Sustainable Building PracticesThe AIDG is experimenting with a large array of sustainable building practices that seek to lower the cost and improve the quality of housing. The methods supported depend greatly on the local terrain and the availability of materials. Methods include, lightweight concrete, sprayed self-supporting concrete domes, straw bale construction, rammed earth tire construction, CSB construction, bamboo housing, living roof growth. Please check our projects page for more details.
Lightweight and Sprayed Concrete The use of lightweight, or acoustic, concrete for construction is something people have been experimenting with since the 1950s. The AIDG is currently experimenting with combining the use of lightweight concrete, with the use of spray concrete in housing construction.
Straw Bale Housing Straw bale housing is a technology for agricultural plains which uses straw stalk waste as a primary construction material. This straw is then compressed into bales. Which are subsequently stacked, roofed and stuccoed. Often a post beam structural support is added for roof and loft supports. When stuccoed straw bale houses look much like adobe houses and often done in southwestern style. They offer excellent insulation values (R40) and extremely low maintenance costs. It is extremely easy to tear a wall down for additions in a straw bale house, and most of the construction waste in the wall (the straw) can simply be used as a garden mulch.
Contrary to popular belief, straw bale housing is exceedingly fire resistant. Because of stucco coating on most straw bale houses, the density of the compressed straw and the high insulation value of the material straw bale houses very rarely burn, even in massive fires which destroy traditionally wood frame houses around them. When they do burn they burn slowly and primarily starting at wood joints and decorative work.
Because straw is an agricultural waste product that is often burned straw bale housing can be a very cost effective and environmentally friendly form of housing Straw bale construction has become exceedingly popular in the US in recent years and has produced a number of fire resistant energy efficient homes across the country. It is a prime example of an appropriate technology finding its way into the mainstream because of its cost effectiveness.
Rammed Earth Tire Construction
Rammed Earth Tire construction was popularized by the Earthship movement near Taos New Mexico. This construction method uses tires filled with earth packed by sledge hammers. Walls are reinforced with rebar, and converted with concrete. Structural roof elements combine with the walls to form a solid structure in a similar manner to load bearing straw bale walls. In earth ships interior walls are often filled out with soda cans and cement. Rammed earth tire rainwater catchment cisterns are often included within the architectural design of the house.
Old tires are a waste resource in many countries. Straight tire fires, most often caused by pressure combustion within massive piles of tires next to energy plants and the plants that burn the tires for electricity are terrible pollution sources. Using tires in construction represents a far better lifecycle solution for the material. It depends upon weather conditions but in favorable circumstances a tire can last over a hundred years as an element within a rammed earth tire building.
Living Roof Growth Green roof technology was traditionally used in Nordic areas as a high insulation roofing technique. Plant and grass growth on the roof promoted the capture of snow on the roof which would add significantly to the insulation value. During summer months, living roof installations also promote cooling. Solar energy that would simply heat tar is harvested by the plants for photosynthesis. Green roof design on a Ford industrial facility has led to a 50% reduction in heating and cooling costs.
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