An ecological footprint highlights human impact on the environment through specific, measurable terms usually relating to a type of material that can be diagramed from manufacturing to use. To understand the impact of a single material, such as clay brick, there must be a cataloguing of the process of excavation, manufacturing, and transportation. In the architectural realm, clay bricks are often used for convenience, but the actual process of creating and transporting clay bricks obviously consumes energy and produces waste affecting the health of the environment and the distribution of resources.
Despite the fact forming clay bricks is less harmful than other building materials, such as glass and chemically formed plastics, clay bricks do take a toll on the environment. By examining the life cycle of a clay brick it is possible to make observations that can potentially alter the process of excavation, manufacturing, and transportation, which allows for a cleaner, more efficient means of production. The Life Cycle Analysis or LCA of clay brick categorizes the various environmental impacts, including climate range, stratospheric ozone depletion, human toxicity, eco-toxicity, photo-oxidant formation, acidification and nitrification.
It is now a common practice to make the LCA of specific materials accessible on the job site as a reference to monitor how an ecologically-friendly process compares to the more traditional practices of the past. By providing a benchmark, it is easier to track the life cycle and easier implement small changes that will lead to a significant difference in the final ecological footprint of a clay brick. Energy and material use can be categorized in the life cycle of brick in two ways. There is the primary use of materials and energy, such as the clay and stone that physically make up the brick.
Then there is secondary energy that is required in the machinery that is used to excavate or to form the brick. Energy for these processes has traditionally been provided through fossil fuels, as a non-renewable resource, some companies have replaced using fossil fuel with more environmentally friendly choices such as, biogas and liquefied rendering fat. From these two types of energy use and consumption comes material and energy waste and emission. To begin, clay and stone, the main material of brick, is excavated from a quarry.
Here energy is consumed by the machinery used to retract the rock. Despite the plasticity of clay compared to many other types of excavation, bracing and support may still be needed for the extraction. With the bracing and support more energy and more resources are consumed. Also, with the clay and rock now gone, there is possible destruction of a habitat along with a new likelihood of erosion due to the large hole created by the excavation. This can lead to long term, if not permanent dangers to the habitat and its creatures.
The future use of the site for any other building and excavation can also be determined by the extent of excavation. The process continues with delivery to the manufacturer. Energy is consumed through fuel consumption, emissions from the delivery vehicle, and heat radiation of its engine. The manufacturing process can now begin with clay processing, continuing on with the brick formation, brick drying and finally firing the brick. Initially, the clay is crushed, ground and screened to reduce it to a fine consistency. Then, depending on the type of clay being used, water is added or taken out.
The stiff mud process, the process most common currently, places clay with 12 percent to 15 percent water into a vacuum to remove any pockets of air. The new bricks are then cut and placed in a kiln to dry for one or two days. During the cutting and drying processes, the cut away parts of the clay are lost, thrown away as waste, the material is no longer used in the clay making process. They then continue on to the firing process in which the bricks are places in an oven as hot as 2400 degrees for 40 to 150 hours. Throughout this part of the steps, co2 is emitted from the burning fuel .
Also as a part of the firing there are fuel emissions and energy waste as a result of machinery use that leads to co2 being released into the air and other heat pollution that can affect the ozone. Those same wastes continue with the packaging of the product and the transportation of the bricks to construction sites. Eventually the bricks make it to their destination where they are used. Combined with mortar, the bricks are used to build walls, or in walkways, etc. , and the actually construction of such structures only adds to the extent of clays bricks ecological footprint.
Technically, pure clay bricks are completely recyclable. Unfortunately due to the building process the bricks come into contact with common building materials that ultimately compromise the of clay bricks. However, in some cases the bricks are eventually taken down, either to be replaced by new bricks that have followed the same process or just to demolition the structure they inhabit. In this deconstruction step, there is cleaning and crushing that requires labor and that also releases atmospheric emissions.
With the crushing process completed, the brick pieces can be reused by taking them back to the initial manufacturer to be reformed into brick. By doing this the bricks formed from the reused pieces are more efficiently produced and in turn the ecological footprint is lessened because the excavation process is skipped entirely. Clay Bricks are usually referred to as a sustainable product. The only real energy consuming aspect of them comes when the raw materials are quarried or the bricks are fired.
When just making the bricks, the energy consumption ranges from 1840-2800 kj/kg. However, recently that number is much higher because it is becoming increasingly common for the bricks to be fired in a “tunnel kiln in which fire remains stationary and bricks are moved on kiln cars through a tunnel divided preheat, firing and cooling zones. ” With this added energy use, 800-1250 kj/kg is added to the total energy consumption of bricks. As seen in the last step of a clay bricks LCA, there are ways to decrease the energy usage of clay brick production and use.
Other than simply reusing materials, another way to make for more efficient production is to combine the areas of production to a unified space so less energy is consumed by transportation and travel. By housing the excavation area, the manufacturing area, and the packaging area into one facility could save transportation costs and energy consumption and waste Also, buyers and contractors can do more accurate calculation to ensure that they are ordering the correct amount, not more than needed as that would lead to more waste and energy loss.
Another method to decrease bricks environmentally impact could lie in the ability to ensure the bricks integrity and recyclability. Many of these ideas are being adapted into construction processes as the LCA of materials make it easier for people to understand the waste that is the consequence of production and use of materials such as clay brick. This proves that awareness is a significant factor in changing human ecological footprints. Essentially clay, as a raw material, is pure.
The environmental impact of clay bricks begins with emissions when clay has been fired, not when clay is in its raw state. It is possible to reduce the emissions caused by the various stages by compacting the out going sources into one factory and ultimately condensing the energy consumed and waste produced. Also, to help maintain the sustainability of clay bricks it is possible to recycle the product in its final state rather than generate new bricks for the same purpose.
The clay brick itself is not a source of waste, rather, the energy required to create a new brick, therefore it is important to recycle clay bricks. By closely examining the ecological footprint it is possible to observe what steps in the process can be altered or improved to stop overusing materials and harming the earth. In essence, by condensing sources and recycling it is possible to continue maximum productivity while eliminating the ability to create a larger ecological footprint by using clay bricks.
http://www. scribd. com/doc/8746950/Clay-Brick-LCA http://www. staywithclay. com/downloads/SustainableBuildingConference-Italy. pdf http://linkinghub. elsevier. com/retrieve/pii/S0360132306000795 http://www. ibstock. com/pdfs/technical-support/TIS16Howbricksaremade. pdf Fundamentals of Building Construction, 4th Edition, Allen and Iano
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