There is a guy on BPL who is a fabric guru, and he posted a chart showing the relative warmth of different grades of Polartec fleece versus other materials used in clothing. The "CLO" value is a standard way to measure insulation value for clothing (like R value for home insulation)
Originally Posted by ljcsov
The warmest grade of Polartec fleece, 300 weight, it is 11 oz/sq yd and has a CLO value of around 1. If you look at the lightest grade of Climashield APEX, it is 2.5 oz/sq yd and has a CLO value of 2.1.
So Climashield is twice as warm and 1/4 the weight - so ounce for ounce, Climashield is 8x warmer than the warmest grade of Polartec fleece.
Temperature ratings for different CLO values are more art than science - but here is one set of ratings, assuming you are in a well sealed bag or quilt. He only starts counting at a CLO of 2 for 40 degrees, so maybe a CLO of 1 is only good for around 50 degrees?
Of course, fleece feels great and drapes nicely, its just heavy and bulky if you need to carry it around for cold weather use.
Last edited by syc; 09-08-2011 at 12:48.
I'm guessing then for a 20 deg bag you'd have to use the Climashield 5.0. Not too sure how low that'll get you though.
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