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  1. #21
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    And... to make matters worse the R value of a bag would change depending on how damp it was, or wet it was, the ambient humdity, because its absorbent, and prone to be used in a lots of different ways.

    Same with lofting time, was it measured after being compressed for a week and allowed to loft for an hour, or allowed to loft for a week?

    The variability would be phenomenal. Just as it is with "warmth" rating on bags now.
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  2. #22
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    It would only make sense that the rating would be based on its performance in the standard test, not under all conditions. Again like the building industry, the R-Value is based on its tested performance, not what it would be when over-stuffed into a wall or wet in an attic under a leaky roof or after a baseball has been thrown through it.

    When a bag/quilt is used in the wild under varying conditions, many adjustments to the hang, tarp, clothes, etc. would need to be made. Those adjustments are at the discretion and experience of the user. But, the base insulating ability of the bag/quilt under the original test conditions haven't changed.
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  3. #23
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    Quote Originally Posted by xutopia View Post
    I see floor mats rated with R value and I can't understand why it isn't the same for sleeping bags and quilts.

    Anyone know why they don't use the same rating for everything that keeps you warm?
    Google is your friend...

    R values are used for building materials. Clo values are used for clothing. Why don't they use the same units? Probably because they wanted a clothing unit that was normalized against a reasonably well understood amount of clothing - 1 clo is the amount of insulation in a 3 piece business suit.

    There is a pretty straightforward conversion ( 1 R-value = 1.137 Clo value)

    The North Face has a blurb about CLO values and sleeping bags and the problems with giving out the number without any context.

  4. #24
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    Quote Originally Posted by Alamosa View Post
    It would only make sense that the rating would be based on its performance in the standard test, not under all conditions. Again like the building industry, the R-Value is based on its tested performance, not what it would be when over-stuffed into a wall or wet in an attic under a leaky roof or after a baseball has been thrown through it.

    When a bag/quilt is used in the wild under varying conditions, many adjustments to the hang, tarp, clothes, etc. would need to be made. Those adjustments are at the discretion and experience of the user. But, the base insulating ability of the bag/quilt under the original test conditions haven't changed.
    Understandably, however, most insulation (in a building) leads a pretty static conditioned life, unless there is some failure in the structure.

    However the same can't be said of a sleeping bag. Even if everything is perfect, every night you sleep in it you add water, even if its not raining and you aren't sweating...

    So it really would be an academic means of comparison although it woudl provide a standardized basis for comparison. But that would be less popular with the sales folks.
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  5. #25
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    Quote Originally Posted by Rapt View Post
    ...
    So it really would be an academic means of comparison although it woudl provide a standardized basis for comparison. But that would be less popular with the sales folks.
    I think that is really the driving factor. I can imagine the conversation going something like...

    Sales Manager: All the other bags that sell for x dollars are rated at 0 degrees.
    Product Manager: I don't camp and I live in Cancun, but I think someone could sleep in this bag at 0 degrees, maybe more. They should be plenty warm.
    Sales Manager: Agreed, we will call it a -10* bag and raise the price 20%.

    How could you do that if there were standards?
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