Carbon Smart Attributes
Straw sequesters carbon
Straw naturally sequesters carbon both in grain stalk itself and by storing carbon into the soil. The amount of carbon sequestered depends on the type of straw, where and how it was grown, and on harvesting methods.
Straw bale construction utilizes a waste material
Straw, as a raw material, is 100% waste of another industries (e.g. the growing of grain for food) and in many cases is otherwise burned, causing air pollution as well as release of carbon back into the atmosphere.
Straw bale construction helps preserve ecosystems
For single family residences, the substitution of straw-bales for wood can relieve the pressure to log old-growth forests, preserving ecosystems for wildlife habitat, air-quality and soil-stabilization.
Straw bale construction is a proven durable method
Properly built and maintained, straw buildings can have a useful lifespan of at least 100 years. For example, Homesteaders in the Great Plains started building with bales in the late 1800’s, and many of these structures still stand today.
Straw bale wall assemblies are naturally high performance
Straw bale construction places all of the wall elements in the right location for high thermal performance: a protective layer on the outside, ample insulation at the center, and thermal mass to the interior. Unlike similar foam-based wall systems, the bales are natural, healthy and rapidly renewable. When laid flat and stacked like bricks in a ‘running bond’ pattern, a plastered straw-bale wall is ±27″ thick, with an R-value of 1.3 per inch, or R-30 total. Stacked ‘on edge’, with straw parallel to the plane of the wall, this same R-30 insulation level is achieved in 33% less width (±18″). This is several times the value of typical insulated wood wall.
Straw bale construction can be cost-effective
The cost of construction with straw bales is comparable or less than other thick-walled construction systems.
Straw is naturally fire-resistant
Baled straw is difficult to burn, as tested in an ASTM E-84 flame spread index and smoke developed index, which established it as a viable commercial insulation solution. A lime-plastered straw bale wall assembly has been tested to achieve a 2-hour fire rating.
Straw bale walls are aesthetically pleasing
Straw bale walls can have great aesthetic value, and lend themselves to a variety of styles and finishes. The thick walls present opportunities for niches, deep window sills and seating areas.