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• Evaluated the environmental impacts of plastic wastes management strategies by LCA. • Industrial incineration is the most potential preferential strategy for Hong Kong. • Mechanical recycling is the second most environmentally sustainable strategy. • Reusing plastics in construction is not an environmental-friendly solution compared to others. • The integrated alternative scenarios can lead to 64–97% reduction of the total impacts. Considering the volume of plastic generation and its persistence in nature, the management of plastic wastes has gained increasing attention globally. To select the most environmentally sustainable solution, insights in the environmental impacts of different management strategies are crucial. This study thus aimed to evaluate different plastic waste management strategies such as mechanical recycling, incineration, industrial incineration, construction and landfill, and exemplified with potential case demonstrations in Hong Kong. The environmental impacts of the developed strategies are comparatively evaluated by the lifecycle assessment (LCA) technique in order to identify the most environmentally preferable strategy. The LCA results indicate that industrial incineration is the most potential preferential strategy for Hong Kong, as it can potentially consume the generated waste locally and substitute the imported coal for the cement industry. Mechanical recycling is the second preferential strategy for the city, as it conserves secondary resources significantly. Grate incineration for generating electricity is the third preferable solution, while the use of recycled plastics in construction may not be a benign environmental strategy for Hong Kong. The findings of this study could help policy makers to design strategic direction for environmentally sustainable management of plastic wastes locally based on the circular economy principle. [ABSTRACT FROM AUTHOR]

Considering the significant consumption of energy in existing building stocks, effective retrofitting has great potential for reducing such consumption and promoting sustainability in existing buildings. This study aims to develop a sustainable retrofit decision-making mechanism for high-rise buildings in Hong Kong, China, by uncovering the optimum set of retrofit solutions based on the local climatic conditions, building features and cost. Based on a prototype building in Hong Kong, the study employed the net present value (NPV) to unveil the most suitable solutions to maximise the energy efficiency of existing buildings and minimise their retrofit costs, integrating the energy simulation. This study revealed that it is desirable to adopt an optimal set of measures for achieving a 40% energy improvement since the energy conservation can be as much as 82 (kWh/m2)/year with the optimal NPV of more than US$3300 over a 20 year life span. However, the cooling system, building energy management system and thickness of wall insulation are the most influential factors to the optimum NPV and energy conservation in Hong Kong. The identified optimal set of cost-effective retrofit measures can be effectively implemented for sustainable retrofit projects in the existing building, and the developed methodological framework can be suitably adapted for sustainable building retrofit projects in different climatic zones. The decision-making model is validated by the process of calculating energy consumption, selecting practical retrofit measures and analysing retrofit benefits when taking the local building standards into account. [ABSTRACT FROM AUTHOR]

Turning waste-to-resources is one of the key scientific interests in recent years, especially within industrial symbiosis networks in order to reduce the waste management problem and associated environmental consequences, improve materials efficiency and conserve natural resources. Considering global concern over fossil fuel burning and CO 2 emission, engineered fuels are increasingly used in cement production. The techno-environmental feasibility of using post-consumer wood derived fuel (WDF) in practical application is rarely reported. This study comprehensively evaluated the process feasibility and environmental compliances of utilizing WDF as an alternative fuel in the co-combustion process. The results revealed that physical parameters of WDF met the required fuel standards, and the air emissions by continuous emission measurements also met the specified limits and comparable to the baseline. The stack emission parameters monitored including particulates, dioxin, mercury, cadmium and thallium, and other heavy metals were about 60%, 2%, 21%, 6% and 7% of the specified limits. In addition to significantly reducing CO 2 emission (16% for using 20% WDF as co-fuel), the characteristics, of the flue gas as monitored by continuous emission monitoring and periodic stack emission at the cement plant, and the produced clinker quality were also not affected by the use of WDF. These have demonstrated the suitability of WDF as co-fuel for cement production. • Techno-environmental feasibility of bio-fuel derived from wood waste was evaluated. • Comprehensively reported the practical application of co-combustion process in the cement industry. • WDF was suitable in the co-combustion based on compliances in emission and process parameters. • About 16% reduction of GHGs emission was observed for 20% replacement of coal by WDF in the plant. [ABSTRACT FROM AUTHOR]

Abstract Waste timber formwork from construction sites was used as fibre to prepare wood-magnesium oxychloride cement (MOC) board. The effect of wood fibre content, pulverized fly ash (PFA) and incinerated sewage sludge ash (ISSA) on the mechanical and durability properties of wood-MOC board was investigated. Greenhouse gases (GHGs) emission, one of the representative and most globally concerned environmental impacts, for the production of different types of composite boards was assessed and compared by using lifecycle assessment (LCA) technique. The 'cradle-to-gate' system boundary with 1 kg of board production was considered as the functional unit in this assessment. The result showed that the wood-MOC composites prepared with a higher content of wood fibre had a lower thermal conductivity, higher flexural strength, higher residual flexural strength after exposure to high temperatures and water immersion, and better noise reduction effect. Even though the water absorption was increased with the increase of wood fibre content, it can still be considered to be low. The wood -MOC composites incorporating ISSA showed higher flexural strength, better high temperature resistance and better water resistance than other composites. In addition, the production of the wood MOC board induces lower GHGs emission than plywood and lower human toxicity than conventional resin-based particleboard. [ABSTRACT FROM AUTHOR]

Abstract A rapid development of building environmental research from the globe is witnessed in recent years to deal with the environmental issues, especially in terms of energy consumption and carbon emissions, due to the substantial environmental burdens associated with the building industry. Thus, numerous scientific efforts have been devoted to buildings through environmental assessment like a life cycle assessment (LCA) and a methodological framework development. Concerning the rapid growth of buildings, LCA is increasingly used for assessing and mitigating the associated environmental impacts from material selection to the whole building systems. This study aims to comprehensively review the LCA implication on buildings by discussing the contemporary issues related to the development of this research field. The study considers a wide range of literature including case studies, reviews and surveys, and these articles are critically examined according to the predefined criteria developed. An in-depth analysis is also conducted on selected studies to unveil the criticality of the assessments and results under different considerations. In addition to demonstrating the research gaps for comprehensive assessment of buildings, the adoption of a circular economy (CE) concept is highlighted by providing a comprehensive framework. The findings show that resource recovery and resource-efficient building construction are seldom considered in prevailing studies. As a result, the framework proposed in this paper should help support a paradigm shift towards a comprehensive research for increasing the accuracy and practicability by introducing the CE principle to the building industry for enhancing its sustainability performance. Highlights • Literature related to building-environmental research was critically analyzed. • LCA implication on buildings was comprehensively reviewed by discussing the contemporary issues. • Selected papers were critically analyzed to unveil the research trends and practices. • Knowledge gaps for comprehensive assessment of buildings under the CE principle are identified. • Comprehensive framework based on the CE principle was proposed for comprehensiveness building LCA. [ABSTRACT FROM AUTHOR]

The scarceness of virgin resources and sustainable management of waste materials in high-density city arouse heightened focus on new technology development for waste recycling and local utilization. Wood waste recovery from construction activities and upcycling into secondary products allow the substitution of virgin resources and minimize the environmental burdens within the frontier of industrial ecology. This study assessed the technical viability and environmental sustainability of cement-bonded particleboards (CBPs) produced with recycled wood aggregates and alternative binder; and compared the performance of its counterpart produced with virgin wood and ordinary binder using experimental analysis and life cycle assessment (LCA). The experimental results showed acceptable mechanical performance of the developed CBPs in compliance with the required standards. Adoption of carbon dioxide curing technology further enhanced the durability of the developed CBPs. Although similar greenhouse gases (GHGs) emission was observed for imported conventional CBPs and locally produced CBPs with alternative materials, the considerations of direct carbon sequestration and landfill avoidance contributed to a 9% reduction of the total GHGs compared to conventional CBPs. The LCA results also demonstrated that substantial amount of GHGs can be potentially saved depending on the recycling rates of wood waste in Hong Kong. Hence, technological innovation can effectively address problem of wood waste disposal and enhance material utilization and sustainability of the construction industry. [ABSTRACT FROM AUTHOR]

The management of a large amount of wood waste generated from construction activities is a challenging issue. However, wood waste is an inherently renewable resource that can be recycled and utilized for the production of green products and renewable energy. In order to minimize the environmental impacts and to provide a scientific basis for the decision-making process on the wood waste management systems, a life cycle assessment (LCA) approach was employed in this study to evaluate the potential management systems from an environmental point of view. Three alternative scenarios, including the recycling and reusing of wood waste to produce organic polymer based particleboard, cement-bonded particleboard and energy were compared with the current disposal strategy (landfill disposal), with the functional unit of 1 tonne of wood waste within a cradle-to-grave system boundary. The LCA results showed that significant reductions of environmental impacts were observed for the production of particleboard (scenario 1) and wood-cement composite (scenario 2) from wood waste compared to that of using virgin wood. However, the results also showed that scenario 3 (energy generation from bio-fuel derived from wood waste) was the best strategy, as this technology reduces more than 1 tonne of CO 2 eq greenhouse gases compared to the energy generation from coal. The analysis conducted in this study can serve as guidelines to design a sustainable and resource-efficient wood waste management system. [ABSTRACT FROM AUTHOR]

As the world’s most widely used construction material, the production of concrete has been recognized to lead to major environmental impacts. To promote sustainability in the concrete industry, various kinds of supplementary cementitious materials (SCMs), such as fly ash, blast furnace slag and silica fume have been used to replace cement in concrete production. The nature of these SCMs has therefore been changed from wastes to co-products or by-products. Life cycle assessment (LCA) has been increasingly adopted in the concrete industry to assess environmental sustainability. However, the choice of an appropriate method for impact distribution in the LCA of concrete incorporating SCMs is a research challenge. This study aimed to present a comprehensive review of the impact allocation approaches for assessing the environmental impacts of SCMs-incorporated concrete. Furthermore, the use of the system expansion approach was compared with the conventional mass and economic allocation approaches. A case study of concrete production using SCMs in Hong Kong was conducted using the different approaches. The results were then analyzed and it was concluded that the system expansion approach is appropriate for the assessment of the environmental impacts of SCMs-incorporated concrete. [ABSTRACT FROM AUTHOR]

This study aimed to compare the environmental performance of building construction waste management (CWM) systems in Hong Kong. Life cycle assessment (LCA) approach was applied to evaluate the performance of CWM systems holistically based on primary data collected from two real building construction sites and secondary data obtained from the literature. Different waste recovery rates were applied based on compositions and material flow to assess the influence on the environmental performance of CWM systems. The system boundary includes all stages of the life cycle of building construction waste (including transportation, sorting, public fill or landfill disposal, recovery and reuse, and transformation and valorization into secondary products). A substitutional LCA approach was applied for capturing the environmental gains due to the utilizations of recovered materials. The results showed that the CWM system by using off-site sorting and direct landfilling resulted in significant environmental impacts. However, a considerable net environmental benefit was observed through an on-site sorting system. For example, about 18–30 kg CO 2 eq. greenhouse gases (GHGs) emission were induced for managing 1 t of construction waste through off-site sorting and direct landfilling, whereas significant GHGs emission could be potentially avoided (considered as a credit −126 to −182 kg CO 2 eq.) for an on-site sorting system due to the higher recycling potential. Although the environmental benefits mainly depend on the waste compositions and their sortability, the analysis conducted in this study can serve as guidelines to design an effective and resource-efficient building CWM system. [ABSTRACT FROM AUTHOR]

With the promotion of environmental protection in the construction industry, the mission to achieve more sustainable use of resources during the production process of concrete is also becoming important. This study was conducted to assess the environmental sustainability of concrete slurry waste (CSW) management by life cycle assessment (LCA) techniques, with the aim of identifying a resource-efficient solution for utilisation of CSW in the production of partition wall blocks. CSW is the dewatered solid residues deposited in the sedimentation tank after washing out over-ordered/rejected fresh concrete and concrete trucks in concrete batching plants. The reuse of CSW as recycled aggregates or a cementitious binder for producing partition wall blocks, and the life cycle environmental impact of the blocks were assessed and compared with the conventional one designed with natural materials. The LCA results showed that the partition wall blocks prepared with fresh CSW and recycled concrete aggregates achieved higher sustainability as it consumed 59% lower energy, emitted 66% lower greenhouse gases, and produced lesser amount of other environmental impacts than that of the conventional one. When the mineral carbonation technology was further adopted for blocks curing using CO 2 , the global warming potential of the corresponding blocks production process was negligible, and hence the carbonated blocks may be considered as carbon neutral eco-product. [ABSTRACT FROM AUTHOR]

The possibility of recovering energy from biomass residues has attracted a lot of research interest due to the environmental problems associated with burning coal. Wood wastes generated from construction and demolition activities and other wood product wastes can be a good potential source of renewable energy. The present study was conducted by using Hong Kong as an example to assess the environmental sustainability of converting recycled wood wastes (from construction and demolition activities and other wood product wastes) to produce wood pellets for direct energy generation. The chemical and physical characteristics of different types of wood product wastes were tested. An attributional lifecycle assessment approach was used to assess and compare the environmental impacts and sustainability for heat generation from the pelletized bio-fuel and coal. The test results showed that the energy content, chemical compositions and the trace metal concentrations all met the relevant standards. The results also showed that significant impacts on health, ecosystem, climate change and resources damage can be potentially avoided by using wood pellets instead of coal for energy generation. The overall findings demonstrated that the proposed “energy recovery” approach for using wood pellets as a bio-fuel in Hong Kong is environmentally sustainable, which can provide an alternative route for managing wood product wastes with the added benefits of energy recovery, and may be more applicable in mega cities especially when city-based incineration is a concern. [ABSTRACT FROM AUTHOR]

Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were performed with a glassy carbon electrode (GCE) modified with polyglutamic acid (PGA) on the three dihydroxybenzene isomers, catechol (CT), hydroquinone (HQ), and resorcinol (RS). At bare GCE, these isomers exhibited voltammograms with highly overlapped redox peaks that impeded their simultaneous detection in binary and ternary mixtures. On the contrary, at PGA modified GCE binary and ternary mixtures of the dihydroxybenzene isomers showed well-resolved redox peaks in both CV and DPV experiments. This resolving ability of PGA modified GCE proves its potential to be exploited as an electrochemical sensor for the simultaneous detection of these isomers. [ABSTRACT FROM AUTHOR]

Substantial amount of resources is consumed by pavement systems, which have resulted considerable environmental impacts. Understanding the environmental impacts would provide opportunity for reducing resource consumption and informing decision-makers in the process of designing sustainable pavement. There is a lacking of comprehensive and comparative sustainability assessment of pavement systems in highly urbanized context currently. Therefore, this study aims to design and comprehensively evaluate the environmental performance of the commonly adopted pavement systems in highly urbanized context using lifecycle assessment (LCA) technique through a case in Hong Kong. According to the codes and practices of Hong Kong, two pavement systems including flexible and rigid pavements were designed based on the same road section. After that interviews with structured questionnaire were conducted to collect relevant practical information of pavement construction and maintenance from the relevant professional bodies and experts for the subsequent LCA of such designs. The LCA results reveal that the two mid-point impacts of global warming potential and mineral extraction are 21% and 54% higher for rigid pavement than for flexible pavement. Yet, the end-point results indicate that flexible pavement is associated with 64%, 65%, and 69% higher human health impact, ecosystem quality damage, and resource damage, respectively. Material production and transportation contribute significantly to the total impact in the two pavement systems. For instance, it is about 57% and 97% of the total global warming potential for flexible and rigid pavements, respectively. The overall results demonstrated that 49% higher total impact was found for flexible pavement than rigid pavement. Therefore, the use of more recycled and environmentally friendly materials can potentially enhance the environmental sustainability of both pavement systems. The findings should provide useful information to the design and selection of sustainable pavement structures in resource-scarce highly-urbanized cities. [Display omitted] • Designed two commonly used pavement systems based on the existing practices in Hong Kong. • Evaluated the environmental sustainability of pavements in an urban context using LCA. • Considerably higher impact was associated with frequent maintenance in flexible pavement. • About 49% higher total impact was found for flexible pavement than the rigid pavement. [ABSTRACT FROM AUTHOR]

Sustainable building retrofit can provide a great opportunity to reduce the energy consumption of existing buildings to commensurate the climate policies and enhance the building energy performance. Given it strategic importance, there is no shortage of research studies on sustainable building retrofit globally in particular the retrofit measures and technologies for different types of buildings. Despite that, sustainable building retrofit is climate and location specific, and decision-makers are still facing challenges to identify an optimum set of retrofit measures for different climatic conditions according to the trade-off between energy saving and retrofit cost. One reason for that is because of the lack of available information especially those related to the cost of sustainable building retrofit measures. This study aims to develop an integrated energy-cost model for selecting the optimal retrofit solutions for existing high-rise residential buildings in various climatic zones in China. Based on in-depth literature review and analysis of published reports, different alternative retrofit measures for wall, window, shading system, heating and cooling systems, and renewable energy technologies for buildings in different climate zones of China are identified. The retrofit costs related to the identified sustainable building retrofit measures are analyzed by referring to the local renovation techniques and cost in each zone through developing a set of equations. A total 28 practical sustainable building retrofit measures along with a set of retrofit options are identified. A deterministic decision framework is developed to facilitate decision-makers achieving a specific energy saving target and evaluating the associated costs based on the identified retrofit measures for high-rise residential buildings in the studied climatic zones. The practical implications of the deterministic decision framework are examined through the prototype buildings in climatic zones being studies. The findings not only actively support the selection of cost-effective sustainable retrofit measures for high-rise residential buildings in China, but the methodological framework and its implications are also equally applicable to other countries with diverse climatic characteristics and standards of living. • Developed integrated energy-cost model for finding optimal retrofit solutions. • Identified sustainable retrofit measures based on climates, building features and retrofit cost. • Developed 28 retrofit measures for wall, window, shading, HVAC, and renewable energy systems. • Optimum retrofit solutions can be adopted from identified set of retrofit options. [ABSTRACT FROM AUTHOR]

• Evaluated the techno-environmental feasibility of using natural pozzolana in concrete production, • Comparable compressive strength was found for the use of VA against conventional SCMs, • VA significantly reduced environmental impacts of concrete compared to OPC and other SCMs, • 11–30% lower GHG emissions was found for VA concrete compared to other cementitious materials. With increasing environmental sustainability concerns in the construction industry and a demand for producing more durable and sustainable concrete, effort is devoted to producing concrete with Ordinary Portland cement (OPC) being substituted by alternative binder materials. By considering the compressive strength, the comprehensive environmental performance of natural pozzolana in concrete was evaluated comparatively by developing six mix-designs of concrete with OPC, and commonly used industrial by-products as supplementary cementitious materials such as fly ash (FA) and ground granulated blast furnace slag (GGBS) based on the lifecycle assessment (LCA) approach. The results show that comparable compressive strengths can be achieved for the use of 20% and 30% volcanic ash (VA) against conventional SCMs. Using the volume as functional unit, the LCA results have demonstrated that higher environmental savings are associated with VA concrete compared to that of OPC, GGBS (30%) and FA (25%), but almost similar when 50% GGBS is used. For example, 15–24% and 10–19% lower global warming potential are associated with VA concretes compared to that of OPC and FA concretes, respectively, but much higher saving is found when considering the strength of the concrete, as they are about 11–12%, 10–11% and 29–30% compared to that of GGBS, FA and OPC concretes, respectively. The results can be used as valuable guidelines for VA-based in sustainable concrete production, which would further enhance the sustainability of the concrete industry. [ABSTRACT FROM AUTHOR]

Sustainable building retrofitting has attracted serious research attention in recent years as it can significantly reduce energy consumption and thus help achieve energy reduction targets set by governments around the world. In this paper, a sustainable retrofit decision-making model is developed to uncover the optimal set of retrofit solutions according to local climatic conditions, building features, and retrofit costs. Net present value (NPV), a common method for analyzing the feasibility of a building retrofit solution, is used to determine the optimal retrofit solution of existing high-rise residential buildings in a temperate zone and hot summer-cold winter zone, involving prototypical 1990s apartments of 116 and 53 m2 floor areas respectively. This reveals that the lighting system, wall insulation, and upgraded window glazing are essential optimal retrofit measures for the temperate zone, whereas the heating system and shading devices are also essential for the hot summer-cold winter zone. The results indicate that the optimal NPV can be obtained by pursuing a 40% energy saving, as it can result in energy saving of up to 50 kWh/m2/year and 95 kWh/m2/year at an average retrofit cost of approximately USD 1.30 and 3.20 m2/year in the temperate and hot summer-cold winter zones respectively. The sensitivities associated with the most influential optimal NPV and energy savings input parameters are critically analyzed; these can be used by decision-makers to determine the risks and uncertainties related to various cost-effective retrofit measures. The model can help in devising the most suitable sustainable retrofit measures for existing buildings commensurate with the energy reduction targets of policy and decision-makers in the two climate zones. It is also amenable to being adapted for other climatic zones to identify the most appropriate sustainable building retrofit for particular local climatic conditions and building characteristics. [ABSTRACT FROM AUTHOR]

• Stabilization/Solidification (S/S) for hazardous materials was evaluated by life cycle assessment. • Sediment and municipal solid waste incineration fly ash remediation was studied with 17 S/S scenarios under five strategies. • Alternative binders and recycled materials reduced the overall environmental impacts. • This decision-support process could facilitate the design of sustainable remediation. Proper management of hazardous materials arouses widespread environmental concerns due to its enormous ecological and health impacts. The development of green stabilization/solidification (S/S) technology for resourceful utilization of hazardous materials, as well as the immobilization of potentially toxic elements is of great scientific interests. Cement-based S/S is often considered a low-cost and highly efficient technology, but the environmental sustainability of a broad spectrum of S/S technologies has yet to be evaluated. Therefore, this study assessed the environmental sustainability of S/S technologies for managing two common types of hazardous wastes, i.e., contaminated marine sediment and municipal solid waste incineration fly ash (MIFA) by using life cycle assessment (LCA). A total of 17 scenarios under three strategies for sediment and two strategies for MIFA S/S technologies were comprehensively evaluated. The LCA results identified the most preferable S/S technology in each strategy. In particular, Scenario 1 (mixture of sediment with a small percentage of ordinary Portland cement and incinerated sewage sludge ash) of Strategy 1 (use as fill materials) would be the preferred option, as it reduces about 54% and 70% global warming potential compared to those of Scenarios 2 and 3, respectively. This is the first initiative for evaluating the environmental impacts of a wide range of recently developed S/S technologies using green/alternative binders for diverting hazardous wastes from disposal. The results can serve as a decision support for the practical application of the environmentally friendly S/S technology for sustainable remediation. [ABSTRACT FROM AUTHOR]

The circular economy (CE) concept has received increasing attention among different parties on various levels recently. Due to the concern on significant resources consumption in the construction industry without concerning the physical limit resources, a paradigm shift of linear economy to CE model is inevitable for conserving the resources and promoting the efficient use of resources. Adopting CE into the construction industry can promote the successful transition to sustainable construction. Although early stage of development in the construction industry, the scientific contribution of CE agenda in the construction industry is significantly increasing. Therefore, this review aimed to identity the implications, considerations, contributions and challenges of CE in the construction industry by systematically analyzing the recent literature. In addition to existing trends and considerations, this study highlighted the numerous challenges under design, materials selection, supply chain, business model, uncertainty and risk, collaborations among actions, knowledge of understanding, relevant policy, integration of urban metabolism, and methodology for CE evaluation. The study found that CE implementation into the case-specific building with full scale evaluation is yet to be conducted, and a comprehensive CE integration and methodology framework is yet to be developed. A prospective integrated framework for CE adoption and evaluation method is proposed by analyzing the contemporary issues. It is believed that the analyzed critical issues for CE adoption, identified future research direction, and proposed frameworks and methodology should help further development of CE research and contribution to effective implementation of CE into the industry for promoting sustainable construction. • Recent development of CE research agenda in the construction industry is critically analyzed. • Implications, considerations, and challenges of CE in the industry are summarized. • Future research directions are identified for comprehensive CE adoption and evaluation. • Proposed an integrated holistic framework for CE adoption and its evaluation methodology. [ABSTRACT FROM AUTHOR]

In recent years, considerable efforts have been devoted to minimizing the environmental consequences from building industry globally, as the industry is notorious for its significant resource consumption and environmental emissions. However, due to a lack of data representativeness in many parts of the world, considerable variations were observed among studies, and thus makes life cycle assessment (LCA) results difficult for the decision-making purpose. In addition, the selection of low impact materials and the management of end-of-life building waste are the most important concern. By considering several strategies including data representativeness, low carbon material, and end-of-life building waste management, this study aimed to enhance the accuracy of such assessment and sustainability performance of building. An integrated LCA framework is proposed for implementing those strategies through a case specific high-rise residential building in Hong Kong. Based on case-specific/regional data, carbon emission of building was evaluated with a cradle-to-construction system boundary with the functional unit of 1 m2 of gross floor area using the IMPACT 2002+ method, and then compared to that of selecting generic databases under different scenarios. The results demonstrate that the application of case-specific and generic data would significantly influence the outcomes of the case study, as the deviations of certain magnitudes were mostly derived from different building materials that it can lead to an underestimation of carbon emissions of up to 28%. Along with using alternative materials, the adoption of the proposed materials cycling and resource recovery approach at the end-of-life building could lead to a reduction of 14% of the total emissions (i.e. excluding the use and renovation of building). The results would support data selection for accuracy of evaluation which can be used as benchmark where recognized database is not available and promote sustainability performance of buildings locally, while the proposed framework could be adopted for comprehensive evaluation globally. • Proposed integrated framework for enhancing accuracy and sustainability of building. • Data representativeness is a prerequisite for the accuracy of building LCA. • Representative data induced significantly higher carbon emission than generic data. • Using alternative materials for concrete reduced building's carbon emission. • Adopting resource recover approach in EoL significantly reduced carbon emission. [ABSTRACT FROM AUTHOR]

The construction industry will play a crucial rule in global carbon emission reduction as the embodied carbon of construction materials shares an increasing portion of a building's life-cycle carbon dioxide (CO2) emissions. In order to reduce CO2 emissions by selecting low-carbon construction materials, it is inevitable that a proper benchmarking mechanism and severity representation of different emission levels should be established, as benchmarking is a useful tool for pursuing consumer purchasing habits toward selection of low-carbon materials. In addition, high variation of carbon emissions is observed among the large number of studies and databases, and there is no consensus on how these should be used in practice. Therefore, standardization and benchmarking of emissions for construction materials are essential. In this study, a novel benchmarking approach was developed for embodied carbon emissions of commonly used construction materials by applying a fuzzy set theory. Given that a reliable local database is lacking, the benchmark was developed by referring to the existing carbon inventories, linguistic variables of severity levels from a questionnaire survey, and the fuzzy set analysis. A six-step method was proposed based on a horizontal and graphical approach. This study offers an alternative approach in benchmarking where a database or a set of real data is not available. It is expected that the developed benchmarks will help practitioners and decision-makers compare the embodied CO2 emissions of a specific batch of construction materials and select low-carbon materials in construction projects. [ABSTRACT FROM AUTHOR]

Over the past three decades, life cycle assessment (LCA) has been increasingly employed to evaluate the environmental impacts of products and buildings. However, the reliability of LCA is frequently weakened by the practice of arbitrary omission of processes and materials and the problem of insufficient data, both leading to inconsistencies in the LCA results. This study proposes an Index of Completeness (IoC) to account for the completeness of an LCA study for a variety of impact categories. An IoC calculation tool is developed to cover the entire life cycle of buildings, including stages of product, construction, use and end-of-life as well as the benefits from recycling and reuse. The IoC helps to identify and remove the inconsistencies in LCA and to enhance its comparability. Residential building projects are tested as case studies. It is found that the IoCs of most impact categories are as high as 98%–99%, whereas of the category of human toxicity the IoC is 85%, mainly due to the fact that plywood formwork was not included in the original model. Sensitivity analysis reveals that dataset changes in an LCA model can not only affect the impact assessment results, but also possibly have influence on the completeness of the LCA model. The LCA practitioners are suggested to combine the newly developed IoCs with the standard four phases of LCA when applying to complex products. Future research should focus on case studies implementing the IoC calculation tool, inclusion of more impact categories in the IoC model, and continuing development to include other complex products. Image 1 • An Index of Completeness (IoC) is proposed to describe to what extent the processes and data are included. • An IoC calculation tool is developed for the building sector. • The case study of a residential building project is conducted. • The IoC of human toxicity is as low as 85%, caused by the exclusion of plywood formwork in the original model. [ABSTRACT FROM AUTHOR]

Ability to forecast the waste electrical and electronic equipment (WEEE) generation can help formulate a robust future WEEE management system. Previous studies applied forecasting models, such as the grey model and artificial neural networks, to predict WEEE generation from a country perspective, leading to less accurate forecasts due to huge socio-economic differences in rural and urban areas. Additionally, there has been the incompatibility of a single forecasting model for all WEEE types, and this remained a research gap. Taking advantage of respective forecasting models, this study presents a hybrid model, Grey Artificial Neural Network, to forecast the WEEE generation of 31 province-level regions in China while evaluating the socio-economic analysis of seven WEEE types via Pearson correlation analysis. More than 70% of WEEE from province-level regions strongly correlates (R > ±0.8) with the gross domestic product and the population, whereas some top WEEE-generating province-level regions (i.e., Tianjin and Shanghai) correlate weakly to moderately. The root mean square error and mean absolute error of the developed Grey Artificial Neural Network hybrid model are the lowest at 8.29 and 6.48, compared to the grey model (13.53 and 11.13) and back-propagation neural network (9.21 and 7.22). Though the Grey Artificial Neural Network hybrid model has the lowest error, posterior mean square deviation ratio analysis indicates that this hybrid model is only suitable for washing machines, refrigerators, color televisions, and personal computers (urban area), while the back-propagation neural network is suitable for monochrome televisions, air conditioners, and personal computers (rural area). Compared to 2019, it is projected that an additional 32.92 M units of WEEE will be generated by 2025, suggesting that China should build at least 15 extra recycling centers (14% more based on 2016) to handle the increased WEEE generation. This study provides policy implications for effective WEEE monitoring and collection systems to build resilient WEEE management. [Display omitted] • Grey artificial neural network hybrid model with higher accuracy is developed. • Province's socio-economic correlation and e-waste prediction are conducted. • Top e-waste-generating province-level regions exhibit different socio-economic correlation. • China's e-waste will reach 286 M units in 2025, 13% more than in 2019. • Policy and strategy are recommended for the increased e-waste generation. [ABSTRACT FROM AUTHOR]

Quarry dust, a by-product of stone grinding, cutting, sieving and crushing, is abundantly available and can create many on-site and off-site environmental problems. This paper investigates the feasible utilization of quarry dust as an alternative to river sand in the production of lightweight foamed concrete (LFC). LFC with a density of 1300 ± 50 kg/m 3 and fixed cement/filler ratio of 1:1 were adopted in this study. Quarry dust was used to replace sand at ratios of 75% and 100%, and four different water-to-cement ratios (w/c) of 0.52, 0.54, 0.56 and 0.58 were studied and compared. For a given w/c ratio, it was found that the use of high volume quarry dust could reduce the fluidity and increase the compressive strength and the thermal conductivity of LFC. However, no significant decrease of compressive strength was observed with the increase of w/c ratio, probably due to the reduction of foam volume requirement in the system. Life cycle assessment results indicated that the LFC containing quarry dust possessed less environmental impact in terms of lower energy consumption and lesser amount of greenhouse gases emission. [ABSTRACT FROM AUTHOR]

Energy simulation and prediction plays a vital role in energy policy and decision making. This study has been conducted to predict the future energy demand in the urban residential buildings of Chongqing a city in south west China. The comparative study adopts and compares the results of different demand models to improve estimation efficiency for future projections. A structured questionnaire survey was undertaken to collect primary household energy consumption data for inclusion in the annual energy consumption simulation model. An ANN model, two Grey models, a Regression model, a Polynomial model and a Polynomial regression model were used to forecast and compare demand. The precision of the models have been used statistical methods. The predicted results show that the total residential building energy and electricity consumption in urban areas of Chongqing is increasing rapidly. Based on MRPE (%) and the statistical tests, the study concluded that an ANN model is the most acceptable forecasting method of the six models. Hence, based on ANN model, urban residential building energy consumption will be at 1005 × 10 4 SCE and electricity consumption will be at 264.81 × 10 8 kW h in 2025 which is about three times and four times higher than that of the 2012, respectively. [ABSTRACT FROM AUTHOR]