Rating System for Infrastructure Projects in Nigeria

Abstract

Undertaking infrastructure development projects and especially the construction of buildings in Nigeria lack sustainable green rating systems has resulted into construction practises that have caused many environmental problems. Lacking the green building rating systems has contributed to the ineptitude of construction managers and other professionals working in the construction industry in Nigeria. However, a research into the best green building rating system suitable for adoption in Nigeria shows the Green Star to be the best candidate for adoption when a research was conducted to evaluate many potential green building rating systems that are available for adoption in the infrastructure development industry in the world.

Among candidates GBRS include the Comprehensive Assessment System For Building Environmental Efficiency (CASBEE), Leadership In Energy And Environmental Design (LEED), the Building Research Establishment’s Environment‘s Assessment Method (BREEAM), the Green Mark Scheme formulated in Poland, and Green Globes. To find the best green building rating system for Nigeria to adopt, the study used the qualitative and quantitative paradigms and a statistical analysis of questionnaire responses that were administered on 350 respondents. A competitive assessment of the GBRS resulted in a high score for Green Star that was formulated in South Africa because it integrates different sections of different green rating systems, making it the best for adoption. However, there is need to conduct further research on the application of the rating system to make the Green Star more suitable for use.

Introduction

Despite Nigeria being a successful oil-producing giant in Africa that has led to a significant increase in the country’s GDP, the building and infrastructure development industry is making similar contributions to the economy, which is estimated to be 12.2% growth of the country’s GDP. However, According to Adegbile (2012), the construction industry in Nigeria is still relatively young and undeveloped because of many reasons such as corruption, the ineptitude of workers in the construction industry, poor procurement methods, incompetent contract management programs, project design changes, financing and payment problems of completed works, shortage of materials, non-adherence to contractual conditions, inaccurate estimates, and poor construction engineering methods among other issues.

Daramola, Oluwatoyin and Oladele (2014) assert that much in common exists between the construction industry and the other subsystems of Nigeria’s economy and the built environment. Such commonalities mean that the effects that occur in the construction industry spread to other subsystems of the economy causing serious concerns. The notable in the construction industry that affect other economic subsystems include poor construction engineering methods, which includes lack of attention to front end activities. The other problems include poor designing, planning and actual construction methods that facilitates the bad effects on the economy. The main cause of the problems, according to Daramola eta al. (2014), is lack of sustainable green construction methods and standards that provide proper guidelines in the construction procedures and standards.

The result has been construction practises and methods that adversely affect the environment by destroying the quality of water at different levels and disturbances made on the environment. In addition, uneconomical and inefficient construction methods, poor quality costs, use of poor quality Portland cement and other construction materials cause degrading effects on the environment. In addition the aggressive impact of chemical agents, the effects of mineral admixtures, the leaching effects of construction materials, and the disposal and lack of reusable materials have compounded to produce serious effects on the environment. In addition, lacking standard practices in the construction processes in urban centers such as using practices such as using localized openings and trenches in urban infrastructure development and maintenance and the poor disposal of primary and secondary aggregates have further added to the burden of construction practices on the Nigerian build environment (Elmasry & Haggag, 2011).

Despite the challenges facing the building and construction sectors, Siew et al (2013) notes that there are many internationally recognized green rating systems for the construction of buildings being strong contenders for adoption in Nigeria’s built environment. Here, green rating systems provide the baseline for ensuring that “sustainable building and construction practices are based on building design efficiency, which lead to water, and energy efficiency” (Siew, Balatbat & Carmichael, 2013, p.3). Siew et al. (2013) define sustainable buildings as those that “encompass environmental, social and economic standards, together with technical aspects” (p.4). However, the green building rating systems provide the technical details for construction workers to follow when constructing green buildings. However, the problems in Nigeria, which demand sustainable construction solutions based on the green evolution include high energy supply where over 40 million liters of diesel o generate electricity and transportation are the main reasons for the large consumption of fuel in the construction industry, which adds to the polluting effects of waste emissions to the environment.

On the other hand, the transport system for moving construction materials from source to construction sites does not conform to green practices because Nigeria has a poor transport infrastructure that contributes to the challenges of implementing a green rating system. The waste management strategies lack the sustainability component because of lack of environmental and sustainability consideration in the planning and design of buildings and infrastructure development. Some of the areas lacking the sustainability components lead to poor drainage of effluent, inefficiently water supply systems, poor planning, disturbance of the subsoil when constructing buildings, and the lack of the sustainability component in many states in Nigeria (Saqalli, Gérard, Bielders & Defourny, 2011).

Typically, buildings and infrastructure projects in Nigeria are the principal sources of environmental destruction because they consume a lot of non-renewable resources such as water, energy, rain forest destruction, and agricultural land. In addition, the resulting infrastructure is not economically sustainable and further demands the use of sustainable practises. The direct impacts on land include air pollution, ozone depletion, climate change and many other problems associate with lack of sustainability practises. The government, on the other hand is defunct of green construction policies and legislation that could provide a framework to facilitate the adoption of sustainable green construction practices, with little buy-in being experienced in both public and private stakeholders.

Siew et al. (2013) emphasise that certifying construction projects based on standard rating systems adds accountability and integrity to the construction processes leading to the protection of the environment. Certification results into several tangible benefits such as high performance cost effective buildings, better returns on investment, better market for green products, better, and good indoor air quality among others. Green buildings result into lower capital costs compared with the conventional construction methods that are evidently being used in Nigeria, low operating costs, better marketability, better health and productive gains, new business opportunities, and high resource efficiency (Otegbulu, Osagie & Afe, 2011). Here the underlying element is to conform to a reliable rating system. Here, the basic use of a rating system is to ensure standards are put in place against which internationally accepted construction methods are followed to create structures with better credentials and to make better commercial value for buildings using effective construction processes.

However, rating systems are used to ensure compliance to standards and technical specifications when construction is done to ensure sustainable development. Sustainable development can only be achieved if the development processes satisfy the needs of the current generation without putting into jeopardy the ability of the future generations to satisfy their needs (Otegbulu et al., 2011, p.10). Developers and stakeholders use the rating systems to ensure that construction projects are done according to the needs of the people, economic capital, and the environment to create value for stakeholders and not just a restricted few. The overall objective is to achieve low energy consumption, better indoor air quality, low emissions, and highly efficient waste management procedures.

A focused survey by Adegbile (2012) of over 600 green rating systems and projects in the world show that professionals who undertake infrastructure development projects use different rating systems and projects to ensure stringent compliance with existing technical specifications and regulations on emissions, structural designs, and consumption and use of non-renewable resources. However, Adegbile (2012) asserts that the problem in Nigeria is different because most of infrastructure development projects lack sustainability because of lack or failure to use sustainable (green) building rating systems. Investigations by Nduka and Ogunsanmi (2015) revealed that the problem is compounded by lack of expertise, institutionalised policies for green sustainable construction, awareness, deficiency in human resource and client knowledge, and effective waste management policies. The effects are compounded by lack of lack of a sustainable (green) building rating system for infrastructure projects, creating a gap to be filled in this study. To address that gap in knowledge, this study will be guided by the following aims and objectives.

Statement of the problem

The purpose of building and infrastructure rating system are to enable all stakeholders to rate and improve the performance of buildings. However, the problem is that Nigeria lacks a green building rating system, making the construction of buildings to environmentally unsustainable. However, there are many green rating systems for adoption exist such as the building research establishment’s environment‘s Assessment method (BREEAM), comprehensive assessment system for building environmental efficiency (CASBEE) and Leadership in energy and environmental design (LEED) among others, the adoption of which to address the economic, cost issues, and sustainability in infrastructure development and buildings being the main problem of the study. However, the lack of rating systems leads to the question on: which sustainable green construction system is appropriate for Nigeria’s construction industry?

Aim

To assess the adoption of a sustainable building rating system for the execution of infrastructure projects in the Nigerian Construction Industry.

Objectives

1. To establish the nature and operation of green building rating systems internationally.
2. To investigate the pros and cons of adopting green building rating system.
3. To establish various stakeholders perspectives and expectations toward green building rating system.
4. To determine the GBRS the Nigerian construction industry should adopt.
5. To propose a road map for the implementation of green building rating system by the Nigerian construction industry.

Significance of the study

The research project is significant because the results could be used to determine the best GBRS that could be used to solve the problem of construction practices in the infrastructure development in Nigeria.

Literature Review

Introduction

Sustainable development is an area that has a global meaning on the construction industry because it is viewed as one the major players that influence the social, economic and environmental landscape of developed and developing countries (Gray, Kouhy & Lavers, 1995). In addition, the consumption rate of virgin materials by the industry has led to a significant depletion of the resources and the discharge of large amounts of waste products into the environment, leading to greenhouse gases that pollute the environment. Many countries use construction projects as a standard measure of sustainable development especially because of the rapid increase in construction projects in many developing countries. However, because of the high demand for construction projects and the adverse effects such projects have on the environment, the demand for sustainable construction methods has increased significantly.

Sustainable development can also be defined as the process of maintaining and improving the quality of nature and life-support systems while developing current economic, social and environmental conditions of the world by carrying out sustainable activities to safeguard the environment for future generations. The successful use of sustainable construction methods is summed up in the prudent use of available resources for sustainable construction practises to protect the environment and enhance social progress, increase people’s income, improve the quality of life, and create jobs (Moktar, 2012).

This literature review is a summary of the findings by different authors on the development of infrastructure projects and the construction practises used in the building industry and how building rating systems as a framework for the best practises in the industry by factoring issues such as cost, environmental, and sustainability practises. Sustainable green buildings are designed and developed or renovated by using design processes that enable engineers to reduce destructive effects on the environment and natural resources based on the life cycle cost of the building (Greider & Garkovich,1994). The nature and operation of internationally accepted green building rating systems is that they enable the construction industry to enhance green credentials. In addition, the rating systems enable construction managers review the constraints and benefits of adopting green building rating systems by assessing the stakeholders’ perspectives and expectations toward green building rating systems. The results provide a roadmap on the best GBRS the Nigerian construction industry should adopt and the road map to use for the implementation of green building rating system in Nigeria.

Nature and operation of green building rating systems internationally

Green standards are defined as “a set of guidelines and criteria against which a product can be judged” (Oyedepo, 2012). Miller, Spivey and Florance (2008) maintain that the guidelines provide a ground for serious considerations on how to integrate green sustainable construction practices and methods that factor green environmental considerations into the construction of buildings and other infrastructure development projects. Examples include meeting the planning requirements for the construction of residential and sustainable green buildings, ensuring that any service within such buildings is provided at low cost, being energy efficiency, linking with adjoining buildings, complying with building regulations, sustainably using the building, and provisioning good lighting during the day.

Nwokoro and Onukwube (2011) maintain that most buildings in Nigeria were constructed without much regard to the environmental requirements for energy efficiency, making most of the buildings to be the sources of greenhouse gases because of the in-house activities such as heating, coking, and waste removal. However, Gowri (2004) claims that such buildings can be renovated by using sustainable green construction methods that factor product safety, price, and availability of the resources. In addition, the green rating system can be used to improve the performance and energy efficiency of new and renovated buildings using the best green rating system. Typically, “the common standards related to building practices and infrastructure development are created through consensus processes by organizations such as ANSI, ASTM, or ASHRAE” (Gowri, 2004, p.34).

However, Castro-Lacouture, Sefair, Flórez and Medaglia (2009) argue that the governance of such standards are supported by the international Standards Organization (ISO) on which consensus is established based on the norms and rules to be used for the in the construction of buildings. According to Castro-Lacouture et al. (2009), the rating systems and certifications are important because the direct impact of using energy to build houses, for renovation, repurposing, demolition, and for occupancy and other activities on the environment are progressively becoming adversarial and rapidly causing severe environmental challenges in developed and developing nations including Nigeria.

However, Nigeria, like any other country has started to experience the impact of climate change and that makes it mandatory for the country to mitigate the polluting effects of construction activities on the environment by improving the construction practices in all aspects of the planning, design, and cost effectiveness when constructing buildings. Gowri (2004), Castro-Lacouture et al. (2009), and Nduka and Ogunsanmi (2015) proposed the adoption of a rating system that could be derived from the best international green building rating systems to help the countries and especially the construction industry in Nigeria to ensure sustainability of the design and construction built environment. Here, Rutherford (2007) proposed environmental considerations that include designing and building local amenities according to the standards and principles proposed for green design and construction practices. In addition, some of the considerations include accounting for the topographical use of land, subsoil conditions, the natural contour of land, natural water ways, lake and bonds, shape of the proposed building and land, the natural vegetation and trees, services available, and approach and access to roads and paths, and proposed future developments.

Gowri (2004) identified the push for sustainable construction on countries as the major reason for international bodies to develop different rating systems to fill the gap. Some of the international standards and systems that have been developed and practically applied on the built environment include the Green Building Council of South Africa (GBCSA) and the Building Research Establishment’s Environmental Assessment Method (BREEAM) in the U.K and Leadership in Energy and Environmental Design (LEED) in the USA among others (Nduka & Ogunsanmi, 2015).

Principles of green design and sustainable development

The results of a study by Anastas and Zimmerman (2003) show that the principles of green design and sustainable development provide the baseline for the development of green rating systems that are suitable for the building industry in many countries and can be adopted as guidelines in Nigeria’s construction industry. According to McDonough, Braungart, Anastas & Zimmerman (2003), the key principle of green and sustainable design are used to minimise urban sprawl that is evident in many Nigerian cities and towns, protect valuable land, steer construction activities clear of habitats and green space to avoid the destruction of the environment. Kibert (2012) contends that an issue such as constituting a multidisciplinary team for their contributions to a holistic thinking of a sustainable site selection is critically important under the green design principles. The multidisciplinary team contributes a lot of expertise and skill to develop an integrated design, which is iteratively constructed with ideas contributed by the team members throughout the phases of the building construction life cycle.

Michael (2013) argues that a collaborative effort is required to establish a culture of integrated design that can explore different design aspects to come up with a suitable sustainable design. The rationale is that coordination and collaboration are very important elements to consider when working in an integrated team. Typically, there should be consensus on what to use for development tools and materials and how to clarify communication roles within a development and design team for sustainable green solutions. In addition, it is important to determine designing goals and objectives and to develop an acknowledgement of the team’s commitment to sustainability. The design team must agree on the scope of the building by defining the services to be provided when the building is used. In addition, once the design has been accepted and the construction of the building starts, performance targets should be laid down that target reusability, recycling of existing materials, reduction of water consumption and disturbance to the environment, effective soil displacement methods, and reduction of storm water runoff (Kibert, 2012).

For sustainable design to be effective, it is important for the Nigerian companies in the construction industry and policy makers to ensure that existing buildings are renovated to enable the occupants to use the existing space more efficiently (Campbell, 1996). According to the principle of sustainable green design, it is important to re-use existing buildings and reconsider building brownfield sites when renovating many of the buildings that are in a state of disrepair in Nigeria. One of the key strategies is to design a flexible building with to ensure that it can be re-used in future to extend its lifespan (Medineckiene, Turskis & Zavadskas, 2010).

Researchers propose that using recycled materials provides builders some with additional benefits such as cost effectiveness and the preservation of the environment. According to the principles of sustainable construction, engineers must consider everything that is recycled from the recycled concrete aggregates, blended concrete using fly ash, and use of recycled content material such as steel.

On the other hand, the use of biodegradable materials such as wood is important because they do not have a lingering effect on the environment but can be degraded using biological means (Anastas & Eghbali, 2010). It is important for the builders to evaluate the environmental impact of the materials used in the construction of buildings to ameliorate their effects on the environment. It has been suggested that construction should be done by considering the use of products that are easy to use and those which are non-energy intensive. In addition, sustainable construction of suitable buildings can be done by using materials that produce the minimum impact on the environment and consume little energy when being separated or recycled (Medineckiene et al., 2010).

When constructing buildings, it is incumbent for the contractor to account for the transportation of construction materials that form part of the green construction practices. Here, the cost of transportation becomes part of the embodied energy of the building by using locally available materials to reduce the cost of transportation to support the regional economy and the income of the local people.

On the other hand, it is important to factor the schematic design of a building to ensure that it is consistent with sustainable design construction practices and outcomes. Typical areas to check include the compliance with the project goals, sustainable guidelines, preservation of vegetation and soils, and preservation of water. Opportunities for sustainable use of water include recycling, capture, and reuse (Medineckiene et al., 2010). Other opportunities include storm water management, ability to capture the rainwater, and doing preliminary calculations to determine the amount of water available.

Design guidelines for sustainable outcomes

Brophy and Lewis (2011) recommended in their research that constructors should use minimal grading to ensure that the fill and cut are balanced when preparing the ground for the construction of a building. It is important to select vegetation that is locally available and easily adapted to the conditions at the site of the construction project. According to Buys and Hurbissoon (2011), it is important to apply vegetation that does not need the application of water to be sustained. Here, it is important to ensure that water use is optimized by harvesting rain water and managing storm water properly. In addition, it is important to follow sustainable material management guidelines correctly and the landscape elements should be designed so that they can be reused later when the building has been deconstructed (Ding, 2008). In addition, it is important to use sustainable and certified products and energy efficient fixtures when renovating buildings.

Indoor Environmental Quality

According to Godish (2010), the principle of indoor environmental quality is important to consider for the sustainable construction of buildings. Indoor environmental quality is the principle used to describe the quality of the internal environment of the building where people live (Ding, 2008). Some of the factors that are used to determine the quality of the internal environment include the quality of air, the acoustic conditions of the internal sections of the building, the thermal and lighting conform, and the daylight views from the building (De Giuli, Da Pos & De Carli, 2012). However, buildings used for residential purposes differ enormously in their construction characteristics such as the design, size, the building materials, and quality of construction, cladding, and the conditions of the site where the building is erected. However, it is recommended that a building design that affords the best possible conditions for the occupants is necessary to create high quality environment (Yu & Crump, 2010).

The strategies and technologies to use to construct a building with good indoor quality include the use of materials that do not emit gaseous products into the environment when they have been used for finishing, sealing, and furnishing the floors and walls. Typically, the same procedure and standards can be applied for the construction of residential buildings which have the same construction requirements. The areas of constriction include wiring, floor finishes, ventilation, plumbing, windows, and crawling space. For instance, when constructing a building, it is important to ensure that it is energy efficient (De Giuli et al., 2012). Energy efficiency can be achieved by applying wet cellulose to cavities in new construction, but should not be applied on walls because it can cause mold infestations. However, it is important to construct a building more tightly to reduce infiltration of air into the building. De Giuli et al. (2012) argue that it is important to consider other additional factors such as exposure of the building to the external environment such as exposing occupants to the toxic indoor contaminants, occupants and occupancy behavior because they are responsible for generating a lot of contaminants such as the production of bio-effluents related to the preparation of food and other activities that consume energy.

It is recommended that good construction practices factor the windows and the ventilation or openings made that are made to a building to ensure sustainable green buildings. However, the windows are not the same, but differ from one building to the other. A good window is used to keep wind, rain, and water away from the building and provide a natural route for air to flow into and out of the building. However, it has been established that windows are the main sources of loss of energy from a building (Yudelson, 2010). Most of the buildings in Nigeria have windows that easily develop moisture in the interior surfaces leading to the loss of large amounts of energy through the windows. In addition, because windows break the continuity of the cladding in a building, they increase the chances of losing energy into the environment and reducing the thermal comfort of the occupants.

However, Smith (2013) maintains that windows should be constructed in a manner that they provide dedicated sources of air from the external environment without compromising the heating and cooling system of a building. In addition, it is important to provide the breaks by use of windows with breaks to prevent the moisture and water from penetrating into the window because moisture can interfere with the heating and cooling system of the building (Von Paumgartten, 2003). In addition, a building should be maintained to avoid the flow of water and moisture into the cavities especially when the building has grown old.

Smoke is another problem that contributes to a poor quality internal environment. Researchers show that occupants of buildings in Nigeria are vulnerable to the effects of potentially toxic indoor contaminants when exposed for 12 hrs. The contaminants include waste gases from the combustion of fuel and antigens such as cockroach that are sprayed inside the building (Smith, 2013). Exposure becomes worse because of the poor ventilation systems and the practice of closing of windows when heating and cooling occurs in a building. However, it is important to ensure that the ventilation systems such as windows are designed to ensure that they allow fresh air into the building without allowing for the loss of heat and other forms of energy. According to Smith (2013), it is important to keep out air having with smoke particles from getting distributed into other rooms within a building to keep the quality of air quality in those rooms good. A building should be designed in such a way that the internal source of smoke can easily be detected and the problem causing the smoke located and addressed as quickly as possible (Smith, 2013).

Sustainable site strategy

One of the strategies to achieve sustainable development is to use development methods at construction sites to reduce the pollution of air by reducing greenhouse gas emissions (Smith, 2013). One of the strategies that have been suggested is to use low energy consuming construction methods from the manufacture and processing of building materials to the disposal or recycling of materials. In addition, it has been suggested that sequestration of carbon in soils helps to reduce the level of expulsion of greenhouse gases into the environment. However, it is important to set performance goals and benchmarks to ensure that are based on green rating systems and green construction principles to ensure sustainable practices are followed in the construction and infrastructure development industries (Yu & Crump, 2010).

Greenhouse gasses

Typically, greenhouse gases are due to carbon dioxide concentrations increasing in the air trapping the heat energy form the sun, leading to an increase in global temperatures and global warming. However, sustainable construction methods have been suggested that can be used to reduce the heat island effects and reduce carbon dioxide emissions into the atmosphere as one of the green approaches to protecting the environment (Oyedepo, 2012).

It is estimated that construction of buildings is one of the largest consumers of materials and energy, taking up to 40% of the global energy and materials, justifying the amount of carbon dioxide produced from such processes. According to Oyedepo (2012), it has been estimated that 70% of the energy is consumed in buildings and the construction industry, which is one of the greatest employers in the world. Some of the strategic approaches suggested to reduce carbon dioxide emissions include using resources that can be regenerated as quickly as they are used, constructing a building by using locally available materials such as solar energy, using drainage patterns that can be constructed without spending a lot of energy, and naturally shading a site for construction work.

Resource efficiency

On the other hand, Abanda, Tah and Cheung (2013) suggested that using resource efficient materials to construct buildings can lessen the local impact of the demand for the construction materials. In addition, it is important to minimise the waste products from construction activities including the design, use, and decommissioning or deconstruction. Researchers have recommended structures to be made on impervious surfaces by using materials that are poor at absorbing heat from the environment (Abanda et al., 2013).

Studies show that the areas that have high energy uptakes such as the embodied energy that is consumed at the construction sites should be evaluated first. However, to reduce the embodied energy, it is recommended that constructors use materials with low energy embodiments, use fixtures and fixture techniques that are energy efficient, design buildings with low maintenance requirements, and ensure that the native vegetation is protected properly when construction work is ongoing and when it has stopped (Abanda et al., 2013).

Vegetation

Construction has always been one of the sources of destruction to the environment because it involves clearing vegetation to create impervious surfaces that prevent vegetation growing at the site. Here, the density of biodiversity is reduced in the clearing process even if the vegetation is replanted on a cleared site. According to Abanda et al. (2013), the worst destruction occurs when runoff water increases and less shade is made on the surface.

However, vegetation is one of the natural features that provide economical, health, and environmental benefits, making one of the most important elements of a sustainable site. Plants are known to filter the air of dirt particles and pollutants such as sulfur dioxide, carbon dioxide, and particulate matter from the atmosphere. In Nigeria, urban pollution is the result of millions of tons of pollutants that have been discharged into the air. According to Abanda et al. (2013), vegetation is used to provide site protection to avoid the green building inherently damaging a building that could be detrimental to the ecosystem (Adegbile, 2012). When construction work begins, it is important to put in place measures to protect the environment by limiting construction to the building site through good landscaping techniques. In addition, it is important for collaborative efforts to be put in place between architects and other stakeholders to avoid unnecessary clearance of vegetation and to identify the best vegetation to plant on a cleared site to create a sustainable landscape that does not consume energy and protect the environment from the human effects.

Nature of the BREEAM, GBCSA, PBRS, HERS standards

Adegbile (2012) maintains that the Building Research Establishment Environmental Assessment Methodology (BREEAM) to be one of the earliest standards developed to ensure the sustainability of buildings. Here, Adegbile (2012) notes that BREEAM provides guidelines for the innovation of existing buildings, refurbishments, and other construction projects that consume water, energy, and other non-renewable resources. In addition, the system can be used to respond to feedbacks on sustainability issues, commitments to sustainable solutions, and strategies for a country that has adopted the standard. BREEAM is defined as “the world’s foremost environmental assessment method and rating system for buildings, with 425,000 buildings certified with BREEAM’s assessment ratings and two million registered for assessment since it was first launched in 1990” (Nguyen & Altan, 2011, p.2). Nguyen and Altan (2011) argue that BREEM was the first green rating system with a wider scope of application compared with the other later rating systems.

According to Von Paumgartten (2003), the rating system was established and designed to provide rules and technical specifications to be followed when putting up new and individual buildings. At this point, it is evident from literature by Nduka and Ogunsanmi (2015) among other researchers that the Nigerian construction industry does not provide stakeholders with sustainable green rating systems to use, but construction projects are done at the discretion of the contractor. Adegbile (2012) argues that lack of green buildings systems in Nigeria makes people living near the construction sites to experience a lot of disturbances, health problems, and ecological disasters as a result of unstandardized onsite construction practices. In addition, construction standards are not followed and solid design and construction procedures are not followed. In addition, the structures face serious problems such as poor surface removal practices, poor drainage systems, lack of proper hot water installations, single and ventilated stack systems are do not form part of the buildings, and poor sanitary fittings. On the other hand, as opposed to GBCSA, BREEAM is the most established and widely used standard in the world for testing, rating, and “certifying the sustainability of buildings” (Buys & Hurbissoon, 2011, p.3).

According to Jaselskis, Anderson and Russell (1996), regulators use the BREEAM assessment scale to ensure that users, proprietors, designers, stakeholders, and construction engineers who make various building designs are made aware of the mandatory minimum requirements for water and energy consumption and the accruing benefits. In addition, the framework provides stakeholders in the buildings industry with the guidelines to use for effective adoption and use of reliable and innovative solutions in the construction process (Adewunmi, Omirin & Koleoso, 2012). The solutions are not only recognized in the buildings industry, but provide innovative constructors the opportunities necessary to be recognized in the market.

A wide range of sustainability issues are covered under the BREEAM international standard. The standard provides scientifically proved methods of sensing and evaluating the usage of different aspects of development, which lead to the consumption of energy and management processes such as health, water consumption, and other environmental issues based on an assessment scale of “‘Pass’, ‘Good’, ‘Very Good’, ‘Excellent, Outstanding” (Moktar, 2012).

The body of knowledge on the standard shows that BREEAM is highly flexible and can accommodate existing design or refurbished buildings and construction engineering projects (Moktar, 2012). Because of the highly flexible nature of the standard, the scope covered by use of the standard includes BREEAM Communities, which provides the guidelines and standards for professionals in the construction industry to follow in making master plans of communities where people could be happy to live and work and become economically successful. The nature and operation of BREEAM communities is that it is “used to mitigate the impacts of buildings on the environment; to enable buildings to be recognized according to their environmental benefits; to provide a credible, environmental label for buildings” (Moktar, 2012, p.2).

Another scope is the BREEAM refurbishment which provides standard guidelines for the refurbishment of buildings, housing refurbishment projects, and a scheme to construct environmentally sound buildings. In addition, the scheme is used to evaluate the performance of existing buildings and help improve its efficiency and suitability rating (Moktar, 2012). On the other hand, BREEAM New Construction provides the standard rules and guidelines on which nonresidential structures are evaluated for conformance. Other internationally recognized rating systems include the Green Building Council of South Africa (GBCSA), Pearl Building Rating System (PBRS)

Home Energy Rating System (HERS) Index

A study by Nguyen and Altan (2011) proposes that (PBRS) can be used to solve the problems because it has widened in scope since it was first developed and today it covers the life cycle construction phases of new buildings. The standard is a rating system that provides guidelines for sustainable design that has widely been used in the building infrastructure in Abu Dhabi for new and old buildings. The standard applies in situation that require construction practices that lead to the preservation of the natural resources, conservation of water and energy, increase of the quality of life and reduction of the impact of the construction activities on the environment. In addition, PBRS provides additional benefits if adopted, which include better lifestyle for residents and improved integration of buildings with the community.

However, Azhar, Carlton, Olsen and Ahmad (2011) proposed the Green Building Council of South Africa (GBCSA), which was established in 2008. GBCSA is defined as a “system that identifies measures that can be taken to produce a green building in the areas of management, indoor environmental quality, energy, transport, water, materials, land use and ecology, emissions and innovation” (Von Paumgartten, 2003, p.3). Typically, it is evidently clear that the standard provides measures such as materials, standards, and rules to ensure the sustainability development of green buildings that can be adopted for the Nigerian situation.

In the context of the Nigerian background, Azhar et al. (2011) proposes the GBCSA rating system, which is defined as “one which is energy efficient, resource efficient and environmentally responsible i.e. incorporates design, construction and operational practices that significantly reduce or eliminate its negative impact on the environment and its occupants” (Yudelson, 2010, p.3). The baseline assumption is to build a smarter, better, and more useful building that operates according to the rules outlined in the GBCSA system. The system provides a framework for educating the stakeholders in the construction industry on green buildings, promotes the construction of green buildings, and provides established rules and framework for rating green buildings and green systems. Typically, the standard recognizes several components of the green building to include materials, energy, emissions, water, and transportation (Yudelson, 2010).

Every aspect of the building must reflect the technical requirements and details to ensure green compliance. Buys and Hurbissoon (2011) suggest that the design should provide a framework with technical details on how a green building should operate, which should be adhered to make it compliant. Among the suggested compliance requirements include protecting the quality of life of the occupants, improving the efficiency of water and energy usage, protecting the health of the occupants, and utilizing available resources efficiently.

The GBCSA rating system “sets targets to be achieved for the different measures, awards points for the achievement of targets, totals the points to give a score and then awards a rating on the basis of the score” (Buys & Hurbissoon (2011, p.2).The targets points include access mobility, thermal comfort, good ventilation and air quality, water quality, efficient use of resources, reusable materials and waste management elements, which Yudelson (2010) strongly argues that they lack in many buildings that have been constructed in Nigeria. According to Buys and Hurbissoon (2011), the mission is to “promote, encourage and facilitate green building in South Africa’s property and construction industry through market based solutions” (p.3). Here, just like BREEAM, GBCSA was developed with the same mandate and objectives designed to enable stakeholders to use innovative and efficient construction methods, which enable efficient consumption of non-renewable resources and energy to protect the environment.

Countries such as Australia, Netherlands, Canada, Singapore, USA, Japan, Argentina, South Africa, UAE, Romania, New Zealand, and the UK among others are signatories to the green building council of South Africa, which gives GBCSA a global status as a recognizable sustainability buildings standard. Here, it is clear that GBCSA and BREEAM can be used for the same purpose with similar objectives. However, the developers of the GBCSA argue that it is meant for use in rating commercial buildings, a position that has long changed because of the dynamics in the construction industry.

Pearl Building Rating System (PBRS)

A distinct analysis of the Pearl Building Rating System (PBRS) by Assaf and Nour (2014) show that the rating system provides a framework for the construction of sustainable buildings just like GBCSA and BREEAM, Home Energy Rating System (HERS) Index, and Leadership in Energy and Environmental Design (LEED). According to Assaf and Nour (2014), the Pearl Building Rating System constituted in the Emirate of Abu Dhabi on April 2010, was designed to address the use of green construction methods for the life cycle of a building. The aim was to provide a framework for the development of green buildings to create sustainable communities while ensuring a balance of the cultural, social, economic, and environmental elements for sustainable development.

According to Moktar (2012), the heart of the PBRS rating system differs from other standards in that it is an integrated development process with an inter-disciplinary collaborative approach based on four pillars. Moktar (2012) notes that the rating system emphasizes on the efficient utilization of water, energy, and locally available resources to enable sustained use of recycled materials just like GBCSA. Up to this point, the main issues are efficient and economical utilization of resources as per the requirements. The rationale for the adoption of such a rating system in Nigeria is that most development projects are responsible for 40% of the waste products with the human habitats contributing to a significant increase in the destruction of the environment.

Leadership in Energy and Environmental Design (LEED)

LEED (Leadership in Energy and Environmental Design) which was established by the U.S. Green Building Council (USGBC) in 1998; CASBEE (Comprehensive Assessment System for Building Environmental Efficiency) developed in Japan in 2001; and Green Globes US created in 2005. Thus, they can be used as a reference point in investigating the adoption of a sustainable building rating system for the Nigerian construction industry.The Leadership in Energy and Environmental Design (LEED) is a rating system “for the design, construction, operation, and maintenance of green buildings, homes and neighborhoods” and on the other hand, PBRS is a standard that “aims to address the sustainability of a given development throughout its life cycle from design through construction to operation” (Oyedepo, 2012). It is evidently clear that the main objective is the construction of green buildings and the issues sustainability but using different approaches. LEED, which was formulated in 1998, is used to accurately represent new and existing green building technologies. LEED was designed to cut down the cost of operating buildings, restore and enhance a positive impact on the people’s health and the environment, provide a framework for the development of enhanced buildings and increase their marketability, create a sustainable community, and implement an acceptable tool for green building sustainability.

Asiedu (2010) maintains that the sustainability of a building implies assessing the conformance and performance of common, and less common (leisure complexes) new and existing buildings based on the assessment scale that has been defined by the system in use. Typically, the standard such as the Pearl Rating System has seven categories of sustainable rating and three levels of certification.

A growing body of research has established that because of the wide adoption and use of BREEAM as an international standard for rating green buildings, BREEAM is widely adopted to be the driver of innovation and environmental protection (Moktar, 2012). In addition, the standard encourages the green use of material and sustainable practices in the built environment by setting sustainability benchmarks and high targets that drive innovation and the need to protect the environment.

The construction of a green building based on the LEEDS green rating system provides detailed description of sustainable sites and the issues to address when undertaking the green building. To be compliant, the construction team must conduct an environmental assessment of the site designated for the construction of the building. The environmental report contains all information about the potential liability of the construction site, which includes floods, water usage, environmental constraints, the presence of fauna and flora, and the remedial measures that have been suggested and the estimated cost to implement the countermeasures.

When doing the construction work, every effort should be put in place to reduce the cost of infrastructure that could be incurred when deciding to put up a new building. In addition, the cost factor includes the proximity to basic services and materials, and the site design and planning that has been done to prevent the destruction brought about by the disturbance from the environment.

However, it is critical to consider the salient features of a sustainable design under the green rating systems, which factors the people, the ecology, and the environment when working under the LEED rating system. Here, the LEED rating system provides that the designer of a building must consider the drivers of green buildings such as the growing evidence of the benefits derived from the use of green buildings. One of the benefits is to use sustainable sites. Sustainable construction must be done on a sustainable site that provides for a non-auto access to preserve open spaces and protect the environment.

In addition, the construction should be made is such a way to avoid the pollution of the night sky. The use of water should be such that it leads to water conservation especially when doing construction work and at the construction site. Some of the measures that have been recommended to ensure economical water use are to reduce the application of water for sewerage use and for irrigation.

The water usage requirements under the LEED rating system is that a contractor must take due care to reduce the consumption of water and particularly reduce the use of surface water and other natural sources by 50%. Some of the suggested strategies include planting trees, using rain water, improving the efficiency of irrigation systems, recycle water for use, and install landscaping that does not require water for irrigation.

On the other hand, the LEED rating system provides guidelines for energy efficiency and atmospheric protection. On the other hand, the rating system recommends that construction material and resources should be used in a more economical way to ensure their protection and minimum impact on their usage. However, the LEED requirement on materials is consistent with the principles of green design on materials and resources. Typically, the green principle requirements are that engineers should minimise the use of non-renewable construction materials, water, and energy by using efficiently designed systems and ensure effective recycling of the materials is done. It is important to use engineered materials that are produced by using reliable engineering principles such as the use of composite materials, insulated concrete forms, and use of frost protection methods to prevent frost from damaging the shallow foundations.

Operation of the rating systems

The nature and operation of the green rating systems are based on the principles of green buildings. On the other hand, a clear understanding of the rating systems provides a clear framework for understanding how to develop and implement a rating system suitable for the Nigerian infrastructure construction industry. Farham and Mohammad (2014) argue that different standards have one thing in common, and that is to provide sustainable frameworks and rules for the construction of green buildings for commercial and residential areas. Despite having the same objective, the rating systems have different operational baseline benchmarks and requirements necessary for a building to be compliant. For instance, the Pearl Building Rating System is applicable on all buildings with different topographical makes such as public places, hospitals, warehouses, hotels, and laboratories (Castro-Lacouture et al., 2009). On the other hand, the Green Star SA rating system is applicable on situations where material used for construction work are assessed according to the impact they are likely to cause on the environment for the entire life cycle of the construction of a building including the design stage, the building phase, and the operational phase of the structure (Gowri, 2004). The operational phases cover the end of life of the material, the point at which it is determined whether to be disposed or recycled for another use.

The key elements used to determine the worth of a material to qualify for green construction under the Green Star SA system include energy efficiency, stewardship towards the environment, and material efficiency (Moktar, 2012). On the other hand, BREEAM operates on a point credit scoring system that is distinctly defined by using the management, pollution, wastes, materials, transportation, health and wellbeing, and land use and ecology elements. However, a small contrast with the Pearl Rating System occurs at the point where it is used to address sustainability (Moktar, 2012). Typically, Pearl Rating System operates on point of integrated development process where different disciplines are required to work together as a team for the construction of a green building. Moktar (2012) argues that despite the call for cross disciplinary teamwork, the standard does not provide the actual or specific disciplines that should be integrated into the team.

However, the key areas of focus, which do not deviate from other rating systems, include establishing livable buildings where the indoor quality of air and spaces should be kept to the minimum requirements, efficient utilization of resources, putting in place innovative practices, and the conservation of natural systems. In addition, the Green Star SA rating system provides opportunities for developers and other stakeholders to ensure resource usability, use of locally available resources, and use of the best green methods for material reductions (Moktar, 2012). At this point, certain fundamental points of the Green Star SA system are similar with those of BREEAM on the rating of water, materials, and land use and ecology. However, other areas of assessment where credits are provided based on the Green Star SA system include emissions, innovation, water, indoor environment and air quality, management, and transportation. On the other hand, the BREEAM credit points are awarded based on the overall management of buildings while the rest of the credits are similar with those of the Green Star SA system. The assessment evaluates each area and wards credits using a specified performance criteria. A weight is awarded to a building by adding the credits earned for a building.

The study by Lee and Burnett (2008) and Moktar (2012) detail the guiding aims and objectives under which BREEAM operates. BREEAM aims to mitigate the effects of construction processes on the environment, stimulate demand in the private and public sectors for green buildings, provide a benchmark for green buildings to be recognized in the construction, and to provide credible labels for green buildings (Moktar, 2012). Moktar (2012) adds that BREEAM was widely tested and approved because it provides credible technical standards for sustainable green construction based on empirical evidence derived from scientifically proved results. Moktar (2012) notes that the guiding objectives that qualify BREEAM to be a highly recognized standard include providing a framework for the construction of marketable green buildings, providing a framework for best practices to be followed in the construction industry, making stakeholders aware of the need to reduce the adverse impacts of traditional construction practices on the environment, setting standards for compliance with construction rules and regulations, and enhancing progress towards green corporate governance objectives (Lee & Burnett, 2008).

On the hand, the pearl rating system provides standards that apply to offices, multi-residential buildings, schools, mixed use, and retail outlets just like LEED. Yudelson (2010) compared pearl with LEED and established that LEED assessment method is based on percentage score while Green Star provided the ratings by estimating the percentage of greenhouse gas emissions. On the other hand, BREEAM depends on the energy performance certificate (EPC) rating that is based on CO₂ index (Siew, Balatbat & Carmichael, 2013). On the other hand, the maximum credit level performance based criteria for the rating systems include 20 points for zero predicted greenhouse gas emission for the Green Star and 15 credits for zero CO₂ for BREEAM, and 10 points when an improvement of 42% is achieved for LEED.

Assessment processes

The assessment and implementation processes for the rating systems have the common objective of protecting the environment from the effects of construction activities, consumption of resources, and use of renewable resources to protect the environment (Adedeji, Aluko & Ogunsote, 2010). Typically, the baseline areas of focus include the environment where the construction process includes site specific oversights that enable the management teams to track, monitor, and report the effects on the environment. Here, each area that has been assessed is awarded a credit is awarded based on the Environmental Management Plan (EMP) as per the Green Star assessment process. On the other hand, (Adedeji et al. (2010) argues that the BREEAM assessment process is done by a qualified and licensed inspector and the assessments are done at the design and post construction stages to evaluate compliance.

All the bespoke, retail, residential and other areas should comply with the rating of excellence. The mandatory performance areas include water, energy, and waste management, use of materials, lifetime homes, and surface water management efficiencies. For BREEAM, the design stage consists of assessing the design drawings and other technical specifications and the commitment to achieve the specifications in the final project. There should be an overall support of the government and those institutions within government given the mandate to protect the environment by enforcing the best construction practices and policies to comply with (Augenbroe, Pearce, Guy & Kibert, 1998).

LEED provides one of the best approaches to use in identifying and enforcing the rating standards beginning by providing a framework to use in identifying the site to be constructed on or the sustainable site, the approach to assure water and resources efficiency, efficient usage of energy and the impact on the environment, resources and materials, indoor air quality, the innovation and process design. However, some of the requirements are applicable in the USA and there is need to adopt certain requirements with slight adjustments that are compliant with other international green rating systems for the Nigerian buildings industry.

Constraints and benefits of adopting green building rating system

Construction project are touted as the greatest emitters of waste products and pollutants to the environment in Nigeria with Africa emitting 3.7% of the global carbon related emissions into the environment and that if Nigeria is 0.2% of the world output (Nguyen & Altan, 2011). However, environmental sustainability is the pressing each country including Nigeria to start considering adopting green rating systems for construction projects to varying degrees. However, Nigeria suffers certain problems that make it difficult and challenging to adopt the green rating systems. Chief among them is the inefficiencies in handicaps in the buildings industry, waste management, transport, and energy systems (Daramola, Oluwatoyin & Oladele, 2014).

The starting point is the government to formulate a policy on green rating systems. There is no clear cut policy on sustainable green rating systems in Nigeria. Okonkwo, Okunola and Ezeanyanaso (2010) assert that the government has instituted the Nigerian Green Building Councils and became a signatory of the World Green Building Council under the emerging membership level, which reflects the maturity of Nigeria as a country in the GBC organisation. The government is in its infancy stages of formulating policies and frameworks for green building construction, which is the greatest challenge in implementing the green rating system. According to Daramola et al. (2014), the main objective of the green councils is to ensure that “framework conditions for energy efficiency (EE) are improved and concrete measures generate energy savings” (Okonkwo et al., 2010, p.12). This is a clear testament of the basic level of green rating system implementation the country is going through.Besides the specific difficulties of implementing the green rating systems, studies show that Nigeria’s urban centers are poorly planned and master plans have not successfully been implemented because of political interference besides the natural propensity that is inherent in the population who desire to avoid disciplined development practices.

Okonkwo et al. (2010) argues that estimates show that Nigeria burns 40 million liters of diesel, which is one the greatest generators of greenhouse gases into the environment for the generation of electricity. However, Okonkwo et al. (2010) assert that the Nigerian energy commission emphasizes on the need to use optimal sustainable energy supply solutions using environmentally sound methods to reduce the adverse effects on the environment. However, the statement by the energy commission is far from being implemented because of lack of policy and legal frameworks to implement the resolutions.

Stakeholder’s perspectives and expectations toward GBRS

Stakeholders agree that GBRS are necessary to provide the guidelines for the infrastructure development and building activities to go green (Asiedu, 2010). However, most of the requirements stipulate in the green rating systems sometimes are difficult to achieve especially because most stakeholders lack the human skills resources and technical capacity to implement the green business rating systems requirements. Despite all that, stakeholders in the construction industry who consist of the government, private and public entities and individual people support the idea of using green rating building systems because of the benefits derived from the use of the systems. However, stakeholders have their own perceptions about the GBRS because of the risks involved in their use as guidelines for the design and construction of buildings.

Perspectives

First the benefits that stem from the use of the rating systems include ability to gather and integrate the added value of engineers, managers, and green consultants on the design of a facility or a buildings before the construction process begins. The rationale is that facility managers are able to identify a building that should be demolished to pave way for a new construction and one that should be renovated. In addition, a manager can estimate the amount of intervention to make for retrofitting a building, the standards to follow based on the tangible benefits to be gained. Here, the economic benefits and show that green buildings have 33% less carbon emissions when compared with the traditional buildings (Mwasha, Williams & Iwaro, 2012). In addition, different studies show that green buildings provide a 45% less power consumption for the occupants than traditional buildings and green buildings also have a 13% less aggregate cost on maintenance when compared with traditional l buildings. Typically, most of the benefits include “environmental, health and community, financial, market, and industry categories” (Smith, 2013).

Most of the stakeholders view the environmental benefits as strong contributing factors to the protection of the econ system and the biodiversity such as the conservation of natural resources. Natural resources are conserved because the design and construction processes do minimise adverse impacts on the environment, consume less energy and resources, and create as little waste materials such as solid wastes as much as possible. With the low amount of solid wastes, the communities that benefit from the buildings that are constructed using green rating building systems easily accept such construction projects and the occupancy of the buildings. The acceptance rate for the construction methods increases because of the positive impact of the on the health of the communities such as improved health, thermal, and acoustic environment come as additional benefits (Ebert, Eßig & Hauser, 2011).

It has been demonstrated that green building rating system enable the stakeholders in the industry to construct buildings that are financially beneficial to the community and the market. Such financial benefits include low operating costs both in the construction and maintenance of the building. Such low costs enable the contractors to make cost savings because it enhances the life cycle costs, enhances asset value and profits, and improves the asset value life performance costs. Contractors want to make buildings that have a longer lifespan and using the GBRS, it has been established that it is possible to make the building to have a longer economic life, which leads to low employee turnover for construction companies, better life cycle economic performance, compliance with the building regulations, increase in asset value and higher profits, lower litigation risks, increased employee productivity and satisfaction, and improved indoor air and water quality.

With the perceived benefits, stakeholders support the use of GBRS based on different findings on the benefits accruing from the integration of the rating systems into their construction practices. A study by Yudelson (2010) showed that a contractor who integrated GBRS in the construction guidelines of buildings was able to achieve 8% operating cost reductions while the value of the building appreciated by 7.5%. O a similar note, it was noted that the rent increased by 3% showing the contractors and other stakeholders appreciated the construction of green buildings using the GBRS to be beneficial. In addition, the study indicated that the return on investment increased by 6.6% because of the use of the GBRS rating system.

Yudelson (2010) argued that most of the costs (78%) incurred by construction companies were directed towards the payment of salaries. Such business expenses are large because it leaves the company with little money for other expenditures such as expansion, maintenance of machinery, and other expenses. However, with the introduction of the GBRS, most of the stakeholders who are out to make profits and avoid conflicts with the government argue that the rating systems are in their favor because they help to enhance employee productivity and lower the absenteeism of the workers. The GBRS are designed to favor both the customer and the contractor because buildings based on the rating systems provide structures with higher occupancy rates, lower advertising costs and meet the growing demands of tenants. However, not all stakeholders perceive the GBRS in a positive manner because of the risks involved in the construction industry based on the rating systems.

Perception of risks

A study by Lee and Burnett (2008) to evaluate the perception of risk by industry stakeholders when using the GBRS to provide the guiding principles in the construction of buildings showed that most employees were less qualified and trained on the implementation and use of green building rating systems in the infrastructure development. In addition, the problem of establishing implementation and post implementation performance benchmarks adds to the risks faced in the industry. In addition, the host of financial risks such as the perceptions that green buildings are expensive and lack of information on the return on investment that companies make after investing in green buildings adds to the uncertainty that grips stakeholders and those wanting to invest in green constructions.

On the other hand, it has been established that lack of skills to support the investment of green technology is one of the hindrances that companies in the construction industry experience. In addition, tax incentives lack in Nigeria for companies intending to adopt the GBRS into the infrastructure development, making it more expensive to use green technologies as compared with the traditional construction methods. Risks such as the loss of financial gain is the building does not meet the standard operational performance requirements, the high cost incurred in retrofitting old buildings so that they measure up to the standards required is an additional risk for contractors working in the infrastructure development industry.

Sometimes the possibility of legal battles between architects and the owner of a building is an additional risk because the contractor might lose a lot of money of a building is not certified based on the rating systems. Another problem is that most company budgets are not structured to accommodate the life cycle costs of construction materials because it is difficult to record and besides, companies do not want to get involved in the additional costs required for the maintenance of a building until the end of its life (Hussin, Rahman & Memon, 2013).

It has been observed that the lack of a common agreement on the standards to use to evaluate sustainable green buildings in the market makes companies and other stakeholders in the industry develop buildings that do not have a common standard to operate on (Demirci & Miele, 2013). In addition, the financial institutions do not have any data on the construction and benefits of green buildings, making the adoption of sustainable green buildings a major concern for the stakeholders. Other risks that hep to shape the perceptions of using GBRS in the construction industry include misconceptions about energy efficiency in green buildings, lack of education on sustainable green buildings in the learning institutions, failure to engage in green practises in the industry, and the need for continuous improvements to maintain the green standards on a building.

Expectations

One of the problems with new technologies is to give the consumer a lot of expectations, which sometimes are not fulfilled and result in disappointments. For the case of green buildings, the performance expectations are high in terms of market value, energy savings, acceptability, market demand, and many other expectations (Demirci & Miele, 2013). However, stakeholders such as governments and private and public institutions’ appetite to use the green rating building systems because they gain confidence that the project is green and has the value required for a sustainable building. In addition, contractors expect green buildings to provide additional value and incentives for all those interested in the industry such as the owners, customers, engineers, and other stakeholders in the industry. Rating is important because it assures the customers of a market filled with green houses and provide the baseline for determining the type of green rating standard to be used. In addition, the rating systems provide information on the products to be used for the construction of green buildings and how such materials should be handled. It is possible for one standard to be suitable for one project and not suitable for another project in the same country. However, it is critical for a contractor and policy makers to ensure that the standards in use are acceptable across the industry.

GBRS for the Nigerian construction industry should adopt.

To answer the question on the type of GBRS for Nigeria to adopt, it is worth presenting a summary of the green building rating systems that have been reviewed and those that have not been reviewed to evaluate the most appropriate rating system to for Nigeria to adopt.

Adopted from Asiedu (2010).

Adopted from Asiedu (2010).

Adopted from Asiedu (2010).

Adopted from Asiedu (2010).

Adopted from Asiedu (2010).

Adopted from Asiedu (2010).

Adopted from Asiedu (2010).

However, as shown above, rating systems are applicable for different situations and environments. Typically, there are factors that need to be considered when making the decision on the type of rating system to be adopted. In addition to that, the existing conditions on the ground are also crucial in providing the guideline to use in selecting the type of rating system. However, in Nigeria’s built environment in Nigeria, the issues are to set criteria for assessing the buildings to ensure they measure up to the green design principles. The criteria could enable the construction manager to rate a building and assign scores, which are compared with the standard criteria to see if they measure up the required performance. In addition, the rating a building gets is important in setting the type of credentials for a building and its market value. In addition, it is possible for a comparison to be done to determine the performance of similar type of buildings using established rating criteria. Smith (2013) argues a sustainable rating system is important to assess the performance of existing and new buildings against a benchmark that is accepted for use in the infrastructure development industry. Such a benchmark could enable construction managers to use green principles in the construction of buildings. However, the major rating systems or assessment tools are summarised below.

One of the rating systems or assessment tools that have been widely used is BREEAM. BREEAM is defined as a rating system with four assessment tools that are used to rate the performance of a building at different stages. The Design and Procurement (D&P) is the first stage where the technical details and requirements are stipulated for the design, renovation or extension of a building. The other phase is the Post Construction Review (PCR), which is important because it is at the stage that the building is evaluated both to determine the performance and the compliance of the design to the stipulated standards. On the other hand, the Fit Out assessment is an assessment tool that construction managers and engineers use to evaluate the compliance of a building that has been renovated to ensure it is green complaint. On the other hand, the fourth tool is the Management and Operation (M&O), which is used to evaluate the operational performance of a building once it is in use.

In summary, the assessment tools under BREEAM include the Design and Procurement (D&P), Post Construction Review (PCR), Fit Out assessment, and Management and Operation (M&O), with each tool having a distinct purpose. It is important to note that BREEAM works by awarding credits into 10 categories based on different performance criteria. Once a building has been rated, the scores from each category are put together and an average grade is calculated. Then, the result is compared on a scale of 1 to 5, with having the Pass, Good, Very Good, Excellent marks. The main strengths of the BREEAM green rating system is that it can be used for different buildings and it can be used in different environments and countries as opposed to where it was first formulated. However, the rating system has some serious weaknesses such as that “it requires very exact requirements, the weighing system is complex, and a market profile is required and has a high cost of compliance” (Smith, 2013).

The other rating system is the “Comprehensive Assessment System for Building Environmental Efficiency (CASBEE)” (Oyedepo, 2012). The rating system, which was developed in Japan, represents an assessment of the total environmental performance of a building. The issues that are given priority when using the assessment tool include environmental load (L), a building’s quality performance (Q), and the impact the building would have on the environment. In addition, the indoor quality of air, the use of biological contaminants, and the ventilation systems in a building constitute the performance measures used to evaluate a building. The main advantages of using the rating system are the stringent requirements and the main weakness is that the rating system is that “there are no external benchmarks, re-certification baseline model or energy model” (Oyedepo, 2012).

In summary, the Green Globes System (GBI) was developed from the BREEAM system to be used in Canada for the assessment of the construction of buildings and in certifying the designs of existing and to be constructed buildings for compliance with the principles of green design. Buildings assessed under the GBI system are rated on a scale of 1 to 4 that correspond to Bronze, Silver, Gold and Platinum ratings respectively. However, a study of the use of the GBI rating system shows that it has strengths that include:

• Reduced costs
• Provides opportunities for self-assessment which leads to better efficiency
• Provides the opportunity for immediate feedback
• It is a web-bases assessment scale
• Does not require one with exceptional skills to use, but can be used by people with general knowledge on green building rating systems
• The rating system can be implemented with immediate feedback
• The rating system integrates the life cycle thinking of the design, construction, and use and demolishing of a building.

However, the weakness with the system is that it does not provide guidelines on how to dispose of waste materials that result from the construction and demolition of buildings.

The other candidate green building rating system that can be adopted and used in the Nigerian infrastructure development and building industry is the Green Star (GS) rating system. The rating system was developed and designed for use in the Australian construction industry. The Green Building Council of Australia (GBCA) developed the system to provide guidelines for construction managers to develop sustainable buildings and for other infrastructure projects. The system has manuals that have been written containing detailed descriptions for the use of the credits and outlines the aims and objectives of using each performance criteria outlined in the rating system and buildings are rated depending on six items. The buildings are rated on “4 Star Green Star Certified Rating (score of 54 to 59) – Best Practice; 5 Star Green Star Certified Rating (score of 60 to 74) –Australian Excellence; 6 Star Green Star Certified Rating (score of 75 to 100)” (Oyedepo, 2012). The strengths of the rating system are that it is rigorous and the requirements are mandatory. However, the weakness with the system are that it lacks a baseline model to use and does not provide the opportunity for a building to be re-certified once it fails in the first assessment.

The IGBC Green Homes Rating System was developed in India and was exclusively designed for use to assess residential buildings only. The main areas of focus include “sustainability site development; water savings; energy efficiency; materials selection and indoor environment quality” (Oyedepo, 2012). On the other hand, the Leadership in Energy and Environmental Design (LEED) system was developed in the United States based on the LEED green building rating system. The assessment criteria used by the LEED system is based on the use of specific credits. The main areas of assessment include “sustainable sites, water efficiency, energy and atmosphere, materials and resources, and indoor environmental quality” (Oyedepo, 2012). The LEED certification system provides construction managers with the ability to market the green buildings and the people who work under the LEED system do not need to be trained on the use of the assessment system or tools. However, construction managers who have used the rating system argue that it is paper based and very rigid for use in different environments except the American environment where it was developed. In addition, the LEED system does not provide a framework for the assessment of a building in its life cycle from design, construction, marketing, occupancy, operation, and demolition.

A road map for the implementation of green building rating system

However, the adoption and implementation of the most appropriate green rating system in Nigeria has to follow a framework. One of the recommendations is to establish the impact the current construction practices on the environment (air, water, environmental, and landfill effects, ozone layer depletions, contributions of the construction practices to the environment, energy generation and use practices, transportation of construction materials and the resulting effects on the environment, opportunities for recycling the materials, and alternative sources of materials and energy), then benchmark the building projects in Nigeria with those countries that have already adopted the green rating systems to decide the best rating system to use. In addition, any rating system that is adopted must consider the people who are the social capital, profits to the people and the nation as well, and the natural capital, which is the earth. In addition, an assessment of buildings in terms of indoor air quality, emissions, energy consumption, building materials, project practices, and waste management strategies need to be established and calculated to compared and determine the right green rated building to establish the rationale for adopting a building green rating system.

Typically, in Nigerian infrastructure development and building industry, the main source of energy is in the burning of oil, which generates a lot of greenhouse gases that are emitted into the environment. In addition, the burning of oil for use in indoor environments such as lighting reduces the quality of air because of the smoke particles from burning oil, transport infrastructure is poor, the government lacks a watchdog to implement the policies and accords developed for the implementation of sustainable development accord, waste management is still very poor, and policies to guide sustainable designs are yet to be implemented.

However, the main factors that inhibit the adoption and use of green building rating systems include lack of policies and institutional capacities to formulate the policies, insufficient human resource capabilities, lack of expertise, and lack of awareness on green building rating systems. Once the weaknesses and the problems that could hinder the adoption of the green building rating systems have been established, then a framework for implementation can be established based on the right rating system that has been selected. The key strategies include:

• Assessment of different rating systems
• Formulation of the most appropriate rating system to adopt
• Definition of problems hindering the adoption of the rating systems
• Assessment of existing building codes
• Merging the existing building codes with new green rating building system
• Formulating policies for the adaption of green rating systems for both new and existing buildings
• Implementation of the green building rating systems
• Assessment of the extent to which such rating systems are accepted and implemented
• Revision of the rating systems where possible

Key implications on construction managers

By formulating a green building rating system suitable for Nigeria has very important implications for construction managers who undertake building projects in Nigeria. According to Ding (2008), the key implications include construction managers improving their skills on construction management so as to be able to effectively plan and schedule building projects. In addition, the skills could enable the project managers to be able to link sustainable green construction methods with the key elements of project values, which include scope, quality, function, time, and cost. Ding (2008) maintains that construction managers who professionally qualified can be able to determine the risks associated with using certain construction methods to ensure sustainability. The risks include labor strikes, defective designs, compliance to building codes, and estimation of errors. In addition, the construction manager can in advance provide advice on the best construction methods to use because they are responsible for estimating the construction project attributes such as cost, size, emissions, materials to use, life cycle of the building, proper management of the construction process, ensure good project quality, and effectively administer contracts that reflect green sustainability.

Methodology

The study was based on qualitative and quantitative research paradigms combined into a single research approach. The first approach was to conduct a content analysis of the literature on different green building rating systems and their implications on the building industry in the context of the Nigerian background. The rationale was to establish the right green building rating system to be adopted in Nigeria. According to Stenberg and Räisänen (2006), the qualitative paradigms were used to investigate different green building rating systems used to rate buildings in different countries, the areas where they are applied, the strengths and weaknesses of the GBRS. In addition, the methodology consisted of investigating the best approach that Nigeria should use to implement the GBRS in the country and the implications that results could have on construction managers. Stenberg and Räisänen (2006), suggests a framework where after doing a content analysis of the literature on different GBRS, further studies were conducted using the quantitative to identify the best applicable rating system to apply in Nigeria (Eichholtz, Kok & Quigley, 2010). The quantitative paradigm consisted of issuing questionnaires to 350 respondents on different factors on an assessment scale with the following points:

• Importance of the rating system
• Knowledge of the rating system
• The number of countries that have used the system
• Number of building projects where the rating system has been applied
• The ease of use of the rating system
• Nature of possession of the system
• Language used to write the rating system
• The cost of acquiring the system
• Availability for on line use
• Case studies that have successfully used the rating system
• Flexibility of adoption of the system
• Life cycle assessment of the system
• Standardisation of the system
• How issues are categorised using the system
• Quantitative criteria for rating the building
• Qualitative criteria for rating the building

The target population are all stakeholders in the infrastructure development and building industry in Nigeria. Because Nigeria is very large, it could not be possible to collect data from every stakeholder in the industry, compelling the researcher to collect data from a sample population (Wu & Low, 2010). The strategic approach of selecting the sample population was to use a random sampling selection method because each participant could be given an equal chance to participate. In addition, the probabilistic sampling method was useful because the sample consists of people skilled in the application of the green building rating systems and the construction codes that are used to provide a framework for the construction of infrastructure and buildings in Nigeria (Wu & Low, 2010).

Data Analysis

The responses to the questionnaires were collected, edited, coded, and entered into the SPSS program for analysis to determine the best sustainable (green) building rating system for infrastructure projects in Nigeria.

Table 1: Responses on the need for Nigeria to adopt a green building rating system.

Table 2 shows the choice of green building rating systems that were used for the study. The responses are shown in table 3 below and the missing values are the questions that were not answered or skipped by the respondents. The percentage responses were determined using the SPSS software for each green building rating system.

Table 3: Frequency and percentages of recommended green building rating system.

According to the results in table 3, different stakeholders in the infrastructure industry recommended different green building rating systems as shown according to their responses. From table 3, it is clear that the 26.2% of the respondents recommended the adoption of Green Star SA, 27.5% recommended the adoption of BREEAM, 19.4% recommended Green Globe, and 3.2% recommended the use of Home Energy Rating System (HERS) Index.

Figure 4: Availability of green rating system for on line use.

Table 5: Importance of the green rating systems.

The importance of the GBRS is shown in table 5 above and Green star, which was formulated in South Africa, had the highest percentage responses with 37.7%, followed by LEED that received 29.4%, followed by BREEAM, which had 22% of the respondents agreeing that the rating system was important.

Table 6: GBRS with the right rating data.

Discussion and Conclusion

From the above data, it is easy to conclude that the average rating for the BREEAM, LEED, and Green Star was the highest followed by Green globe and Home Energy Rating. In the context of the study, where the researcher was seeking to established the best GBRS for Nigeria to adopt, different criteria has been used and the responses provide an overview of the GBRS that is popular and recommended by stakeholders. First it is highly recommended that Nigeria adopt a green building rating system, which would provide a framework for green infrastructure development. The cumulative percentage of those who support the use of a GBRS in Nigeria is 60.8%, showing that many stakeholders could be ready to work with the government and to use GBRS frameworks because of there are many benefits derived from their use.

A critical analysis of the data in table 3 shows that Green Star has the highest percentage of recommendations for adoption in Nigeria, with 28.4% of the respondents proposing its adoption, BREEAM getting 24.7%, LEED getting 19% and Green globe getting 21.8% of the responses. The relative percentages are because of the benefits that could be gained by the use of the rating system in the Nigerian environment. One of the benefits of using Green Star is that the materials used for construction work must be assessed for their use in all phases of the construction life cycle of the material and the building. Other areas that are assessed based on the Green Star rating system include the energy efficiency of the construction work and tools, which is a significant problem affecting the infrastructure development industry in Nigeria. However, BREEAM scored 24.7% because some of the items used to rate a building are similar to those found under the Green Star system.

On the other hand, the Home Energy Rating System (HERS) Index scored 3.3% under the frequency and percentage of the rating system that were recommended for use in Nigeria. On the other hand, the Green Star SA scored 67.3% for its on line presence and availability for use, LEED scored 14.8%, BREEAM scored 7.9%, Home Energy Rating scored 2.3%, and Green Globes scored 3.9%, showing that Green Star SA scored had the highest score of an on line presence and availability for use. Green Star has many benefits that makes it suitable for use in the Nigerian environment because it is available on line and can be used to evaluate a building for compliance to a predetermined criterion.

In addition, it is possible to see that the Green Star system provides a framework to assess the compliance of a building to the principles of green management. In addition, the rating system provides the guidelines to mitigate environmental effects on the environment such as the emission of greenhouse gases such as carbon dioxide into the environment. Greenhouse gas emissions are a problem in Nigeria because most of energy consumed in the country such as electricity is generated by burning fossil fuels. In addition, indoor activities such as lighting use fossil fuels that end up generating a large amount of greenhouse gases and waste products. In general, the Green Star rating system emphasizes on the stewardship towards the environment, efficient utilization of energy, and efficient use of materials for construction work.

Table 5 shows the importance of GBRS for use in infrastructure development in Nigeria. It is shown on the table that respondents regard Green Star to be the most important because of the 37.7% score while LEED scored 29.4%, BREEAM scored 22%, and Green globes scored 10.2% and Home Energy Rating scored 0.06%. It shows that the respondents preferred Green Star to the other GBRS. On the other hand, it is clear that Green Star provides the right information because of the 54% score while LEED scored 20.7% and BREEAM scored 14% in providing the right information. The implications are that most people could be inclined to use Green Star to the other GBRS because of the ease with which they can access the right information to use. The rationale is that most of the rating systems are copyrighted and can only be issued at a fee. On the other hand, the most frequently used GBRS as per the stakeholders is Green Star and the least used is Home energy rating, which scored 1%.

In conclusion, it is worth noting that different green building rating systems are suitable for different environments. However, it was noted in the study that the Green Star rating system that was developed and now being used in South Africa is well suited for adoption in the Nigerian infrastructure development environment. The rating system is flexible and accommodates most of the details and specifications in the different rating systems into one usable rating system. In addition, it is easily available and factors all environment issues and concerns that affect the built environment in Nigeria.

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Appendix

You are asked to provide candid responses to the questions on this questionnaire as possible and where you do not understand, you are requested to ask for clarification as much as possible. This questionnaire is for collecting the opinions of stakeholders on the recommended green building rating system for adoption in Nigeria and the data provided shall not be used for any other purpose except for the research for which it was intended.

1. Does Nigeria need to adopt a green building rating system?

   • Yes…..No….
2. Which green building rating system do you recommend?

   • Write down………..
3. Please rate the importance of the green building rating system

   • Very poor…Poor…..Good……better………Excellent………
4. Do you have any Knowledge of the green building rating system?

   • Yes………….No…………………………..
5. How many countries do you know use the green building rating systems system?

   • Write the number down…………………………
6. How many building projects do you know where the rating system has been applied What is the ease of use of the green building rating system rating system. State the number………………………………………..
7. Does a country need to some skilled workers to use the green building rating system?

   • Yes……………..No……………………….
8. Are the green buildings rating system written in English?

   • Yes……………..No……………………….
9. Is it expensive to acquire the green building rating system?

   • Yes……………..No……………………….
10. Is the green rating system available for on line use?

    • Yes……………..No……………………….
11. Do you know of case studies where the green rating systems have been used successfully?

    • Yes……………..No……………………….
12. How flexible is the adoption of the green building rating system?

    • Very flexible……….Flexible………..Not flexible………………….
13. Dows the green building rating system allow for the life cycle assessment of a building?

    • Yes……………..No……………………….
14. Can the green rating system be standardised?

    • Yes……………..No……………………….
15. Does the green rating system you have recommended categorise green rating issues?

    • Yes……………..No……………………….
16. Does the rating system you recommended provide a quantitative criteria for rating the building?

    • Yes……………..No……………………….
17. Does the green rating system you recommended consist of qualitative criteria for rating the building?

    • Yes……………..No……………………….