How Well Does it Work?  The HeatStore Reflective Survival Sleeping Bag Part 2 of 2

How Well Does it Work? The HeatStore Reflective Survival Sleeping Bag Part 2 of 2

                                                                                    By Jeanette Vale


I'm a tester by nature.  I wanted to know if the HeatStore Reflective Survival Sleeping Bag a.k.a. bivvy-- actually worked!  I spent three nights testing it out, BUT six hours across those three nights actually in the bag.

 Three night trials show  how the bag worked best

Bivvy Test Conducted 2/16/22  FIRST NIGHT

Test begin:11:30 PM 2-16-22    Test ended 2:00 AM 2-17-22  Duration 2.5 hours .28 degrees.

Location: Mapleton, UT

1 Inch of snow on ground.

Laid a clear plastic down

Laid a thick Yoga mat down

Laid in the Bivvy with bare feet.

No sleeping bag was used.

No tent used.

No protection like a tarp over me.

BUT I was in my foam clothes. (I blog on foam clothes)

This is a photo of foam clothes 

My test results on the Emergency Zone Bivvy that we sell:  First night:  MIXED, Meh. 

I had regular (not foam) socks on  that I had worn in my snow boots all day.  I began the test with those on, but even the smallest moisture in the socks made my feet uncomfortably cold in the bivvy.

 As soon as I took off the socks, my feet felt better.  But soon the chill worked its way into my feet.

My bare feet were uncomfortable the whole time (2.5 hours)  except for when I could pull my pant legs down trying to cover my feet.  

My feet barely warmed up because I moved around a lot due to hard lumpy ground.  My feet would not stay inside the pants well.

Feet are not a heat producing feature on any body.  The torso is.  So it's not fair to expect  my feet to warm up the bivvy down there.  

The rest of my body was perfectly warm because of my foam clothes.  But this factor did not add heat to the bag to warm my feet. (it did the next night though, read why)  The air pocket down by my feet was cold air inside the bivvy.

I ended the experiment because of this, and this kept me from falling asleep.  I was very bored.  And there was a warm house 30 feet from me.

The rest of my head, body, hands were in Balmy San Diego due to the foam clothing I was wearing. 

Also pulling my pant legs down around my feet meant my waist area was no longer covered by foam and this began my demise.  It affected my core temperature.

Whether I was in the bivvy or outside the bivvy the foam clothing was excellent.  I felt perfectly protected from cold. 

2:00am I reached into the bivvy and ran my finger along the metallic surface and I felt a thin sheen of moisture.  This concerned me at first.  But the second night I realized I did not feel it change the temperature inside the bivvy.

Very simple sleeping bags can be made from foam. These can slide into the bivvy creating a superior wind breaking and warm sleep bag.  

What caused the moisture to be inside the bivvy?   Heat from my body is always radiating off of me.  The heat passes through the foam clothing fine, as this is open cell foam, but it is stopped by the metallic barrier.   The water stays in the bivvy with me and it turns into ice, if it is cold enough outside.

In the morning I took the bivvy into the kitchen and shook it upside down to see how many ice crystals fell out.  None did.  The moisture was so little.  This is good.  Plus it was a 28 degree night.  

Great things about the bivvy:

The quality is great.  It is a tough piece of material, not flimsy, not easily torn.  The stitching that holds it into a sleeping bag shape is very strong.

It provides great wind protection.  I ran water over it, repellant.

It is large enough for an over weight person to be in it.  My foam clothing makes me even fluffier than I already am and I was able to be in the bivvy comfortably.  Turning semi-comfortably. 

If you forgot your tube tent, the  bivvy would be a great option.  

I held one hand out to the open air and compared it to my feet inside the bivvy.  They both seemed equally cold.  Not that it was very cold outside. 28 degrees.  

Worrisome things about the bivvy & Solutions

It’s  loud, crinkly noises, but wear ear plugs- no problem. 

It may reflect your heat back into you, true, but it also holds the moisture in with you.  Being near moisture over time, in freezing temps, can have an ill effect. 

Questions I have for my next test AND other things I will plan for

To be able to do an 8 hour test - too wimpy, never did this.

can I slide way down into it and pull it over my head and  enclose myself like a burrito. Yes, did it the 2nd and 3rd night.

How does that feel?  cozy. 

Can  I stay dry in it if water were poured on me? Yes

How much condensation builds up in it over 8 hours?  Not sure.

If I don’t have to carry a tent –all the better.  The bivvy is good as a tent in an emergency.  But is this true at 0 degrees? I don't know.


Bivvy Test Conducted 2/17/22  SECOND NIGHT TESTING

Test begin:10:30 PM 2-17-22    Test ended 1:00 AM 2-18-22  Duration 2.5 hours .24 degrees at coldest time of the night  with wind chill.  

see detailed weather report attached below:

Location: Payson, UT

No snow on the ground.

Slept on a cot

Used a 2 inch memory foam pad (which goes hard in cold temps)


This time I wore two dry socks on each foot. 

No sleeping bag was used.

No tent used.

No protection like a tarp over me.

But this time I did have a light quilt.  I used it part of the time for my data gathering.  Now as I type this I do not recall what findings were attached to the quilt on me or off me.  I can tell you, I did like having that quilt on top of the bivvy.

Again, I was in my foam clothes. I slept in the open air.

Wind chill was a factor on this night.  It made it feel much colder on my face, which was not covered.  The bivvy totally protected me from the wind.  

Findings:  Being off the ground and having a 2 inch memory foam (even though it was hard when I first laid down on it) made a huge difference inside of the bivvy.  Recall the night before only a yoga mat separated me from the snow.  

Being off the ground is important.  The bivvy did not heat up well when I was on a yoga mat on the snow.  But it did excellent when I was elevated on the cot w/ memory foam.

The bivvy was very nice.  It was reflecting my heat and making the air warm.  Was there still a damp sheen of moisture on the inside with me?  Yes.  Is that a problem?  Yes, but in my foam clothes I did not feel it.  And at 2.5 hours the moisture did not effect the warmth in the air of the bivvy.

I concluded this test and went into the house because I proved that the bivvy does reflect my body heat.  I also went into the house because I heard a scary noise.

Takeaways:  Do not expect the bivvy alone to be a comfortable warm resource.  Although, It is better than nothing.  It stops wind.  You do need to protect yourself from cold by wearing a hat that preserves your heat.  The more layers you have the better.  Like a sleeping bag etc.

I TESTED A 3rd Night and the above paragraph is not very true.

Here is the weather from this night:


3:39 am to 4:55 am  16 degrees fahrenheit.  I tested the bivvy in my van.  Thick ice rivulets was on my windshield.  Wore flip flops and shorts.  Long sleeve shirt. (no winter hat, gloves, shoes, socks, coat, blanket or sleeping bag).  My feet were wet due to trudging through snow.  I couldn’t dry them much.  Climbed in the Heatstore sleeping bag and closed it over my head.  I think it was very important to be fully enclosed inside. I made sure to get into the bivvy fast enough before my core temp had lowered.

 My feet dried off by probably 30 min in.  where my back touched the car seat  it was very toasty warm, the bivvy reflected heat well because of the plush car seat.  Where my knee caps were near and touching the bivvy it was cold but mildly.  I used one bare foot to warm the other and it worked.  

 The bag is big enough that It was high enough to go over my head,  by 4 inches.  I pinched it to a close above me wishing I had a clip to hold it shut.  But when I gently let go, it stayed the way I pinched it.  Carbon monoxide might happen if one does seal it tightly (?) I’m no scientist and these are sloppy studies I am conducting w/out the knowledge of Emergency Zone.  

The air inside was very comfortable and warm.  If I had a relaxed mind I could’ve easily fallen asleep.  I realized my cell phone was left outside on the seat.  I was bored.  I wanted something to watch to pass the time.  I opened the bag to grab my phone. 

 It was freezing outside the bag. 16 degrees. Very miserable.  There was a huge difference between the air outside vs in the bivvy.  I was sad to lose all the heat to get the phone.  I seized my prize and quickly closed the bag over my head.  As soon as I did, it were as if I had never lost all that heat.  It was warm again immediately.

 Condensation had formed on the walls immediately when I first climbed in.  This was only up near my head.  It only bothered me if my bare hand brushed against the bivvy and I could feel the water. It was very cold water.  But it did not effect the warmth of the air.   My bare legs and knees could not detect that the bivvy had moisture at all.  I think it was up near where I was breathing.

 My cell phone showed me the time and then promptly died.  Boo.  I had been in for 50 minutes.  I became more relaxed and warm as I neared the end of my time.  There was plenty of room for me.  I am 5’4”.  I'm overweight by 70 lbs (the things I tell you!)    The bivvy was 4-5 inches from my face.   I am not claustrophobic.  It was a perfect cell phone movie chamber if I had a working phone!

 After over an hour in:

My feet never got perfectly warm, but they were not uncomfortable (like the first night).   My core temperature was excellent, super warm.  When I felt my arms they were a bit cold to the touch.   My face was warm.   I was bored.  I proved my point.  I wanted to know what it was like without the comfort of a foam winter suit.  The bivvy works really well even if you are in shorts, thin shirt, with wet bare feet.

On my short walk back through the snow in flip flops, my feet were in tremendous pain from how cold it was (walking in snow).  I was surprised at the pain.  It didn't feel like this on the way out to the van.   I can’t imagine being exposed to the elements.   We are so sure of our comforts.  We think these will always be available to us.   Because they always have been. 

But tonight I watched  the Ukrainian people all leaving their homes to flee.  Their babies and small children with them.    It is winter time.  In a blink, they are homeless.  It is horrible.  I pray for their success to find a place to go.  

I am happy to test stuff.  I love being warm.  I want to know I can stay that way.    I wish I had the discipline to test for longer hours and give you all a better report.

We are not guaranteed  the promise of sunshine and lollipops.   We live in a politically charged world and there are millions of refugees living in makeshift shelters.    One moment they were in homes, they had careers, and then something became unstable and now they are in deplorable conditions.

It can happen to us.  I still feel we have a window of time to keep getting our preps in place.  

Well.  I’m going back to bed.  It is now 4:55 am.  God bless the hungry, cold and displaced.   

Step on, prep on and enjoy a HeatStore Reflective Survival Sleeping Bag.

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