Inflatable Pad Inside Sleeping Bag, Instead of Underneath... Is it Warmer?

[kory_tams]

I've got some theories about this, and I've slept both ways before... But here goes:

-Inside bag: inflatable pads are filled with air, and that air maintains a higher temperature being inside the sleeping bag. In theory, when it's outside the bag, it has more surface area exposed to the ambient temperature, therefore losing a little heat. BUT, I have found that with the pad inside, the rest of my bag is more tight on the sides and top, sacrificing loft.

-Underneath bag: my pad may lose heat through the thin fabric due to direct exposure to ambient temperature, but my bag is free to be as loose and lofty as needed, great for heat retention!

My question is, what do you think? Would a body stay warmer by maintaining heat in the pad itself, or by maintaining loft and sleeping on top of the pad?

For reference, I do sleep with the Klymit Static V Ultralight Insulated SL, so the insulation does hinder loss of heat to the environment. I love the pad!

Just curious to know your thoughts! Thanks guys!

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[BRWNBR]

I sleep right on my pad with my quilt, seems plenty warm to me.

 

[rklein]

The difference should be pretty marginal. You lose your body heat through conduction to the cold ground. Once you lay on your sleeping bag and compress the insulation in the bottom, it's providing extrmemely little protection from the cold. Inside or outside of the bag I can't see a material difference.

R value of your sleeping pad is the key variable.

 

[kory_tams]

The difference should be pretty marginal. You lose your body heat through conduction to the cold ground. Once you lay on your sleeping bag and compress the insulation in the bottom, it's providing extrmemely little protection from the cold. Inside or outside of the bag I can't see a material difference.

R value of your sleeping pad is the key variable.

From what I've experienced, it is a marginal difference, but I think the lowest I've tried my current bag-pad combo is around 20°

And.. the loft that I'm losing due to compression in contact with the ground is, I'll bet, doubled when my pad is inside, rather than when I'm sleeping on top and really able to fluff my bag up around me.

Something to think about I guess...

If I had a pad with and R rating of 0 or 1 I might feel a difference, but with a 4.4 of the SL, I sleep tight.

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[oldgoat]

I don't know the answer, but here's my two cents, I have slept in big Agnes with pad inside and in Kifaru Center Zip on top of same pad, was warmer in big Agnes, but it has a warmer rating. What scares me is the pad ripping out bad enough that I can't repair it and I'm sleeping on the ground without insulation with the big Agnes, where as with a regular sleeping bag, I still have insulation under me. Last couple of trips I used the mini egg crate foam pad, Sol Lite or something like that, really liked it and feel like it's more bomb proof, other than a big Agnes, I don't think I'd try to fit a pad on the inside of a bag!

 

[RustyHazen]

I shared this story on another thread a few weeks ago. I has nothing to do with warmth directly, just something to keep in mind. A friend of mine with little to no backpacking experience went on a scouting trip with me. We spent the night on a ridge that turned horribly foggy, damp, and cold. He was running a Klymit Inertia X Fame pad inside his bag. In the middle of the night, in a tent with a nice bathtub floor, he rolled over the bite valve on his water bladder, dumping 3 liters of water in his tent. Since the pad was in the bag, his bag soaked up 3 liters of water. As it turns out, it was a cold wet night, and the next day. I'm not saying this would happen to anybody, just an interesting risk.
More wear on the bag fabric would also be a concern. Lightweight fabrics these days have high tear strengths, but not much abrasion resistance.

 

[kory_tams]

Glad to hear your opinions guys! All good stuff... I think the best way to go is sleeping on top of the pad itself, and even then, I wouldn't do it without a ground cloth or tent floor under the pad!

All this makes me ready to get out!

 

[BRWNBR]

I shared this story on another thread a few weeks ago. I has nothing to do with warmth directly, just something to keep in mind. A friend of mine with little to no backpacking experience went on a scouting trip with me. We spent the night on a ridge that turned horribly foggy, damp, and cold. He was running a Klymit Inertia X Fame pad inside his bag. In the middle of the night, in a tent with a nice bathtub floor, he rolled over the bite valve on his water bladder, dumping 3 liters of water in his tent. Since the pad was in the bag, his bag soaked up 3 liters of water. As it turns out, it was a cold wet night, and the next day. I'm not saying this would happen to anybody, just an interesting risk.
More wear on the bag fabric would also be a concern. Lightweight fabrics these days have high tear strengths, but not much abrasion resistance.

Sounds like another reason to not have a water bladder inside your tent!!

 

[RockChucker30]

R value of your sleeping pad is the key variable.

^This.

Air pad with no insulation = cold either way. Air pad with ridgerest on top of it = warm either way.

 

[BRWNBR]

^This.

Air pad with no insulation = cold either way. Air pad with ridgerest on top of it = warm either way.

Agree with this! Got my new neo xtherm pad and laid on it in the house. Stuck my hand under my back and could feel the heat difference. I was impressed.

 

[Idahomnts]

In my last set up I had a klymit pad insulated ul from mass drop and a mid weight bag ,I had slept on top of that pad with said bag in the 20’s , didn’t freeze but wasn’t toasty,
Last year was in a spot with a lot of sharp objects an such so I thought I’d prevent a hole n my pad and put it in the bag , froze my sss off, I think more energy goes into heating that pad than what is gained by insulation of bag , after watching a recent review on here on sleeping pad durability test I am just goin to sleep on top the pad in my bag , I started a thread sleeping pad safety and the reviews title is in there, you’ll be amazed and confident in your pad lol

 

[juan trueno]

I won’t put the pad in my bivy because Little Rock’s and sticks makes pinholes in the goretex. I won’t put it in the sleeping bag for the same reason. Just harder on the equipment for no gain


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[juan trueno]

Sounds like another reason to not have a water bladder inside your tent!!

For me personally nowadays I only have to worry about water freezing overnight in about 1/3 of the trips I do. Going back a few years it was about 2/3s or 3/4 of the trips I did would have water freezing overnight if not in your tent and often times in the bag with you. Keeping water in a cooler can help in that weather if you have that kind of camp or between some puffy layers in the pack if you have that kind of camp. But if it’s cold cold- it has to come into the tent.




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