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RE: GSBN:FW: 3-layer passive insulation?

I don't think I understand the material described.  As I envision the
straw/paper sandwich, I have trouble understanding how it will work.  It
sounds like there will be multiple straw-to-paper-to-straw interfaces.
This would imply that no straw connects the inside to the outside of the
bales.  How are the different layers held together?  Are the inside and
outside surfaces plastered?  Does the plaster key into a layer of straw?
To what extent can this design act as a stressed-skin panel?

Like John, I have doubts about the convection question.  Convection is a
gravity-driven, largely vertical phenomenon.  It seems odd that vertical
divisions within the wall would have a major effect, and even more odd that
the paper dividers are said to be less important in horizontal insulation.
I would love to hear more information.


Derek Roff
Language Learning Center
Ortega Hall 129, MSC03-2100
University of New Mexico
Albuquerque, NM 87131-0001
505/277-7368, fax 505/277-3885
Internet: derek@...

--On July 20, 2006 11:33:36 AM -0700 John Swearingen
jswearingen@... wrote:

Sounds interesting.  Also sounds like a lot of work.  I wasn't aware that
convection within the bales was so problematic.  Then again, we have very
tight, dense bales, and it would seem that breaking them into flakes would
lower the density more than paper would help convection.

Sorry I can't make it to Czechia this weekend to help out.

John "Flakey" Swearingen

John Swearingen
design and construction

-----Original Message-----
From: GSBN [<a  target="_blank" href="mailto:GSBN@...";>mailto:GSBN@...] On Behalf Of Joyce
Coppinger Sent: Thursday, July 20, 2006 10:14 AM
Subject: GSBN:FW: 3-layer passive insulation?

Has anyone heard of or used the three-layer passive insulation method? Any
comments about it's effectiveness?

From: Jan Hollan jhollan@...
Reply-To: European strawbale building discussions
Date: Thu, 20 Jul 2006 00:19:20 +0200 (CEST)
To: European strawbale building discussions
Subject: [Strawbale] Volunteers for 3-layer passive insulation?

We will insulate one wall of the building (author: Georg W Reinberg)
being currently constructed there. At least 3-ply straw sandwich (40
cm thick) will be used.  Well separable layers taken from jumbo bales
will be employed, about 7 cm thick (taken as pairs in this case). At
wall, they will be separated by paper, at least each 14 cm of
thickness. The purpose of dividing straw by paper is to suppress heat
transport by convection to almost negligible values (convection takes
place just inside the individual chambers of 1/3 thickness, at 1/3
temperature drop and less then 1/3 flow speed, so the total convection
heat transport is about 1/10 of the case with just a single undivided
straw layer). Such suppression is a prerequisite to achieve
passive-house U values of about 0.1 W/m2K.