Best bag insulation for use with an eVent Bivy

Assumption: your question is timed w/the approaching winter in the Northern Hemi hence you might be considering winter use.

my winter experience is extremely limited to just 1-2 nights so i'm not the best one to answer. the following suggestions i'm merely "parroting" from info i gleaned fr/far more experienced winter hikers who have posted here in the past.

long trek in sub-freezing temps may be best to go with synth. insulation. this appears to be the general consensus and, IIRC, even DrJ has written such.

shorter trek of, maybe 2-3 nights, doesn't matter as loft degration in a down bag fr/freezing water vapor in the insulation will be more minimal in the short haul.

keep in mind i do mostly shorter treks: 1-3 nights, sometimes a week if i can get enough vacation time strung together.

also, understand that i'm in humid, rainy New England (at least it's humid spring through fall, with some drier days in summer, but still can be very humid many times in summer, and very rainy in the spring and for part of the fall). New England rain can last days on end and then a couple weeks with no rain. also, rain can frequently happen for a couple to several hours after midnight. this could be showers or T-Storms, depending upon time of year and other factors.

ok, with the aforementioned in mind:

1. i get some condensation in the Spring if it's raining all weekend. however, any shelter will have it under these conditions. I've had it even in a Seedhouse SL when wind would cause the wet underside of the fly to contact the all mesh inner tent and soak the mesh, or it has been so humid that it condenses on even the mesh. I've even had it drip off the mesh in the Seedhouse. So, this isn't just a criticism of the eVENT Uni. My impression from using different bivies in somewhat similar conditions (but NOT a sideXside comparison test) is that the eVENT Uni is better than all except an eVENT bivy sack. Why? with the eVENT bivy sack (i have two diff. ones – a custom-modified WT eVENT bivy and an ID Bugaboo – which i only have used 1 night) i can position my mouth closer to the opening so my exhaled breath escapes even when there is no breeze. The hoop in the eVENT Uni (and similar bivies) keeps the opening too far away and the exhaled breath must, of course, pass through the bivy's air space before escaping. I have a BD Lightsabre bivy which uses Epic fabric, but since i'm still too sheepish to try it out during a solid weekend of rain, i can't say how it would fare compared to the eVENT Uni.

I'm sure DrJ has more nights in the eVENT Uni than i do and he likes the eVENT Uni. He can perhaps give you some better advice than i can. Maybe his uses are closer to your intended use.

I'm beginning to lean more towards floored tarptents (SMD LSe and GG/HS Squall Classic) for my rainy, humid, and buggy uses WHEN i know i'll be where i can find sufficient real-estate to set it up. Out here, apparently it's not like out West. In some places, around here, there's just not a lot of real-estate (outside of established bivouac/camping sites which i generally avoid). My daughter has told me about out West – a lot of room, no humidity, no rain, no bugs – she loves camping out West.

2. i'm surprised at how little condensation there is when it's dry outside or very little rain (sometimes we get just a couple of hours of rain before sunrise). I leave the Uni open enough (unless it's raining and wind is changing direction – then, it's open just a little) that my exhaled breath stands a better chance of escaping the bivy. that said, the eVENT fabric is vapor permeable and this seems to help a lot.

3. i like the head room the pole affords; i like the ease of setup; everything fits in the bivy with me, either at the head end or the foot end, since it's 90" long. i like the ease of finding a place on the forest floor to sleep; someplaces a floored tarptent or tent simply won't fit, and even a larger tarp is a pain.

4. no vestibule is a bummer if i'm planning to heat water for green tea or oatmeal; if just eatin' GORP, then no problem. I can erect my poncho or cape in some fashion if a temporary vestibule is needed.

5. i can usually find running water in the winter (depending upon where i am), so not having a vestibule to melt snow in is not a problem, but otherwise see the first statement in #4 above.

6. it doesn't have enough bug netting to allow it to be used on summer nights when it's 87deg at night and 90+ %RH.

7. rain WILL ENTER during ingress or egress – especially if it's coming down in torrents – that's the price one pays for the ease of entering/exiting a rear facing entrance vs. something like the Nemo Go-Go bivy or the ID Sola/Megasola forward facing entrance which while rain can still get in at least it's not necessarily falling right on top of your sleeping bag. a cape or poncho helps, or use natural cover (my usual choice, but be careful of "widow makers" and lightning strikes) to help ameliorate this situation.

bottom line: one either loves bivies and puts up with their limitations, or one hates bivies (sometimes even under optimal conditions).

oh,… and i'm not the least bit claustrophoic, so i don't any bivy – sack or shelter. so, you should consider this issue also.

hope this info helps.

David, PM me, please. i might be able to come up with a couple of other acceptible suggestions for you to get you started with bivies.