Is Enlightened Equipment temperature rating accurate?

[Woubeir (from Europe)]

0,85 m2.K/W is the RSI-value.

R-value (U.S.) = RSI (SI) × 5.678263337

So the R-value (U.S:) = ~4,8

[chris s]

Some places just go by inches of loft, which has worked out well.
——–
Original unreadable version replaced by a readable version – Roger Caffin
But not without a huge amount of hassle due to the lousy formatting used by this Forum SW!

Single Layer Loft and Estimated Temperature Rating
Temp   Loft   Temp   Loft
(F)      (in)     (C)     (cm)
50      1.0      10       2.54
40      1.5      4.4      3.81
30      2.0     -1.1      5.08
20      2.5     -6.7      6.35
10      3.0    -12        7.62
0.0     3.5    -18        8.89
-10     4.0    -23      10.16

[chris s]

well that didn’t work…

[Michael Glavin / Zenbivy]

I have been studying the EN rating / pad interface issue for a couple of months, and am about to undergo testing to quantify the findings.  I too, was a bit shocked to learn that the test uses a warmer than usual pad.

At a minimum, virtually every person who buys a bag is getting lower thermal performance than they expect based on the EN rating.  This inevitably results in people sleeping cold and blaming it on the bag, when the pad is the real culprit.  It is also causing us to overbuild bags (or folks buy 15 degree bags for 3 season) to accommodate for “light” mattresses.  The new air mattresses, with common R values down to 1, really amplify this.

[Roger Caffin]

a bit shocked to learn that the test uses a warmer than usual pad.
That’s a matter of semantics and should not be misinterpreted.
I would instead say that the test uses a suitable pad for the conditions, but that many users do not.

This is not a problem with the EN test; rather it is a problem with the general perception of what is suitable. The excessive emphasis on ultra-ultra-light weight (more appropriately called ‘stupid-light’) has led to some grossly inadequate mats being on the market.

How often do we see people boasting about how they have cut their mat down to be even lighter, and then they moan that their quilt or bag does not meet the vendor temperature rating? Folks, the ground is COLD!

</soapbox>

Cheers
PS: NO criticism of Michael intended. He is right.

[Tim Marshall]

I am concerned a pad with such high R value skews the test in warmer weather bags. We see bags rated 40* by manufacturers getting 32* ratings via the test. The pad has to be a play here correct?

It’d be nice if they tested bags with pads that matched the target rating instead of the same pad for 50* and 0* bags.

-Tim

[James holden]

The reason is probably so they can eliminate as many variables as possible

similarly we can ask “but happens if the person is older/ill feed/its windy/yr bag has condensation, etc …” …. But you need to draw the line somewhere

for an apples to apples comparison of how one bag compares to another you need to elimnate the pad

For example will 15F bag need to be tested with a slighly higher value than a 20F one if we use a sliding R value scale (which is not how we use pads) …. Or will there be a specific point where one jumps from a R2 to a R3 pad? …. You know EVERYONE is going to game that point ….

pad technology is one area where improvements have been made for weight vs insulation (neo air xtherm) …. So it shouldnt be hard or to heavy to get the proper pad

Quality down bags on the other hand havent changed too much in the last decade or two …. 850 fill is still 850 fill …

Which is why a WM from a decade ago is still more or less the same bag

;)

 

 

 

 

[Jeff McWilliams]

For YEARS our backpacking club has maintained the practice of loaning out gear for classes and trips to members who haven’t acquired their own.  Of course, being budget conscious folks, the club purchases synthetic sleeping bags and Thermarest Ridgerest pads.

Both the Ridgerest and the ZLite are popular pads that I see backpackers carrying often.  At an R-value of 2.6 for the Ridgerest and 2.2 for the Z-Lite, it’s no wonder so many people complain of sleeping cold.

I also see a lot of beginners complaining of being cold while using a 0 degree rated synthetic bag and the Ridgerest pad on damp nights in the high 30’s.

When one realizes that synthetic bags lose loft due to use and compression sacks, and that the pad may be underrated, it’s no wonder the beginners are complaining.

My poor wife always complains of sleeping cold.  Maybe I should upgrade her from a NeoAir XLite (R=3.9) to something like the Exped Synmat HL Winter (R=5.0) or a NeoAir XTherm (R=5.7)

 

[Michael Glavin / Zenbivy]

Tim:

I agree with you.  What we don’t know, however, and what I am trying to find out, is what is the “match”.  Your theory (which I agree with) is that a r value 5 is overkill for warmer temps, and that a lower r value pad may match a 50 degree bag.  But we don’t know, really.

It may be that we are better off with a warmer bag/quilt, and a lower r value pad, though the EN rating of the bag would be misleading.

But think about all the folks that buy 15 degree bags for 3 season use.  Virtually nobody (users of this site probably an exception) uses these bags in those temps.  I’ll bet a lot of it is because the pad is not warm enough.

It certainly changes the whole equation of which is lighter.  It may be that our current systems with “overkill” bags and “underkill” mats (by EN standards) is actually the lightest way to go.  But I doubt it.  I’ll bet we would all be better off with warmer pads and lighter bags.

But again, we don’t know.  All we know so far is that the EN rating people think they are getting, is in most cases not what they are getting.  And since both you and I have been making sleeping bags for several years, and we did not know that, I think it is safe to say that virtually nobody knows it.  And its a pretty big deal, actually….

If you want to partner on some testing, let me know….;)

–Glavin

[Roger Caffin]

Hi Tim and Michael

Yes, I can well imagine that a quilt might get different EN ratings depending on what mat is underneath it. But what does that tell you?

It tells me that in some cases the limiting factor is not the quilt but the mat. In that case it is not the quilt which is being tested: it is the mat. And this is just plain stupid. I suspect the designers of the EN test had not known enough when they designed the test conditions. A pity, but that can be fixed.

In this case I suggest the EN Standard does need revision. ALL testing should be done on a mat with an R-value of, say, 10+. Yes, to be sure, you would not be likely to find such a mat in the field, but at least you would be testing the quilt and only the quilt!

This does also mean the whole quilt/SB industry must take up the role of explaining to the customer that what mat they use IS going to affect how well they sleep. Doubtless there may be some kickback from some of the mat industry interested in selling minimal mats. Tough.

The quilt industry has only itself to blame for many of the ‘cold’ problems. The idea of a hoodless quilt for anything other than mid-summer is stupid. Up to 50% of the heat loss from your body is through your head. Designing a hoodless quilt for winter use is really creating huge problems for yourself. No, a little bonnet (call it what you will) is NOT enough: there is still a huge gap at the neck, and the amount of heat from a bonnet is often too much – but you cannot regulate that without removing the bonnet. A hood on the quilt works and can be adjusted during the night:

Should the R-value of the mat used in the test be matched to the expected rating of the quilt? Definitely NOT. That would be confusing and would lead to all sort of gaming of the system. We don’t want that.

There is one other thing you need to educate the customer about, and that is how an air mat ‘fails’ under some conditions. Consider a nice thick 75 mm (3″) airmat – blown up softly. That should be plenty warm, shouldn’t it? Nope! It can be very poor.

First of all, we KNOW that empty airmats (ones without any fill) are cold. Our testing has shown that. But what is less undestood is that a 75 mm air mat blown up softly may be only 20 mm thick under the hips and shoulders. And a 20 mm gap is not good enough. But users still under-inflate their mats for better comfort, not realising that they are killing the R-value.

My 2c.
Cheers

[James holden]

Micheal…

its actually been known for around a decade that you needed a R4+ to meet the en-rating on BPL

if you dig up the old threads that was one of the criticisms of it

jeff …

just give her a loeaner ridgerest or zlite for use with the xlite

if it makes a difference then consider getting her a xtherm

;)

[John Vance]

I am one who has been sleeping year round on an R6 mat for years (currently an (xtherm) and enjoying the benefit of a very light quilt.  Having been extremely cold on a trip with lows in the 30’s sleeping in a WM Versalite all buttoned up atop a POE air mattress, taught me first hand the importance of a warm pad.

I should have remembered as a teenager freezing in the summer in temps in the 70’s when the heater in my waterbed went out.  The ground (and an unheated waterbed) is one big heat sink you need to insulate yourself from.  Many will need an instrumented test to have it proven to them, but my experience, while anecdotal, has been proof enough.

I write this while laying atop a 14″ thick memory foam mattress that is certainly R12+ and I don’t expect the temp to dip below 68f tonight.   Over me will be a down comforter with 2″ of loft and fully baffled with 800 fill down.  Come to think of it, I just may open the window and push the EN comfort rating of my “home” system to test the limits in a controlled environment.?

[Roger Caffin]

Hi John
I had not thought about a water bed withOUT the heater. Ugh!

a 14″ thick memory foam mattress that is certainly R12+
Just so. My feeling is that novices do not realise just how warm their mattress at home is, and do not understand how cold the ground can be. They blithely imagine that the only function of the mat is ‘comfort’.

Cheers

[Rex Sanders]

And then there are those trips where I sleep much colder on some nights with measured higher temperatures, using the same sleeping bag and pad, inside the same tent, when the wind isn’t significant. EN ratings, R-values, and similar lab measurements don’t capture all the variables.

That problem aside, the industry needs to find a way to teach people about the importance of pad insulation, and (ideally) all use the same measurement, so we can compare pads. Many pads don’t even report R-values.

I’d be thrilled if all bag specs showed both EN values, if quilts could report something comparable (maybe using a “standard” balaclava, comparable to the “standard” pad?), and all pads came with R-values. An imperfect but consistent comparison is better than “trust the manufacturer ratings.”

— Rex

Add: For quilt makers that also sell hoods/balaclavas, could you report EN ratings for a combo?

[Rex Sanders]

This could be a blindingly obvious idea to someone, but how about running the EN testing protocol using the same sleeping bag, but swapping sleeping pads?

Would be interesting to see how much difference that makes to the computed EN rating of the bag, and a step toward finding the sweet spot between bag rating and pad rating.

— Rex

[Roger Caffin]

Hi Rex

Excellent idea – but those tests are $$$. Problem.
And I don’t have the facilities.

Cheers

[James holden]

rex …

 

 

 

 

as a note 0.5″ foam pad is roughly 1.3-1.5 R-value

as one can see with a simple plot … the effects beyond 1.5″ diminish quickly for synth … while for down it slows down but is still significant ..

synth provides more ground insulation than down (moot point in a quilt)

also for “higher clo” bags … the pad is more important, no surprise there ….

;)

 

[Jeff McWilliams]

Some insulated air pads (Big Agnes Insulated Air Core, REI Flash) use synthetic insulation such as Primaloft to provide their R-Value.

Richard Nisley has shown that a Primaloft puffy such as the Patagonia Nanopuff loses as much as 30% of its loft after a season of use, stuffing and un-stuffing into a pack.

Does the same thing happen to the insulation inside a sleeping pad? Does the R-Value of synthetic fiber/filament insulated pads degrade like synthetic puffies do?  We’ve had a Big Agnes Insulated Air Core for about 4 years.  When not in use, it sits as it came packaged: rolled up and inside its stuff sack.  Eek!

Exped says they laminate their “Texpedloft” insulation to the top and bottom of the pad baffles, which apparently causes the pad to pull the insulation apart as the pad is inflated.  I don’t recall seeing similar design claims from REI, Big Agnes, etc.

 

 

 

[Jerry Adams]

“If manufacturers do not want to pay for a manikin test to determine the insulation… they can estimate…using equation #3 and #4”

Just what I was suggesting : )

although -5.062 – (-0.43 * bag thickness,cm) + (10.781 * bag weight, kg) doesn’t seem like the best.  Maybe weight of down would be better than weight of bag.  maybe factor in something about the construction technique

you could measure a bunch of bags with the EN test to determine the equation and see what the variation is from calculation to actual test result

then, consumers could accurately compare bags from different manufacturers.  If someone knew they slept cold, they could just add 10 degrees or whatever which is what they have to do anyway with the EN test…

[Michael Glavin / Zenbivy]

“This could be a blindingly obvious idea to someone, but how about running the EN testing protocol using the same sleeping bag, but swapping sleeping pads?”

Rex:

This is exactly what Zenbivy is doing right now…..stay tuned….

[Michael Glavin / Zenbivy]

Roger:

Well, here is what we do know.  The only quilt that I know of that has been tested is the backcountry quilt from SD, and it got an EN rating of 27 limit.  So we know an R value of 5 works, and can be part of a system that will realistically get folks down to freezing, which is what a 30 degree EN bag ought to do.

So honestly, I would have a hard time recommending that anyone use a quilt with any mattress less than an R value of 5.  It absolutely will be the limiting factor in your warmth, and unless you are going to own more than one mattress, R value 5 is the minimum, given the info we currently have.

Based on that Zenbivy’s plan is simply going to be to recommend mattresses with an R value of 4.8-5.1, because that is what is required to achieve the EN rating (just like every other sleeping bag in the world).  Anything less than that will be colder, and we are going to tell them how much colder, since we are running the EN test with different R value pads to test exactly that.

Do you think that makes sense, and that people will understand it?  Is there a better way?

 

[Jerry Adams]

you can have a warmer pad and less warm bag and have the same total system warmth

you have to look at total system

[James holden]

jerry …

i dont know if thats totally correct …

taken to an extreme one can claim that we could use an xtherm with a fleece bag and be warm … but that wouldnt be correct as while yr back might be warm, you would still be pretty cold at a certain temp

similarly its like folks using a 20F down quilt (hoodless) with just a thin merino beanie … yr head might wel get pretty cold and be a major point of head loss

there was some discussion about localized issues for en-ratings … ill have to see if i can dig it up

;)

[jimmy b]

you can have a warmer pad and less warm bag and have the same total system warmth

you

have to look at total system

True, try an uninsulated or under insulated pad at temps dictating the use of a well insulated pad with a bag  that exceeds the conditions. Your gonna be cold. Now increase the pad insulation and drop the bag rating to what is appropriate. Happy camper.

Of course you can push things to the extreme to disprove the above but lets assume a little common sense is play.

 

[Matt Dirksen]

“That problem aside, the industry needs to find a way to teach people about the importance of pad insulation, and (ideally) all use the same measurement, so we can compare pads. Many pads don’t even report R-values.”

It is certainly in their best interest to educate folks on why adequate pad insulation is so important, but the educated consumer might conclude that topping a “simple” air mattress off with a $15 closed celled foam pad is much cheaper and just as thermally efficient as shelling out $150-$200 for the flagship R-5+ mattress.

And regarding independent R-value testing – does anyone know if the manufacturers are any closer to agreeing to the criteria on this? I know they’ve been chirping about it for years, but haven’t heard anything new.

It’s been almost 20 years now since pad companies started marketing pads with “R value”measurements. It’s probably about time they back their claims up with independently verifiable testing.

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