Down filler bags – full body, or half-body pied d’éléphant?

I was in my quilt.  It was 34F.  I slept on my side. I was wearing a shirt and insulated vest.

On the side facing up, the quilt was against my side.  I measured the temperature at the surface of my insulated vest.  It was 70F.

On my front, which was facing sideways, there was an air gap of several inches.  I measured the temperature at the outside surface of my insulated vest.  It was 68 F.

If my entire body surface area was facing an air gap like that, I would be 2F colder.  If I could put the quilt against me all around, I would be able to sleep in 2F colder temperature.

Since that air gap is over only about 1/3 of my surface area, putting the quilt against me would allow me to sleep in 2/3 degree F.

I don’t think this is a significant factor.

Of course, if you filled the gap with insulation that would add warmth, but it would also weigh more.

Good lord. Quilts introduce problems with leakage of cold/warm air. New quilt designs attempt to solve this issue with various straps followed by other elaborate systems. Meanwhile the weight of quilts keep climbing, if they’re to be effective. Finally, the good ol’ mummy bag with high power down ends up being the lightest alternative. but, wasn’t this intuitively obvious from the beginning?

Some here have issues with sleeping in a bag rather than a blanket/quilt. as with all life skills, there’s a learning curve required. And with all of life, there are compromises that must be accepted. There are no perfect solutions. I tend to hike at altitude. Even in the Sierra in summer, temps most often drop to near or well below freezing overnight. I like to sleep warm. A quilt, with drafts? No thanks!

I’ve mastered the art of turning over inside my bag without bringing the bag itself up over myself. think of a chicken inside of a rotisserie oven. that’s me, the chicken turning over in the oven. If things turn truly nasty and cold, I put on any number of garments.

Mummy bag: simple, no straps, no systems, no filler bags, etc.

My quilt is really a sleeping bag with no insulation on the bottom where the pad goes.  There are no gaps for air to leak through.

But it does have that space where the quilt is pulled away from my body.

Definitely a mummy bag is a good solution

I’ve never used a quilt. So as is often the case, I speak with authority about something I’ve never tried. so, take that into consideration. I might some day try a quilt and become a convert. Not likely, but who knows?

Or you were losing more body heat through the top of your vest where it was compressed?

I can use my 20* quilt in 50* weather while staying covered. While you can unzip to vent a mummy bag, you’ll struggle to keep covered and it’s inefficient.

My vest may have been compressed a little

A mummy bag may have the same problem if it’s bigger than you, a space on both sides where the bag drapes down

But, mummy bags are tried and true, good solution

If R2 = R1, then T2 would be 50*