The Physics of Insulation in Sleeping Bags

2 thoughts on “The Physics of Insulation in Sleeping Bags”

  1. Excellent points. I was wondering about the physics of a quilt vs. a sleeping bag. You’re point about flattening insulation would suggest that a quilt is more efficient. Is that correct? Or is this just for “extreme” (4 season) weather bags?

    1. G’Day, Josiah

      A quilt has an advantage over certain sleeping bags in the following respects:

      – There is no insulation under the sleeper, and thus there is no insulation which might be flattened by the sleeper’s weight
      – A quilt cannot fit tightly around a sleeper, and thus there will not be points around the sleeper’s shoulders, hips and knees where the insulation might be flattened (which is the case with certain narrow sleeping bags)

      However:

      – The issues of down quality and baffle construction mentioned in the blog post still hold true. The down can shift inside the chambers of a quilt away from the sleeper if those chambers are not well designed and filled with quality down (in fact, the down shift effect may be greater in a quilt because of its much broader cut and thus larger chambers).

      Additionally:

      – A quilt will not have a hood to retain warmth from the sleeper’s head.
      – A quilt may be subject to cold air leaking in under its perimeter as the sleeper moves.

      Given all of the above, we would stop short of using a term such as ‘more thermally efficient’ to describe a quilt compared to a sleeping bag. As with all designs, quilts have advantages (most particularly weight and compressed volume) and disadvantages (the possibility for down shift, the lack of a hood, and the potential for drafts).

      Cheers

      B

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