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Plastic Bag insulation?

 
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Since China stopped importing plastic waste, our local "plastic film" - usually polyethylene bags - goes to the dump.  I wonder if we could use it in place of other insulation batts by building up layers of bags and wrapping, etc, laying them flat but wrinkled enough to trap some air.  They would be held together at random points within the stack, perhaps using waste adhesive tape or local melting.  I'm thinking of just enough bonding to keep it flat with careful handling.  Is there any experience or data on this?  This pertains to buildings of any size, of course.  
 
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Hi Bob;
Interesting idea.
I don't think commercial builders could take the time required to use it.
But folks building their own tiny home sure could.  
No telling without testing, just how effective it would be as an insulation versus commonly used insulators.
Maybe just staple it down against the outer wall as an extra seal and then use conventional insulators to finish the job.   That might make selling later much easier.
 
Bob Stuart
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As a craft process, it would be very labour-intensive, but to put a dent in the plastic waste problem, someone might build a machine that produces batts that are about as easy to handle as fiberglas ones.  I'm wondering what the potential r-value might be.  
 
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There are actually two separate and mostly unrelated issues in play here ... insulation (energy savings) and plastic disposition. Trying to "kill two birds with one stone" in this case may end up solving neither problem and might actually make things worse. Thermal transfer is a very well understood science and insulation technology is available and inexpensive. If you want to save energy, save the planet and stop putting carbon in the air, then place appropriate amounts of insulation in your dwelling. Rock wool is a terrific alternative to pink insulation ... easy to come by and not very expensive. Now, what to do with all that plastic? Well, first we should figure out how to stop needing and/or using it ... cloth or paper sacks is a nice step in that direction. Second, we need to find a efficient way to collect it and then lastly, of course, remanufacture it into something useful ... or even decompose it and return it to the Earth safely. Trying to solve both problems, one user at a time, is not going to help much ... if at all?
 
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You should check out this new process that recycles plastic by using steam cracking to reduce plastics to their molecular components that can then be manufactured into the Same quality plastics as the original materials, thereby making the waste plastic more valuable (likely to be recycled) and create a circular, sustainable plastic paradigm rather than it all just being down cycled into mats, benches, etc or going into landfills.
 
Bob Stuart
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That process still requires sorting by type of plastic.  Making batts should work fine with any film, and tolerate some paper contamination, etc.  
 
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We used waste plastic at our school as insulation, but only in places where people won't sleep. We used it in the north wall and roof of the water-tank room. We were concerned that if it should ever happen to catch fire, it had better not be near a place where people are sleeping.
 
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My understanding is that insulation needs to
- stay where you put it (not settle down to the bottom of the wall)
- not catch fire easily and not spread fire easily
- breath well enough to let the moisture escape
- and not break down over time.

I don't see how plastic bags could do these without substantial change to their structure.

Current plastic bags are designed to break down over time.  Try touching that old grocery bag down in the bottom of the bag bin that has been there for four years.  It's brittle and falls apart.

Personally, I wouldn't want to have extra plastic in my living space, especially soft plastic that off-gas as they degrade.  



China is accepting plastic bags for recycling from some places (like where I live) but only if it's properly sorted.  The people at the recycling centre are extremely militant about proper sorting as about 1% miss-sorting can ruin the entire batch (apparently).  Since most of The West is terrible at sorting their recycling, China got fed up with accepting it as most of it ended up in the trash once it got there.  The key to solving this is public education campaigns on how to sort your plastics.  Or better yet, use less plastic!

A better solution would be to reduce the amount of plastic produced.  Our city had a single-use plastic bag ban for a couple of years and it's amazing how quickly the population could adapt to not having plastic bags.  

Lots of little things had to change, like the law requiring all garbage be wrapped in plastic.  Now we have two garbage collections, one for organic waste and one for non-organic.  The inorganic is so dry, we can wrap it in paper or not at all.  

People had to learn to bring their own reusable bags, but after a while, shops started making fun bags and now tourists go around the different shops buying the reuseable bags as souvenirs.

Paper bags are still available for ten cents each and the quality of paper bags has greatly increased so we can reuse them two or three times before transforming them into craft projects, fire starter, or garbage bags.

It only took two years to train the population to get rid of plastic shopping bags.  Now the ban has been lifted (temporarily) many of the shops aren't brining the plastic bags back because it says "hey, look at me, I hate the environment!"  In the neighbouring municipalities with no bag-ban, it's become difficult to find plastic grocery bags because the shops are voluntarily eliminating them.  It makes them look eco and saves them a surprising amount of money not providing free plastic bags.

So...insulation as a solution?  No.  I don't see it.  I think solving the source of the problem would be a far greater opportunity.  
 
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