The Pied d’Elephant / Half Bag Concept
Having been an avid fan of the bivvy bag for some time now, I quite like to take a down jacket with me, in order to keep my upper half warm while sitting upright or walking around camp. A full sized sleeping bag has often felt like a waste, as my jacket keeps me well insulated from the waist up. I was interested to discover that PHD sell a “half bag” – intended to insulate the user from the waist down, saving on weight and bulk in the process.
The half bag approach originated from the weight-saving attempts of alpine big wall climbers, who took to cutting full sized bags in half to save weight. They were already carrying their down jackets for core warmth, so it didn’t make sense to bring along a full sized sleeping bag. The phrase pied d’Elephant, or “Elephant’s Foot” refers to the bag’s characteristic shape.
If you already have a down jacket which you like to bring on your camps / trips, the half bag approach may well help you save weight and pack bulk, while staying just as warm, if not warmer.
I’ve used the Hispar for the past six months on everything from summit bivvys to casual coastal camps. I’ve even used it a few times on those rare occasions where I bring a tent.
First off, some vital statistics:
- Outer fabric: water-resistant Ultrashell
- Inner fabric – Ultralight MX
- Rare 950 fillpower European Goose down
- Box wall construction to allow full loft
- Oval foot-piece for comfort
- Reflective strip for night location
- Stretch draw-cord with cord lock
- Rated to -15c
- Price £217 at time of review (2016) Now £410 (2025)
Thoughts from the trail
As someone who uses a bivvy bag almost exclusively, I’ve rather enjoyed the Hispar half bag’s lack of a zip. When it’s time to sleep, I just slip into the bag and pull the drawcord tight. There’s no problems with the bag being twisted or sitting the wrong way.
The waist-down nature of the half bag has also been much more comfortable in my bivvy bag when the morning comes. While the others attend to breakfast in their cold, clammy hard-shells after a good night’s sleep, I can comfortably sit up in my bivvy and take care of my morning meal. Then I pack everything away while the others are taking down their tents.
If it’s particularly cold and the first few miles in the morning are going to be relatively relaxed, I can keep my down jacket on for a while, retaining the heat built up during last night’s sleep. Once we’re moving for a while, I can swap it out for my hardshell.
The 950 fill power goose down makes the Hispar half bag exceptionally warm for its weight. I’ve never felt that my lower half is cold in this bag. Infact at times I have felt a little warm. In such cases, loosening the drawcord and letting some air in around the bag is enough to keep things from getting too clammy.
There is ample room in the foot box which is very comfortable and well insulated.
Little details like the reflective strip are interesting, although I’ve never found myself in a position where my bag was hard to locate.
The Hispar half bag packs down extremely small too. Its packability is an integral part of my being able to pack for a comfortable overnight bivvy with only a 32 litre pack.
The image below shows the Hispar half bag and a PHD Alpine Ultra jacket, packed down in an eVent compression dry sack:
As you can see the half bag packs down very well. Even when using a robust compression drybag the pack size and weight are minimal.
Long Term update
It’s now been a year since I first wrote this review. I continue to use the Hispar half bag for every trip. I’ve found it much more versatile than I expected. It’s extremely warm, but even in warmer weather I’ve found that leaving the drawcord completely loose, and pairing with a lighter upper body option (such as a wafer jacket and a fleece) means I can use it in weather which I would have previously considered too warm.
Even when things do get a little warm, loosening the draw cord and letting some air in works wonders. I’ve since sold my two full size sleeping bags, they weigh more and are less versatile.
Many other campers have commented to me about how they would miss the cosiness of wrapping yourself up in a big sleeping bag. This isn’t something I have missed. Putting up a down hood keeps the face warm and the jacket pockets are a fine place to keep my hands if I’m sleeping on my back, as I usually do.
Long Term Update (August 2025)
It’s now been almost 10 years since I wrote this review. I still use the Hispar and a down jacket on every trip. Even in summer, I’ll just drape them over me like a quilt, rather than bringing a dedicated summer bag.
The bag has been some utterly bitter nights on summits over the years and has never failed to keep me warm. Highly recommended!
Conclusion
The light weight, small pack size and high insulation performance of the Hispar half bag make it a winner for anyone who brings a down jacket to camp. Those who like to bivvy will enjoy the flexibility of movement and lack of messing around with snagging zips. This bag comes with my highest recommendation, with the only downside being its high price.
The Hispar half bag is available directly from PHD. Click here.
Ed – I’ve been thinking of this combination for much the same reasons as you, so it’s interesting to find someone who’s tried it.
What’s the lowest temperature you’ve experienced, and how did it work out? Jacket’s aren’t really rated for sleeping in so it’s difficult to judge how cold this setup could comfortably go…
It’s an expensive experiment if it turns out not to to work!
Hi Geoff,
The coldest I’ve used it in so far was around -5, where it was comfortable. I wouldn’t say however that PHD’s “operating temperature” for the jacket of -10 degrees is one that your average man could sleep toasty.
My advice would be to overshoot a little, you can always unzip the jacket if you’re feeling warm.
Ed
Thanks Ed.
I’d like to be toasty at -5c and bearable at -10. So I think that if I go for this system I’d get the PHD Yukon jacket rather than the Alpine and keep a little bit more in hand, as you suggest. Hopefully a medium base-layer and a light fleece + balaclava/socks/mitts would take up any slack on the worst nights.
PHD don’t claim that those jacket operating temperatures are for sleeping – they’re for active use during the day. The site’s got an interesting new section on bag+clothing sleep systems, but it’s still incomplete. They’ve been doing some research in cold-chambers and in the field. Worth keeping an eye on.
I’m tempted to try this. I’ve never slept well with my arms trapped inside a bag, and mostly have the opening under my armpits anyway. When I’m forced inside the bag by cold, hoods always seem to end up over my face. So for “active” side-sleepers like me, wearing your upper-body insulation makes a good deal of sense, even if it’s a bit less efficient thermally.
And as you say, the lower efficiency is compensated by the additional uses of the jacket in and around camp. Even in bed it’s much better for reading, brew-ups etc, not to mention 2am bladder-related activity…
The alternative would be a US-style quilt. They are boxed at the bottom, giving the same effect as the half-bag. But the top is problematic in the cold, requiring all kinds of faffing with straps and clips to keep out the draught.
You’ve reminded me of an old story. The only night I ever forgot my bag turned out to be a near 20-degree frost. Luckily we had a couple of heavy-duty down jackets with us. With one on top and one on the bottom, I actually slept through the night…
Yeah, I don’t blame PHD for not providing sleep ratings for jackets – lets hope this evolves with time. I wasn’t able to find the section you mentioned (I looked under technical briefings) could you link me to it?
As regards the Yukon you’re in luck, a slightly modified version of it is in the PHD spring sale at this very moment: PHD Spring Sale
The only other option I’d suggest is pairing up an Alpine Ultra with a wafer vest to wear under it during colder nights, but you still won’t have hand pockets in the Alpine – and that’s been an irritation for me.
I sleep on my back and the pockets are a natural place to keep your hands during sleep, rather than inside the half bag.
A balaclava is something of a fixture for me when bivvying, allows me to sleep with the head out and enjoy the stars as I fall asleep. I just use a cheap thinsulate one, works well.
I’d say you’d be very pleased with the Yukon + Hispar half bag approach. Do keep me posted on how you get on, this wee experiment of ours isn’t one that many people bother with, so it’s great to hear some thoughts on it.
Just spotted a comment in one of the PHD videos where they estimate that the sleeping comfort of a jacket is around 7-10 degrees less than the working temperature, which sounds about right. So that would make the nighttime comfort limit of the Yukon somewhere in the -5 to -8 range.
https://www.youtube.com/watch?v=fCllvk6SseU
The problem with the Alpine jacket is that it’s been designed for technical use with a harness, so no handwarmer pockets. I agree that hand pockets are very nice to have around camp and at night – another argument for the Yukon.
It’s tempting to go with the warmth and simplicity of a vest, but a full zip offers the option of opening up the jacket on a warm night and using it as a mini-quilt, which I think would add some value. Just experimented with this and it seems to work OK.
Like you, I’m a fan of sleeping in a balaclava when it’s cold – I’ve been doing this for nearly half a century! I’m also one of the last people I know to take a scarf into the hills – something very comforting about a warm neck and it would help seal the air inside the jacket.
My problem is that I’m planning some long alpine walks where nighttime temperatures will vary from -5 or even lower on high bivvies to +25 for lower camps. I like to sleep warm, but the zipless Hispar bag may be too much for the valley. One of their lighter half-bags with some down trousers might give me more flexibility. PHD seem to have a lot of experience with this kind of issue so I’ll be asking their advice.
[…] have been using a PHD Hispar Half Bag (review here) in concert with a wafer vest or Yukon jacket (conditions depending) for some time now. I have […]
[…] of using a full sized sleeping bag, I use a PHD Hispar half bag, which comes up to roughly the waist. I pair this with a down jacket to insulate the upper […]