The clay at the excavation of the basement of the
was kept for cobbing. The main structure of the house is 2 x 4. The
inside and outside walls were plastered with a clay mix. Komai, which
is a traditional bamboo net used for cobbing in Japan was tried out,
but it took too much time. Therefore, only an inside wall was done in
this way. The other surfaces were nailed with battons. Following the
Japanese way, a mixture of clay and cut grass was used. But due to
miscommunication, sand was added to the first coat. In the second and
third coats, cement was added to the mixture.
In the Japanese way, a mixture of
clay and cut rice straw grass are
plastered over a Komai net as the first coat, making keys on the back
side. Time has to be allowed for the first coat to dry, after which
there will be some cracks which serve as keys for the second coat. Some
sand has to be added to the mixture of the second coat, and the surface
cracks are smaller. After drying, the third coat with more sand and
finer fiber is applied. For a finishing surface, rice gruel or glue
from sea weed, for instance, gloiopelitis, can be mixed as a bond.
At the experimental house the 2 x 4 structure contains an air gap of
about 14cm wide. A variety of porous material was used in separate
sections to fill the gaps to avoid air convection. Later on each
section will be compared with a heat rate meter. The materials used for
filling include crinkled newspaper, crinkled plastic, bulrushes, fiber
glass and wool fleece. The windows and doors are triple glazed in
different styles. Later, heat flow will be measured in different
styles. When the thermal conductivity of bulrushes filled in a 12cm
width of the 2 x 4 wall is estimated at 0.063, the overall coefficient
of heat transfer is 0.43 - which compares equivalently with that of a
commercial modern wall.
nature-friendly material from the local area.