So, bottle walls and roofs seem cool, but a lot of work.
Plus, they seem like they would be leaky.
Double layers of plastic sheeting can be inflated, but what if we strung plastic bottles on a cord like beads on a string and used them as spacers in between two sheets?
It would be passive instead of requiring energy, and it would isolate more air.
I suppose the places where they touched both sheets could allow thermal bridging,and more layers means less light,but it seems like  this could be  a useful option.

I like that you are thinking outside the box. It will help me if you better define what you are trying to achieve.

A greenhouse, a house, a hybrid? Long or short term structure?

I have a greehouse/coop/run that needs to be reskinned, and more greenhouses planned in the future.
The planned houses are on land without  power,so passive solutions are better.
I'm poor,so scavenged matirials are better.
Pallets,tire,bottles  cardboard.

Even if you're not poor, I think scavenged materials are better :)

William: Good idea for air space! I'm still not a big fan of the plastic sheeting, but I deal with a lot of wind, and I have different needs.

I am, however a dumpster diver and reuser type, and having looked in a LOT of trash and recycle bins, if I were going to do this, I'd be accumulating this shape of bottle:   They are a rectangular footprint, and if you cut the tops off, they stack REALLY nicely and tightly with each other and get pretty close to structural, definitely closer to holding themselves together than just stringing them. This would add stability to your greenhouse walls, that the film lacks, as well as your dead air space for insulation. I can take you a picture of what I mean by how they stack and hook together if you want. They are useful for some things when you do that to them, and your greenhouse might be one of those things. And it's a common shape, lots of brands will hook together, and the recycle bins are full of them. Check trash at a daycare or nursing home, they toss lots of these.

Edit: just found this picture:  That is what I'm thinking of, sort of, they used different bottles, I like the rectangular footprint better. Is that what you mean by "too much work?" Actually, I suspect it's not, as far as long term. Cutting the bottom off  is a one time thing. At that point, you have something you can work with. I took pics, will get them here in a bit, you can see how easy the structure holds together. I suspect not cutting them, just stringing them, every time you deal with them it's snake wrestling, and attempting to make them behave yet again. I have strung bottles for various reasons, and they are a total PITA to cope with. I like Chris Kott's idea below about some strung to make curtains and doors, but anyplace you don't want to move them easily, I'd say use a system that is easier to deal with long term.

Edit again: What I did with some of the rectangular ones. Was not using them for anything like what you are, so they are taped together for my reasons.


Cut bottles taped together sideways, and then stacked into a block



My mom holding up that block with one hand. It's SO easy to deal with when it's like that. No snake wrestling! And really easy to cut the bottles once, and then it's done.

Me being me, I kept some of the cut off bases, they look interesting, might abuse them for something. They kinda look like glass blocks when put in a window.

If you have strings of bottle-necklaces, you could hang those on some type of rail or curtain rod assembly to pull them back when it's warm enough, or to admit more light. It would be like a plastic bottle bead curtain that you could sweep aside at need.

-CK

Good on you William!    Clear bubble wrap could be a good option too.   I use it to wrap my window air conditioners in winter.  Very flexible to wrap around odd parts of the construction and over curves.      Large bubbles (about 2' diameter and 3/4" thick) usually come in large pieces, but small pieces are easy to tape together.   I can't remember where I collected a huge pile but probably dumpsters.    I'd check with local stores that unpack large things like TV's and appliances (Best Buy, Lowes, metal parts and glass suppliers, furniture stores that sell lamps...)    Not sure what R-value one layer it would give.

I like the bubble wrap idea even better than the bottles.  People on greenhouse forums use them to insulate in the winter so it is somewhat proven.

As for the bottles between the two poly layers, they should add an R 1-2.  I'd use round ones so they only touch the poly in a few spots.  Where they touch you'd still have effectively two layers so no worse than with just the poly (probably better due to the added thickness).  In between the contact points you'd have up to 4 pieces of material between the inside and outside of the greenhouse.

I believe poly reacts unfavorably with pvc.  I'm not sure what drink bottles are made of but that could be worth checking.

On my greenhouse I'm planning on two layers of poly and then sliding a piece of pole barn insulation between the layers at night.  Pole barn insulation is basically two layers of bubble wrap with a reflective mylar coating on one side.

I use bubble wrap on windows in winter, dampen the glass and they stick to it. I'd say they don't add so much R value (which is a very specific thing being measured,) they add dead air space, which slows down the heat gain/loss. It's more a speed of loss change than a definite R value. The only actual R value added is maybe the plastic film. But they ARE effective, to a point, they won't do magic, but it's enough to bother with them. Putting bubble wrap between 2 layers of plastic sheeting would help a lot. Even more, if, as Mike Jay said, they don't touch anything else.

I know someone who scavenged bubble wrap for his house windows, ended up with a bunch of the green stuff, being in his house felt like being in an aquarium :) He liked the effect, I found it cute, but wouldn't cope with my house being so dark all winter.

It just occurred to me that a potential problem with any of these plans might be that plastic layers touching will hang onto condensation, resulting in mold and mildew in summer.  So some sort of framework to separate layers would be necessary.

Green wrap for the Greenhouse - that works!    Pink is another bubble wrap option - always seeing life through rose colored glasses :)

Susan Pruitt said
Green wrap for the Greenhouse - that works!    Pink is another bubble wrap option - always seeing life through rose colored glasses

And then there's me being me... Cut out leaf shapes of green bubble wrap, and flower shapes of pink bubble wrap and make stained glass bubblewrap mosaics!
Ok. I've had too much tea this morning :)

Cool replies!
I'm totally down with the stacking, I'm iffy on the collecting.
I don't want to need too much of anything, free or not.
That's why I considered the string of beads method, to avoid needing 24 bottles to go two feet!
Now you got me wondering about the interactions of the plastics, I realize that I want the bottle wall to be impervious to water, but I don't care how.
If I could glue or melt the bottles together I would.
Silicon is expensive, but I do have a scavenged vat of flooring adhesive that promises to dry clear.
PET bottle plastic will shrink up when exposed to quite mild heat,it melts at 491 F, but now we are getting into more complexity.
At a certain point, we might want to forget the whole idea, if it is more expensive in time, energy or money than seeking out a sheet of glass.
Also, PET definitely degrades when exposed to UV, mores the pity.

Right now, I'm seeing more and more application of the bottles as insulation stuffed into  a north facing pallet walls along with dry soil, than on glazing side of the equation.
I like the idea that they could be retrieved and recycled, when the structure starts to fail, or otherwise needs to be dismantled.

William Bronson wrote:Cool replies!
I'm totally down with the stacking, I'm iffy on the collecting.
I don't want to need too much of anything, free or not.
That's why I considered the string of beads method, to avoid needing 24 bottles to go two feet!

Good point!
To me collecting them isn't a problem, I do it as a hobby :) Digging in trash is my stress reduction. I don't have money to do things, and I'm in a tiny town where isn't a lot I care to do at best, so I dumpster dive for fun. But I realize it's not a fun thing for most people :)

And yeah that stack section there is a large amount of bottles. It did what I wanted it to, and was worth the experiment to me.
There are better ways to insulate though. The bubble wrap is worth considering. What about multiple layers of bubble wrap? I wonder at what point you block too much light?

I have used a double layer of 3/4" bubble wrap for 2 years now. Works very good. Comes in a 4' x 250' roll for under $100. No mold issues, great diffused light, plants are A+++ with no shade cloth needed.
I do however think using bottles could work extremely well if care is taken in installation. I would only used bottles with caps, labels removed and no tape as it will deteriorate in the heat. If you are concerned with the air gaps, then maybe put the bottles in a zip lock bag first.
Best of luck and may your experience be fruit for all those who follow.

I like that Lorne,    "may your experience be fruit for all those who follow" - you should put it in your salutation :)

Pearl you're a woman after my own heart :)   But it's true that these kinds of projects take a LOT of scavenging.  I once thought I would do one of those cool roofs out of tin can lids for my chicken coop.   I saved mine and got everyone I know to save them but after a year I still only had enough to do about 4 sq ft so I gave up and used asphalt shingles that were a free Craigslist find.  I hate anything derived from the "P" word (petroleum)  but we have to be practical sometimes - at least I repurposed someone else's trash and saved it from the landfill.

William are you in or near a city?   It seems once a week I see someone giving away old window sashes on Craigslist.    I have a pile of those too for cold frame  projects :)  But that's another time consuming collection process so I'm quite sure if you called a couple window replacement companies, they'd give you all you can use pretty quickly.  10-20 for a whole house renovation.    Then you'd just need some lumber for simple framing (pallets and 2x4s -  and screws (get your screws now before the tariff wars start price inflation!)  

Pearl do you think your taped bottle contraption would work as a mini greenhouse to put over my young rosemary bushes this winter?     I cannot keep a rosemary alive thru winter.   I've tried deep mulch of various types, and a burlap cover to no avail.  It could be taped into a cylinder and add a cover for the cold nights that can open during warm afternoons.    

Susan Pruitt wrote: Pearl do you think your taped bottle contraption would work as a mini greenhouse to put over my young rosemary bushes this winter?     I cannot keep a rosemary alive thru winter.   I've tried deep mulch of various types, and a burlap cover to no avail.  It could be taped into a cylinder and add a cover for the cold nights that can open during warm afternoons.    

Absolutely!
And if you leave the bottles intact and fill them with water, you have just added a bunch of thermal mass to it. There are things for sale that do this:

Wall O Water
Even leaving them empty, or with some gravel for wind resistance, would help a lot. 
Low budget Wall O'Water!! Customizable for the size you need...

Lorne,  good to hear that it's working so well for you.  Are your double layers of bubble wrap with the bubbles facing each other - smooth sides on the outside?   That's probably allowing more air circulation between them, mitigating trapped moisture,  as opposed to two layers of smooth plastic together.   

I have the bubbles facing each other. Without adding heat this allows me to get an average overnight temperature of +10 degrees over real temperature at daybreak.