[Strawbale] convection in S-house walls

Jan Hollan jhollan at amper....muni.cz
Mon Jun 16 12:07:28 CEST 2008

Having to describe S-house as an example to the new edition of Czech
brochure ``Passive House'', I've encountered some old graphs showing
temperatures inside a strawbale wall and four text boxes where straw had
been replaced by another plant-based insulation stuffs. At the first glance
it seems that the measurements ``are somehow wrong''. However, in my
opinion, they demonstrate how different is the situation in a thick wall
(50 cm insulation thickness) compared to the lab with a hot plate above
the sample. Convection seems to play a role even in the fine-fibre
cellulose infill. And the neighbouring convection cells affect the
temperatures too. Having just a pair of thermometres in fixed positions
gives no detailed answer what proceeds in the porous cavity (twenty times
the amount would say more). See the graphs at

or the first published ones within page 150 of the pdf file available
at http://www.hausderzukunft.at/results.html/id3133
                Endbericht (4.7 Mb)
  URL:  http://www.hausderzukunft.at/hdz_pdf/endbericht_shouse_id3133.pdf
 (the schemes of boxes and of the measurement geometry is some pages
before that).

I guess even the heat flux measurement plates are being affected by the
exact positioning with respect to the several nearest convection cells --
of course I'd be glad to see the results...

(The strawbale sensors seem to be placed just in the cold part of the
convection loop, guessing from the three graphs available on the net).


More information about the Strawbale mailing list