[Greenbuilding] [BULK] Re: Vacuum walls

[Lawrence Lile]

Seems like I remember an article where someone at MIT tried this on a
house.  


Here is my approach:  hollow recycled plastic vacuum spheres.  I was
just thinking about this the other night during yet another bout of
insomnia.  Spheroids will take the pressure better than any other shape.
A large, flat vacuum is the absolute worst shape you can have for a
vacuum bottle, structurally, since you've got 14.7 PSI crushing in on
either side.  A vacuum bottle that could fill up a stud space would have
almost 20,000 LBS of force on either side trying to crush it flat.  Not
gonna do that with plastics.  

So you blow these hollow vacuum filled spheres into the wall, or if you
make them out of 12 sided objects, they would go to a closest packed
configuration with very little air gap in between.  I am imagining
spheres that are at most 1/4" diameter. 

The path through the sphere walls would be an energy short-circuit, just
like studs are in a conventional wall.  So you want to minimize that
path, or make the spheres out of something that isn't a very good
conductor in the first place.  That's why stainless is out, not to
mention the cost. Plastic is the way to go.  

Now we just need to patent this within one year of today's date, or
someone else will grab it and we'll miss out on being millionaires.  



Lawrence Lile, PE, LEED AP
Project Solutions Engineering

-----Original Message-----
From: greenbuilding-bounces at listserv.repp.org
[mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of Chris
Green
Sent: Wednesday, August 22, 2007 3:01 PM
To: Greenbuilding at listserv.repp.org
Subject: [BULK] Re: [Greenbuilding] Vacuum walls
Importance: Low

Michael K. Lough wrote:

Ben said:
>> That being said, I would guess that--thermos wall
>>     
> cavities can't be 
>   
>> that far off. Could there be a more energy efficientdesign than that?
>>
>>     
MKL said:
>> Completely brilliant  Ben 
I say:
Agreed.
Now, how do we go about building these, and out of what? Molded, 
extruded recycled plastic, maybe? Just for a giggle, let's say we shoot 
for a machine that continuously makes thin hollow tubes, and seals in a 
vacuum as the fibre is being produced. Then another machine to simply 
chop them up and stack them into 36" long bales.
Seriously--a recycled plastic vacuum straw strawbale.
Or the fibres could be made into panels, gluing the fibres together in a

radiowave curing  chamber. Sort of like using microwaves to cure glue, 
but using frequencies that will soften plastic enough to melt them a bit

so the can be forge- or pressure-welded together.

While we're at it, we might also fill some of the straws with CO2 and 
help get rid of that for a few hundred years. That might be an option to

look into since there is a remote possibility that there might be a 
benefit in using CO2 in part of the bales or panels. What makes me say 
this is knowing about the old parlour trick of sealing one end of a soda

straw tightly with a thumb and then driving it through a potato or
apple.

If someone wants to test the feasibility of this, it shouldn't be too 
much of a problem to order a couple of cases of soda straw and devise 
some way of sucking the air out of them (old fridge compressors work 
perfectly for this...as wooden boatbuilders have discovered-- )and then 
sealing in the vacuum by plugging the ends. Once there is a supply of 
straws, and we're ready to build some blocks, the spaces between the 
vacuum straws could be filled with a runny papier mache type compound 
(no need to use papercrete here, I think.If we can avoid using PC we're 
one step ahead of the game right there. ) and left to set: additional 
moisture could be sucked out in an extra vacuum stage, if that doesn't 
compromise the papier mache.
The bricks could then be used in an infill wall arrangement. Unlike 
straw bales, they could also be used in below-ground 
elements--foundations, etc. If they can withstand the weight.
>  A bit pricy but
> if some dullard number cranker  can be prodded 
Let's work on prototyping the thermos wall first and worry about number 
crunching later.

I can't think of why this won't work. Any real engineers want to jump in

on this one?


Cheers,

Chris Green.

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