Down down deeper and down

[downsouth]

Go for any one of the Canada Goose collection

Expedition Parka is the outstanding

[doodab]

Handy, as -20 C was the temperature forecast for Scotland overnight.

It's curious that clothes designed to keep one warm offer no quantitative measure for the shopper to use other than what a salesman says, and £200 is a heck of a lot of money to spend on heresy. What and where are the losses in good quality clothing? Convectional losses are presumably related to how closely the clothes fit (a body suit being best?) and independent of the material used. Radiative losses, no idea. And thermal resistance dependent on the material and its thickness, which is never specified as e.g. a Tog or "U" rating.

I wonder where the heat goes? The aim being to retain about 150 Watts at -20 C in a moderate breeze.

The trouble is, a bit like broadband speeds, there is no single number you can stick on a coat to tell someone how warm it is without someone else complaining that it's bulltulip.

The main factor seems to be trapping air and keeping it trapped. Fit, as you say, is important to avoid draughts and also to avoid pumping air in and out when you move around, and windproofness is important as otherwise the warm trapped air just gets blown away.

In SI units the standard unit of thermal resistance is the reciprocal of watts transferred per square meter per kelvin of temperature gradient, so K.M^2/W, and 1 tog is 0.1 of those.

I managed to find ratings for a few materials:

1.1" of 550 fill power goose down (this is bog standard down) = 0.67, or 6.7 Togs
Primaloft One = about the same as 550 fill power down
AVANSA Thermolite 150g/m2 = 0.46, or 4.6 Togs
Thinsulate 150g/m2 = 0.3, or 3 Togs

Synthetic materials have their advantages, especially in the UK where it rains a lot, but high fill power down seems to be the best insulator you'll find in clothing.

It's not obvious how much warmer it is than lower fill power down but the coat I just bought is about the same thickness as my old (550 fill power) one, quite a bit lighter, and a bit too warm above -5 or so, although less sweaty. It was about -3 on the way to work this morning and I was the warm side of perfect, I actually had to let heat out when I was walking. I can recall a few times where I've had the old one on and it's been -15 or so and windy and although I wasn't exactly shivering I was starting to feel the cold after a while. I'm pretty confident the new one will keep me warm on those sorts of days.

My "autumn" coat has thermolite 150g/m2 in the body with 100g/m2 in the arms and it's warm enough for the journey into work when it's freezing or just above, in fact it's probably good down to about -5 with a fleece under it.

Of course it depends how much you feel the cold as well. Some people are just warmer than others.

[Paddy]

Know what you mean

I am considering these - but they're made from wabbit - I'll ask AtW to comment if squirrel is better

Bought mine in Russia and then bought a load more for friends after they saw it. The fur ones are best rabbit being the cheapest.

They are VERY warm especially with the flaps down and tied. I also bought a full length sheepskin coat that is too hot to use above -5c.

[Pondlife]

I went for the of these ones

The chap in the shop reckons it should keep me warm down to -20

Oh My God! They Killed Kenny!

[TimberWolf]

Bought mine in Russia and then bought a load more for friends after they saw it. The fur ones are best rabbit being the cheapest.

They are VERY warm especially with the flaps down and tied. I also bought a full length sheepskin coat that is too hot to use above -5c.

Looks cosy, but you have to be under or over a certain age (4 and 50 respectively) to be able to wear them in the UK though? I see those things in the clothes shops, with groups of people trying them on and looking at themselves in the mirror and laughing, taking photos etc, and then putting them back.

[Paddy]

Looks cosy, but you have to be under or over a certain age (4 and 50 respectively) to be able to wear them in the UK though? I see those things in the clothes shops, with groups of people trying them on and looking at themselves in the mirror and laughing, taking photos etc, and then putting them back.

[doodab]

Well I just went out into the minus fiveness and it was lovely, except my fingers hurt because I forgot to take my gloves.

Perhaps now I'm suitably attired I can make some of those early morning frozen world photos I keep meaning to do.