Extending the range of your Quilt/Sleeping bag Quantitatively

This is in addition to the layer needed to meet the EN conditions?

For winter bags this being medium to heavy weight base layers plus sock,gloves and a beanie or balaclava

I go by the US army tables re insulation needed but use one level higher as the US tables are optimistic by 10C in my experience. Gerry Cunningham used to say that additional clothing had minimum benefit once the clothing thickness got over an inch but I have never noticed any downside to wearing as thick a layer as needed up to the compression point of my sleeping bag. Simply use the 4 Clo per inch value to estimate the warmth

Purely anecdotal- I sleep outside as much as I can all year in Maine (around 100 nights usually) I enjoy testing the efficacy of my sleep systems in low temps in my own backwoods so I feel confident I won’t freeze going into the backcountry.  Sorry I don’t use charts or EN ratings as a guide. Not sure how many inches of clothes I actually add but I use a 40F bag right down into the teens comfortably by adding sleeping layers. Then I bust out extra quilt :)

…of course all the variables…

starting point 40-50F (5-10C)- NeoAir xlite- 40 degree EE Convert- lightweight capilene top and bottom- warm hat- warm socks

30-40F (0-5C) – add wind pants and EE torrid hoody

20-30F (-7-0C)  – add another lightweight base layer top and bottom and thermal weight PTG capilene hoody- add fleece gloves and insulated booties- add sleeping pad booster- 1/8” ccf

0-20F (-18 – -7C) – here I add thermarest zlite pad under xlite to get around r 5. Add Insulated pants and/or insulated snow skirt, add another insulated hoody (nano air light), add insulated Balaclava over hat and hoods, add insulated mittens. In this zone I may swap the 2nd lightweight base layers with thermal weight capilenes.

Below 0F (-17C) – I add a 20F full inner quilt and tweak sleeping layers to accommodate. Around 0 Usually I can eliminate the second puffy and snow skirt once the second quilt comes out. Add ski goggles and buff :) tested to -20F

Ps – all insulated pieces are synthetic

thats me in a nutshell 🥜

I have found that extra layers are best added during the night. If I am a bit cold going to bed and wearing a puffy, I need to take it off but keep it with me in the sleeping bag. Otherwise, the puffy makes it difficult to warm up the bag. After the bag is warm I can put the puffy back on.

I almost always sleep in merino long johns and a capilene top. I find the possum down socks worthwhile for cold conditions. If my feet are cold I can’t get to sleep. My latest experiment involves a hooded (micropuff) puffy. My sleeping bag is like a quilt with a zipper, it doesn’t have a hood. We’ll see if the hood helps as much as I think it will.

PHD go into all this in some detail on the Sleep Systems section on their website. They cover the gains you can expect from additional clothing, filler/liner bags, liner half-bags plus jacket and overbags, and they give recommendations for a wide range of different scenarios.

I think their advice is based more on pragmatic experience than any lab work, but that’s probably more useful anyway:

https://www.phdesigns.co.uk/what-is-sleep-systems

There offer lots of advice and case-studies, but this table is particularly interesting:

https://www.phdesigns.co.uk/plan-your-own-system

@david-paradis

this is what i’ve been looking for, for a long time! thank you!!!  this is a great way imho to keep weight light and have versatility! all backed back personal experience!!

i’d also love to see your gear list :)

Erica,

I’m with you on layering too soon.  Layering too early can mean perspiration and gets me cold.  If I layer-up when I get chilled, I’m good to go til wakeup time.

I would definitely agree with layering too soon also above 30-40F. Also in climes which fluctuate dramatically at night (desert, shoulder season,etc). Above freezing I sometimes will sleep with extra layer in the bag or have top quilt handy as temps drop. When it is at zero or below zero degrees I need the layers from the get-go however because the act of unzipping the bag in order to don extra layers in the middle of the night allows too much frigid air intrusion IME and makes the whole system colder. Then I have to “reheat” again from 0. At zero degrees I don’t want to become chilled at night, if possible, otherwise Intense shivering or vigorous sit-ups become imminent.

For those looking for a great source of experience based information and never ending entertainment, check out Shug’s you tube channel here.  https://www.youtube.com/channel/UC27nqmEhKzD9YHK1IFwG7qA\

He discusses in numerous videos his approach to dealing with a range of conditions including precipitation,  very cold temps  and high winds using  tarps, hammocks, quilts, and additional insulating pieces.  Warning:  his videos are addictive!