According to conventional wisdom sewn through construction results in cold spots and therefore is less warm then baffled construction.
Thats obvious. But I had a thought that challenges this idea- that I wanted to share and hear what other have to say.
When we are comparing a sewn through bag with baffled bag what we are comparing is warmth for its maximum loft. And here we find that baffled bag is warmer.
But has anyone ever tried comparing bags of equal "effective" lofts?
Baffled or sewn through I think heat loss is proportional to effective loft. Anyone with science back background wants to support or refute this?
How do you calculate effective loft in a garment? I dont know.
But let us consider a special case in which baffles are:
> sewn through
> continuous
> are spaced 2" apart
> overstuffed 2.5X for optimal performance
> pressure give us cylindrical baffles
Spacing=πr
Effective loft=πr^2/2r
Max. loft = 2r
Then we will have max loft=1.27" and effective loft=1"
I have been able to find two credence to support my argument.
1>"Winter Backpacking Comfort: Lightweight Gear and Techniques for Shelter, Clothing, and Sleep Systems"
It said in part, …"The Rab Neutrino has overstuffed sewn-through baffles, a hood, and a full zip. Despite its sewn-through baffling, we found the Neutrino to be warmer than many other down jackets using baffled construction – a testament to the attention to detail and fit that Rab paid to the design of this jacket. For the winter alpinist, this jacket may offer the highest warmth:weight ratio of any insulating jacket available…"
2>A New Paradigm for Understanding Garment Warmth
"The Montbell Alpine jacket has 2” of loft and box baffles yet the New Balance Fugu, which uses sewn through construction, and only has 1.5” loft is 64% warmer."
