Sleeping bag ratings

[Brekel]

I'm in the market for a new sleeping bag for use in Tas.
My old down bag has lost a lot of its loft and isn't as warm as it use to be, as well as being heavy.

I understand the EN/ISO rating system, and how it relates to Male/Female, sleeping position, thermals, mat etc.

What I'm interested in is people's actual real world experience with how the Comfort/Limit temperatures relate in real life. I've seen in a few places that as a guy you should add 4 or 5°C to the Limit temp for a more realistic assessment - what are your thoughts on this?

I've pulled some stats from the Liawenee weather station (1057m elev) for a guide as to what conditions to expect in Tas at reasonable altitudes, at different times of year. But knowing the temps doesn't help decide on a bag if the ratings aren't realistic.

I use to be a warm sleeper, but now I'd maybe classify myself as average. Unfortunately my old bag was made well before the EN rating system, so I can't use that as a comparison (and don't know specs on the bag).

[neilmny]

My take on this is ignore limt and focus on comfort rating. A lower limit comes with a lower comfort rating.
Know yourself in terms of whether or not you are a cold, warm or even hot sleeper.
The limit rating is more or less a theoretical survival rating and entails the right clothing and shelter to be meaningful.

[Nuts]

If they actually have a standards rating it's usually pretty accurate. On comfort ratings, personally I still feel they are 2-3c generous but thermals and a liner gets them close, as an average sleeper.

If bags are not rated (many good bags aren't) I would suggest comparing the weights (of the down fill and down type) to a similar bag that does have a rating. Just as a ballpark, I 'feel' a good Tassie sleeping bag, made from the lightest down and fabrics, should be from 700g to 1kg summer/winter (experience mainly with Marmot rated bags, and a small number of other brands one-off).

PS. Yes, agree, ignore 'extreme ratings', survival is a long way from comfort

[Brekel]

On comfort ratings, personally I still feel they are 2-3c generous but thermals and a liner gets them close, as an average sleeper...
PS. Yes, agree, ignore 'extreme ratings', survival is a long way from comfort

Thanks guys.
Yes, I certainly ignore the Extreme rating. Being hypothermic but alive isn't my idea of fun
Nuts, just to clarify (as I see people using all different terminology), when you say the COMFORT rating is 2-3° generous, are you referring to the EN Comfort rating (the higher of the 3 ratings given, some call women's Comfort), or the EN Limit middle rating (that I've often seen referred to as the "men's comfort")?

Cheers,
Brett.

[Moondog55]

You have to understand that the rating is making several assumptions and that the comfort rating is based on the occupant/mannequin wearing a full coverage clothing layer and an insulating mat underneath. Most makers will use the Mens comfort rating. S2S state this, others use an average of the two, if you use the female comfort limit it gives a small margin for safety.
One of the assumptions is that you are a fit and healthy "average" of a certain age, if older than this you need to deduct about 5C per decade. That is an older person needs a warmer bag
If not wearing long winter base layers, sox, gloves and a beanie then naturally you need to deduct 5C from that comfort rating.
So my own winter bag rated at -18C is now only comfortable at about -5C.
A rule of thumb is to use a bag with a safety margin of about 10C on a worst case scenario.
As to your old bag have you washed it and given it a good tumble?

[Nuts]

Yeah good question. I'm most familiar with Marmot and as they make a male or female specific bags I'd suspect I'm thinking of the Male comfort rating.

Indeed, their Helium is called a -9c bag and 'comfort tested' at -5c iirc. I'd rate that pretty accurate. I've slept in this bag at -9c and it took thermals, a down vest and the bag was closed to a peep hole but I recall being comfortable. If -5 C is the average male comfort rating it is still several degrees out for all but the warmest/biggest nude bloke . But can be made comfortable with a few carried extras. I'd consider this weight bag an adequate minimalist for Tassie winter.

Marmot's Hydrogen (another in the same product range) is their '-1C' bag and comfort rated to +1C. I'd say this is similar, needs something eg. thermals/liner to be comfortable in the minuses. But is otherwise a comfortable bag through the range of summer temps (prepared for a cold butt with the odd summer snow event, which tend to also come with a couple of -2 to 3c nights as you may know).

As mentioned, I'd take the weight of down fill you are buying (and hedge a bit for the down fill power rating) to compare between brands rather than the temperature rating. But this info may give you somewhere to start from/ to compare to bags rated to standards.

PS. All assuming you are trying to keep the weight/size down... I've also used Marmots bulky -18c rated bags for a couple of winter walks and really, when it's anywhere in the minuses, more down is always appreciated.

[Brekel]

Thanks heaps Nuts.
The Marmot Helium is one I was looking at. Not quite as light/warm as some of the others, but I saw a Long (which I'd need) on special for $419. Much cheaper than anything else that's fairly warm and fairly light.

Have you been happy with it overall, quality/comfort wise?

[Nuts]

No problems with quality. I sold the ones we had in a quest to save a few grams. Several were sold on this forum, so someone else may chime in (?)
Helium is a long-standing model for Marmot, I seem to recall these bags were that price.. in $US, 10yrs ago.

PS. They don't use the lightest zips or shell fabric, other than shedding a few grams in higher FP down, there is the possible weight savings, the design is very minimalist.

[Brekel]

Bags I've considered so far are:

S2S Spark spIV
Comfort -8; Limit -15 (extreme -36 )
880g Reg/985g Long.
The lightest and warmest. Temp data indicates I may not need one this warm if I'm using layering on cold nights, but its darn light for its rating. The spIII version probably isn't warm enough for winter(-2°/-8°).
Not the cheapest.

One Planet Cocoon-11
Comfort -4°, Limit -11°.
898g Reg/1001g Long.
Has the advantage that the Regular size supposedly does people 187cm tall- my exact height, so I MAY not need to go for the long.
If the true temp for the average man is -11, then based on Liawenee temps it would only be cold 1 night every 3 years on average.
If it's more suitable for middle of the range, say -7°, then on average it would be too cold 8 nights per year. May be ok with layering, or avoiding the worst
winter nights.
The Reg size is lighter than the long S2S (I wouldn't fit their reg), but not as warm.

Mont Spindrift/Brindabella
About the right temp range, but Long models nearly 1.5kg. I'm hoping for lighter.

Mont Helium600 - can only find in Std, not in long?

Marmot Helium
Their rating-9.
EN ratings I've seen vary, between -2 C/-8 L and -5/-10.
Cheaper than Spark iv, similar weight, not as warm
EDIT: the official EN ratings for the current Helium is -5.2°Comfort/-12°Limit.

[Brekel]

Sorry Moondog, I missed your reply.
Yes, I've looked into the EN testing, clothing, mats they test with etc. And given that I'm not as young as I was, the men's limit temp is probably optimistic for me even though I use to be a very warm sleeper.

I have washed my old bag. But we're talking about a tapered rectangular Pasdy Pallin bag that is 28 year old

Hmm, the more I think about you're aging comments, the more inclined I am towards the Spark spIV

There are other brands that are more expensive, but warmth/weight/cost of this seems a good compromise

[Moondog55]

Depends how broad your shoulders are. My wide shoulders and large chest [117cm] is the reason I've never looked more seriously at the Spark series. Would that be a Hotham by any chance?
Needing more warmth is why I am adding 100g of down to my S2S Traveller, but I am a firm believer in overstuffing. The OP Cocoon is a big bag but the shell isn't windproof, not a concern for me as I always use my old Goretex bivvy in winter.
The OP Cocoon was on my shortlist, in the warmest fill amount. Gone a different way now with an overbag method.

[Brekel]

The shoulders aren't a problem. I'm a skinny runt, just tall. That's why I hate having to gu up to the larger bags - they're wider as well as as longer, but I don't need the extra width. Just a smidge more length than the regular bags.
My old bag was a feathertop.
Back in the day I'd climb out of my bag, off my ccf mat, and step out of the tent to find ice all around without even knowing the night turned cold. A combination of the bags age, and maybe mine, and I need something a tad warmer now.

[Moondog55]

Dint wee awl

[Al M]

If it hasn’t been mentioned already, if a bag liner is used to keep it clean and extend its lifespan consider in the warmth equation that a 100-150g silk liner is commonly said to add about 2-3 C warmth and a 400g stretch polypropylene or similar liner about 4-5 C.

I have always been a warm sleeper and in my late 50s still am and have got by with -2 to 0 C down bags and quilts weighing about 550 - 1100g of various down quality and fabric weight, plus liner and usually sleep with minimal clothing and would put on layers if needed. I’ve got by in a range of overseas hikes like numerous times in Nepal, NZ and Japan in winter. I don’t think Tasi presents temperature conditions worse than those though extremes can happen anywhere. Depending on your needs it is possible to end up with too warm a bag that is only useful in smaller number of scenarios, which you will survive through at the extreme lower rating plus layering up. Unless you own several bags for different seasons, a one bag scenario with a too warmth a product in warmer camping trips elsewhere makes it less useable the majority of time elsewhere in southern parts of winter Aust, unless you are happy with it around your ankles or waistline when too warm on those occasions. Then it becomes an issue of your legs are toasty but upper body is cold and you toss all night flipping it back and forth.

Also, consider the down quality rating among products and higher warmth factor, where it’s possible not to increase bag weight, infact decrease it vs another bag that uses less quality down though one has to pay for it. If you counting grams fabric weight among bags should be considered as well and together with fill helps achieve the ideal bag weight.

There are bag designs with horizontal baffles that allow one to shake the down from top to bottom and back to vary the temperature.

[Brekel]

For anyone interested, some data on the daily minimum temps you can expect. Data for Liawenee at 1,057m, as far as I'm aware the coldest weather station in Tas. Obviously if you camp at higher altitudes the temps can be lower.

Graphical data

Tables

[Al M]

So what temps are you going to aim for then? If it’s the average and most common number of days, during the Tasi hiking season around summer and autumn then it’s no big deal. Something like around 1 C + cold sleeper adjustment of -5 C = -4 C comfort rating, then add -3 C silk liner -5 C layered clothing = -11 C capability so a bag comfort rating of around -2 to 0 C should do.

If an uncommon below average low temperature event occurs you would still survive at the lower sleeping bag temperature rating wearing all pairs of undies and socks.

Even winter hiking is no problem with an average low of -1 C and lower infrequent recorded -10 C events.

Meanwhile would you also like to be able to use the bag throughout the rest of Australia in warmer conditions for the majority of the sleep bag ownership life potentially for about 20 odd years or more. A -2 to 0 C comfort rated bag would also be usable for all of southern Australia, central desert winter conditions and there are plenty of 600 to 700g bag or quilt options, which is also a very sensible light weight to carry.

The bag criteria can then be summarised as:
1. 600-700g
2. down fill of highest warmth grade you can afford
3. Mummy shape with collar muff design to reduce heat loss and not too generous size for warmth efficiency retention
4. Lightest outer fabric to maximise ratio of fill to total weight and warmth unless you do want moisture resistant fabric
5. Decide on whether you want bag or quilt design, with head section to stop significant heat loss or no head section and redirect fill elsewhere in the bag or quilt (over width design for side sleepers)
6. Edit: if possible a down fill shifting baffle design to regulate temperature
7. Edit: allow 2-3 C added warmth for any bag liner used

[Brekel]

I'll probably be aiming a bit cooler than that.

My old bag is still fine for summer walks (unless the forecast is bad) so I'll be aimng the new bag at the autumn/winter/spring colder season, without worrying too much about its warm weather versatility.

Aiming for a system that is comfortable at the average temp doesn't work, as that means you'll be ok half the time and too cold half the time (well, apart from the days that hit spot on the average). You also have to weigh up the weight & cost of extra clothes for layering up vs the weight of a warmer bag.

My thoughts are that a bag and sleeping arrangement that is ok down to -6° (PERSONAL comfort limit, not bag rating) while wearing a light layer means that in a typical year, I'll be fine on the coldest night in April at this altitude (coldest night average is -5.5°). In the middle of winter, on a week long walk, there would typically be 1 night I'd have to add an extra layer. Conversely, I could strip off a layer on warm nights.

If camped at higher altitudes (which I intend to some nights) the temps could be 2-3 degrees colder, in which case the colder months have about 10 nights per month (1 day in 3) where I'd have to rug up extra.

Bear in mind too that even in the Dec-Feb summer months, the table shows that in a typical year (not a cold year) there will be a total of 1.6 nights at or below -2°.

I think it's better to sleep warm and comfortable rather than cold, lacking in sleep and lacking in energy the next day. So for a colder season bag that will be comfortable and still retain a bit of versatility, I'm now thinking that somewhere around that rating may work - but I'm open to other thoughts and opinions.

That just leaves the question of how my personal comfort levels sit against the ratings...

[Moondog55]

Also how your technique for boosting a bags rating is dialed in.
Assuming a skinny bag with hot much room to layer up inside it; what warm layer do you have or intend to buy that can be used on top of the sleeping bag? Bearing in mind that an UL bag with high FP down and an UL shell fabric may not work best with a heavier layer on top of it.
My personal comfort levels have always been at least 5C lower than my walking mates and I've always made an allowance for that. I also sleep less warm now than in my prime so I make a further allowance for that. Having suffered thru a few cold bivvys I know that one cold nite with minimum sleep takes me 3 days to recover from I now tend to overpack a little on the sleeping gear.
I've always been a user of double bags and/or the use of a lighter bag and a half bag plus parka method of sleeping warm. I've tried using a parka over the top of my bag but I toss and turn when I sleep and that was never totally successful.
A while ago I had a custom synthetic overquilt made and that has worked out very well, it's good for summer on its own and adds a good 10C to any bags rating when used as an adjunct but it isn't the lighter option.
I'm heading out soon to the High Plains ad doing Falls to Hotham, while average minimums in March are around 5 to 6C the record minimum is much lower than that.
I don't want to use my new summer bag because I want to have extra down added to it so I'll be using my "survival" winter bag rated at about 14C, no safety margin there so I'll pack my Patagonia Puffball pants [ 90GSM Polargard ] and add the Nanopuff pullover to my usual Uniqlo UL down parka and perhaps a light fleece layer or winter thermals also.
There is more than one way to cover temperature extremes but my solution isn't the lightest, only cost effective for my needs. It weighs at least a kilo more than the equivalent down bag.
Is your personal comfort level when sleeping the same or similar to my own 10 degrees?

[Brekel]

Thanks Moondog, it's useful to hear examples of the layering methods people use or have tried.
I've got long thermals I can wear. I have a thin lightweight down vest that, given my body shape, I could wear inside the thinnest bag without issues.
I also have a thicker down jacket that could be put over the bag if it didn't fit inside (it might). Once I'm asleep I generally lay very still overnight if I'm warm enough.
I'm intending to do a number of walks through Feb-Mar this year, so I guess that will be a good opportunity to test my bag of choice and layers in warmer weather, and see if I need to make adjustments before it gets colder.
I always use to find I needed less clothing/bedding than my companions, but haven't had many cold nights out for a number of years

[Al M]

It’s up you what lower bag ratings you want and any margins, but the summer and other data you posted says the great majority of days are warmer than you indicate. Example, 1.6 lower temp days in summer out of around 60-90 days indicates these are much less likely events. With increasing global warming those lower average temperatures are less than the past 20 year figures so out by 1-2 degrees and the number of lower temp event days are also going to be less. I’ve been trekking in Nepal EBC at 3000-5500m over the last 30 years in the same place same months about every five years and noticed global warming has made big changes in warmer months, glaciers receding dramatically, with lower rated sleeping bags becoming less critical and I can now get by with a Tasi rated bag that suits me.

Also, if it’s for hiking use there is no carrying of extra clothes and associated weight. They are what one would normally carry in a well researched, sensible and recommended layered clothing system for use in the morning, day and night before sleeping.

There is also the downside of the need for an overly generous bag size to allow for extra clothing as the increased air volume makes the bag less efficient at heat retention and maintaining it without the clothing because of the cold spots in extremities further away from warm skin. Otherwise why would the concept of mummy shape bags over rectangular shapes be justified in well made designs across every manufacturers model range. If you are one of those that find it impossible to sleep that way then pick a wider bag at less efficiency. In fact this could be the reason why some are finding their rated bags not warm enough coupled with unusual hypothalamic heat regulation issues.

[Moondog55]

Don't agree with that Al M, while a generously sized bag might take a little longer for the trapped air to warm up the insulation the bag gives is the insulation it gives, A large bag is not cooler/colder than a tight bag. Mummy bags are more efficient because of the cut and weight saving, less fabric and a lower weight of down or fibrefill for the same thickness of insulation.
A smaller and tighter bag may have a slightly smaller surface area but radiation from a bags surface is not a major factor in heat loss from a sleeping bag in normal circumstances.

[Al M]

No it doesn’t work that way. The science and physics of it is that surface area is proportional to the heat transfer, ie, with same insulation thickness, and same temp differential, you lose more heat when one bag has more surface area (loose fit) than another (snug fit). Larger bags have more surface area, lose more heat. It takes a larger heat source inside to make up for that in the initial longer warm up phase and then to maintain it all night long. That coupled with excess air spaces to heat up and maintain warmth makes the larger bag less efficient.

However, if it is too tight a fit, apart from the feeling of discomfort, there is a risk the fill will be compressed and loose insulation value, particularly at pressure points like the shoulders and hip and feel the cold there.

This is a commonly discussed topic in many outdoor gear forums and product manufacturer websites. Example https://www.outdoors.org/articles/amc-o ... eeping-bag

It’s unlikely that it will be that critical for typical Tasi conditions as it still really doesn’t get cold enough apart from rare freaky times compared to other more extreme cold temperature places in the world such as constantly below -10 C most of the night (not when it may dip for a few hours there only and rise back up) where every bit starts to count more. It may still matter if ones temperature capacity is starting to waver for reasons given. There can be about a 7% surface area (Edit) and about 14% internal volume (assuming equal cylinder volume calcs) difference between medium and larger bag sizes so not big but not tiny either that would correlate to heat loss differences that one might notice when it dips to a relevant low temperature. Edit: Based on these figures there might around 10% less efficiency in terms of surface areas and internal volume of large vs smaller fit bag.

[stry]

I'm going to disagree with you on this one MD.

I weigh around 60kg and having used bags of very similar loft and construction in both semi rectangular and mummy, I many, many years ago adopted mummy style exclusively for cold conditions.

Far too many nights sleep interrupted by encountering internal surfaces that had shed the heat contained in them when vacant and cooled down. Plus a general, albeit unscientific impression of coolness.

I am also unconcerned about needing extra space to wear clothing inside a bag. Even if my down pullover is slightly compressed, the increase in warmth is very noticeable. Never needed any more than thermals on my legs, and sometimes I may have two sets available. I also have, but seldom carry, Polartec 100 (not generic) fleece pants.

I always take a bag that should sufficient for the expected conditions without supplementation, and the availability of supplementation is insurance only.

[Moondog55]

Differences of even 20% in surface area are pretty much irrelevant compared to insulation thickness and stuffing density, most sleeping bags on the market now are sold at lower than optimum down density.
Air exchange though pumping may be a factor if the bag is not designed well but personally I've not considered it a major factor at -30, at really cold temperatures it might be different.
But sleeping in your camp clothing is part of the systems approach decisions we all need to make when looking at new purchases

[Al M]

In practice I’ve experienced cold spot sleep bag extremity issues in temps much less than -30 C such as -10 to 0 C particularly when using -2 to 0 C rated bags and -9 C tapered rectangular bags especially on foot corners, around legs. When one moves around in a floppy bag limbs cross areas where the body heat has not reached and wakes one up until that spot warms up.

I usually sleep with just undies and T shirt as wearing bulky clothing and socks is restrictive in itself after all day wearing socks and clothes so you want a relief from that and don’t want it 24/7, stinks things up and reduces clothing freshness on longer duration hikes. I’m a shorter stocky build with still good warm sleeper capacity so it will be different for others.

I used to have for many years a 1.5kg -9 C semi rectangular wider bag and reckon that I can achieve the same with my snugger fitting modern Western Mountaineering -2 C 600g mummy bag plus liner and normal warm clothes for backup if needed in emergency. Few years ago I was trekking in Ladakh Indian Himalayas at 5000m sleeping in the WM bag with silk liner, undies and T shirt and was fine with this setup.

[Brekel]

While I agree with most of what you have said Al M, there is one point where my reasoning and research deviates.

I understand global warming and know that it has started to have a big impact in some glacial regions.

However, climate change is much bigger than just global warming. Another effect of climate change is more extremes in weather.

The effects are also vastly different in HIGHLY localised regions - eg some the effect on Tasmania's west coast and east coast are almost opposite in modelling.

Looking at that same data set of minimum overnight temperatures at Liawenee, the frequency for cold nights below x temperature has actually trended up over the twenty years the station has been in operation, ie cold nights are becoming more frequent, not less frequent, and last year the coldest night was a full 2°below anything previously recorded (not that a 1-off event is significant of itself).

As an example, looking at 5 year rolling averages, in 2000-2005 there was an average of 2.2 nights/year at or below -8°C. Every 5 year period since has been higher, and in 2016-2017 there were over twice as many.

The average temp throughout the day may have risen, I haven't looked at that as it is less relevant for sleeping bag discussions. But all observations show that colder nights, in this location, are becoming more frequent.

Like I said, I have another bag I can use in summer so I'm after a winter and cold season bag. As such, the way I view it is that the decision comes down to how much winter walking a person intends to do, and how often they are prepared to have a cold night, and balancing that against weight and personal temperature tolerance.

[Al M]

OK good points on the localised climate trend, still fairly negligible and normal clothing as backup would still address it.

Another question is whether choice of bag should be with full head cover or none as this makes a big difference in handling lower temps, apparently 80% heat loss via this pathway. If correct then quilts and headless cover bags are less capable. I general find bag head covers annoying but in extreme conditions was glad to have them draw chord to max breathing thru peep hole, especially with lower rating bags that I use.