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World is reaching a critical stage where we have to take serious action against the threat of global warming The construction industry is a significant part of any economy and contributes both positively and negatively to the quality of life. This important sector provides employment to 1.5 million people and also contributes 10% to UK GDP, However. According to the Worldwatch report (2001), the industry accounts for 40 per cent (approximately three billion tons) of the total flow of raw materials into the global economy every year. The production and processing of these materials impacts heavily on the landscape, and can cause air pollution, toxic runoff into watercourses, and loss of forests and agricultural land (Crossley, 2002). Therefore there is a big responsibility and pressure on to the construction industry to construct more sustainably.
The concept of sustainability was probably intuitively understood by early human civilizations such as the South African Bushmen. These hunter-gatherer people recognized the importance of utilizing the resources provided by nature on a sustainable basis and had practical experience of the fact that humans are dependent on the Earth' s life support systems for survival (Van der Post and Taylor, 1984).
Sustainability was not identified by the construction industry in the past but nowadays they became famous and considered as a business opportunity. Also Construction companies planning to develop sustainably need to carefully look into their operations in four key areas: energy, materials, waste and pollution
The term `sustainable construction' was originally proposed to describe the responsibility of the construction industry in attaining `sustainability'. November 1994 saw the holding of the First International Conference on Sustainable Construction in Tampa, Florida, United States of America. A major objective of the conference was `to assess progress in the new discipline that might be called "sustainable construction" or "green construction" (Kibert, 1994a),..The conference convener, Kibert (1994b), proposed that sustainable construction means "creating a healthy built environment using resource-efficient, ecologically based principles".
One response to the confusion inherent in the term `sustainable construction' would be to revert to the use of the term `sustainable development'. Sustainable construction is one of the subject of sustainable development. Sustainable development is a path that we can move towards Sustainability. Sustainable development mainly focussed on improving the quality of life for all without increasing the use of natural resources.
Sustainable construction deals with Minimising environmental impacts, Maximising user health, satisfaction, productivity and Minimising whole life cost. Actually it doesn't have to be more expensive. Basic advantages of sustainable construction are reducing operating costs, insurance against future energy price increases and environmental regulations, other litigable operational benefits such as improved productivity and performance, reduced absenteeism & health problems and an enhanced reputation
Both public and private sectors are willing to understand sustainable construction practices. Because of this reason the demand is continuously increasing. The practices not only helping the environment but also improve economic profitability and create strong relationships with stakeholder groups.
For construction to be sustainable there must be an efficient use of materials with an increase in the use of recycled materials. Traditional construction costs represent 10-20% of a building's total life costs, 5% of which are due to wasted material. A study carried out by BRE revealed that nearly 20% of all construction wastes in UK are materials that are delivered to site and never used (BRE, 2009). In an effort to make the construction industry more sustainable; building regulations now require every project to have a site waste management plan (SWMP). This encourages a greater control on waste. This is an extra benefit of minimizing the amount of material sent to landfill and economic benefits of less landfill tax. It also provides a greater incentive to recycle where possible (CIB, 2010). Using material more efficiently as part of sustainable construction leads to greater economic efficiency of the both construction industry and country (WRAP ,2002).
Sustainable construction can be implemented through regulation, planning policy and use of innovation technologies .Sustainable policy may be enforced through the construction regulations and codes. It can be included in the construction process by formulating a sustainable environmental plan, specifically designed for a project. It may then be implemented and managed through the construction process by allocating specific responsibilities within the construction team. Implementing sustainable construction is the responsibility of all parties, the client as the promoter of a scheme should be an active member of the team in ensuring sustainability. The designer is also essential, in terms of material choice and the contractor is fundamental in terms of method of construction (Gyadu-Asiedu, 2007). The relationship between the different parties is important, as there is a greater chance of success if all parties work together, sharing information and experience.
Technology is a very important role in sustainable construction. The reason behind this are that is one of the way we interact with environment, we use it to extract natural resources, to modify them for human purposes and to adapt our man-made living space. It is through use of technology that we have seen drastic improvements in the quality of life of many people. Unfortunately, many of these short term improvements in the immediate quality of life have also exacted a great toll on the environment. In order to move toward sustainability, we will have to be more deliberate and thoughtful in our employment of technology. We need to develop and use technologies with sustainability in mind. We need "sustainable technologies." (Moore 1972, p. 5).
There are many ways that the construction industry is able to introduce greenfull environment both locally and globally. They are Recycling of materials rather than using all new construction materials, it is often desirable to utilise materials salvaged from buildings which have been demolished. Bricks and tiles are a good example of this, Minimise transportation costs. By sourcing materials locally we can cut down on the amount of fossil fuels involved in transporting goods to the construction site(Aircrete, 2010), Renewable energy sources include wind, wave and solar power. These sources of energy are limitless and replenish themselves constantly. They create no harmful by-products and, after an initial expense in constructing the means of harnessing the energy, is essentially free, Solar power is a type of renewable is probably the most established. Humans have been using heat energy from the sun in simple ways to heat their homes and water for thousands of years( Farret & Simoes 2006. We have all hung out washing to dry on a sunny day and found it to be very effective, Wave power that could be generated by the movement of waves is incalculable. There is more than enough potential energy in the seas and oceans of the world to meet all mankind's energy needs many times over. The problem we have is how do we harness that energy?, although wind turbines are very tall, they don't actually take up much ground space and it is possible to graze sheep and cattle in the same area, as there are no emissions or by-products likely to contaminate or harm livestock.
Construction sites have an impact on the environment local to a site. These impacts include interfering with daily life of a community, with dust, mud, noise, traffic congestion, safety and visual intrusion ( Couto & Couto 2007). Some of these impacts can be reduced by simple changes to site processes. For example, noise adversely affects the local community, especially noise resulting from the use of pneumatic hammers, compressors, concrete mixers and communication amongst workers. This impact can be minimised by considering each piece of equipment and by locating the noisiest equipment at the farthest possible point from residents. Noise can also be reduced by using off-site manufactured materials which minimises the on-site use of high power equipment. Simple changes can have accumulative positive effects on site noise levels; such as using ready mix concrete instead of mixing it on site and using walkie-talkies for communication instead of screaming at operatives. Noise can also be reduced by carrying out work properly the first time, minimising the need to cut out work and start again (Couto & Couto 2007).
UK Government introduced the Strategy for Sustainable Construction On 11th June 2008.Main aim of strategy to take long run view on how UK construction becomes more sustainable and move towards to achieve the targets of UK sustainability .The Strategy has released in a number of initiatives including Constructing Excellence, the ICE Demolition Protocol, Materials Resource Efficiency in Regeneration(WRAP, 2010). In order to launchÂ of the Sustainable Construction Strategy, the CSU's Â 'HYPERLINK "http://www.berr.gov.uk/files/file34979.pdf"Review of Sustainable Construction 2006HYPERLINK "http://www.dti.gov.uk/files/file34979.pdf"'Â that was published in October 2006 was taken into account.
Against these backgrounds, if ever there was an industry best placed to demonstrate the business case for sustainable development, it has to be the construction industry: where competition is fierce and profit margins are low. The UK government has challenged the industry to take the lead in achieving a sustainable society and improving the quality of life, in terms of employment, housing, utilities, transport infrastructure and the surrounding built environment. Sustainable construction is the application of Sustainable development to the construction industry. That is, equal consideration of economic, social and environmental issues in delivering construction projects. To promote more sustainable construction, several national initiatives have been initiated and documents. The most notable point among others is a strategy for more sustainable construction "building better quality of life" (DETR, 2000), which recommends key action themes to kick-start adoption of more sustainable practices within the industry.
Sustainable construction is an oxymoron
1.3 Aims and Objective
Having provided some background context on sustainability, this section will now outline the principal aim and Objectives of this Dissertation.
Principal aim of this dissertation is to prove that sustainable construction is possible and being undertaken.
The main objectives of the Dissertation are:
To provide a general overview of what is meant by sustainable construction
To investigate how sustainable construction may be implemented.
To investigate the possible barriers to sustainable construction.
To investigate the advantages and disadvantages of sustainable construction.
To investigate possible changes to the construction process to make it more sustainable.
1.4 Scope of the Dissertation
Due to the time constraints placed upon this dissertation. It is identified that significantly more primary research on possible barriers to sustainable construction and how sustainable construction may be implemented are possible, but in practice not within the companies of the dissertation. This dissertation primarily looks at the U.K construction industry.
1.4 Structure of the dissertation
Chapter 2 Reviews the literature on the concepts of Sustainability and sustainable construction.
Chapter 3 Details the research methodology utilised.
Chapter 4 Outline the Primary research analysis
Chapter 5 Outline the Finding and analysis
Chapter 6 details the conclusions and recommendations for the further research.
Chapter 2.0 LITERATURE REVIW
2.1GENERAL OVERVIEW OF WHAT IS MEANT BY SUSTAINABLE CONSTRUCTION
2.1.1 INTRODUCTION TO SUSTAINABLE DEVELOPMENT AND SUSTAINABLE CONSTRUCTION
Sustainable development is the process by which we move towards sustainability. Sustainable development focuses on improving the quality of life for all without increasing the use of natural resources beyond the capacity of the environment to supply them indefinitely. As defined in 'The Brundtland Report' (1987):
In general, sustainable construction is used to describe the application of sustainable development within the context of the built environment. The discourse and practice around sustainable construction often focus on the efficient processes of construction, use of materials, availability of technology and other technical facets, which do not compromise the health of the environment or the associated health of the building occupants, builders, the general public or future generations (Rydin, Y. & Vandergert, P., 2006: 5).
"Development that meets the needs of the present without compromising the ability of future generations to meet their own needs"
The awareness on sustainable development is growing widely around the world for the last few decades. Many international and national meetings, as well as conferences were held to develop awareness on the concept of sustainable development. These conferences include UN Summit on Environment and Development (1972) and the UN Earth Summit (1992) in Rio de Janeiro
2.1.2 Triple Bottom Line of Sustainable Development/Construction
It is important to acknowledge and identify the other aspects of sustainable construction. As a whole, sustainable development or sustainable construction comprises of three broad themes of social, environmental and economic accountability, often known as the 'triple bottom line'. The objectives of these three themes are (Constructing Excellence, 2004):
To recognise the needs of everyone impacted by construction, from inception of a project to demolition. The list will include construction site workers, local communities, the supply chain and people that will use the finished product.
To protect the environment from the impact of emissions, effluent and waste and where possible, to enhance it and use natural resources, carefully.
To increase profitability by making efficient use of resources, this includes labour, materials, energy and water.
2.1.3Strategies for Sustainable Construction
There are many mandatory as well as voluntary strategies, aimed at encouraging and enforcing sustainable construction practices in the construction industry. One of the earliest strategies for changes in the construction industry has started with the publication of 'Rethinking Construction' in July 1998, which is famously known as The Egan Report. This report has criticised the under-achievement of the construction industry and hence, has urged for changes and improvements in delivering construction projects.
Following the Egan Report, the UK Government has taken an initiative in promoting sustainable construction through the publication of 'Building a Better Quality of Life' published by DETR in 2000. Within the publication, the government has suggested the following key themes for action on sustainable construction strategies by the construction industry:
Re-use existing building assets
Design for minimum waste
Aim for lean construction
Minimise energy in construction
Minimise energy in use
Do not pollute
Preserve and enhance biodiversity
Conserve water resources
Respect people and local environment
Set targets (i.e. monitor and report, in order to benchmark performance)
Later in March 2005, the Government has further emphasised its commitment towards sustainable construction through the publication of 'Sustainable Development Strategy, Securing the Future'. As a substitute to the previous strategy, this publication has proposed four key themes for action, as follows:
Natural resources protection and environmental enhancement
Climate change and energy
Sustainable consumption and production
2.1.4Drivers for Sustainable Construction
In promoting and encouraging the take up of sustainable construction, the UK Government has introduced more stringent legislation and fiscal policies such as Revision to Building Regulation Part L, Landfill Tax, Quarry Tax, Aggregate Levy and Climate Change Levy. It has been acknowledged that legislation is the main driver for change towards sustainable construction. However, there are also other drivers, which play significant roles as well.
These other drivers include (Vetter, A. et al., 2006; DBA, 2002):
In a highly competitive field, sustainability is becoming a potent differentiator, capable of providing a vital competitive edge.
The new technology and innovation such as Modern Method of Construction and Leans Construction could offer many benefits such as increase speed of construction, costs savings and better delivery of products and services.
Requirements from funding bodies
Funding bodies are laying more stress on the risks associated with unsustainable development. The risks will affect future profitability and shareholder value.
"The construction industry is coming under increasing pressure to make its activities more environmentally acceptableâ€¦good practice on site to preserve our environment is now usually a high priority for clients, their professional advisors, contractors and regulators".
Sustainable construction has increasingly gain popularity in the construction industry. It has been recognised as the way forward to improve the performance of the construction industry in the UK.
2.2 HOW SUSTAINABLE CONSTRUCTION MAY BE IMPLEMENTED?
The construction industry produces approximately 70 million tonnes of waste each year; of which 13 million tonnes consists of material delivered to site but never used (BRE 2009). It also has a very poor health and safety record with the third highest fatality rate when compared to other industries. In addition, it contributes to the depletion of non-renewable resources by employing inefficient construction processes and using unsustainable materials. It is obvious therefore, that the construction industry must become more sustainable by implementing policies that reduce waste, promote the use of sustainable materials and use these materials in an efficient manner. It can also be implemented, by using innovative technologies that use renewal forms of energy, either by harnessing the energy of the sun, wind or water (Meisel 2010).
Sustainable construction can be implemented through regulation, planning policy and use of innovation technologies and by improving the current construction methods. Sustainable policy can be enforced through construction regulations and codes. The government are committed to sustainable development and are changing planning policies to reflect this commitment. They have set out their planning objectives in planning policy statement 1 (PPS1) stating the developments must be built in "the right place and at the right time" (ODPM 2005:p.2). PPS1 (ODPM 2005) requires developers to build quality developments that have minimal impacts on the environment including impacts such as air pollution, noise, visual intrusion, land contamination and light pollution. It requires builders to consider the materials used in construction and to minimise the use of non-renewal resources and waste. It also requires planners and developers to consider the sites where developments are planned. Those involved in the construction industry, from planners, developers, designers and contractors must consider the long-term effects of developments. In order to protect the natural landscape and environment they are encouraged to choose higher density developments on brownfield sites over lower density developments on greenfield sites.
The 2009 Renewable Energy Directive sets a target for the UK to achieve 15% of its energy consumption from renewable sources by 2020. It aims to achieve this target by providing financial support for renewable technologies and developing emerging technologies (DECC 2009). This can incentivise the construction industry to become more sustainable through greater use of new technology.
Unsustainable resources such as fossil fuels are the main source of electricity generation in the UK. Burning fossil fuels contributes to CO2 emissions, which increases the likelihood of global warming. In the UK 33% of the electricity generated comes from burning coal, 32.5% from gas and 26% from nuclear energy. These processes resulted in approximately 150 million tonnes of carbon dioxide and 19000 tonnes of methane, both of which are greenhouse gases. The UK government is committed to reducing carbon dioxide emissions by up to 60 per cent 2050 (DTI 2006). The construction industry can help reduce reliance on these non-renewal resources by increasing the use of innovative technologies in developments and in this way become more sustainable.
2.2.2 Innovative methods of implementation
Innovative methods of generating energy harness naturally occurring resources such as the energy from the sun and wind. These technologies include using solar power for heating and generating electricity, harnessing wind energy to generate electricity and using ground source heat pumps as a source of heat for buildings.
Solar panel technology converts the radiated energy from the sun into heat and /or electricity ( Farret & Simoes 2006).There are three main types of solar panel technology. Flat Plate Collectors use heat collected from the sun to warm a liquid that circulates through these thermal solar panels. This warm liquid then passes through a coil in the water tank, which in turn heats the water stored in the tank. They can be used; in either residential units or commercial uses and could potentially reduce carbon emissions by up to 400kg per year on an average domestic system (Doty & Turner 2009). This system is easy to integrate with other heating systems and can reduce hot water energy costs. The units are not visually intrusive and can reduce the reliance on fossil fuel technology (Twidell & Weir 1986). Photovoltaic panels (PVP) use solar cells to generate and store electricity from the sun's energy. The panels are easily fitted to a roof, do not emit noise and are not visually intrusive. It can also reduce reliance on mains electricity and as such improves the sustainability of development (Doty & Turner 2009).
18.104.22.168 Wind turbines and wave power
Urban wind turbines generate electricity by turbines. The turbines can be fixed to a building or clustered to provide electricity for a community. Alternatively, large wind farms can be built either offshore or on land. The use of wind energy over conventional methods of generating electricity include; low level of greenhouse gas emissions; the fuel supplies are from a sustainable source and supply will not deplete; the fuel is effectively free and does not have to be imported; wind turbines are relatively quick and easy to construct and there are no waste products . Wave power that could be generated by the movement of waves is incalculable. There is more than enough potential energy in the seas and oceans of the world to meet all mankind's energy needs many times over. The problem we have is how do we harness that energy? Since the 1970's much research into methods of harnessing wave power has been done, but our wave technology is nowhere near as advanced as our solar and wind power technologies. One of the major problems in constructing a wave farm is that heavy waves are so destructive (DTI 2000).
Another renewal resource is biomass, which uses waste and residue material from plants and animals. This organic carbon based material reacts with oxygen in combustion and natural metabolic processes to form heat. This heat can be used to generate electricity (Twidell & Weir 1986). A biomass boiler can be used produces heat for a central heating system, which reduces conventional energy requirements. Ground source heat pumps use the solar energy that is naturally stored in soil, bedrock and ground water as a heat source. The pumps do need electricity to operate but can produce up to five times as much heat energy for every unit of electricity they use; this makes the system environmentally efficient. They may be installed as horizontal lengths of pipes buried between 1-2m below ground level. Alternatively they can be installed as a vertical system, which requires a vertical pipe system bored between 50-200 m below ground level (Meisal 2010).
2.2.3Material selection and procedures
Implementing sustainable construction should begin at the concept and preliminary phase of a construction project, preferably with the inter-disciplinary team as previously mentioned. It is at this point that an appropriate and realistic environmental policy can be set out and enforced through each stage of the construction process (Halliday 2008). The environmental plan should include a summary of the project and set out the sustainable goals for the project. It should for example, include fundamental information such the client's objective for a scheme, a list of local recycling resources and a list of suitable materials (Harden 2009). Sustainability can be achieved by using materials, technologies and processes which minimise the adverse effects of construction on the environment (Santos et al. 2007). The environmental plan should therefore detail the processes required for each construction activity and where possible should use innovative measures and materials (Cooper et al. 2008).
In choosing sustainable materials and methods of construction, the team must consider the whole life cycle of a material. The design must be evaluated against criteria such as economic performance, available resources, function, recycling and ultimate disposal of materials (Howard 2000). There are two stages to this process.
The first stage considers the end use of the project and its desired energy performance as required by the client. This stage focuses on the energy used during the operation of the building. It aims to optimise energy usage which will reduce the associated environmental impacts, such as depletion of fossil fuels and carbon dioxide emissions. The first stage takes account of the materials required to achieve design factors such as thermal mass, insulation, window glazing and other design issues. It provides a design that uses acceptable sustainable materials and identifies suitable processes necessary to construct the project. Responsible sourcing of construction products includes consideration of the whole life of the material, including its origin and its environmental impact through the life of a scheme. The origin must be considered for example whether it has been mined or harvested in its raw state; the manufacturing process; its environmental performance during use, re-use and recycling, until its final disposal as waste with no further value.
The second stage of the process is achieved during construction, followed by maintenance and finally demolition at the end of the life cycle of the building (Kashima et al.2005). A contractor can enhance the sustainability of a site by controlling the quality of workmanship and by using of machinery and materials efficiently.
2.2.3 Implementation of SWAMP and MMC
A major barrier to achieving greater sustainability in the construction industry is the volume of waste it produces each year. This barrier has been addressed through the regulatory process. It is now a legal requirement that all sites above a value of £300k, to monitor waste by implementing a site specific waste management plan (SWMP). The SWMP is set out at pre-construction stage and estimates the volume and type of waste likely to arise from the construction site. It is the responsibility of the main contractor to keep the SWMP and to check the actual waste used against that estimated. In this way it is more likely that there will be greater efficiency of material usage on site, which helps both the sustainability of the project but also has economic benefits for the construction team (CIB 2010).
The most effective method for dry construction is to use Modern Method of Construction such as pre-fabricated cladding systems and pre-manufactured units (e.g. bathroom and kitchen pods). Innovative techniques under Lean Construction such as using ready mix cement/concrete and dry plaster linings can also contribute to minimising water used on-site.
It is clear from this investigation that the fundamental ways of implementing sustainability in construction are through regulation, management, training, Renewable energy sources, material greater efficiency of site materials and each party taking responsibility for the environment, throughout the life cycle of a scheme Long term improvement in the industry can only be achieved if there is continual monitoring, assessment and management of this process. Sustainability must be company policy throughout the company, not just for a single project and not just for management. If a sustainable plan is to be successful then all parties from top management down to the unskilled site worker must be involved. The people employed in the industry must also be appropriately trained to deal with sustainability issues and appropriate sustainable construction techniques (Atkin et al, 2003). It is also clear that sustainability has a greater chance of success if the whole project team are involved from the outset.
2.3Investigate and explain the possible barriers to sustainable construction
Construction in mostly connected labour intensive sector and have a large set of stakeholders. Each member is critical important to the construction chain, therefore everyone is
Rydin and Vandergert (2006) point out the key barriers in six headings. They are cost, time, people, technology, market and legal.
Cost is considered as a major barrier of the construction. Some barriers related to cost are
2.4Investigate and explain the advantages and disadvantages of sustainable construction.
2.4.1 Advantages of sustainable construction
There are many benefits that can be obtained from the implementation of sustainable construction. For example, Yates (2003) has listed the benefit of commercial advantage through efficient construction processes in a sector where profit margins are low and adversarial conflicts frequent. Other benefits have also been identified by Addis and Talbot (2001), which include Reducing costs, Increasing productivity and staff motivation, improved management, improving business performance, Reducing risk and liability, Market growth and the opportunities for innovation, Enhanced public relations and community liaison
Sustainable construction can be achieved, through regulation and increased use of alternative energy sources. There are advantages and disadvantages associated with each of these issues, the impact of which can be local to a construction development or experienced on a regional or even global scale (Luther ,2005).Every construction project affects the environment. Adverse environmental impacts include noise, air pollution, visual intrusion, safety, global warming and depletion of resources. Some of these impacts will be a direct result of the construction processes carried out on site. Others impact will be indirect, experienced on a wider scale; for example the impact of using quarried stone on site, affects the area where the quarry is located (Smith 2003). Some of these impacts will be short term, for example noise due to a particular process on site; others will be long term, for example the energy use of a newly constructed building (Gyadu-Asiedu 2007).
There are three main types of benefits associated with sustainable construction including environmental, economic, health and community benefits (Luther 2005).
Environmental benefits of sustainable on-site construction include improved efficient use of materials; improved quality of construction and reduced time of construction on site. Sustainable construction can also lead to reduced noise and air pollution, especially in the areas local to a site. These advantages have wider benefits, including improved air and water quality, reduced energy and water consumption, and reduced waste disposal (Halliday 2008).
A major advantage of sustainable construction is the increased use of alternative energy sources, such as solar panels or wind power, biomass or ground source heat pumps. The advantages of these technologies are experienced not just on a local scale but also on the wider national and even global scale. These technologies can reduce the energy required to operate a building, making the building more efficient and less reliant on mains statutory suppliers ( Maczulak 2009). This has associated economic benefits for the building operators. When a building uses less mains energy, this equates to a reduced use of non-renewal resources and a reduced impact on the depletion of non-renewable resources. An additional benefit occurs in cases where the alternative energy system over-produces electricity as this can be sold to the mains provider ( Farrett & Simoes 2006). It could be argued therefore, that using alternative energy in construction can reduce carbon emissions and contribute to reducing global warming. The effect is accumulative as more developments are built with modern alternative energy technologies. In addition solar energy systems do not emit noise, they are not visually intrusion and are safe (Twidell & Weir 1986). Many of these technologies have wider benefits. Take biomass as an example, it is carbon neutral, as the carbon dioxide emitted during the burning or digesting process is naturally recycled (Twidell & Weir 1986). It could therefore, be used as in modern house building to achieve zero carbon houses by 2016, as required by the government. Wave power is a very attractive alternative to traditional fossil fuel sources because, like wind power, it is clean and there is an unlimited supply of it. Wave power generators would be sited offshore so there are no complaints that they spoil the natural beauty of the landscape. They do not interfere with the fishing industry and any noise they create would not be heard over the sound of the waves
themselves. This benefits the environment and makes the construction industry more sustainable.
Sustainable construction which protects the environment and helps preserve non renewable resources; can also have positive potential business benefits. These benefits include short and long-term cost reductions from waste and disposal costs, as well asÂ increased energy and resource efficiencies. It can give a contractor a competitive advantage when tendering for contracts, especially public sector contracts where minimising environmental damage is specified in procurement guidelines. It can also result in better compliance with building, environmental and health and safety regulations. More sustainable construction can lead to better relations with the local community; better staff relations because staff better motivated and better trained .The client can benefit from reduced energy and maintenance costs (Levy 2006).
Construction is an inherently dangerous industry. Statistics released by the Health and Safety Executive indicate that during the period 2009/2010, the industry employed 4% of all employees in Britain and was responsible for approximately 7% of reported injuries to employees. It also has the largest number of fatal injuries of the main industry groups, with a fatal injury rate of approximately 2.2 per 100Â 000 workers .Sustainable methods of construction such as MMC can enhance site safety by reducing the amount of work carried out on site and the actual time spent working on site. Off site manufacturing also reduces the level of noise, local air pollution and number of deliveries to a site, thus reducing the impact of construction on the local environment. This is beneficial to both the client and the contractor; as it gives the client a faster rate of return on the initial investment and the contractor has smaller overheads due to the shorter construction time (Luther ,2005).
The advantage of using innovative materials where up to 80% of the work is done off-site, can improve the safety record on site. Another advantage is the fact that sustainability requires that employer to provide better working conditions for workers. The advantage of this is that the government and the construction industry have recognised that training and development within the industry can also have a positive effect on safety (SFSC, 2008).
All the blocks and bricks used in the construction are bonded together using a soft mortar, which means that when Economic itself is demolished, the bricks can be reclaimed more easily and re-used a second time. Most of the construction is in timber. This timber is all specified from sustainable forestry and is mostly of fast growing soft woods such as Western Red Cedar, which contains natural preservatives and can therefore be used outside in its raw state without the need to be treated with harmful toxic preservatives. Where treatment of the
timber is unavoidable, preservatives used are of a 'fixed' variety, which will not allow leeching into the environment. Much of the structural work is in Masonite, manufactured hardboard that is strong and light, thus reducing transportation costs. Masonite also requires 40-65% less raw materials than conventional timber. The joinery techniques used should prolong the life of the timber and reduce the need for future maintenance. The slates on the roof are locally sourced and reclaimed from redundant buildings. Again this reduces energy expended on both production and transportation of the material.
2.4.1 Disadvantages of sustainable construction
There are also some disadvantages with alternative energy technologies. For example, photovoltaic solar panels are manufactured using the same technology as that used to create silicon chips and this involves using toxic chemicals (Doty & Turner 2009). It could be argued, that the excavation required for installing ground source heat pumps impacts on the local environment or that wind turbines are visually intrusive. However, these disadvantages must be considered as minor in comparison with benefits of these technologies. There are also some disadvantages to sustainable construction. An example is the cost of constructing a sustainable building. The capital cost of which can be typically 2 to 7% higher than ordinary buildings. While the operating and maintenance costs of sustainable buildings are generally lower than conventional buildings, not all projects can recover their overall net increased costs in a short period of time (Luther 2005).
Another disadvantage of sustainable construction is the confusion over the actual definition of sustainable construction. This investigation found that there are two schools of thought regarding sustainable materials. One school believe that sustainable construction is achieved by reusing and recycling materials. These materials should be used regardless of the energy required in the process; on the basis that nature itself is effective but not necessarily efficient. The second school states that virgin materials should be used, if the energy needed to recycle is greater than using new materials (Kibert 2008). In addition there is conflicting information on what constitutes a sustainable material. For example the construction industry is encouraged to use rapidly renewable resources, such as timber with a growth and harvest cycle of ten years or less. However these materials require a significant amount of fertiliser, water, pesticides and herbicides to achieve that growth. Some would argue that these processes are unsustainable and it could also be argued that these monoculture forests reduce biodiversity (Kilbert 2008).
Using MMC indirectly affects the sustainability of a construction site. It reduces the amount of work required on site and also reduces the number of material deliveries to the site. This minimises the impact of the construction site on noise levels, local air pollution and general disruption to the local community. There may however be a disadvantage to the wider community and road network, as it is likely that prefabricated units will have to be transported long distances from factory to the site, with negative impacts on the wider road network. Also materials will be sourced near the fabrication factory so there will the local business community is unlikely to benefit from the construction site (POST 2003).
There does not appear to be clear specific guidance available for designers and contractors. There is a need for clear and concise guidance for a construction team.
To investigate possible changes to the construction process to make it more sustainable.
The government have set out a strategy to improve the sustainability of the construction industry (DEFRA, 2005), the measures proposed changes to procurement, design, innovation and regulations. In terms of procurement, the industry is aiming to achieve improved whole life value by integrating the procurement and supply system used in projects. It is recognised within the industry that the most successful projects have been achieved using an integrated design and construction team. This involves all parties working together, the client, the designer, the contactor and sub-contractors to achieve best value for a project (Bennett & Jayes 1995).
To make possible changes to construction it is necessary to consider in the following methods. They are Gain high level support, appoint sympathetic architects, Environmental brief/code of practice, BREEAM assessment, An environmental voice on design teams
Sustainability can be also be improved by good design which, should ensure that buildings, infrastructure and public spaces are fit for purpose, use sustainable material efficiently and are designed to maximise the use of renewal resources such as sunlight. The code for sustainable design aims to improve the design process, so that issues such as energy loss, insulation, thermal and acoustic standards, water consumption and waste can accounted for, at the design stage. Final designs should aim to blend into the natural environment with minimal impact on natural ecosystems. In order to minimise the impact of the construction process on the natural environment all construction projects over £1m will require a biodiversity surveys with impact mitigation measures to reduce potential impacts. The government is encouraging innovation in the industry to improve the construction process. There are also government initiatives to reduce the UK carbon emissions to the extent that all new homes will be zero carbon from 2016, with public building zero carbon rated by 2019 (SFSC 2008).
Long-term improvement in the industry can only be achieved if there is continual monitoring, assessment and management of this process. Sustainability must be company policy throughout the company, not just for a single project and not restricted to management. If a sustainable plan is to be successful then all parties from top management down to the unskilled site worker must be involved. The people employed in the industry must also be appropriately trained to deal with sustainability issues and appropriate sustainable construction techniques (Atkin et al, 2003).
Sustainability can also be improved by changing aspects of the construction process on site, such as increasing the amount of off-site fabrication used, improving on-site processes, minimising waste and being more efficient in using materials.
Sustainable off site processes include using prefabricated units as a substitute for on-site work. An example of a prefabricated product is a panellised modular system, which consists of flat panel units, used on site to construct a three -dimensional structure or used separately to fit within the existing site structure. These units can be used for floors, walls and roof panels. (NHBC Foundation, 2006). The manufacturing process is carried out in a controlled factory environment, can improve the quality of the finished product, which is particularly advantageous as the thermal and acoustic performance of a building is dependent on the materials used and the quality of workmanship (POST, 2003).
Re-use of existing buildings. Older buildings, which may be in a bad state of repair, can be renovated and refurbished for new occupation. In some cases, buildings which may have fallen into disuse through changes in society, churches or dockside warehouses for example, can be refurbished and turned into modern flats.
The construction process could be more sustainable by reducing the volume of waste generated on site and by using materials more efficiently. Sustainable construction could also be achieved by carrying out a task once, finishing a project to a high standard and reducing the need for repairs. A site could also reduce potential environmental impacts such as noise and disruption to the local community by careful planning of construction processes.
Couto & Couto (2007) maintain that all construction processes lead to waste; with the volume of demolition material resulting from construction being twice the amount of material actually used in construction. A report by BRE found that using off site fabrication can reduce waste on site by up to 22%. This is because the manufacturing process is a more efficient process, which uses materials more efficiently (BRE , 2009). This efficiency can reduce the impact of a site on the environment by reducing the volume of waste that is taken to landfill (WRAP ,2011).
There have also been a number of improvements in the on-site construction process that aim to improve the efficiency and quality of construction, thus improving sustainability. These processes aim to reduce waste and improve efficiency including using recycled material. Examples of these processes and products include the use of Tunnel form and Insulating formwork. Tunnel form is an innovative site base MMC. It is a formwork system, which allows a contractor to cast walls and slabs in one operation. It results in a fast, accurate, quality, load-bearing concrete that is comparable to off-site manufacturing products. The formwork system uses locally produced concrete, which means less environmental impact on the road network and wider economic benefits for the local community. It also allows a better efficient use of materials, with less waste (TCC , 2010).
Increasing the use of recycled materials can make the construction process more sustainable. Only an estimated 50% of materials wasted on site are recycled. In an effort to make the industry more efficient, there are an increasing number of products that use recycled material; an example of which is Aircrete. Aircrete is a light weight form of concrete that is manufactured from recycled materials. Aircrete blocks are light, easy to use and do not need a cavity ((Aircrete, 2010). They can be used with a thin joint mortar system, which results in a more efficient product with good thermal and acoustic insulation properties. Using Aircrete can reduce waste, reduce site time and improve quality, all of which increase the sustainability of the on- site construction process.
Finally both on-site and off-site MMC could reduce the level of deliveries to site. Construction traffic currently accounts for 13% of fuel usage in the UK and the associated environmental impacts of road congestion, adverse impacts on noise, visual intrusion, safety and local air pollution (BRE, 2003). Any reduction in deliveries to site can also improve the sustainability of the construction project. Although prefabricated materials may add to the capital cost of a project, the faster construction time and less defects generally results in a quicker return on the client's investment; reduced overheads for the contractor with an increased potential profitability (Luther, 2005).
The manufacturing process is carried out in a controlled factory environment, which often leads to a better quality product and finish, when compared to site work. This can improve the sustainability of the finished product, especially as the thermal and acoustic performance of a building is dependent on the materials used and the quality of workmanship. Using MMC also reduces the likelihood of defects in construction and increases the potential BREEAM rating of the finished building (NHBC Foundation, 2006).