Which Criteria Might Be Most Appropriate for Assessing the Sustainability of Building Materials - Essay Example

?The industrial and scientific progress made in the past few centuries has revolutionized the lifestyles of people. It has modified the way we travel, enjoy, communicate, and build. However, the benefits of this progress have come at a cost. The human activity has drastically affected the environment and the natural ecosystem of the planet. The resources used to fuel this economic growth (fossil fuels, minerals, fresh water, wood etc.) are being depleted at a very alarming rate. Issues such as global warming, pollution etc. has raised concerns about the future of life on the planet. Realizing the gravity of the situation, the community of scientists and engineers are now promoting sustainable practices in the various fields of engineering (Braganca, Mateus and Koukarri, 2010). This includes lesser dependence on the fossil fuels with increased power production from renewable energy resources, energy conservation through more efficient production systems and building designs and the use of sustainable and recyclable materials in construction industry and consumer goods. The construction industry currently consumes a huge amount of resources mainly the building materials such as structure steel, concrete, cement, sand, gravel, wood, and glass etc. The current annual consumption of structure steel in USA alone is 7.1 million metric tones. On the completion of its lifecycle, as the building is destroyed for renovation or incorporation of new designs, this material is usually dumped in waste land and creates environmental issues. Moreover, the materials traditionally used for construction such as masonry bricks and concrete are good conductors of heat and hence they significantly increase the energy consumption for cooling and heating the building. Operation and maintenance of buildings is also a very important concern while selecting the building materials. Deterioration of traditional building materials causes waste materials to escape in to the atmosphere. The maintenance of buildings usually causes use of the same materials with the same drawbacks. It is also reported that the traditional construction materials are responsible for toxic emissions to both outdoors and indoors of the building causing damaging effects on the human health. The above discussion shows that the traditional practices involve wastage of materials and energy and in most of the cases has deteriorating effects on the environment. It is hence of great importance that the materials used for construction must be environment friendly and sustainable. When it comes to engineering design and material selection process, it is important that the decisions are made on the basis of quantified data rather than abstract observations and experiences. It is important to measure how much a material is environment friendly or to what extent it has the damaging effect on the environment. Hence as the first step towards the use of sustainable materials in the building design, the criteria on which the sustainability of a building is measured should be specified. This paper discusses the research made in this regard and summarizes the criteria used by different researchers and in different regions around the globe. According to Oxford dictionary sustainability is defined as the ‘conservation of the ecological balance by avoiding depletion of natural resources’. With reference to the building materials, the term implies that the selection of building materials should be made considering the environmental effect of their production and usage. Such materials should be given preference which are recyclable, have none or negligible emissions, have very low carbon foot print during their production and transportation. There are several different properties which are desirable in building materials in order to increase their sustainability. The manufacturing processes for the materials should involve minimum green house gas emissions or other harmful environment effects. The emissions from the building material can also have harmful effects on the quality of air indoors of the building which in turn may affect the human health. The composition of the materials especially the insulation material should be determined carefully so as to avoid hazardous emissions. The life of the building is also an important consideration. All the investment environment friendly building designs and materials are of no use if the building does not last for a reasonable period of time. The material itself should not cause pollution when disposed off at the completion of its life cycle. The above considerations when incorporated in the building materials increase their sustainability. The use of sustainable building materials has numerous economic, environmental and health benefits. Apart from having low emissions during manufacturing and operation, these materials are easily recyclable and have reasonable service time compared with the traditional building materials. These attributes the overall life cycle cost of the building materials starting from their manufacturing to their operation and reuse. As discussed earlier, it is very important to specify criteria for the quantitative evaluation of the sustainability of building materials. This is important for the comparison and selection of building materials by the engineers. Various factors affect the selection criteria, a few of which are discussed here. The most important aspect of the sustainability criteria is the political and legislative part. It is very important that the political leadership should acknowledge the importance of the use of sustainable building materials and then make sure that the assessment criteria set for the evaluation should be widely accepted and appreciated. The political will for unbiased assessment criteria is vital to the success of the same. The criteria should be set with the objective of promoting environment friendly practices rather than protecting any business group or lobby or promoting any specific products etc. Moreover, it is important that the criteria should be protected by legislature so that it can be effectively implemented. The cultural values and background must be considered while setting the criteria. Extra points should be awarded to materials which are more easily incorporated in the existing building and construction culture of the society. For instance the rammed earth structures used in the African and Arabian countries are highly sustainable buildings because of low carbon foot print and good energy efficiency (Hall, 2007). The material is hence culturally desirable for the people in those areas but the same is not true for more urbanized societies of the west. These factors should be considered while setting the criteria. Geography of the region can also influence the assessment criteria. This can also be explained through an example. The ceramic tiles in Spain are made by locally available materials and hence the carbon foot print associated with manufacturing and usage is very low. The same tiles if used in Britain have to be manufactured through imported clay which has to be transported mostly using fossil fuel powered vehicles (Amsterdam, 2000). Hence the carbon foot print of the same clay tiles is high in Britain. The sustainability assessment criteria should hence be defined so as to award more points to the same clay in Spain but regard it less acceptable in Britain. Ethical considerations regarding the assessment criteria are also important. The personal ethics of the individuals should be in line with the assessment criteria so that the people themselves can act as the agents of change. When assessing the sustainability of a building various parameters are to be considered but the most important parameter which defines the sustainability is the use of construction materials. Each and every construction material involved in the construction of the building is significantly important while assessing the sustainability of the building. 60% of the raw materials extracted from the Earth’s lithosphere are used on construction (Bribian, Capilla & Uson, 2010: 1133). From manufacturing to installation and then recycling the construction materials go through an extensive life cycle and therefore for assessing the sustainability the life cycle assessment of all the building materials involved in construction is very important. The materials like steel, concrete and glass which are very commonly used in construction have large amount of energy changes and carbon footprint associated with them during their life cycle from manufacturing to recycling. Therefore in order to minimize the environmental impact of the building materials the assessment of sustainability is done from the extraction and manufacturing stage so that appropriate technology and methods of construction can be decided for achieving a sustainable construction. Life Cycle Assessment (LCA) does not only help in minimizing the environmental impact of the buildings but it is a very effective tool in minimizing the cost of the building. Energy behavior assessment of building materials is very necessary while deciding about the sustainability of building materials. Researches done by various organizations under the United Nations Environment Program have revealed that the use of natural building materials like rammed earth and stone masonry is environmentally the most favorable solution however certain quality control conditions do not allow the use of natural materials for construction. In such a scenario the use of artificial materials like bricks, concrete, insulation materials, glass and steel have become mandatory in all types of construction therefore while assessing sustainability these materials are more significant. When we do Life Cycle Assessment for finding out the sustainability of the materials we have to take into account all the environmental effects of a certain material or product from manufacturing to disposal or reuse (Ferguson, 2009). Another strategy for assessing the sustainability of a building is through carrying out EIA (Environmental Impact Assessment) however LCA is better because it covers all the aspects and criteria which should be checked for assessing sustainability i.e. energy and water demand in addition to carbon footprint (Mora, 2007: 1331). On the other hand EIA only undertakes the carbon footprint associated with the materials. In the following paragraphs the results for various artificial or manufactured building materials based on LCA strategy are summarized, all of these materials play significant role in assessing sustainability of any building. Bricks are very important while deciding the sustainability of building because a large difference exists in the energy associated with the manufacturing process of various types of the bricks. The variation clay content in bricks varies the initial energy demand of the bricks in the manufacturing process. Similarly the large amount of natural gas required for the manufacturing of ceramics tiles makes them high energy consuming materials and thus concrete tiles are more desirable than ceramic tiles. Another issue associated with ceramic tiles is the raw materials which have to be imported from other countries which significantly increases the energy demand and carbon footprint associated with the tiles rendering them undesirable for use in a sustainable construction (Young, 1998). Insulation materials are also very important while assessing sustainability because the artificial insulation materials like polystyrene, phenolic resins etc have a very high environmental impact as compared to natural insulating materials such as wool which has 80% less carbon footprint then synthetic insulation materials, therefore appropriate LCA should be conducted on insulation materials as well while assessing the sustainability of the building (Arnaud, 2009). Cement and Concrete though have very less impact on the environment but these are also very important in deciding the sustainable nature of building because 50-60% of the building is made up of these materials thus the minute environmental impact is maximized because of use in large amounts. Concrete is environmentally more desirable as compared to cement because it has environmental friendly materials incorporated in it i.e. crush and sand, while the manufacturing process of cement involves large energy demand (Meyer, 2009). Glass, steel and other metals are also very vital in assessing sustainability because of the large energy demands in their manufacturing process. The assessment of extent of sustainability of these materials provides guidelines for deciding between technologically synthesized alternatives (Lawrence, Health and Walker, 2009). For example after an LCA analysis of glass and EIFS (External Insulation Finish System), EIFS turns out to be much more sustainable material despite being a synthetic material. This is due to the fact that an EIFS cladding minimizes the use of insulation material as compared to glass cladding, the amount of insulation material saved also adds to the sustainability of EIFS. Therefore assessment of sustainability is a very extensive phenomenon and all the materials are significant because apparently insignificant materials affect the sustainability of other building materials (Charles, Crane and Furness, 1997). The use of wood greatly impacts the environment because trees serve as natural carbon dioxide absorbers and cutting them down for lumber deteriorates the environmental balance thus the use of wood should be minimum for sustainable and environment friendly construction. The most appropriate criteria for assessing the sustainability of a building material is Life Cycle Assessment which allows a very extensive analysis of the energy and environmental specifications of different building materials and the results derived from LCA can be used in technology selection, material selection and improvement. The most appropriate method for carrying out Life Cycle Assessment is by using the various methods to calculate the energy demand, water demand and carbon footprint of the different building material. Concurrent Energy Demand method can serve as an index for calculating the energy of any system. The energy demand calculated with by using Concurrent Energy System can be utilized for determining the energy changes involved during the manufacturing, use and recycling of a material (Hernandez and Kenny, 2010). Similarly the carbon footprint of the material can be calculated by calculating the global warming potential (GWP) of the material. The GWP of any material can be easily calculated by calculating the amount of greenhouse gases emitted during the manufacturing, use and recycling of the material (Vallero and Brasier, 2008). Similarly the water demand of the material can also be calculated during the various stages of life cycle of the material. The best methodology will be to select each material separately and calculate the amount of energy, carbon dioxide and water use associated with it during its life cycle i.e. from manufacturing to recycling or disposal. The materials which are recyclable thus are more sustainable because when they are recycled and are reused they actually replace some new material thereby saving the amount of energy, water and carbon footprint which is associated with the new material. Therefore when a material is recycled the carbon footprint, energy and water demand are added to its initial negative values of these parameters (Worrell, et al., 2001). For example if a brick has a carbon footprint of 200 kg from its manufacturing to its use till recycling, when the brick is recycled it replaces a lower quality brick which has an average carbon footprint of 120 kg during its lifecycle then the overall carbon footprint of the brick after recycling will be 80 kg. Therefore recyclable materials are highly sustainable and environmentally desirable. The criteria selected for assessing the sustainability of materials i.e. LCA can be readily applied by calculating the various parameters associated with the materials according to a set schedule. The functional unit for carrying out various calculations for the assessment is selected to be one kg of material. After selecting the functional unit the next stage is to identify the various steps in the lifecycle of the material at which the calculations are to be made. The various steps during the lifecycle include material manufacture, transportation and installation, demolition, disposal and reuse. For carrying out Life Cycle Assessment firstly the parameters important for assessing sustainability are decided and then their values are calculated at the various steps of the lifecycle of the material. LCA provides a very effective way of deciding between two alternative materials in the same location. The sustainability of the two materials can be easily assessed by comparing the values of the total energy demand, water demand and carbon footprint associated with the materials and the most sustainable material is identified as the one which has the lowest values of these parameters. Thus LCA is a very flexible method which can be applied on all types of materials in all types of situations. While deciding the sustainability of a building material a number of criteria need to be considered, these criteria are based on the overall environmental impact of the material. The environmental impact of any material can be calculated by determining the values of various parameters which include energy demand, water demand and carbon footprint. The total environmental impact of the material will decide the extent of its sustainability. Life Cycle Assessment provides a perfect model for evaluating the values of these parameters and therefore it is selected as the most appropriate methodology for assessing sustainability. Assessment of sustainability is a very extensive process and there are various direct and indirect factors associated with it, LCA incorporates the effect of all these factors in it and thus provides a very reliable analysis of sustainability of the material. References Amsterdam E. (2000) Construction Materials for Civil Engineering, Juta and Company Ltd. Arnaud L. 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