on R values and the new camp mattress test instrument and ASTM standard.

https://thermarestblog.com/rating-sleeping-pad-insulation-astm-r-value-standard/

“R-value is reduced when a pad is compressed, but I doubt it’s a linear relationship.”

It is very much a liner relationship. The formula for R is precisely linear and the math is very clear.

If you blow you Xlite to it’s max thickness, and you’re 100 lbs and lying on your back, you won’t compress it nearly as much as a 200 lb person on their side.

Thats precisely why I’m concerned.

But the closer my ass gets to the frozen ground, the colder it’ll get. And I’m afraid it will become colder in a very linear way.

Roger Caffin did a great market report back in 2011 going over this. While the samples he used are older, his findings were pretty notable.

“Because [a Z-Lite Sol] is much more dense, my side sleeping posture may only marginally distort its thickness (maybe 5 percent – max.)”

Only 0.0375″?  Measured how? Measured where?

And …

Employing a wild imagination, if on a CCF matt, I wonder if the knees, hips and shoulders provide a “standoff” for the rest of the body, thereby minimizing the compression area and hence the overall heat loss, whereas on an air matt a much larger area is compressed and compromised.

(Ahhh … nothing like a strong cup of morning coffee for casual speculation.)

“Ahhh … nothing like a strong cup of morning coffee for casual speculation.”

Time to get my 2nd cup!

Yes – I did allude to the idea that “MY side sleeping posture might distort it only 5%” After Thanksgiving, its probably more like 10% ;>D

And yes – because air mattresses are so soft and squishy, they will distort more which will compromise their R value even more-so.

It’s funny to me. Being in architecture, when I ask a co-worker what is the “best” (thermally efficient) building insulator to use for a wall, floor or roof assembly, even under concrete – the answer is always one of the many closed celled foam products out there (except for Aerogel but were not there yet.)

And that’s because when something has the “highest R value”, it’s due to it’s R value per inch.

Even though a 2.5″ X-Therm has an R of 5.7, 2.5″ of cheapo blue foam padding has an R value of 9.3.

“R-value is reduced when a pad is compressed, but I doubt it’s a linear relationship.”

It is very much a liner relationship. The formula for R is precisely linear and the math is very clear.

Not exactly.  The linear R-per-inch thing only holds if the density of the material is constant, which it’s not when it gets compressed.  You can get insulation batts that fit in the same 3.5-inch wall cavity that are R-11, R-13, or R-15 by changing the density of the fiberglass.  When you lie on an air mattress, the compression increases the density of the insulation in the compressed spots, which increases the R-per-inch a bit.

So it’s not linear, though I don’t know how nonlinear it is.  I too would like to see a test that accounts for the nonuniform compression, or at least some research that would characterize the effect in a way we could apply to the existing test’s results.

Hi Todd:

“The linear R-per-inch thing only holds if the density of the material is constant, which it’s not when it gets compressed.”

That’s true –  but if I am using a down filled or open celled foam air mattress, then the density would change in the compressed portions of the mattress, and the R per inch would increase slightly.

I was specifically referring to air-only mattresses, where the density is the same, regardless of it’s thickness. Quite simply: unlike fiberglass batt, down, or open celled foam, air does not get more dense inside a compressed pad.

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Interesting news.   Will ISO (the organization that creates EN specifications) adopt this specification?

I doubt that the UK or European companies will use a ASTM spec.  Exped for one comes to mind.

EN test uses a dummy.

To test mattresses properly, you should have a dummy so you can get the effect of more compression under the hips and shoulders, less under legs, etc.

But the proposed test is pretty good. Similar to Roger’s. At least you can do apples to apples comparison between different mattresses. And if you were cold with a mattress of a particular R value, you could then try a different mattress with significantly bigger R value.

I use a Ridgerest and Prolite when camping on snow. Just Prolite the rest of the time. The other day they said it was going to be 30 F, but it was 20 F, I stayed pretty warm in just Prolite. I did not want to get out of quilt.

Jerry, you use a Prolite for winter? I dunno about yours but my Prolite is a very thin summer pad with diamond cutouts in the foam. Even with my Ridge Rest I think it would be cold below zero F.

In the past I’ve used the TR Trail Pro (4.0 R value) for winter and been OK down to -5 F.  Now I’ll be using a new REI FLASH Insulated air mattress with, as noted above, a 3.7 R value. We’ll see if that’s enough for below zero F. temps and if not then a FLASH All Season mattress is next.

Of course it depends on how warm the rest of your gear is.  You can have a colder pad and a warmer quilt for example.  My Prolite is 1 inch thick, foam, R value 2.4.  I was warm at 20 F.

The difference with be quantitative not qualitative, while the testing isn’t going to be a “Real life” test it will be consistent over all makers. At least I hope it will be.

It will just allow better comparisons between products. We all “know” that side sleepers need thicker padding for comfort and simply knowing what the standard R values are won’t be changing that. We will still have to rely on trial and error to get our own personal warmth and comfort system dialed in and one set suits all doesn’t apply; it never did.

I think Sea To Summit have been using the “New” test procedures for a while now. My own feeling about the testing is that none of the mats are as warm as the tests indicate when actually being used. Perhaps we should all downrate the laboratory tests by 30 or 50 percent to account for real life usage