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The SUDU – the Sustainable Urban Dwelling Unit – is a low-cost housing prototype built with local materials and local labor, utilizing techniques analogous to vernacular Ethiopian building technologies. The premise of the project is to design for a combined goal of environmental and economic sustainability.
1: By utilizing the cheapest of Ethiopian resources (soil), and the skill base presumed to be present in working with soil construction technologies, the construction industry in Ethiopia can thereby reduce its reliance on imported, expensive, and high energy-intensive building materials such as steel and concrete. Further, through this expense reduction, the SUDU may become a model low-cost housing unit for the urban poor.
2: One of the most challenging present problems for Ethiopia, and Addis Ababa in particular, is the tremendous deficit in housing for the urban poor, coupled with the statistics of population growth in Ethiopian cities. This is reflected in the ubiquitous informal housing, comprising perhaps 80% of the built environment of Addis. While the most common vernacular, Ethiopian construction method – construction with Eucalyptus and mud – is an economically and environmentally sustainable method of construction, the great limitation of such constructions is that they do not address the problem of necessary of urban density, the limitation of the land available and the expense of this land.
Thus, this vernacular technology has been more recently replaced by large urban housing projects of reinforced concrete – massive edifices of concrete and steel, which neither offer a model for frugal, environmentally or economically sustainable construction, nor do they offer a low-cost alternative to housing, as driven by the expense of their construction. These constructions are being built all over Addis Ababa, displacing massive numbers of squatters in informal housing networks, who cannot afford to be relocated to such housing units, and are therefore relegated to the growing numbers of urban homeless.
The SUDU in an exploration of a “medium ground” between single story informal dwelling and massive scale urban density, as studies have shown that even a 2-story urban density dramatically impacts urban density.
3: Thus, the goals of the SUDU are to build to two stories in soil – a significant challenge without the aid of imported steel, concrete or milled lumber.
By adapting local soil knowledge to the production of soil stabilized tiles, however, it is possible to introduce the technology of timbrel vaulting (thin-shell vaulting technique developed in Spain) to allow floor and roof systems of pure compression, without the excessive requirement for such imported materials. The timbrel vaulting technology is a radically minimum-material construction system, by virtue of its catenary structural efficiency and by virtue of the use of plaster mortar, which eliminates the need for comprehensive formwork.
4: My role, as the ‘visiting expert’ on timbrel vaulting construction, is to ascertain if/ how timbrel vaulting can be considered as an ‘appropriate building technology’ for the skill base of local workers, if/ how such a method of construction can be trained in Ethiopia, and also what are the risks involved in the introduction of a new technology of unreinforced structural masonry, both for the safety of workers and the ultimate reliability of structural masonry shells built by untrained labor.
Photo by C. Lippuner
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