Quilts and Drafts: Are Quilts Warmer than a Mummy Bag? Infrared testing.

[Erik Norseman]

Hi folks,

I came across this video where a Youtuber (Adventures In Reach or “AIR”) used an infrared camera to try and see what caused more heat loss: drafts from rolling in a quilt vs. rolling a mummy bag and exposing compressed down along your back to cold air. Watch it here.

There are a few problems with the methodology, which are pointed out in the comments. For one, he does not allow the down in the mummy bag to loft back up and also I’m not sure if infrared radiation is even an accurate measure of heat loss/perceived warmth (e.g. quilt drafts would have convective heat transfer, also, I imagine, as you warm up the cold air that entered). I’m sure there’s more problems. To be honest, this is beyond my understanding of the physics of heat loss but I thought it was interesting and wondered what people think. I’ve enjoyed BPL’s various infrared tests (e.g. synthetic insulation degradation) and thought this would add in to that.

Moreover, on the quilt topic, the same youtuber has another video on how to attach strap to minimize drafts. Watch it here. I figure it is worth pairing this discussion of “are quilts warmer than comparable mummy bags” with a discussion of how to minimize quilt drafts, as the whole thing falls apart if you are getting constant and/or significant drafts (also proper head insulation is key in a quilt, of course).

In the real world I usually find mummy bags warmer, but would love to hear from more experienced folks as I know I am not an expert on draft free quilt sleeping.

[David D]

I use synth because of allergies.  Sleeping at 20F in a synth mummy bag, I freeze my back off when rolling on my side.  Constantly waking up.  No way around it unless I get a much bigger and heavier bag.  I much prefer my EE apex wide quilt at those temps.  I use the straps, do up the foot box and tuck it in under my torso.

His test method doesn’t need to wait for the under insulation to uncompress in the bag.  That doesn’t happen in real life

The other problem with a bag is its almost impossible to roll on the side and have the hood come with you without exposing your back to the meagre under insulation.  You can roll in the hood but then your breath migrates into the bag.  To get around this you can use a much bigger bag.  I have the Sea to Summit bag meant for side sleeping but its big cut meant the weight was too heavy unless using the milder temp rated bag, and then I just use a quilt anyway.

These are non issues for back sleepers but deal breakers for me, a side sleeper

[George H]

The dual pad attach straps the AIR guy ultimately applies around 5:20 are similar to Katabatic. However, last I checked, Katabatic’s patent for including TWO of these has not expired yet, thus Nunatak, EE and others are limited to include only one in the box, plus a simple body only strap. Users are free to purchase another after the fact, like the Air guy did, lol.

I got my first quilt in about 2004 and used mummy bags since way before then.

Experience background: I still go out for many trips every year in all conditions, from skiing with a pulk to long adventures in the Utah desert. In the past I’ve climbed Himalayan peaks, had bivys on north faces in the Alps in winter, and spent weeks in snow caves in Norway. Last weekend I welcomed the first real snow in Colorado from a high camp in the Sawatch with my dog

Based on this I found that even the most thought out quilt designs are fine when it’s above thirty, and tolerable to 25 or so.

Below that the drafts, even with Katabatic style straps and Nunatak ETC, become an issue, and I switch to a hoodless and zipper less bag until real winter hits. At that point, infra red censoring and all, a true hooded mummy is obv unbeatable.

[David D]

George, do you side or back sleep?

[George H]

90% side

[David D]

How do you avoid a cold back when on your side?  Oversized bag and take the weight penalty?

[JG H]

“ How do you avoid a cold back when on your side?  Oversized bag and take the weight penalty?”

I’m curious to know this, too.

I’m a rotisserie side-sleeper, married to my Katabatic quilts, and I don’t have issues with drafts and heat loss. That said, I don’t really camp in temps much below 20°, either. I also don’t use any pad straps or attachment systems designed by any quilt makers. I snap my wide-width quilt directly to the top of my pad and voila… no issues.

[jscott]

I wonder what folks are wearing beneath their quilts, or within their bags? And are folks sleeping in single wall tents that are more open to breezes,  or double wall tents?

I’m a bag guy for sure. And I roll around a fair bit, side to side. I’ve never had issues with cold coming in from the back. But if it’s cold, I wear more layers in my bag. Are you a naked sleeper or a well wrapped burrito? oooh la la! It makes a difference in your reporting.

[JG H]

For me, less is more in my bag. I prefer to sleep in a t-shirt and briefs, but I’ll layer up when necessary.

As for my tent, I’m either in a Duplex or XMid Pro 2+, so no double-walled delight for me. I’d love for someone to make a Copper Spur 2+ in DCF. Sign me up for that dream!

[David D]

At those temps, octa top, lifa bottom, socks

I like these because they work sleeping, in camp, and when hiking if it gets really cold.

Don’t like taking single use stuff

If it gets really cold, will throw on the fleece and hiking pants

If it gets even colder, the wind shirt

[Jerry Adams]

I watched that video. Very good.  Helps figure out what’s happening.

The biggest heat loss I could see was through the head.  So, you need a better hat/hood.  Like, with synthetic or down.  I haven’t really found a good solution, I wonder what other people do.

It’s really hard to estimate total heat loss over time.  You’d have to take video, then integrate heat loss and area over time.  I’m skeptical of his conclusion that a quilt is warmer.

He showed pictures of the sleeping bag.  If the person rolls over and carries the sleeping bag with them, then the lower edge will glow in IR – so it’s losing a lot of heat – it’s colder.  But if a person rolls over in the sleeping bag and doesn’t carry the sleeping bag this won’t happen.  If it does, then the lower edge will gradually quit glowing in IR and losing heat.  You have to integrate over time.  I don’t think it’s clear one way or the other which is warmer – quilt or sleeping bag.

The video does tell us to carefully manage the lower edge.  In a quilt, you need something like a strap.  In a sleeping bag don’t carry the sleeping bag with you when you roll over.

[Dan]

I prefer a quilt for comfort reasons if the temperature isn’t too far below freezing, but my experience tells me that a mummy bag is warmer in practice regardless of a few IR videos.

[David D]

It depends on the bag.

I need synth so had to go with a minimalist bag to keep weight and bulk down.  Rolling over in the bag causes the edges to lift exposing the underneath and makes my back cold.  Unavoidable unless adding a lot more weight and bulk using a bag with a more generous cut.  For this use case, quilt wins hands down.

If using a generous cut (weight penalty!) down bag so the edges don’t lift to expose the bottom when on your side, then that’s a start.  Like George says, use a hoodless bag to avoid dead weight.

Regarding that videos head heat signature for the quilt, that little beanie doesn’t cut it.  Here’s what I wear.  It’s a layering system good for 60F down to 20F.

– Decathlon Fleece balaclava $8Can, 1.7oz.  I love this thing.  It’s not itchy, covers much of the face, doesn’t load up on moisture under the nose and has a clever little breath panel

– Mountain Hardwear Polartec fleece beanie, 0.8oz. Much warmer than the oft recommended smart wool merino 150 beanie and with a weight penalty of only 0.2 oz.  Also great when static in camp and it breathes very well so I also use it hiking if its really cold out

– Buff rolled into 3 layers and wrapped around my face to cover my eyes and nose. At even warmer temps, its my do-rag hat to sleep in

Below 20F there are some pretty serious balaclavas that probably make more sense like the MLD Apex, tactical balaclavas or some serious silence of the lambs inspired designs for -20

 

[jscott]

Jerry makes important points. Regarding heat loss through the head: I wear a full on over the ears soft cap that cinches under the chin. Oh and I find a hooded sleeping bag is worth the weight penalty.

I’m pretty sure I roll inside of my bag, and not with the bag,  when I switch sides while sleeping.

[Dan]

Fleece cap and a buff for me. Gives me a lot of flexibility.

[stenslat .]

I’m also a rotisserie sleeper … R side, back, L side, back, R side, and so on all night.  I’ve been using quilts in recent years, but definitely get a little cold air every time I rotate.  This year I switched to Zen Bivy and absolutely love it.

 

[JG H]

“Fleece cap and a buff for me. Gives me a lot of flexibility.”

This… for the win.

[Paul McLaughlin]

Regarding the original question of quilt versus bag; if, rather than rolling the bag with you, you roll inside the bag just as you roll inside the quilt, then the answer is going to be bag is warmer than quilt if all other things are equal; but of course all other things are not equal which is why is is mostly a hyoh kinda thing. Personally I am a side sleeper who cannot stay on one side for along time so I go from one side to the other, which means that if it is a mummy bag I either roll it with me, or end up breathing into the side of the hood. So, I now like quilts – but with a caveat or maybe you’d call it a trick – I added a piece of fabric and light zipper such that when zipped I have a bag with an uninsulated area on the bottom (reducing drafts). Kinda nice compromise. As for the head coverage thing – I made a climashield balaclava. The difference between that thing and a combination of base layer hood, AD 60 hood, light fleece beanie, and buff (which is pretty warm all together) is huge. It is not just the big difference in loft between the climashield balaclava and the combination of hats and stuff, but also the complete neck coverage at that higher loft. I am now a firm believer that if you are using a quilt, or a hoodless bag, some kind of puffy balaclava, whether down or synthetic, is a must in order to get the most out of the quilt/bag.

[Jerry Adams]

I wear a fleece cap, but when it gets down to 20F it’s not enough so I use something I made with 2.5 oz apex, but I’m not really satisfied, still working on it.

[Erik Norseman]

Hey Paul,

So you converted your quilt into a modular false bottom bag? What quilt? MYOG or purchased? Got pics?

Anyone got a link to a thread on making a fancy puffy balaclava hood? I see the EE torrid one and it is pretty cheap, but would be fun to try and make one!

Also, why not just wear your puffy to bed and wear the hood? Or do you have a hoodless jacket usually?

[Terran Terran]

I applied for a chance to test a Zenbivy next weekend. A local influencer is setting up 6 people with a quilt and a layered closed cell pad, gradually removing the layers until it gets cold. Testing comfort ratings vs. the actual ratings. I didn’t ask about clothing. Up in Denver. I offered to do it here. Usually colder then Denver. Should be around 25*F here. They seemed interested, so I’ll see. If it meets their needs. It should be interesting either way. If they do, I get a free bed.

[Erik Norseman]

Terran,

Zenbivy looks neat. I haven’t really taken the time to fully understand and evaluate their product lines though. But there is some hype. What is the appeal and the strengths/limitations of their designs?

[Paul McLaughlin]

Erik – quilt is a Nunatak. I do not have photos of it. The piece of fabric is not very big. Pointy at both endsand only about 9 or 10 inches at the widest point. When zipped it gives me the same interior dimensions as my old Marmot Hydrogen had, which I found comfortable. My light down jacket is hoodless, I made the choice to go with a separate hood because I thought I would want the hood for sleeping at times when I would not want to sleep in the jacket. I expect my hood (2 layers 2.5 clima) is warmer than the jacket hood would have been.

[Terran Terran]

Erik,

You probably know as much as I do. Its a bit heavier due to the design. A wrap around footbox. Apparently leaving a small gap at the end. I think they may have addressed the issue though. High quality material. I imagine the actual build would follow suit. I’m mostly interested in the sheet with the hood. I never liked the hoods on the mummy bags. Then the fastening system looks interesting. Looks like it would work as hyped.

The weight doesn’t bother me so much. At my age, I’m doing more truck camping than hiking. Their sales price was decent last time. Black Friday sale coming up if you sign up with your email. I think Nanatuk is up in Leadville. Katabatic is in Salida. I’d like to look at them before I buy anything. But if I can get a free one. I’ve had a little correspondence with them. I’m not really counting on it though.

[Terran Terran]

I get my ZenBivy next week. Then I can say more. I asked permission to post information about the test. The influencer is Steven Smith from My Life Outdoors. YouTube. Six participants wearing the same brand of thermals. Just an off brand from Amazon. Trying to follow ASTM standards. As I said, they’ll use a layered pad, then gradually remove the layers until I get cold. It should be interesting.

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