Like the pioneers of the late 1800s who settled in the nation’s Great Plains and baled prairie hay to use as a building material, today’s pioneers in green building recognize that straw (the stalk that remains after the harvest of wheat, rice, and other grains) has many benefits as a building material but often is underutilized or regarded as waste. Some straw is incorporated back into the soil to ensure soil productivity, some is used for animal bedding, and much is burned in the field, which has raised concern about air quality, visibility, and release of carbon dioxide back into the atmosphere. This has created renewed interest in finding alternative uses of straw. According to the U.S. Department of Agriculture’s Economic Research Service, about 78.5 million tons of wheat and rice were produced on average during 1990 to 1996. During that same period, about 123 million tons of straw were produced annually. It is estimated that between 125 and 177 million tons of straw are available each year from all grain crops, a significant percentage of which could be available for construction.
Buildings consume one-fourth of the world's wood harvest and one-sixth of its fresh water usage. In the United States, more than 40 percent of the primary energy produced annually is used to heat, cool, light, and operate our homes, offices, schools and other buildings and to manufacture and transport building materials. Building operation accounts for 39 percent of annual U.S. carbon dioxide emissions, and an additional eight percent of greenhouse gas emissions can be attributed to the extraction, manufacture, transportation and assembly of building materials.
On June 20, the Environmental and Energy Study Institute (EESI) hosted a briefing about straw-bale construction and how it can help address some of our most serious national policy challenges, such as record energy prices and unemployment, inadequate supply of affordable housing, the threat of climate change, and pressing needs in transportation and infrastructure funding. The modern building industry places heavy demands on the energy and transportation sectors. Straw is a locally-sourced, widely available, and renewable resource that builders, architects, engineers, and home owners are turning into affordable, safe, durable, and energy-efficient buildings in many climates. The following presenters discussed the benefits of using this American invention, the regulatory barriers and institutional biases against straw-bale construction, and the role of the federal government in resolving these issues.
Straw-Bale Eco House Exhibit
A straw-bale house built by Builders Without Borders is on exhibit at the U.S. Botanic Garden at First & Independence, SW (across from the U.S. Capitol), through October 13, 2008.
- Plastered straw-bale walls can have an insulation R-values of 30 and higher (up to 113 in one example), greatly reducing the need for heating or air conditioning, even in harsh climates. This means fewer greenhouse gas emissions and lower utility bills.
- Building are responsible for 40 to 50 percent of the energy use in the United States, and energy efficiency is the most cost effective way to reduce greenhouse gas emissions from the building sector.
- In addition to the energy savings seen in heating and cooling, the straw itself has much less embodied energy than other conventional building materials (i.e. less processed and locally sourced). In fact it is a carbon sink, storing carbon much like its wood cousin.
- Straw is inexpensive and widely available.
- Straw-bale construction is labor-intensive, meaning job creation in the local community.
- Straw-bale construction is a promising building strategy for many Native American communities with high unemployment and substandard housing that costs a fortune to heat and cool.
- When paired with natural plaster, straw-bale construction improves indoor air quality.
- Straw bale is a nearly ideal seismic material, making buildings safer in earthquake prone areas.
- Building code officials, lenders, insurers, architects, and contractors often lack knowledge of this type of construction and its benefits.