domingo, 23 de dezembro de 2007

Novoram_Novas Possibilidades

John Novotny, a Melbourne resident, has developed a very simple and innovative method of rammed earth construction that results in houses massively cheaper than conventional ones and with amazing environmental benefits. Mixing the ancient universal simplicity of earth with modern engineering principles, Novotny developed a concrete-jacket rammed-earth wall system (“Novoram”) that is simple to construct and structurally robust. The resulting walls are built mostly of earth but have a thin concrete jacket and concrete posts integrated into the wall.

O texto seguinte foi retirado daqui:
http://www.greenleft.org.au/2007/735/38047

Worldwide, building construction and use accounts for around 40% of greenhouse gas emissions (materials, actual construction, heating, cooling, lighting etc.). The use of green building materials and construction techniques must be a key element in the drive to curb global warming.
One of the most widely applicable green building techniques also happens to be one of the cheapest. John Novotny, a Melbourne resident, has developed a very simple and innovative method of rammed earth construction that results in houses massively cheaper than conventional ones and with amazing environmental benefits.
Now 82 and a convinced socialist (he recently joined the Socialist Alliance) he passionately wants to see this technique widely used to benefit ordinary people and contribute to a better world. Facing persecution by a Stalinist regime, Novotny fled Czechoslovakia in the late 1940s and ended up in Australia. His interest in building really only developed in retirement when, travelling between California and Mexico, he came across an old adobe (mud brick) mission building, still standing solidly centuries after it was built. Novotny set about developing a more modular version of the earth construction he had seen in Mexico. He looked at earth buildings from around the world as well as the post-war development of low-cost earth building techniques in Australia by what became the CSIRO.
Mixing the ancient universal simplicity of earth — earth buildings house over half of the world’s population — with modern engineering principles, Novotny developed a concrete-jacket rammed-earth wall system (“Novoram”) that is simple to construct and structurally robust. The resulting walls are built mostly of earth but have a thin concrete jacket and concrete posts integrated into the wall. By introducing the concrete posts and shell, the buildings have a uniform engineered minimum strength. Regular mud brick, cob or rammed earth walls vary in strength according to the composition of the soil that is used. The concrete jacket overcomes a major hurdle to the use of earth — the excessive red tape surrounding the assumed structural weakness of earth buildings. Because earth walls are generally made of earth from the building site itself, this minimises emissions from transporting the primary building material. Also, because the earth is unbaked, and is simply rammed into the formed wall spaces, the energy embodied in manufacturing the walls is extremely low compared to straight concrete, bricks or timber.
A case study of a 320-square-metre Novoram home revealed that only 129 kilograms of CO2 were produced to compact the unprocessed earth walls, compared to 70,000kg to simply manufacture the bricks for an equivalent-sized brick home! Moreover, earth buildings have a high thermal mass and therefore superior thermal performance. Thick earth walls (300mm or greater) maintain a stable mild temperature but will also soak up and re-radiate the warmth or coolness in buildings. This means that they keep buildings cool in summer and warm in winter, and will actually maximise the effectiveness of space heaters, heat from the sun, or air conditioners. As a result, so long as they are properly insulated from the outside environment, buildings incorporating thermal mass walls require far less heating and cooling.
If a significant portion of buildings nationwide worked on thermal mass principles and incorporated other “passive” design features including insulation, sun shading and passive ventilation, there would be substantial energy savings. Several large power stations could be shut down and major emissions reductions achieved. A study conducted in 2000 by Victoria’s Sustainable Energy Authority (SEAV) into a house at suburban Clyde North made using Novotny’s Novoram technique is testament to the environmental performance of its earth-based construction.
Tony Isaacs, manager of SEAV’s building performance department, stated in a letter to Novotny: “The rating of this house is five stars, however, its performance far exceeds that of most five star homes with a predicted energy use almost half of the maximum allowed for five stars. In addition the performance of the house in summer is such that it is likely to need very little artificial cooling. Of the 1200 houses assessed by SEAV since 1995 only 12 have achieved higher ratings, making this house one of the most energy efficient ever built in Victoria.” Since the Novoram system is based on using earth as the main building material, houses made using the technique are quite literally “dirt cheap”.
Raw unprocessed earth, as opposed to solid concrete, brick, or timber, is free in virtually all cases. In most cases the earth excavated in order to lay the foundations for a building (which usually goes to landfill) is sufficient to fill the walls. Because the walls are earth-filled they also have excellent (sound deadening) acoustics and are not prone to fire. Given the structural soundness of Novoram walls, as well as their environmental friendliness, low cost, and acoustic and fire performance, the system has clear and enormous potential to be used not only for housing, but also in schools, universities, hospitals, small to medium office blocks etc.
Upon developing the jacketed rammed earth system to a “commercial”, modular system (a system which Novotny says is so simple it can be constructed quickly using unskilled labour), Novotny approached a number of commercial organisations and the Victorian government to see if they were interested in trying the system out.
A state government official in charge of building performance told him that the “r” value of the wall (its thermal conductivity) was “too high” and that because the wall did not insulate effectively, the environmental benefits of the system were minimal. This shows a complete non-comprehension of the basic principle of thermal mass — and a highly irrational and unscientific obsession with “insulation” as the sole benchmark of eco-friendly building materials.
Novotny also approached big housing developer AV Jennings and reports that the company’s architects at first seemed genuinely interested then failed to follow up. Presumably they were told by higher authority not to waste their time on something which could only reduce the company’s profitability. What are the best available solutions to the social and environmental functions that buildings must perform?
This question cannot be solved under capitalism. The housing and construction industry is intimately linked to the manufacturers of bricks, timber, concrete, steel and aluminium. The choice of building materials used is determined not by what is most socially rational but by what is most profitable to these interests. Social and environmental needs come a distant second behind the drive for corporate gain. A raft of environmentally and socially friendly technologies and systems like Novotny’s earth construction method are waiting to be plucked from the patent offices and put widely into practice by a social system which actually values their social utility. [John Novotny is seeking to build more homes using the Novoram system and to show other builders how to build using his concrete jacket rammed earth method. For more information email .]

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