Straw Bale insulation remains a part of the craft movement, relegated to the work of artisans and restricted from the world of commercial construction. All of this despite it’s strong thermal resistance properties, extremely low cost, and low embodied energy. This is caused by a difficulty of integrating it within standard wall sections. Straw bales require rain, moisture, and damage barriers for them to last long term. Since the goal was to optimize them for insulation, it was realized by wrapping the straw bales with Tyvek or other moisture barrier would satisfy the rain and moisture needs. Now, the wrapped straw bale could be inserted into a standard wall cavity just as easily as other commercially available products.
A mock-up was created and testing was then done to see what the effects of this Tyvek would have on the thermal characteristics and its relative performance vs. other cavity insulation products. Testing showed that wrapping of straw bales actually improved the bales resistance to transmitting heat, though the value per inch of insulation was less than that of most insulation.
In conclusion, wrapped straw bale insulation offers a cheap and environmentally friendly way of insulating a wall, as long as the cavity provides enough space for the minimal thickness of the bale.
Extracts from presentation: Wrapped Straw Bale(pdf)