I remember my Dad telling me that 2 inches of newspaper is as warm as 2 inches of feathers. I’m not sure if that is actually true or not, my Dad had a lot of this kind of knowledge stored in his brain, but I’ve learned some things about down ( as in duvets) that follow along with this theory.
The warmth of a duvet is dependent on the amount of warm air trapped in the fibers of filling. The quality of down is measured by fill power and good down duvets will have this figure listed on the label or packaging. Fill power refers to the number of cubic inches that one ounce of compressed down will ‘fill’ when uncompressed. If the number is 500-550, it is considered good with higher numbers 550-700 being the best. So, a high fill power rated down will give a higher loft and trap more air, thus being warmer than a lower fill power down. This is also the fluffiness factor. The same thickness can be achieved by adding more down of lesser fill factor, but this increases the weight of the duvet. Duvets are also rated by weight, a king size bed duvet would be 50 ounces for the warmest, 35-40 ounces for the medium and 30 for the light.
Down is not feathers. Down is what grows on the bird at the base of the feathers. Feathers are not interchangeable with down and a feather pillow, or comforter is decidedly different than a down one. Most down found in ready made duvets is harvested from young birds that have been raised for consumption. Eiderdown is considered the ‘gold standard’ and is harvested by hand from the abandoned nests of the Eider duck, in Europe, and the cost of an Eider down duvet can approach $12,000.00.
Down is warmer than synthetic insulation ounce for ounce, it retains its shape and loft and will wick body moisture away but down looses it’s warmth when wet and is difficult to dry. It is highly compressible and lightweight but requires special cleaning and may contain allergens. It certainly wins in the fluffiness category but needs to be shaken and fluffed daily to keep this look.
I understand that in some European countries employees are allowed a certain number of days off work per year (just ‘cause) and they are often referred to as ‘Duvet Days’; days to just stay home and snuggle under the down duvet. What a good idea.