Talk:Inga's House/Invitation

I'm a materials scientist, so here are a few thoughts, mostly regarding locally-available materials:

I've read many good things about rice husks as insulation. They are naturally flame retardant and have good insulation value, and I seem to remember reading that they can be improved by pyrolysis, which gives a structure that is partly carbon and partly silicon carbide. I understand that some structures in Ireland and elsewhere are built with two isolated layers of masonry, with an air gap for insulation, and it has recently become fashionable to blow loose insulation into that air gap.

I also like the idea of plaster and/or whitewash sealed with water glass. The chemical reaction is CaCO3 + Na2SiO3 = CaSiO3 + Na2CO3. Two OH can be substituted for CO3, and/or K can substitute for Na. Water glass can be made from wood ashes and silica-containing minerals; a similar process was discussed on this site as a way of purifying colored glass. CaSiO3 is not water soluble, and has a greater volume per mole than CaCO3 or CaOH; this swelling closes pores in the surface of plaster, whitewash, or concrete.

In my opinion, wood is a better plan for structural pieces than homebrew synthetic polymers, for now. If decay of wood is a concern, there are several options to treat wood before it is painted. One option is the afroementioned water glass. Another is acetylation. Your pyrolysis system should be able to produce acetic acid, which preserves wood by turning some of the cellulose into a rayon-like material. If you do a little more organic chemistry, you can make acetic anhydride, which does the same thing but works better. As a side note, methyl acetate may be worth considering as an engine fuel if the pyrolysis system produces more acid than oil.

If you would like to make paint on site, obviously flax can supply drying oil for the binder, and natural thinners include citrus oils and turpentine. Less obvious is that plant pigments can be processed into lakes (mineral powders precipitated onto organic dyes) to give those paints color. Lithopone is the only homebrew non-toxic opaque pigment I know of, and I don't think it's worth it if you can live with translucent color. I imagine paint will only be necessary for woodwork, since many pigments can be added buon fresco to wet plaster, and need no binder at all.

A three-stage recirculation system for a potable-water swimming pool (like the one described in the letter) is shown in moderate detail in Mollison's Permaculture Designer's Manual. That book seems to recommend channeling blackwater under a half-pipe to the root system of an orchard. I'm not sure why you would want to generate blackwater, though...I could imagine improving your composting toilets with a downdraft exhaust and a system that blows sawdust into the container using a fan, perhaps based on this open-source cyclonic dust separator. It could be operated by pushbutton or automatically by a gas sensor (H2S sensors are also available).

My username is polyparadigm in several different contexts, including wikipedia and gmail.

Best,

Joel