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[Strawbale] Fw: [FWD] rainscreens, straw decay


Ref. rainscreens/tolerable moisture levels. Very useful website below Brian

http://www.buildingscience.com/documents/digests/bsd-112-building-science-for-strawbale-buildings/?full_view=1




Ref. Rainscreens:
When I started my design of strawbalehouse I was concerned about keeping moisture levels in the bales at an acceptable level and unhappy about just using roof overhangs to keep the walls dry because this area of the UK (the Lake District) is the land of horizontal rain. No amount of eaves overhang would be satisfactory and a veranda would be out of place. So I have totally covered the bales with clay tiles and the chimney effect created by the ventilation air entering at gutter level which is one meter up and exiting at the ridge at 7.5meters should draw plenty of air over the exterior of the (lime rendered) bales. This natural draw should be amplified by any solar warming of the tiles. To see more visit www.strawbalehouse.co.uk and/or ask for detailed sketches from myself. Unfortunately, I am the first to admit, my design will have no credibility until I can build the prototype to prove it's predicted performance. (I have been fighting the planners for two years) Brian
----- Original Message ----- From: "RT" <ArchiLogic@yahoo...> 
To: "GSBN" <GSBN@greenbuilder...>
Cc: "SB REPP" <Strawbale@listserv....org>; "Euro SB" <strawbale@amper....muni.cz> 
Sent: Saturday, February 28, 2009 7:35 AM
Subject: [Strawbale] [FWD] rainscreens, straw decay




========= Forwarded from SB-r-Us @Yahoogroups =======

Hello.

Iâm a graduate student at Nihon University researching the
interstitial hygrothermal environment of straw bale buildings in Japan. I 
have
several questions on a couple of different topics.

1.           Iâm monitoring eight straw bale buildings in Japan.
Generally, interstitial humidity and straw moisture content increases
towards
the exterior.  Comparing indoor and outdoor humidity levels suggest that
rather
than exfiltration or diffusion of indoor moisture, external moisture is the 
primary cause of interstitial moisture.  Iâd like to investigate the
influence of rain screens on the interstitial environment.  It may be too
much
to build identical straw bale structures, but I could build two or more
straw
bale walls protected from any unintended moisture.  The structure of the
walls
would be identical except that one wall would have a rain screen. I could 
spray the walls with a measured quantity of water (in liters per minute)
and
monitor interstitial relative humidity and straw moisture content.
The recent conversation on ventilated rainscreens has been helpful. Thank 
you.  Iâm looking for construction details of straw bale walls with rain
screens to share with an architect.  Iâve found rough wall sections in
Kingâs âDesign of Straw Bale Buildingsâ, Minkeâs âBuilding with
Strawâ, and Chirasâ âThe Natural Houseâ.  If any one could provide
construction details or detailed photos, Iâd be grateful. (Thank you John 
in
Australia and Andrà in France for the descriptions.)

2.           I removed samples of straw from two straw bale structures
at our research center.  Samples of straw were taken from around five
temperature and relative humidity sensors.  One structure has been
monitored
for six years, the other for two years.  The condition of the straw was
analyzed for mold and decay.  63 times magnification revealed fungal
hyphae in
what was to the naked eye clean straw.  A Yamaco MT-700 C-N Corder was
used to
measure total carbon concentrations.  As fungi digest straw, they consume
the
carbon in the straw and give off carbon dioxide.  The percentage of total
carbon in the straw should, in theory, decline as the straw decomposes.
Carbon
concentrations were compared with new straw from 2008 grown and dried at
our
research center.  As expected, the straw from around sensors with a
history of
high relative humidity had the lowest carbon concentrations.
              For those who know more about this then I, is total
carbon a good measure of straw decomposition?  What other tests could be
done
to determine the extent of straw decomposition without samples of the
original
straw at the time of baling or building?  I was considering comparing
stable
carbon isotopes C12 and C14.

3.           Iâd like to submit a paper to the Journal of Asian
Architecture and Building Engineering, a peer reviewed Journal sponsored
by the
architectural associations of Japan, China, and Korea, by April 8 for
publication in November.  Would anyone be interested in helping me with a
statistical analysis of the carbon experiment described above? Last year I 
received help with a paper from a couple of people on this list.  Many
thanks.

Kindest regards,
Kyle Holzhueter
Nihon University
Graduate School of Bioresource Sciences
Architecture and Regional Ecological Design Studio
1866 Kameino Fujisawa-City Kanagawa-Prefecture 252-8510
JAPAN


TEL/FAX (81)466-84-3364


http://hp.brs.nihon-u.ac.jp/~areds/
http://www.cnes.brs.nihon-u.ac.jp/

============= End of Forwarded Material ============

--
=== * ===
Rob Tom
Kanata, Ontario, Canada
< A r c h i L o g i c  at  ChaffY a h o o  dot  C a >
(manually winnow the chaff from my edress in your reply)
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