Adobe: A Green Building Material

One of the best building materials for homes in the hot, dry climates of the desert southwest is adobe. Adobe is made from clay which is often mixed with other natural materials such as straw and even dung. The process for making adobe bricks for building is simple: The base clay is mixed with water until a proper (mixture) consistency is achieved, it is then transferred into buckets and poured into preset frames (usually wooden). The resulting wet bricks are allowed to set or cure in the frame for several hours before being removed from the preset frame and left to dry (which can take a few days). Adobe can also be poured into blocks using a hydraulic or leverage press.

Some of the benefits of using adobe or other natural earth material to construct a home (from a green building and sustainable development perspective) are:

1. Reduction of energy costs related to transportation (if you are using local material). 2. Reduction of material costs due to reduced transportation costs, especially for well-established industries (again, as long as materials are coming from the local area). 3. Support of local businesses and resource bases. A concern with regard to use of local resources is the over extraction of clay from a prime area(s). "Care must be taken to ensure that non-renewable earth materials are not over-extracted. Ecological balance within the region needs to be maintained while efficiently utilizing its resources. Many local suppliers carry materials that have been shipped in from out of the area, so it is important to ask for locally produced/quarried materials. (Source: Earth Materials website)

Growing up in the Southwestern part of the United States, I spent a lot of time in adobe homes. These homes stayed cool in the blistering summer heat without reliance on air conditioners (because of the thermal mass of the bricks) and stayed warm during cold winter seasons using fireplaces or inexpensive heating units (because of adobe's radiant heating properties).

Adobe homes are relatively inexpensive to construct because clay is a natural, sustainable building material readily available in most places. The cost of labor for making the bricks, assuming, a professional or skilled crew is hired rather than the owner making them himself or herself, should still be competitive enough to keep down construction costs for an adobe home build.

Although people living in the United States primarily associate adobe homes with the architecture of the Southwest, it's actually been used as a building material all over the world. In West-Asia, Spain, South America and throughout North and West Africa, it is the predominate building material. In fact, one-third of all human beings live in an earthen home.

One of the problems with using non-stabilized, all natural adobe is it's tendency to crack and chip as a result of weather erosion. This requires regular maintenance and/ repair work to be done by the home owner. For the most part, repairs consist of nothing more than a clay slip ( or paste) being painted over the chipped area or used as filler for cracks. Once the slip dries, the repair is complete and, generally, blends in with the original adobe brick so there is no damage to the home's aesthetics.

Mixing in stabilizing agents like cement does not always prevent cracking and/or chipping. However, the use of "super adobe", a process that hardens natural adobe, has proven to be very effective. Iranian-American architect, Nader Khalili, invented the "super-adobe" process. Khalili started setting natural "mud" walls (interior and exterior) of structures on fire using adobe bricks to concentrate the intense heat in targeted areas. The structure is more or less turned into a "kiln" and, after 3 to 4 days of cooking, the walls are hard enough and strong enough to resist both rain and wind erosion. In explaining the impetus for this revolutionary approach to green design and architecture, Khalili said,

"It's not the time that arrives with an idea. It's a place that arrives with an idea. Somewhere in the world the time is always right." ( Source: Design Like You Give A Damn, Thames & Hudson, 2006)