Variance in EN ratings on same sleeping bag? (Mountain Hardwear Phantom 45)

Eric, exactly my point. They do not isolate all the variables. As Jerry was saying, they are only a test and are fairly self consistent. But, 10% is still 10%. Wind speed? They allow it:
<div data-canvas-width=”24.479999999999997″>Section A.4.3 gives ranges for environmental conditions that are acceptable. However,the</div>
<div data-canvas-width=”59.4″>wide range for air velocity– from still air conditions to 0.5 m/s– will contribute to inter-lab variability since air velocity affects the external air layer around the manikin. In addition, the</div>
<div data-canvas-width=”535.8399999999998″>direction of the air flow may affect the results. ( Is it horizontal or vertical flow in the chamber? Does it flow across him or along his length?). The relative humidity range is wide (40-80%), but acceptable since at steady-state, relative humidity does not affect insulation (i.e., there is no absorption or desorption of moisture by fibers under steady-state conditions). In addition, the actual moisture content of the air is very low in cold temperatures.</div>

jerry ,,,

thats roughly what richard does …

the problem is that its an extrapolation … and not actual measurements …

perhaps one day we will get to the point where all this can be modeled accurately prior to a single goose being plucked … then manufacturers can truly optimize their designs to squeeze out every bit of efficiency …. we do it for airplanes and cars afterall

the problem isnt cottage makers … their sales volumes are small enough and the consumer educated enough that it doesnt really matter for that marketplace (other than fanbois making outrageous claims)

the issue is the average consumer being able to make an apples to apples comparison between whats commonly available  ..and in that regard the en-ratings has succeeded admirably as most major sleeping bag manufacturers have moved to it even in the US

recently EE made a 20F quilt for massdrop and they claimed to have had it en tested …

20° EN Tested (31° Comfort, 20° limit, -12° extreme)..

http://sectionhiker.com/massdrop-20-degree-ultralight-down-quilt/

ummm … james … i believe you are working off the old standard there

regardless even under the old standard the difference was ~3-4C MEASURED between laps not 10-20C … the goal was always a 2C total difference since inception (+-1C) which us why they updated it in 2012

its not like your loft calculations (which makes assumptions on how it relates to thermal resistance) takes in to account windspeed …

;)

The point is that a test should be as close to 100% as possible. A rough calculation based on loft was just as accurate as the old standard. I fully supported the standard then and still support it now. But there is still too much “wiggle” room to make it an absolute number.  I used .01% in my calculations for a lot. Even this would leave a large error. Some stuff in biology and chemistry, especially envioronmental testing, can be parts per million. 10% is just sloppy.

recently EE made a 20F quilt for massdrop and they claimed to have had it en tested …

20° EN Tested (31° Comfort, 20° limit, -12° extreme)..

I wonder how Tim did that as EN13537 doesn’t apply to expedition and military sleeping bags, QUILTS, etc …

actually sierra designs does en-rate their quilts ….

for example …

https://sierradesigns.com/backcountry-quilt-600-2-season/

james … you can call it “sloppy” all you want … but those eurobums are putting quite a bit of effort into making it as accurate as feasible …

for example each lab needs to test 6 reference bags to calibrate their measurements and to minimize the variance between labs … and every so many years they are updating the standards

its not like folks here or anywhere else do any better, or even try

as to “loft” … ill let other BPLers look up richards old posts (or ask him) rather than rehash that … needless to say you dont see much modern literature in the testing or papers make claims on loft for accuracy since the en-ratings came out in the last decade or so, for good reason …

;)

Of course and I know some more manufacturers who claim that, but the fact remains that EN13537 was never developed for quilts.