Insulation is measured by R-value, the resistance to heat flow. The R-value of wood is 0.2 per inch, brick is 0.05 per inch – the higher the R-value the better the insulation.
Research done in Arizona found both wheat and rice straw to have a R-value of 0.5 per inch across the grain, giving strawbales a R-value from R6 to R9, almost 10 times the insulation factor of a double-brick cavity wall.
Strawbale walls therefore allow a house to be highly efficient in heating and cooling. Strawbale walls:
• dramatically increase the efficiency of a solar-passive construction, and can reduce the need for any heating and cooling equipment
• because of their increased insulation, allow installation of heating or cooling systems smaller than those in conventional homes
• provide substantial savings in gas, electricity and wood-fuel bills
• are 30 times less energy-intensive than wood-frame walls to manufacture.
Values per inch. The R-values are measured in imperial measures, the numbers in parentheses are their SI equivalents.