Twinwall Polycarbonate Sheets with Vacuum Seal

[mechanicalchad]

I find ourselves in situations that often require that we put up a shell that keeps out the rain and wind. However, cost is always a factor and I am always looking at ways to do this more economically.

I know that twinwall polycarbonate sheets allow sunlight to come through, and if there was a vacuum, could be a very good insulator too. Polycarbonate sheets could then basically act as both my cladding and insulation, and replace the need for lights providing a triple advantage, if there was a vacuum of course. Basically a big greenhouse.

Does anyone know if anyone makes, or could make such a product? The bigger the sheet the better. I'm located in Alberta, Canada.

Thanks,
Chad

 

[MikeHalloran]

This is made from translucent white polyethylene:

http://www.homedepot.com/p/Coroplas...te-Corrugated-Plastic-Sheet-CP4896S/205351385

https://www.homedepot.ca/en/home/p....-157-inch-x-48-inch-x-96-inch.1000171722.html

I remember the polycarbonate version as being _much_ more expensive, despite its many fine qualities.




Mike Halloran
Pembroke Pines, FL, USA

 

[moltenmetal]

Plastic materials are at least somewhat permeable, so you'd have to convince me that a vacuum, once drawn, would remain over the long term. Each panel would similarly lose its vacuum everywhere you put a screw through it to mount it, or had to cut it, so you'd be looking at building frames around the edge of each panel. Basically what you're asking for is more or less a double-glazed window thermal unit, except made out of polycarbonate rather than glass. Note however that unlike in a window, there's a thermal bridge between the inside and outside layer at each corrugation/rib in a corrugated polycarbonate sheet, and that probably already dominates the heat transfer between the two sides irrespective of whether the inside of each cell is filled with air, argon or vacuum.

 

[MikeHalloran]

This may be of interest. The contraption in the photo cools my travel trailer using a small cheap window air conditioner, on a normal 15A circuit, as opposed to the roof unit, which draws somewhere upwards of 22A when starting. The various adapter boxes are made of Coroplast, folded to suit, with edges joined by staples and 1/2" square dowels, sealed with Gorilla Tape.

The Coroplast does not sweat, suggesting that its insulating properties may be sufficient for your purposes, even without the vacuum. Certainly a double layer would work for you, and the stuff is pretty cheap.