It is established practice to express the thermal efficiency of sleeping bag materials as a warmth-to-weight ratio by dividing the insulating value of the material (in Togs), by the weight of a typical sleeping bag made from the material (in kilograms). The table shows typical values for synthetic and down sleeping bags (as ascertained by Leeds University), and for a Reflexcell™ sleeping bag.
Using a tog rating of 8 Togs and a weight of 330 grams for the Reflexcell™ bag gives a value of 24 Togs/kg. This is well over twice the value for goose down, which was previously regarded as having the highest possible warmth-to-weight ratio among usable insulating materials. It is worth noting that the warmth-to-weight ratio of goose down is drastically reduced by the presence of moisture, whereas that of Reflexcell™ is hardly affected.
Blizzard Protection Systems Ltd.
Unit 2, Coed y Parc Industrial Estate
LL57 4YY, UK
Tel: +44 (0) 1248 600666
Fax: +44 (0) 1248 600444