Bringing Nature Home: How Natural Building Techniques Elevate Green Construction to a New Level
Environmentalism has emerged as a robust social movement that has impacted the entire United States, and the principles behind the movement are no more apparent today than in the construction industry. Advocates of green construction aim to approach the building process in a way that minimizes environmental impact. That includes using energy efficient materials and attempting to reduce construction waste. But while modern technological advances have paved the way for innovative (though sometimes expensive) alternatives to traditional construction methods, some builders, architects, and homeowners are rejecting technology and are instead consulting history for inspiration in the effort to go green. Natural building techniques harken back to a simpler time when people used the resources immediately available to them to create structures for shelter, taking into account the local ecology and climate. Today, that approach has reemerged, as many Americans are embracing natural building techniques as an often less expensive alternative to some of the modern approaches to green construction.
The word "adobe," which dates back roughly 4,000 years to ancient Egyptian and Middle Eastern cultures, means "brick" or "mud brick." Adobe structures are made from a mixture of clay, sand, and water. In certain applications, fibrous materials may be included to strengthen the substance. Regardless of the exact formula or proportions of ingredients, the wet mixture is formed into bricks and left to dry. The result is an extremely strong, resistant building material that forms the structure of some of the oldest buildings in the world.
In the United States, adobe buildings are found mostly in the Southwest, where the dry, warm climate makes it a good, sustainable construction option. The thick walls of adobe structures provide a good thermal mass, which also makes it energy efficient in the right climate.
The ingredients used in cob construction are identical to adobe; the only difference is how the clay-sand-water mixture is used to form a structure. While adobe bricks are stacked together, cob construction involves sculpting the still-wet mixture into monolithic structures.
Cob structures date back centuries in different parts of the world. In Western Europe, they became popular around the 13th century. Perhaps because of the abundance of trees in North America, cob construction never became a staple in the United States building industry; however, that is slowly changing. Cob's popularity has grown in the United States because it is one of the least expensive building techniques available. In addition, many admire cob because, unlike with traditional construction methods and architectural designs that favor 90 degree angles and square/rectangular-like shapes, cob offers endless opportunities in terms of creating interesting architectural shapes.
The concept behind earthbags is not new; however, its use in residential construction is just starting to catch on. Earthbags, or sandbags, are basically fabric sacks filled with soil. Commonly stacked to create protective barriers or bunkers in the military context and to guard against flood waters during natural disasters, earthbags are now being used as innovative, sustainable residential building materials. The sacks can be filled with whatever abundant natural materials can be found in a particular geographic area, which is both environmentally sensitive and inexpensive. From an architectural standpoint, use of earthbags has advantages similar to cob. Earthbags can be stacked in a variety of different shapes with contours not possible with traditional wood framed construction, and those shapes can be clad with additional protective coating to create architectural interest.
Bamboo, which is technically a form of grass, is widely known for its fast growth rate, which makes it an incredibly valuable renewable resource. Bamboo is also extremely strong, so it's no surprise that it has been utilized in the building process for thousands of years in Asia and tropical areas around the world. However, its use in residential construction in the United States has really taken off just in the last decade, particularly as a floor covering. Although much of the bamboo used in construction in the United States is imported, both indigenous and transplanted forms of bamboo are now harvested in various parts of the United States for use in the building process.
Straw Bale Construction
Archeological evidence suggests that our human ancestors built shelter using grass and straw. Today, millions of years later, in rural areas of the United States, particularly in the Midwest, straw bale construction is making a comeback. Bales of straw are being utilized more and more as insulation materials, as structural components, and as infill in wood frame construction. As structural elements, bales of straw are stacked together and secured with other materials to form walls, which can support a roof and which are covered with some sort of protective coating, such as plaster or stucco.
Because straw bale construction is still so new in the modern context, the process is continually being perfected. Although it is not a method commonly used in the United States yet for residential construction (in fact many jurisdictions do not permit use of the method), it has gained more popularity for use in constructing sheds, barns, and ancillary structures.
Brent Hardy oversees all corporate construction & facilities management activities for Extra Space Storage and leads corporate sustainability programs, implementing solar power, energy efficiencies and more. He writes about corporate sustainable practices at http://extraspace.com/blog/category/Sustainability.aspx.