[Cob] Thermal attic/PET offgassing?

[Jill Hogan]

In South Africa the early settlers use what they called a fire attic. They used reeds as viga's or a ceiling. They then put woven mats on top of the reeds or thatching grass to stop the cob falling through the ceiling. On top of that they put a good healthy layer of cob. This gives the most wonderful insulation. But not only insulation it was called a fire attic because if the thatch caught alight only the roof burnt and nothing below this. We had confirmation of this two years ago here in McGregor when one of these old house's thatch caught alight. The only damage to the furniture and house below was water damage from the fire hoses. Can't see plastic bottles would give you this protection in fact know someone to my horror uses plastics bottles to light his barbecue.

We predominantly use this method now.

Regards Jill
McGregor Alternative Technology Centre
"MAT"
023 625 1533
www.mat.org.za

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  ----- Original Message ----- 
  From: Shody Ryon 
  To: coblist at deatech.com 
  Sent: Sunday, April 05, 2009 8:33 AM
  Subject: [Cob] Thermal attic/PET offgassing?



  Here is what I am thinking about this, I think building with thermal storage, super insulation and a sun space or solar furnace, if done in a thoughtful manor, in colder climates, reduces other energy requirements reduces cost and is therefor green in a very important way, and is a responsible way to build. 
  This can be important in hot areas too, although hot areas have the option of thermal earth coupling or low thermal mass. I do not know the pros and cons of these different options, but I tend to think I would prefer super insulation and thermal storage in a separate (from the living spac) insulation envelope.

  I am not sure, but I assume there are cool areas of new mexico, depending on the elevation.   

  I have been thinking that I would build enough shelves for 2L PET bottles and then use any and all containers of any sort, and if it works, fine and if I find that glass works well, I could up grade over time as I collect them.

  I think polyethylene is a fairly low risk plastic, especially if it is used for the short term. I agree with view point of reducing plastic, but just a reminder, there in a lot of plastic in most peoples lives, many computer, car parts, seat belts, food wrappers and storage containers, water and soda bottles, medical supplies, clothing, work gloves, protective tyvek coveralls, tools, electrical cords, electrical outlets, switches and cover plates, beds upholstery and clothing, shade cloth, micro irrigation tubing, on and on which are made from plastic and may be harder to deal with than shelves of containers.

  So common alternatives to plastic water bottle thermal storage are fire, electrical heating elements and gas heaters. Granted this thermal storage system requires thousands of bottles, but the heat would probably be in the 150 degree F range, while the others are in the 1,500 F or higher range and have other consequences too.

  Shody


        

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