The conventional wisdom among backpackers is that storing stuffed leads to a loss of loft (insulation thickness) and therefore warmth, over time. the best practice is considered to be storing it flat, under a bed or something. That goes for self-inflating pads, as well. Manufacturers usually advise against storing stuffed.

Backpacking stores, such as REI, sell very roomy and breathable cotton or nylon storage bags big enough to hold a bag without compression. That's what I use for my "good" bags, with the appropriate stuff sack inside. A cheapo bag stays stuffed and in the car over winter.

My team keeps our gov't issue bags (warm and intermediate) and bivi sacks stuffed and stacked in shipping boxes, ready for deployment. I've never used them in cold, but they seem all right. If your bugout will be by car, maybe the storage bags are good enough to grab'n'go until you have a chance to stuff 'em?

Thanks, Jeff. I apprecaite the info. This is something I would have never thought of. Then again, that's why I came to this forum, to learn.

Now, I keep the three bags that come with the ECWS (military issue) put together within each other. If I were to lay them out flat as you have suggested, would having them all connected within each other for convenience sake also create the same effect, or it is the compression that causes the loss of effectivness to maintain their isnsulative ability?

Like others have said, no problem in putting them in a stuff sack.
Most manufacturers just advise that you should stuff them into the bag instead of trying to fold or roll them. That is so you don't make folds in the same place repeatedly and make the quilting move or thin out at that point by stretching it.

Grab and go is the whole idea behind BOBs (Bail Out Bags) too.
A lot of people end up with their BOB being a scaled down camping kit in a backpack or small duffle bag with a few mods and tweaks.
When you think about it the requirements are pretty similar.

I read the specs for the concrete slab insulation.
I think I just possibly found a new ground sheet for winter camping.

Using a stuff sack is still valuable, but you don't have to use either the stuff sack that came with the bag or the smallest one possible. Get a larger stuff sack and stuff it in more loosely. That would be better than a box (more adjustable) unless the box serves some other useful purpose (table?).

Sue

I would think the weight of the bags, laid out flat, wouldn't inflict much compression on each other. My understanding is that it is compression that is alleged to reduce loft eventually.

Many thanks to all so far. Lots of solid info and advice. I'll probably go with buying an inexpensive zero degree synthetic and leave it compressed in my van when the weather might be cold. In summer I'll rely on a couple of blankets I carry all year long and "relax" the sleeping bag(s) - oops, almost left my wife out in the cold ... guess I'll get two.

I recommend a Wiggy's bag because I have the Ultra Light FTRSS system (also Wiggy's sweater and poncho liners). In warm weather, over 40 degF, I use the outer bag. At 40 to 20 degF, I use the inner bag. Below that temperature, I use both. (I would probably get the Super Light FTRSS if I had to do it over again.) Wiggy's bags can be stored compressed, and washed in a washing machine!! Because the bags drape to reduce convective air space, they keep me very warm and comfortable. The bags are expensive and weigh, but they really work for me.

Note: My soon to be ex wife threw my Wiggy's bag in the trash. My son let me know, so I went over around 2am and fished it out of the trash, covered with the the evenings spaghetti dinner. Two washings at the laundry mat, air drying, and they seem as good as ever. Think you could do that with a down sleeping bag?

Spud

Coleman -10 Synthetic @ Wal-Mart. I believe it was 59.99 and for the price it's worked great for me. Leaving it stuffed I have no worries about losing much temp rating since I don't stuff it tiny, and it's cheap to replace years later if this occurs. I've used it for snow camping, and fall/spring camping (unzipped w/blanket).

The last couple days I used this in the 40*s and it was obviously too warm so I unzipped it 100%, and used my thin smartwool blanket to cover me, and adjusted covering of the bag over me under depending how cool or warm I got. Worked great.

-10 Synthetic Coleman + Surplus Wool Blankets = good range, and good when wet

Ace Hardware sells Reflectix 'off the roll', by the foot. Just ask at the store where its at. FYI buy a roll of reflective foil tape to seam seal. It looks like a roll of tin foil duct tape.