The Tog is a measure of thermal resistance developed in Britain by the Shirley Institute. It indicates how well clothing or bedding insulates (in the dry). FurTech garments provide about 2.5Tog (0.25K.m^2/W or 1.6Clo).
A Clo is the amount of insulation required to keep a resting person comfortable in a windless room at 21.1'C... a typical home or office environment.
Lab measurements conducted at the University of Manchester show GoreTex has no significant insulating ability and this is likely to be the same for most membrane hardshells. The warmth you get from such jackets is because windproof shells improve the insulating properties of under layers, even in still conditions, by reducing convection.
Table 4.12 Thermal Resistance of Fabrics
AB 1 |
AB2 |
Mean AB |
C1 |
C2 |
Mean C | |
Thermal Resistance of the test specimen (m².K/W) |
0.23463203 |
0.25313283 |
0.24388243 |
-0.015873 |
-0.015873 |
-0.015873 |
(AB is FurTech and C is GoreTex - the slightly negative numbers indicate the error range at near zero measurements.)
FurTech offers an excellent warmth to weight ratio when compared to conventional hardshell layering systems!
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