First of all, I applaud anyone who is seeking sustainable solutions for building technologies, as these are essential for our continuing health and success as a species. The aspects of the concept presented for manufacturing building blocks from rice straw and cement that I would consider sustainable are:
- One component (the straw) is a surplus renewable material that when utilized will take it out of the waste stream and avoid possible air pollution from burning it.
- The straw is free, which lowers the cost of the production
- The straw-cement blocks can be produced locally by relatively unskilled labor, again lowering costs
- The resultant blocks provide better insulation values than conventional concrete blocks.
- Every component (clay, sand, water, straw) is potentially free
- Every component has little embodied energy
- These materials are potentially available on site, or locally
- These building blocks can be used in load-bearing walls, or for other compressive purposes (which the straw-cement blocks cannot)
- The mud bricks provide nearly as much thermal resistance as the straw-cement blocks (R-1 per inch)...neither of which is very impressive, especially in a hot climate, but at least the mud blocks provide better thermal mass, so under certain circumstances they will perform better thermally.
- Mud bricks can be "stabilized" with a relatively small amount of Portland cement (or asphalt emulsion) for use in circumstances where a greater degree of durability is required.
- Mud bricks can be produced with relatively unskilled labor.