I’ve mentioned using rice hulls for use as insulaton.  They are definitely worth consideration. The biggest negative that I can see is handling.  When compared to bagged cellulose, the cost to package rice hulls in neat little bags is too high.

Today’s bag of cellulose insulation costs approximately 65 cents per cubic foot after the bag is opened.  Bags of rice hulls at the local garden center are priced at $10 to $14 per bag containing 3 cubic feet after the bag is opened.

An innovative mind is needed to figure out how to compact the rice hulls for packaging and shipping, then bounce them back to fluffy insulation when the bag is opened.  Cellulose can perform this stunt very well.

Too keep the costs for rice hulls minimal, they have to be shipped in bulk. The container being used to transport the hulls needs an open top because rice hulls are dropped from overhead storage or loaded with a front end loader.   Freight rates vary little between a short truck or a tractor-trailer; the bigger the truck, the cheaper the hulls.

If the truck is hired, the hulls must be unloaded pronto and then stored in a large container.  That scarce container has to provide a dry environment.  A trailer load, 3000 to 3500 cubic feet would be a six foot deep fill for a two car garage.

If the house being insulated is 1500 square feet with 12 inch wall capacity and 15 inch attic/ceiling capacity, 3000 cubit feet — or a trailer load.  Anything less than 12 inches in the walls or 15 inches in the ceiling will not save enough energy to make the effort valuable. According to my ‘indisputable’ calculations, 12 inches of rice hulls in the walls should equal R-40 and 15 inches in the ceiling figures up to R-50+.  That’s a very GREEN house.

Depending upon how far rice hulls have to be hauled, 3000 cubit feet will not cost much more than 2000 cubit feet.

Now for the strawbale promo.  Figuring an 18 inch wall with straw and a 12 inch wall for rice hulls. there is approximately 80 square feet more living space in a 1500 square foot house using rice hull insulation in walls over the 18 inch thick walls of straw.  Cost for the materials — straw or rice hulls — is about the same.  So much depends on what you have access to — straw or rice hulls