Disclaimer: This is _not_ advertisment or product placement. Any product shown here I have bought on my own, and in this test you only get to read my opinion about it.
After many nights in the ultralight Helium Bivvy by Outdoor Research in weather conditions ranging from permament rain, thunderstorms, extreme dryness and heat, and snow, I feel able to give my two cents about the goodness of this bivvy and the things on the bad side.
++ Weight
This thing is all what ultralight is about. The Helium Bivvy comes at about 467g which easily beats many competitors in the ultralight scene. It also packs very small and finds place in any backpack.
++ Weather protection
The material it is made of almost guarantees one thing: it keeps you dry. I have tested this in thunderstorms accompanied by heavy rain all day, and long term exposition due to slowly melting slow. What's inside of the bivvy is protected from outside weather conditions.
++ Quality
I found the material to be very sturdy even when extremely lightweight. Also all zippers are of quality, always easily useable and easy to find even in low light conditions. The moscito netting is very tight, and of high quality. The flooring material is even tougher, so you not necessarily need an external floor mat when you sleeping on a grass ground.
+ Condensation buildup
First and foremost: you get condensation in every bivvy, that is due to the single wall setup. The question is how much condensation buildup you get in which condition and with which wall material the vendor used. It's no difference with the Helium Bivvy, you get condensation, but it is not that much as one would expect. In general, the breathing material of the Helium Bivvy is not as good as GoreTex, but if the temperature difference between out- and inside is at some scale, breathing works just fine. There were times in the Summer and Spring where this setup works out nicely and I had just no condensation at all. Of course, having snow on the bivvy kills any breathability regardless of the material, but that is a problem any bivvy would have. For a bivvy, I can say overall, the Helium Bivvy performs very good with (partly-) solving this common problem.
+ Enough space
The Helium Bivvy has enough space for myself and a 8kg backpack to sleep comfortably in.
- Construction deficits
Allright, the Helium Bivvy has a huge moscito netting in the head part. This could be just great. Welcome nights staring at the stars when you know the weather will be just fine. But don't forget to wear something like a hat or anything that keeps the netting away from your head. I absolutely do not understand as to why the netting was designed to hang in your head. For the price of the bivvy, I would have expected that this would have been taken care for in the design. This is a major painpoint for me, especially when I think about the experience in this bivvy could be so great.
-- no way to completely close the bivvy, acompanied with construction deficits
This is my biggest contra for the Helium Bivvy. First of, the material is breathable, but it is not that breathable that gasflow is high enough for a person to safely sleep in. In fact, the vendor warns on a sign at the inside, saying danger of suffocation when the bivvy is fully closed. Now I could accept that, even though there are bivvy constructions nowadays that are so breathable that they can be fully closed, albeit at a much higher price compared to the Helium Bivvy. And my first reaction would be that this doesn't depcit a problem, because you have the big moscito netting of course. So why not keep a little part of the entry open, but use the moscito netting to keep you free from critters? The answer is simply, the way that the shell is constructed, one can never leave a part of the bivvy's entry open without also letting rain in. There are overlapping lips in the "door" of the bivvy, which should overlap the flooring so that no rain comes in. But on the Helium Bivvy, these lips are too small, and if you find the magic setting that would no rain come in, just hope that you don't move inside the bivvy so that this setting is being disturbed, and your inner floor runs full of water like a bath tub. This problem is mentioned by only a few reviewer, but I am for sure not alone, similar comments can even be found in Amazon reviews. The whole problematic could have been solved with a different shell design, one that features forced gas flow being supported with a moscito net, like a small venting hole in the upper part of the shell, or by having venting holes on the side of the bivvy. Yes, one can stay dry in the bivvy, yes one can survive, but for the cost of a few grams it could have been made much more comfortable,
- only enter the bivvy from the front
The Helium Bivvy is a front loader. While the setup is super easy as any bivvy, bringing in the isolation matress and getting into the sleeping bag is a bit of a hassle. I would have wished for a side zipper opening the bivvy on the side to have an option to comfortably and also be quicker to enter the bivvy. On the other hand, I have to understand that the Helium Bivvy's ultimate goal is to be a super lightweight solution, when additional zippers and potentially additional mesh would come at a weight cost. So, if one buys the Helium Bivvy, you know it's a front loader and you're prepared for it.
Overall:
The Helium Bivvy is a really good bivvy. For someone who sacrifices comfort for weight it is a very good solution. No additional Tarp is needed in theory, because the Helium Bivvy really is of superb Material. I personally would wish for a version of the Helium Bivvy with no moscito netting falling on my head while sleeping plus a side entry.
