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The building-and-construction industry has been researched extensively over its life cycle regarding green and sustainable processes and techniques due to its major contributions towards energy consumption and its environmental impacts. Over the past decade, the construction stage of a building is often criticized for overlooking or approximating the environmental impacts as compared to other life-cycle stages of a building. This is evident through strong research findings regarding other building life-cycle stages in building-emission-assessment studies. With the drive towards digitization, the construction industry is receiving significant research attention in order to minimize environmental impacts at the construction stage. Despite these research initiatives, only a handful of recent review studies have systematically furnished current advances, gaps and future directions in environmentally sustainable building-construction techniques. The current study represents a systematic literature review of the environmental impacts at the building-construction stage with the objective of identifying the current findings, gaps and future research scopes. A bibliometric assessment revealed key author contributions, key research areas and collaboration aspects of research works related to environmental impacts of construction in building projects. Four major barriers and knowledge gaps in conducting a comprehensive assessment at the construction stage of a building were identified, including the lack of definition of a generic system boundary, difficulties in data collection, complex modeling issues and complications in the classification and analysis of emissions. The findings would provide key knowledge for passionate construction-industry stakeholders who are keen to benchmark green and sustainable construction practices in the building industry.

PurposeThe issue of building defects is a growing concern that affects all major construction stakeholders as a result of costs and time implications of reworks. The magnitude of the problem is severe with statistics highlighting defects often result in 4% of the total cost of construction of a building. Despite the importance of this problem, studies have seldom considered development of systematic approaches to enhance the quality control process in construction.Design/methodology/approachBuilding defects is a growing concern that affects all major construction stakeholders because of costs and time implications of reworks. Magnitude of the problem is severe with statistics highlighting defects often result in 4% of the total cost of construction of a building. Despite the importance, studies have seldom considered development of systematic approaches to enhance the quality control process in construction.FindingsResults indicated that poor workmanship is the main cause of building defects and incomplete works is a frequently detected defect type. Results categorised defects based on cost and frequency to identify the severity. Findings also identified four focus areas including control measures, technology use audit and inspections and promotion of best knowledge.Research limitations/implicationsThe study lacks generalisation as it covers only Victorian scenario and further studies are needed to generalise the findings.Originality/valueThe study provides a deeper understanding of the challenges currently facing the residential construction industry in Victoria, Australia, and underlines the need for developing quantitative models and methodologies to improve current processes, practices and policies for effective defects minimisation in Victoria, Australia. The systematic methodological framework can also be adopted by researches across the globe to effectively analyse the options for minimising residential building defects.

PurposeThe main objective of the study is to present a systematic process that can assess, compare and benchmark different geographical levels environmental impacts of using sustainable materials at construction stage.Design/methodology/approachCurrent study presents a methodological framework to evaluate environmental impacts at the construction stage of using sustainable materials through a cradle-to-gate process based quantitative LCA study. Scenario analyses and an optimisation analysis using Monte-Carlo simulation are conducted to investigate the influence of external factors on environmental impacts at different geographical regions.FindingsMaterials account for 98% of greenhouse gas (GHG) emissions. Carbon monoxide (CO) and non-methane volatile organic compounds (NMVOC) record significant non-GHG emissions. Particulate matter (PM10) emissions are significant from transportation and equipment. High significance of global warming potential (GWP) (38.98%) and photochemical oxidation formation potential (POFP) (34.49%) at global level and eutrophication potential (EP) (52.83%) and human toxicity potential (HTP) (25.30%) impacts at local level were observed. Shortest transportation distance reduces 14.91% PM10 and 4.69% nitrous oxide (NOx) emissions. Inventory variations have major influence on POFP impact at global level. Local level impacts are not significantly affected by inventory variations. Optimisation analysis indicated, high fly ash in concrete increase local level carbon emissions, if OPC concrete transportation distance is less than 23.7 km.Research limitations/implicationsUse of case-specific information for validation may lack generalisation. However, methodology can be used for future sustainable decision making over using sustainable materials in construction.Originality/valueThe study estimate environmental impacts at different geographical levels when sustainable materials are used for construction.

Traditionally, the construction industry has predominantly used Portland cement (PC) to manufacture bricks, as it is one of the most-commonly available building materials. However, the employment of waste industrial material for brick production can lead to a significant improvement in terms of sustainability within the construction sector. Geopolymer bricks made from brown coal fly ash, a promising industrial waste by-product, serve as a potential alternative. Conducting a life cycle assessment (LCA), this study thoroughly evaluated the entire manufacturing process’s environmental impact, from source material acquisition and transportation to brick manufacturing, distribution, usage, and end-of-life, for brown coal bricks as compared to PC bricks. The LCA of the brown coal bricks revealed that their primary environmental impacts stemmed from the raw material manufacturing and usage, while exhibiting substantial reductions in ozone depletion, water depletion, and metal depletion. These findings highlighted the environmental advantages of the brown coal bricks and their potential to revolutionize sustainable construction practices.

White topping is a popular road rehabilitation technique that uses Portland cement concrete overlay on top of any existing bituminous pavement. However, this often results in additional cost and carbon emission escalations which complicates market useability of the product. The current study aims at comparing carbon emission and manufacturing cost of concrete topping mixes with three different fibre types. The study optimises the benefits and promotes the use of effective materials in sustainable road rehabilitation. Samples with polyolefin-twisted (F2) fibres indicated least carbon emission escalation while the sample with polypropylene (F3) exhibited least cost escalation with 0.75% and 7.17% from the control sample respectively. A multi-objective genetic optimisation study was conducted to identify the mix designs with least carbon emission and production cost escalations. Sensitivity analysis illustrated that transport distance is a critical contributing factor for production cost while carbon emission is highly sensitive to emission factors for transport and cement production. These results indicate the importance of considering locally available materials and clean energy for production processes. Future research can be focused on exploring the long-term environmental and economic benefits including the durability characteristics to benchmark the sustainable benefits of using waste fibre materials in the mix.

PurposeThe purpose of this paper is to identify and assess the perceptions of constructional professionals on barriers to implementation of building information modeling (BIM) within the Nigerian construction industry.Design/methodology/approachA scoping literature review was conducted to identify the fourteen barriers to implementation of BIM, which were employed to design a questionnaire survey. Data collected were analyzed using descriptive statistics, mean score, Kruskal–Wallis test, analysis of variance and multivariate techniques such as factor analysis.FindingsThe descriptive and empirical analysis demonstrated a disparity of ranking of the 14 barriers factors among the groups; however no statistically significant differences among the 14 barriers to BIM. Based on the mean score ranking results, only three (out of 14) barriers are identified as critical (mean score greater than 3.5): few studies available on BIM and lack of knowledge, inexistence or inadequate government policies, and high cost of implementation. The results of the one-sample t-tests show that they were statistically significant differences in 10 out of 14 barriers as follows: few studies available on BIM and lack of knowledge, lack of demand for use and acceptance of BIM, inadequate contractual coordination, lack of specified standards, cost of data and information sharing, technological availability issues, reluctance of other stakeholders, business and cultural changes, data and intellectual property issues, and interoperability issues. The study, through factor analysis, categorized the fourteen barriers to BIM implementation into four principal factors. The factors are: technology and business-related barriers; training and people-related barriers; cost and standards-related barriers; and process and economic-related barriers.Practical implicationsThe identification and assessment of the key barriers to BIM implementation would be useful for the construction professionals and other stakeholder of the construction industry with the view to advance BIM adoption in Nigeria. This could also be extended to other developing countries through considerations of the local economic conditions, given the status of BIM as being in the germinating stage of development in Africa.Originality/valueThe study provides insights on the barriers to BIM implementation across the Nigerian construction sector environments. The innovative aspect of the study is the identification of the ordered and grouped (composite) set of barriers to BIM which could be used to developing appropriate mitigating solutions.

Waste from used solar panels will be a worldwide problem in the near future mainly due to the strong uptake in solar energy and the necessity of disposing solar panel systems at the end–of–life stage, as these materials are hazardous. While new techniques and strategies are often investigated to manage the end–of–life of solar panels effectively, there is huge potential in recycling and reusing solar panel waste as components for alternate products. Numerous studies have been conducted on using alternate materials instead of conventional materials in pavement construction. The current study presents a detailed review and a discussion on using solar panel waste materials in pavement construction. The findings present opportunities to use different solar panel waste materials such as glass, aluminium (Al), silicon (Si), and polymer waste as potential replacement materials in various types of pavement construction. The study also presents the current progress and future focus on experimental developments in pavements with solar panel waste to benchmark short–term and long–term characteristics. Finally, the review discusses the impediments that restrict and the drivers that can facilitate the implementation of solar panel waste in pavement construction. The main findings from this review can be used as a quantitative foundation to facilitate decisions on using different solar panel waste materials in pavement construction applications. Furthermore, such findings will also be beneficial for policymakers and industry stakeholders to implement effective supply chain strategies for promoting solar panel waste as a potential pavement construction material.

The concept of green building has gradually formed with the increase in public awareness of environmental protection, which also covers a wide range of elements. The green building is the fundamental platform of sustainable development. This review paper provides solutions for the multi-dimensional and balanced development of green building. Since green building is the development trend of the construction industry, it presents an opportunity to mitigate global warming and accomplish energy efficiency. However, the problem is that the development of green building’s implementation is restricted by the lack of government policies, imperfect technical abilities and unreasonable economic benefits. One conclusion drawn from the results shows that the benefits of green building implementation include environmental, economic, social, and health and safety aspects. Moreover, it is crucial to improve the awareness of stakeholders to promote the development process of green building. The government should launch campaigns to encourage developers and tenants to embrace green building, which can add value to buildings. The novelty of the paper provides a more systematic review on the sustainable considerations of green building than previous efforts in the literature. Bibliometric analysis is conducted through VOS viewer software. This review paperdiscusses the relevant benefits and challenges of green building through a critical review of existing research knowledge related to green building. The current advancements in green building are highlighted in this paper. Importantly, future recommendations for standards and policy formulation and future research directions are proposed in this review article.

Electricity dependent heating-cooling (H/C) system has increased rapidly to provide thermal comfort to the occupants. H/C is a major source of energy consumption in residential buildings around the world. Studies revealed that the thermal properties of building materials are converted into the same unit as thermal resistance (R) in the USA, Canada, The UK, Australia, and other countries. However, none of the previous studies have considered the adaptation of national insulation codes to reduce electricity cost and greenhouse gas (GHG) emissions with the correlations of energy consumption (Q) to thermal resistances (R) of the building envelop (A). Therefore, this study attempts to review the optimum energy consumption of a selected house due to H/C at different choices of national code standardized R values. Accurate envelop areas (A) of the selected house components are estimated by applying the Autodesk Revit Building Information Model (BIM) to use in the energy model. The case study critically evaluates the variation of electricity cost, GHG emissions, and selection of the optimized thermostat settings for energy savings in different climatic regions and seasons of a year. Different correlations are obtained using risk analysis software on energy consumptions with code recognized arrays of insulations. This sensitivity analysis result shows that the corelation coefficient of energy consumption with medium-low insulated building envelop (r = 0.44) is more significant than improved, maximum, medium-high, and minimum insulations (r = 0.14–0.29) which indicates the insulation range where more emphasis should be put to get an optimized solution. Thus the developed analytical framework supports inclusive decision-making by selecting appropriate kinds of insulation for the design of a sustainable house.

Emissions at the construction stage of a building have been overlooked due to several impediments and complications. Identification and categorization of these complications could be the initial st...

Precast technique has gained significant reputation in the construction industry due to improved efficiency and reduced construction waste. Pile foundation is often built through driven precast or cast-in-situ construction technique. The two types of pile foundations have been widely utilised in various building construction types. The selection of the piling methods has been largely based on the project scope, soil conditions and availability of resources. However, little research has been conducted on environmental impacts brought by driven precast piles compared to cast-in-situ bored piles. The paper aims to address the research gap by conducting a comparative study to measure greenhouse gas (GHG) emissions of driven precast and cast-in-situ piles construction using two case studies in China. A process-based quantification model is developed to measure the major emissions and impacts due to materials, transportation and equipment usage. Results of the study indicated 113.04 and 107.46 kgCO2 per pile per metre of excavated depth for case study A and B respectively. Results of the study also observed a reduction for equipment usage and an increase for transportation in GHG emissions for driven precast piles as compared to cast-in-situ piles. Four scenarios were selected to further investigate the GHG emissions variation. Results indicated that use of sustainable materials can achieve the maximum GHG emissions reduction for both types of pile construction. Transportation distance was recorded as a key factor to be considered in reducing GHG emissions for driven precast piles construction. Results of the study can be effectively utilised to compare life cycle GHG emissions of precast construction with cast-in-situ construction.

Building construction sites are responsible for significant energy consumption and emission production. The emissions at building construction stage vary from greenhouse gases (GHG) such as carbon dioxides (CO2) to non-GHG emissions such as carbon monoxide (CO), nitrogen oxides (NOx), particulate matter (PM) and sulphur dioxides (SO2). The construction emissions are often neglected due to the low amounts of emissions compared to high use phase emissions over the building life cycle. However studies have shown that these impacts from building construction can be significant at national and local level. Several difficulties and complications in estimation have restrained the possibility of effective decision making to minimise these emissions. Stakeholders in the construction industry seek the necessity of an emission calculation tool that enables the decision making in construction related emissions with minimum effort. The Construction Emission Evaluation Tool (CEET) presented in the study allows designers and contractors to estimate and compare emissions from the major emission sources in building construction. Emission analyses at project, equipment and activity levels provide in-depth scrutiny of emissions in minimising emissions and assisting the decision making for effective resource planning. Foundation construction corresponding to a case study is presented to demonstrate the functions and the capabilities of the developed calculation tool. The tool can provide a strong basis for the construction industry stakeholders and related researchers to make better decisions in maintaining a sustainable work environment. The study is also the initial step towards developing a sustainable decision making tool that can optimise cost, emissions and other construction related issues.

Replacing virgin materials with recycled or sustainable materials to reduce energy consumptions and emissions is the focus of contemporary research to reduce building related emissions. Geopolymer concrete produced using 100% fly ash is a similar sustainable construction material capable of replacing Portland Cement (PC) concrete. As a replacement for PC, fly ash seems to be a sustainable solution, however the benefits from the production process of fly ash geopolymer (FAGP) concrete is the subject of considerable debate. In addition, factors such as local availability and transportation issues could potentially increase the emission profile of FAGP concrete. Thus, this study aims to evaluate the emission profiles for different types of fly ash in Australia considering availability and transportation. A case study and a scenario analysis are also presented to demonstrate the factors that affect the Green House Gas (GHG) emission profile of FAGP manufacture. The results indicate that to the GHG emission profile for FAGP concrete changes considerably based on the material availability, transportation and mix design. Alkali activators and elevated heat curing processes also significantly contribute the total GHG emissions of FAGP concrete production. The results further signify that the case study location could influence the employment of FAGP concrete in terms of GHG emissions. Further studies are encouraged on optimising the cost, GHG emissions, availability and strength characteristics to strike a balance between in sustainability for selecting the best FAGP type for construction. The results also provide the initial factors to be considered in developing a guideline for employing sustainable materials in the building industry.

Public-private partnerships (PPPs) come in so many schemes and the selection of the right PPP model is crucial to the success of a project. Therefore, the purpose of this paper is to explore the criteria on the selection of the public-financed PPP scheme in developed and developing countries. Twenty-five PPP scheme selection criteria were identified based on a comprehensive review of existing literature and expert interviews. A web-based questionnaire survey was used to collect data with experienced PPP professionals from both industry and academic. The mean score ranking and Mann–Whitney U test was used to analyze the survey responses. The ranking results indicate that the top important criteria are related to the stability in political and legislation system as well as the mature legal system. The Mann–Whitney U test reveals that professionals from developed and developing countries view the importance of six out of 25 criteria differently. The results are hoped to develop the well-integrated decision-making framework for selection of the appropriate scheme for a particular project in both developing and developed countries.

Purpose The Nigerian construction industry, like in most emerging economies has been slow with technological advances such as building information modeling (BIM). More so, the application of BIM among Nigerian practitioners is rather limited to architects’ usage for schematic design and presentation of drawings. The purpose of this study is to enhance BIM’s uptake, this study explores the drivers for the implementation of BIM within the Nigerian construction industry. Design/methodology/approach An interpretivist epistemological design was adapted to extensively manually review and search the literature on BIM implementation drivers. Based on 14 drivers for BIM implementation drivers identified, a survey questionnaire was used to collect data from the Nigerian construction practitioners. The data obtained is then subjected to descriptive, inferential statistics and multivariate techniques such as factor analysis. Findings The study, through factor analysis, categorized the 14 drivers to BIM implementation into four principal factors. The factors are construction related-drivers; process digitalization and economic-related drivers; sustainability and efficiency-related drivers; and visualization and productivity-related drivers. Practical implications To effectively adopt BIM in the construction industry, it is necessary to identify the BIM implementing drivers, which can act as catalysts of change and, thus leading to sustained adoption of BIM. Therefore, the identified drivers and categorization of principal factors could provide managerial implications for better execution and adoption of BIM, as well as the creation of the required change for the BIM implementation. Originality/value The research provides insights into the implementation drivers of BIM in lesser studies in a developing country such as Nigeria. The study further contributes to this research sphere by using factor analysis to customize and contextualize the drivers that were previously identified.

Voice recognition technology has been in existence over several decades but its application in the construction industry has been minimal. Despite the several advantages it offers, its application has been limited to smart building integration only. This study has made a significant contribution by integrating voice recognition technology into key-in building quantities estimation software. The Visual Basic programming language was used to design and code the interface of the voice recognition system and key-in estimating software model. The prototype model continues to have some challenges because it cannot work efficiently in a noisy work environment and there is limited range of vocabulary it can recognize. This paper seeks to challenge the stakeholders of the construction industry to maximize the benefits of voice recognition technology and integrate it into other construction tasks. In addition, future research can consider integrating building information modeling and voice recognition technology.

Greenhouse gas (GHG) is a major air emission pollutant that creates environmental burden in buildings. Timber buildings are gaining notable popularity in the building industry due to life cycle environmental and economic benefits over conventional buildings. However, little or no studies have made attempts to compare greenhouse gas emission variations in timber and concrete buildings during the construction stage. Knowledge of emission at the construction stage is critical for passionate contractors who wants to maintain an environmental friendly built environment. The study presented in this paper aims to compare GHG emissions and energy consumptions during timber and concrete building construction. A process based quantitative assessment is conducted for evaluating emissions from materials, equipment and transportation stages. The comparative results of the study indicated that use of timber can reduce embodied emissions as well as transportation emissions during the construction stage. Scenario analyses results comprehends that recycling of materials and use of regional materials influence GHG emissions the most while transportation distance has medium effect on total GHG emissions at the construction stage of timber building. The results of the study are important in aggregate level decision making of timber and concrete buildings. Further studies are encouraged on conducting comprehensive assessment of different timber usages in a building to investigate the GHG emission variation.

Different construction activities may indicate distinct environmental impacts due to their uniqueness. Ability to assess and compare the environmental impacts from different construction activities can aid the process of minimising emissions at different building construction processes. The study presents a comparative impact assessment methodology to evaluate environmental impacts at different activities during the building construction stage. Significant impact related construction activities for five major impact categories namely global warming potential (GWP 100), acidification potential (AP), Eutrophication potential (EP), Photochemical oxidation formation potential (POFP) and Human toxicity potential (HTP) are compared from the global, regional and local perspectives. A case study of a residential building in Australia is used to demonstrate the application of the functions of the developed method. The results of the case study indicated that the method can be effectively used to compare environmental impacts of different construction activities at different geographical perspectives considered. The method can be used by designers and contractors in comparing impacts of various construction activities to identify the most emission effective construction processes.

The building and construction industry is one of the leading generators of waste in the worldwide economy. Use of excessive quantities of virgin materials to manufacture building materials is a growing dilemma that needs urgent attention. With the excessive general of waste, research focus has been directed toward the use of waste to substitute and reduce the requirement for immense extraction of virgin materials. After glass and plastic, cardboard is considered as the most prominent recycled waste material that could possess potential use in mortar and concrete applications, thereby reducing virgin material extraction. The current study aims to conduct a systematic review in using cardboard waste in mortar and concrete. A bibliometric assessment of 874 research publications demonstrated that cardboard waste related studies on mortar and concrete remain seldom considered. An analysis of literature indicated kraft fibres within cardboard can be recycled into building materials. The key findings discovered matrix modification and fibre pre-treatment are essential for the enhancement of mechanical and durability properties. Researchers have developed mix designs including supplementary cementitious materials (SCM) to mitigate fibre degradation and enhance mechanical values. However, further research is required to comprehensively analyse an effective material matrix to reduce the degradation caused on the fibre. Therefore, this paper presents key findings of current trends, limitations and future research directions related to the use of recycled cardboard in concrete and cement-based materials.

Due to its dynamic nature in construction, benchmarking environmental emissions of road construction projects can be a daunting task. Often stakeholders will have to prioritize the economic and environmental indicators based on the project objectives. The study presents a methodological framework to compare economic and environmental impacts to benchmark sustainable transport construction projects. Through findings, the study aims to inform focus areas and key stages of infrastructure projects to benchmark sustainable performance. Process-based emission and cost estimation models are presented with an AHP based weighting factor that enables prioritization of emissions and costs based on project scopes and objectives. Using a case study, results are represented to validate the framework and methodology. Concrete and steel are identified as the main materials that contribute to total carbon emissions, while soil and gravel are responsible for the highest costs. Electricity consumption is discovered as the major fuel type contributing to carbon emissions. Concrete and dump trucks are discovered as the top two sources of emissions and costs, respectively. Scenario analyses revealed that the choice of equipment significantly affects the project’s emissions and costs. The application of sustainable materials can significantly reduce emissions and cost. The use of the case study approach results in a lack of generalizability. However, the same methodology and process can be adopted for the sustainable benchmarking of different projects. Researchers are encouraged to investigate processes to automate sustainable benchmarking of transport infrastructure construction projects. The study is one of the first attempts to compare cost and environmental impacts using a systematic methodology of transportation infrastructure construction projects.

Previous studies have seldom investigated the effects of direct emissions at different stages of a building construction. This study aims to estimate and compare direct and indirect emissions and environmental impacts at foundation and structure construction stages of a building using a case study. The case study is multi-storey commercial building construction with concrete framing. A process based methodology is developed to estimate emissions from seven sources that contribute to both greenhouse gas (GHG) and non-GHG emissions. An impact assessment is also carried out to compare the environmental impacts for different stages of construction from global, regional and local perspectives. The results highlight an overpowering indirect GHG contribution of 89% from material embodied emissions at the structure construction stage. Direct GHG emissions at the foundation construction are prominent with a contribution of 12.7% and 13.4% for emissions from equipment usage and transportation respectively. Nitrous Oxides (NOx) and Carbon Monoxides (CO) are recorded as the most prominent non-GHG emissions. The results were further analysed based on four scenarios corresponding to direct and indirect emissions. The results signified a GHG emission reduction of 12% can be achieved by adopting sustainable materials such as fly ash and blast furnace concrete. The impact assessment results illustrate a large contribution to global warming potential (GWP) with a value of over 98% for the construction stage from the global perspective. This large contribution from GWP is reduced to 60% and 57% with relative high contributions from Photochemical Oxidation Potential (POFP) with 26% and 34% at regional and local levels. The scenario analyses on direct emissions highlight the importance of resource utilisation in reducing impacts at local level. The results indicate that identification of the significant emission sources and impact categories at different construction stages, prior to implementing emission reduction opportunities such as usage of sustainable materials and operational optimisation of construction equipment and transportation vehicles is key to minimising impacts at building construction.

Emissions from equipment usage and transportation at the construction stage are classified as the direct emissions which include both greenhouse gas (GHG) and non-GHG emissions due to partial combustion of fuel. Unavailability of a reliable and complete inventory restricts an accurate emission evaluation on construction work. The study attempts to review emission factor standards readily available worldwide for estimating emissions from construction equipment. Emission factors published by United States Environmental Protection Agency (US EPA), Australian National Greenhouse Accounts (AUS NGA), Intergovernmental Panel on Climate Change (IPCC) and European Environmental Agency (EEA) are critically reviewed to identify their strengths and weaknesses. A selection process based on the availability and applicability is then developed to help identify the most suitable emission factor standards for estimating emissions from construction equipment in the Australian context. A case study indicates that a fuel based emission factor is more suitable for GHG emission estimation and a time based emission factor is more appropriate for estimation of non-GHG emissions. However, the selection of emission factor standards also depends on factors like the place of analysis (country of origin), data availability and the scope of analysis. Therefore, suitable modifications and assumptions should be incorporated in order to represent these factors.

The building sector is the cause of about 36% global energy consumption and 40% of greenhouse gas (GHG) emissions. A considerable portion of this energy is consumed for the thermal comfort of the building inhabitants. Thermal resistance (R) on building envelop is the most powerful component for reducing energy consumption. Therefore this study aims to estimate the correlations between energy reduction and different design parameters of a building by varying insulation R (W/m^2.K) values. A case study is carried out for a single story residential house in a climatic zone of Australia to find the effects of insulation on energy reduction with building components. Energy rating software, FirstRate5, was used to simulate energy consumption for different ranges of R values. Hence the obtained energy consumption (MJ/m^2) and case study house parameters are used as input variables for the correlation analysis using Palisade DecisionTools software, @Risk. The results show that building energy reduction has a very strong correlation (0.92-0.95) with the ceiling, a medium correlation (0.20-.25) and (0.01-0.20) with the wall and floor respectively and weaker correlation (0.01-0.15) for other components. Further, this correlation analysis provides a basis for an energy reduction strategy for buildings.

Adaption of reclaimed resources within the construction industry, in order to move towards environmental sustainability and a carbon neutral society is essential. To address this issue this study focused on the investigation of the long term performance, carbon emissions and coast savings of Alkali-activated slag (AAS) concrete incorporating recycled coarse aggregate (AAS-RA) up to one year of age. The performance and sustainability aspect of AAS-RA concrete was then compared with AAS concrete incorporated with natural quarry aggregate (AAS-NA) and PC concrete, respectively. Both AAS concretes achieved similar compressive strength of approx. 40 MPa and tensile strength of approx. 3.3 MPa after one year. Hence, full replacement of quarried coarse aggregate using recycled aggregate in AAS concrete did not display any evidence of an adverse impact to the strength characteristics. However, the 7-day and 28-day water cured AAS concretes demonstrated 32% and 16% higher drying shrinkage at one year in excess of the maximum permissible limit specified in AS3600. Both AAS concretes displayed high water absorption but low chloride permeability and sorptivity. A highly porous external surface layer interconnected with numerous capillaries and microcracks is hypothesised to be the reason for the high water absorption. Gel formation densified the microstructure and filled the capillaries in the bulk matrix, which in turn resulted in the lower permeability and secondary sorptivity. The AAS-NA and AAS-RA concretes displayed 43.5% and 52% carbon emission reduction compared to an equivalent strength of PC concrete having similar binder content.

According to United Nations, cities situated in the tropical belt occupy only 36% of the Earth's surface yet account for 1/3 of the entire global population. The increasing number of compact dense cities and the rapid population growth in the tropics have also been accompanied by increased urban air temperature. Increased air temperature is often associated with heat waves, and increased energy consumption. Therefore, the urban heat island (UHI) phenomenon and thermal stress have received much research attention and, as a result, the establishment of heat mitigation technologies has become critical. Although studies on urban climate in the tropics have shown progress, the situation in these areas remains complex and warrants further investigation. Accordingly, this paper examines the available heat mitigation techniques and their effectiveness in tropical areas from five perspectives, namely, shading (modifications in urban geometry), urban ventilation (street orientation, sun, and wind), urban greening (green roofs, trees, parks, and walls), albedo, and water bodies. This review paper showed that adopting a combination of mitigation approaches is the most effective method in reducing temperature in tropical cities. The use of shading and/or urban ventilation has also been proven to be more promising than the extensive use of vegetation, water bodies, or albedo modifications in reducing air temperature in tropical cities, where there is already a high level of humidity exists. Some key planning actions to combat UHI and thermal discomfort in tropical areas are eventually provided that can help urban planners integrate urban climatic knowledge into their practices.

Building construction incurs direct emissions from equipment operation and transportation. These emissions at a collective level seem to be high, which alerts contractors who are keen to explore reduction possibilities for emissions. Understanding emission contributions at the activity and equipment level are important to achieve this target. However, none of the past studies have conducted an in-depth analysis to identify direct emissions reduction prospects at the construction stage. This study aims to develop models and method to enable the estimation and analysis of emissions at project, activity and equipment levels in a building construction. A framework is then established to provide a systematic procedure to aid the decision making for reducing direct emissions at the construction stage. A case study of foundation construction in a commercial building is presented to validate and demonstrate the functions of the framework developed. The results show a GHG emission distribution of 77.13%, 13.53% and 9.34% for materials, equipment usage and transportation respectively at the project level. CO and NO x were the governing non-GHG emissions recorded. In-depth equipment level analysis concludes the importance of considering emission rates to compare and identify critical equipment for emission reduction. Activity level analysis ushers the identification of activities with significant emissions from transportation and equipment.

Concrete is the most used construction material in the world. Consequently, the mass extraction of virgin materials required for concrete production causes major environmental impacts. With a focus on promoting sustainability, numerous research studies on incorporating waste materials to replace virgin substances in concrete were undertaken. Despite this vast volume of published literature, systematic research studies on these sustainable concrete mixes that inform various stakeholders on current research trends, future research directions, and marketability options products are seldom conducted. This paper presents a decade review on sustainable concrete with a focus on virgin materials being replaced with waste materials. It aims to inform researchers of current research trends and gaps in the research area of waste material use in concrete. The review also identifies key parameters that restrict the marketability of these sustainable concrete products. The three-step research methodology involves a bibliometric assessment, a key review of selected waste materials, and an interview with a panel of experts focusing on impediments towards the transition of sustainable concrete products into the industry market. Bibliometric assessment was based on 1465 research publications in which five key materials (plastic, glass, fly ash, slag) and construction and demolition waste were selected for the review. The interview was conducted with ten industry experts to discuss the industry limitations in the commercial establishment of materials. The review of existing knowledge and the findings on sustainable concrete presented in this paper provide directions for both research academics and industry stakeholders to systematically focus on sustainable concrete products that are market-ready.

Green materials are considered as one of the prominent elements in designing an environmentally sustainable construction project. Studies have highlighted cement replacement is a popular method of reducing greenhouse gas (GHG) emissions and replacing virgin materials in concrete. These options incur cost implications through sophisticated designs and technologies. The importance of maintaining a balance between environmental and economic benefits of a green design is critical for the decision making stakeholders in a construction project. However, designers often lack the resources and tools to initiate informed decision making for the optimum selection of a green material. In order to systemize the optimising process, the current study suggests a multi-objective optimisation based decision making framework for optimising the cement replacement materials in concrete. The study aims to present a sustainable criterion optimisation framework that could well be adopted to assess the sustainability of green materials in concrete production. A case study using fly ash geopolymer concrete in Melbourne demonstrated a reduction of 3.63% to 41.57% and 23.80% to 30.25% can be achieved for GHG emissions and production cost respectively if the developed optimisation based framework is implemented. The scenario results highlighted around 3% to 8% GHG and cost increase if material is not available locally. A similar approach can be utilised to optimise the environmental and cost savings of other cement replacement materials. Further studies are encouraged on comparing environmental and cost savings of other cement replacement materials using the developed framework. The framework will be valuable for designers in making decisions on sustainable cement replacement materials.

This study investigates strength development, reactivity and environmental/economic benefits of blended High Volume Fly Ash (HVFA) concrete mixes utilizing 65% and 80% cement replacement utilizing a combination of fly ash and hydrated lime, with and without nano-silica. The carbon and non-carbon emissions are considered as environmental impacts while life cycle costs from cradle-to-gate, which is from material extraction to production, are considered for comparison of the economic benefits. The compressive strength of the HVFA mixes increased with the addition of nano-silica. The HVFA–65 and HVFA–80, without nano-silica, achieved 25.0 MPa and 14.5 MPa at 7 days, respectively, and 42.7 MPa and 29.5 MPa at 28 days. With the addition of nano-silica the HVFA–65 ns and HVFA–80 ns concrete had compressive strengths of 37.5 MPa and 28.8 MPa at 7 days and increased to 47.1 MPa and 40.1 MPa at 28 days. Incorporating 3% nano-silica into HVFA concrete increased the early age hydration reaction. This is attributed to the reaction of the C3A and C4AF phases and the formation of monosulfoaluminate, which contributed to the early age strength gain. The majority of Ca2+ ions were consumed during the initial hydration, with few Ca2+ ions remaining for the subsequent hydration reaction with the C3S phase. The HVFA concrete mixes displayed between 51 and 60 % carbon savings and a reduced Global Warming Impact. The non-Greenhouse Gas emissions, i.e. SO2 and NOx, reflects minor savings in the Acidification Impact (AI) and Photochemical Oxidant Formation Impact (POFI) environmental impact indicators. Further, HVFA concrete incorporated with hydrated lime shows a 10% cost reduction compared with Portland Cement concrete.

Off-site construction is a popular construction technique due to improvements in construction time and efficiency. However, a typical construction will incur several air emission substances which can be categorised as direct and indirect emissions. The effect of these pollutant substances may have severe health impacts on the immediate surrounding environment of the construction site. The study attempts to quantify direct and indirect emissions associated with off-site construction and compare with traditional on-site construction. Two case studies in Chengdu, China is used to investigate the direct and indirect impacts of off-site construction as compared to conventional construction. The results indicate GHG emissions reduction of 8.40% for off-site construction. Impact assessment revealed pre-fabrication having more reduction on global warming and oxidation formation at global level and eutrophication, human toxicity and acidification at regional and local environment. Further analysis revealed a strong relationship between the transportation distance and the level of pre-fabrication on total carbon emission reduction. The methodology provided in the current study exemplified the importance of conducting a well-articulated assessment to help decision making on environmental impact reduction in off-site construction. The results conclude the importance of developing a structured decision making platform to assist the sustainable decision makings in future.

The level of emissions to the environment imposed by different human activities has been increasing at an alarming rate over the past decades. Measurement and control of air pollutant emissions into the atmosphere can lead towards reducing the emission level considerably. Construction industry is a major contributor to the environmental emissions due to the extensive use of construction equipment, which is responsible for greenhouse gas emissions and harmful substances such as carbon monoxide, nitrogen oxide and particulate matter emissions. Pile foundation is extensively used in high-rise buildings construction and it involves operation of heavy construction equipment. This study developed a process-based model to quantify environmental emissions of equipment usage in a typical pile foundation construction using the US EPA methodology. The emissions of excavation works govern the total emissions at site because of the high usage hours of excavators. In general the emission rates of piling rig and concrete pumping truck were found to be the highest although excavator emission rates are higher for carbon monoxide and particulate matter. It is seen that careful selection of machines and equipment can reduce the emissions up to 10 %. These findings of the study could be effectively used for minimizing the environmental emissions by careful selection of suitable equipment and technology.

Emissions at the construction stage seem to be getting a lot of attention in the research area for its relative significance over shorter time spans. Applications of various construction methods are recognised as one of the options to minimise emissions at the construction stage of a building. The focus of this study is to compare emission distribution of different construction methods. Two case studies of conventional and semi pre-fabrication construction methods in Australia are employed to compare this emission variation of adopting different construction methods. It sets a system boundary of embodied emissions from building materials, emissions from construction equipment, transportation of building materials, pre-fabricated materials and construction waste. Quantitative models are developed to compute both greenhouse gas (GHG) and non-GHG emissions. An impact assessment was also carried out to examine the relative importance of impacts at global, regional and local perspectives. The case study results indicated that adopting pre-fabrication method offers a GHG emission reduction of 1.7% while an increase of non-GHG direct emissions by 0.9 to 3.5%. Global Warming Potential (GWP) remained the highest impact category for all the perspectives considered, with an overpowering 86.8% contribution from global perspective. However, this relative importance is reduced to 52%, with a relative increase in Eutrophication (EP) and Photochemical Oxidant Formation Potential (POFP) up to 21.74% and 27.14% at regional and local perspective. Emission increase due to transportation shows a relative increase in POFP potential for pre-fabrication. These results signify that non-GHG emissions should be given importance at regional and local perspective when using pre-fabrication method in construction.