Sample Inquiry for Down Insulation Manufacturers

The down gear industry has not done a very good job of providing its consumers with valuable information regarding warmth comparisons. Sometimes it seems to me as if the industry has completely forgotten all of humanity’s previous efforts to quantify insulation, and started from scratch, as if we’ve never done it before. Wild and bizarre, trial and error flailing that I think are eventually headed towards reinventing the wheel. Total fill weight is a shot in the dark since the total volume the fill is spread through is unknown and confirmed to have huge variability. Target loft is a vague term that has been confirmed to mean entirely different things to different manufacturers. Some of the ideas about what it is measuring refer to things that aren’t even all that relevant and if everyone is referring to different things, then it doesn’t have much value for comparison. Measured loft is rarely provided and, while of some value, isn’t very accurate on its own. More or less down can be stuffed into a set volume and the amount of insulation will increase or decrease, without changing measured loft much, or at all.

To make matters worse, every single builder or manufacturer that builds with down, has much more valuable information in their hands. They just don’t provide it, and with good reason. The consumer base typically lacks the education to understand any of this, so nobody is apt to change anything. My hope is that consumers will become more educated and push manufacturers to provide something more indicative. We all have it. Nobody asks for it. In an effort towards that goal, I am putting together a sample questionnaire that consumers can use to obtain functional information from a manufacturer.

 

For box chamber:

For your (temp rating here) degree system, how tall is the measured baffle height, not including seam allowance?

For your (temp rating here) degree system, how wide is the chamber?

If your baffle is (fill in here) tall, your chamber is (fill in here) wide, and your chamber is 20″ long, what is the formula for filling?

 

For sewn through:

How wide are the sewn through chambers?

If your chamber is (fill in here) wide and 20″ long, what is the formula for filling?

 

The answers to these questions will provide you with a very clear picture of the amount of insulation any given section of this item has. There will likely be some deciphering of the info, but this will provide you with enough info to know almost everything about it. Using these answers, I could easily and accurately compare the R-value of two completely different items, with no blind spots or variables to isolated R-value. There would be variables in the design of the item this R-value is in, but this would be a stable foundation from which to assess those. For instance, you might get a clear picture of equal R-value but then see that one item is a quilt with a pad strap system and one is an enclosed bag. It would be safe to say that the quilt with straps is going to suffer from draft issues and will be less warm than the bag, even with equal isolated R-value.

 

How do we decipher the info they provided?

For box chamber:

The first two questions are establishing the chamber volume. The baffle is height, the chamber width is the width, we added in a length of 20″ just as an arbitrary something to fill in. The last question will establish the fill volume. So if the baffle is 2″ tall, the chamber is 6″ wide, the chamber is 20″ long, we have 2 x 6 x 20 = 240 cubic inches chamber volume. For fill volume, they may simply use this formula 4″ (calculated loft) x 6″ x 20″ = 480ci fill volume. You can take that to another item and see which one has more / less fill. You can see from this that there is 100% overstuff, since the baffle height to calculated loft is doubled. You know that a system the has the same amount of down, but has a taller baffle is going to be lower overstuff density and potentially less control. You could also see that one system that has the same amount of fill, the same baffle height, but wider chamber spacing might achieve higher mid chamber measured loft. This means it might be a bit warmer but have a little less control.

There are multiple ways that manufacturers work this formula, and they may look different, but they are all getting to the same place with all the same info. It might look like this….chamber volume is 2 x 6 x 20 = 240ci. Their filling formula may be 2 x 6 x 20 = 240ci / 900 fill power = .27 ounces to get a base fill amount, which they then multiply by an overstuff amount of 100%. So .27oz x 2 = .54oz fill amount. If you’re given the formula in this format, to find calculated loft, you would simply multiply the baffle height by the overstuff amount. 2 x 2 = 4 calculated loft.

 

For sewn through:

Sewn through chambers have no volume to begin with. There is only a fill volume that goes in and creates a 3 dimensional space. The width of the spacing determines the amount of density and control the fill has, but with the drawback of creating cold spots. They might answer the first question with 3″ chamber spacing. Then the second question will be pretty simple. For fill volume they would take 3″ wide x 20″ long x 1.5″ tall (calculated loft) = 90ci. With sewn through, from here, there are really only two things you’re assessing. The fill amount, obviously, but the chamber spacing determines the amount of cold spots and the amount that the fill is allowed to loft up between lines. So, an item with 1.5 calculated loft and 90ci fill quantity in 3″ spacing will be considerably less warm than one with 1.5cl and 90ci in 6″ wide chambers. There is a ceiling on this though because at some point the level of density and control falls to a point where major shifting can occur, which opens up gaps in the chambers. A low density filling all the space is still very warm, but once you have actual gaps opening up, you start to lose a lot more through convection than you gain from loft.

 

Yes, there is a lot to consider, but it’s better to have a stable and accurate foundation to consider things from, then to have inaccurate and unreliable metrics, just because they seem easy. Well, they seem easy because they aren’t considering any of the important factors. There is potential in the future for the model here to become pretty easy. It is all getting the the route of a single number that tells you the quantity of down in any given portion. That number is calculated loft. It’s a number that really means something and tells you something solid.