No. 47, May 2000
Desert Architecture for a New Millenium
by Katherine Waser
"Pima County (along with the City of Tucson) has been much more open to permitting the use of alternative materials. This exhibit, arranged by the Pima County Building Department, was planned as an educational event to promote awareness of regionally available and appropriate alternatives to conventional, wood-based building products."
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The exhibit crammed a wealth of information-gathering opportunities into nine hours, by means of seminars and exhibit booths. Some 27 vendors exhibited both traditional and commercially developed building products. Three seminars ran concurrently during every hour of the entire exhibit. In general, the exhibitors were also the seminar-givers. I decided to attend the overview, adobe/rammed earth, and straw bale seminars, then visit the exhibit booths.
Throughout his talk, Eisenberg stressed the need for the building industry and consumers alike to place more emphasis on the legacy of building materials--that is, their effects on the environment not just during the life of a building, but also during their own manufacture and after the useful life of a building is over. Currently, where building codes exist they typically focus merely on not harming the physical safety of the occupants of a building during its lifetime. This idea that "buildings should do no harm" should be expanded to include what happens before the building is constructed and after it is no longer used.
After Eisenberg's talk, I attended Paul McHenry's presentation on adobe as the quintessential global/local building material (5). McHenry's slides showed a rich diversity of adobe structures from around the world, and his accompanying talk combined both personal reminiscences from his long career and technical observations on the nature of adobe and regional aspects of its use. For example, in the US where building is largely regulated by building codes, those codes that allow adobe construction at all typically restrict its use to two stories at most (6). Yet, several of his slides of multi-story dwellings, typically in the Middle East, belied the need for this restriction. His slides of a 1972 trip to Iran showed that the adobes there are typically smaller than those traditionally used in the southwestern U.S. and Mexico. These smaller bricks lend themselves to the construction of barrel vaults and vaulted arches, a considerable advantage in regions where virtually no wood is available for making roof-supporting beams and lintels.
From Europe, McHenry showed slides of rammed earth structures both humble and aristocratic. Europe's cold and wet climate has led to such regional adaptations as the use of stone foundations to keep the earthen walls out of snow, and roofs with large overhangs to protect the tops of the walls - their most vulnerable point - from erosion. In South America, the Incas raised carved and decorated adobe walls atop stone foundations that were so intricately and tightly fit together as to withstand centuries of seismic events. Unfortunately, the adobe walls themselves are more susceptible to earthquakes, and this is one of the major problems to be overcome with adobe. Another problem is that, due to its very ubiquity and low cost, adobe has become associated with poverty in many areas, despite its many advantages.
The seminar on straw bale construction was given by Matts Myhrman and Judy Knox of Out On Bale (7), an organization that has been active in promoting the straw bale revival of recent years. Myhrman and Knox illustrated their comments with slides of straw-bale structures, both new and old, from around the world. For example, one current program they focused on is a UNDP project to build straw bale health clinics in Mongolia. Throughout their talk, Myhrman and Knox stressed that straw bale is a building technique that should be explored and promoted in any area where significant amounts of grain crop residues are available. Many types of straw are usable, including wheat, rice, rye, barley, and oats. Among the many environmental benefits of straw bale construction is the possible role of such construction as a viable mechanism for carbon sequestration (8). This is a role that definitely needs further testing and consideration.
Myhrman and Knox emphasized that the basic technology of straw-bale construction is well understood; what's needed now is lots of local experimentation, to make the technology accessible in a wide range of areas and with a wide range of materials. In fact, bales could potentially be made with materials other than spent grain. For example, various construction projects have used shredded paper bales. Elsewhere, straw bales are being used to construct vaulted roofs, sometimes with bamboo ribbing. Ancillary roof products, such as roof skin materials using recycled latex paints and cellulose-based roof insulation, are also being tested. In short, throughout their talk Myhrman and Knox strongly promoted the idea of extensive, grass-roots experimentation to refine and adapt this technique to local circumstances.
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I found one such tool in the notion of "Life Cycle Analysis," a "cradle-to-grave" analysis that can lead to a better understanding of a material's true long-term costs (18). This concept is still very much being refined and developed as a practical tool, and is most often used to consider buildings as a whole system. However, I also found some documents on applying LCA to building materials in particular. In one such schema from the University of Michigan, building materials can be analyzed in terms of the following three phases:
In the long run, evaluative tools such as LCA will probably be most useful to product manufacturers, as they work to design more sustainable products. However, in the meantime, such tools can help architects, builders and consumers begin to evaluate a product's sustainability and incorporate that information into their product decisions.
In order to compare products at all, however, they must first know what products are available - and that's where events like the Pima County Alternative Building Materials Exhibit come in. As an educational event, this exhibit was a complete success, and the organizers and participants alike deserve thanks for their efforts. I'm hoping for another email from the Pima County Building Department soon - this time announcing that the Pima County Alternative Materials Exhibit will become a yearly event.
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(2) David Eisenberg is the Director of the non-profit Development Center for Appropriate Technology (DCAT). DCAT supports the development and use of sustainable approaches to meeting human needs through the appropriate use of technology. A major DCAT focus is addressing the institutional and technical barriers to sustainable and restorative development and construction. DCAT's web site (http://azstarnet.com/~dcat/) houses a wealth of materials on straw bale construction in particular.
(3) A 1993 article from the Environmental Building News, "Cement and Concrete: Environmental Considerations" (http://www.buildinggreen.com/features/cem/cementconc.html) looks at how these materials are made and reviews environmental considerations concerning their production, use and eventual disposal.
(4) Athena and Bill Steen are co-authors of The Straw Bale House, a well-known sourcebook for straw bale building. Through their books and other publications, and through workshops held at their homestead in Canelo, Arizona, they promote the creation of simple, comfortable shelter using local and natural materials. The Canelo Project web site (http://www.caneloproject.com/) has a good article on their straw bale work in Ciudad Obregón, Mexico (http://www.caneloproject.com/pages/articles.html#officebldg). as well as photos of the work done there on the "Casas que Cantan" (http://www.caneloproject.com/pages/cqc.html) and the Sonoran Save the Children Federation office building (http://www.caneloproject.com/pages/stc.html).
(5) Paul McHenry is the Managing Director of the Earth Building Foundation, Inc. (http://www.earthbuilding.com/), formerly the Earth Architecture Center International. He has more than 30 years of experience with adobe around the world. Please see Mr. McHenry's article in this issue of ALN for more adobe stories.
(6) According to material from The Natural Builder (http://www.naturalbuilder.com), the New Mexico State Adobe Building Code of 1991 (http://www.naturalbuilder.com/nm%20adobe%20code.html) restricts buildings using "masonry of unburned clay units" to a two-story maximum. The City of Tucson, Town of Marana and Pima County, Arizona Earthen Building Code (http://www.naturalbuilder.com/cobcode.html) restricts earthen buildings to one story or 16 feet in height, unless the structure is designed by an engineer or architect and approved by building officials. The City of Boulder, Colorado, Adobe Code (http://www.naturalbuilder.com/Boulder%20adobe%20Code.html) imposes the same general restrictions as does the Tucson/Marana/Pima code.
(7) Matts Myhrman and Judy Knox have been involved in experimenting with and promoting use of straw bale construction since 1989. More information on their activities, and a series of online articles about straw bale, are available from the Out on Bale web site (http://www.azstarnet.com/~dcat/outbale.htm). A closely related site, DAWN/Out on Bale by Mail, (http://www.greenbuilder.com/dawn/default.html), acts as an information resource center and mail order business.
(8) Carbon sequestration is a strategy aimed at helping mitigate the effects of global climate change. It refers to the removal of carbon dioxide (CO2) from the atmosphere. This CO2 is then stored in 'carbon pools' such as forests (in temperate climates), soils (in arid climates) and, in this case, in buildings. David Eisenberg's "Comments in response to the White House Climate Change Conference Local Meeting [Tucson, Arizona, October 6, 1997]" (http://www.azstarnet.com/~dcat/climate.htm) provide more information on the possible usefulness of straw bale construction as a carbon sequestration technique and gives practical suggestions as to how such potential could be further researched and exploited.
(9) For more information on Blue Maxx, contact:
(10) The E-Crete Company does not currently have a web site. For more information on E-
(12) Fi-dobe does not currently have a web site. For more information, contact:
(16) Rastra Blocks are manufactured and marketed by several licensees world-wide, so no one contact address can be given. The easiest way to obtain further information is electronically:
(18) I found several good documents on sustainable design and sustainable materials at the University of Michigan's Sustainable Architecture web page (http://www.umich.edu/~nppcpub/resources/compendia/architecture.html#sdes). The documents are available either as PDF files for free, or as paper documents for a small fee. The documents in the "Sustainable Building Materials Module" were particularly useful for their application of the principles of Life Cycle Analysis to building materials alone, as opposed to a built structure in its entirety. Another interesting online document I found is "Building Materials: What Makes a Product Green?" (http://www.buildinggreen.com/features/gp/green_products.html). This January 2000 online report from the Environmental Building News describes how EBN editors developed criteria for judging the appropriateness of building materials for inclusion in their "GreenSpec" Directory.
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Katherine Waser is the editor of the Arid Lands Newsletter.
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Center For Maximum Potential Building Systems
This non-profit education, demonstration, and research organization based in Austin, Texas, has more than 70 years combined experience in the application of appropriate technologies and sustainable design practices. Its principal aim is economy of means in the construction and operation of human habitats and the support systems.
Sustainable Building Sourcebook
This online sourcebook is a product of the Austin, Texas, Green Building Program, which was recognized at the 1992 Earth Summit by the United Nations Local Government Honours Programme as one of 12 exemplary local government initiatives from around the world. Aimed at residential building in the Austin area, the Sourcebook nonetheless contains a lot of information that is applicable in other areas, as well.
House of Straw - Straw Bale Construction Comes of Age
This 1995 online report from the US Dept of Energy details a demonstration project to build low-cost, energy-efficient housing for the Navajo Nation, located in the arid southwestern United States. Navajo community leaders wanted housing that boosted the local economy, used local materials and labor, and maintained the integrity of their culture. The final design that was agreed upon was a unique combination of "Nebraska-style" straw-bale walls and adobe walls with passive solar orientation.
Straw: The Next Great Building Material?
This URL leads to a series of articles from the Environmental Building News concerning straw bale and other straw-based construction materials.
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