Embodied Carbon Emissions Research Articles

Exploring Embodied Carbon Comparison in Lightweight Building Structure Frames: A Case Study

Structural components represent major contributors to embodied carbon emissions of buildings. While there have been numerous research efforts dedicated to modelling and assessing the embodied carbon impact of buildings, there is a conspicuous gap in research that concurrently examines various material options in building structural designs, accounting for technical, economic, and carbon implications. In this study, an integrated approach is applied to assess the embodied carbon and life cycle cost impacts of three different building structures, i.e., timber-framed (TF), steel-framed (SF), and the timber–steel composite (TSCF) framed, scaffolded with Finite Element Analysis (FEA) simulations for a strength and stability analysis of different design options. A lightweight frame-structured residential building type is examined as the data source for the modelling and simulations. The results of a comparative scenario analysis highlight that both TF structures and TSCF structures have notable advantages over their SF counterparts for embodied carbon saving and building load reduction. Assessment results indicate that the TF design offers 35.56% embodied carbon reduction, followed by the TSCF design with 8.12% decarbonization, compared to the SF design. The lifecycle cost assessments also reveal the promising cost saving potential of TF and TSCF structures for the application, with cost savings of up to 7.93% and 4%, respectively. Meanwhile, the simulations further demonstrate that TSCF materials in particular can have significant benefits for lightweight building structures in overcoming the deflection problem of long TF components and the buckling of thin-walled SF members. The results help to identify the potential of TSCF structures to minimize the material use for a “Build with Less” through design optimization, which can lead to further embodied carbon and lifecycle cost reductions.

Spatio-temporal changes and root-cause identification for embodied carbon emissions based on production and consumption in China's Yangtze River Economic Belt.

The Yangtze River Economic Belt (YEB) is at the centre of China's economy and development. Its regional carbon emissions account for about 36.9% of the country's total carbon emissions, and thus, there is an urgent need to sustain the development of a low-carbon economy. However, the complex patterns of embodied carbon flows arising from multi-scale trade in such a megaregion are often ignored in carbon environmental governance. This study incorporates a megaregion into an environmentally extended multi-regional input-output (EEMRIO) framework and identifies the drivers of production and consumption-based carbon emissions using four measures through structural decomposition analysis (SDA). The results show that (1) the YEB strengthens inter-provincial trade links while reducing international trade links; (2) there is obvious carbon transfer in multi-scale trade in the YEB, with a corresponding transfer of responsibility for carbon reduction occurring; and (3) consumption volume and carbon intensity are the main drivers and inhibitors of the increasing carbon emissions, respectively, and the optimisation of production structure and consumption structure are effective ways to control production-based carbon emissions (PBEs) and consumption-based carbon emissions (CBEs), respectively. This study extends the research scale of "national-provincial-city" to a megaregion. Studies based on multiple trade scales would provide additional insights to understand the carbon reduction responsibilities of megaregions and help achieve coordinated regional carbon reductions.

AI-guided design of low-carbon high-packing-density self-compacting concrete

Self-compacting concrete (SCC) has gained substantial traction in modern engineering due to its exceptional fresh and hardened properties. However, traditional SCC design methods encounter significant challenges. Conventional experimental design approaches often necessitate a considerable number of trial mixes to fulfill diverse performance objectives, incurring escalated material, time, and labor costs. Additionally, conventional SCC designs tend to use high cementitious material content, leading to elevated carbon emissions and energy consumption compared to ordinary concrete. To address these issues, this study proposes a novel approach that combines the compressible packing model (CPM) with machine learning (ML) techniques. This approach innovatively utilizes particle packing theory to guide ML in optimizing SCC aggregate grading and mix proportions. By integrating physical principles into artificial intelligence, this approach facilitates the intelligent design of low-carbon, high-packing-density SCC. Compared to the conventional method, SCC designed using the innovative AI approach demonstrates a 57.2% reduction in embodied carbon emissions.

Evaluation of Embodied Carbon Emissions in UK Supermarket Constructions: A Study on Steel, Brick, and Timber Frameworks with Consideration of End-of-Life Processes

Buildings and the construction sector as a whole are among the chief emitters of carbon, and the structural system of a building contributes substantially to its embodied carbon emissions. Whereas extensive studies exist into carbon missions, a detailed evaluation of real multipart building systems in brick, steel, and timber (glulam) substitutes is lacking. This paper employs whole-life-embedded carbon as a sustainability metric to compare a current UK supermarket building system of steel, brick, and timber. Four construction systems by the supermarket, referred to as CS1, CS2, CS3, and CS4, are used in the investigation. Comparisons are also made between two end-of-life treatment methods (recycle and landfill) along with the benefits that can be realised in future construction projects. The outcome from the comparative assessment reveals that there are minor variations in the embodied carbon of building systems used by the supermarket. CS4, while currently presenting marginal gains (approximately 148,960.68 kgCO2eq.) compared to CS1, loses its advantages when recycled contents for future construction projects are considered. The result indicates that CS4 generates about 18% less carbon emission reduction potential than CS1, whilst CS3 generates approximately 16% less than CS1. The findings of this article can enhance the knowledge of embodied carbon estimation and reduction capabilities of timber, steel, and brick buildings. Also, the detailed method for quantifying embodied carbon used in this article can be adopted in similar projects around the world.

Transfer of embodied carbon emissions from provincial transportation industry in China

This study employs a multi-regional input-output (MRIO) model to measure these emissions and examines the growth and transfer patterns of embodied carbon in the transportation sector across different regions of China. Then we utilize Structure Decomposition Analysis (SDA) to identify the driving factors behind the observed emissions patterns. The findings of the study indicate that the transfer of inter-provincial transportation embodied carbon emissions follows a general trend of shifting from economically developed areas to underdeveloped areas along the industrial chain. The study also highlights that the per capita demand structure plays a crucial role in driving the increase in transportation embodied carbon emissions. On the other hand, the study identifies the direct carbon emission coefficient as a key factor that inhibits the rise in transportation embodied carbon emissions.

Embodied carbon emission flow network analysis of the global nickel industry chain based on complex network

Nickel is an energy-intensive resource, and with the expansion of global demand for nickel, the embodied carbon emissions of its industrial chain in international trade are also increasing. The study of the embodied carbon emission flow of the global nickel industry chain can provide support for the low-carbon development and sustainable supply of nickel resources. Under the accounting framework of life cycle assessment, this study analyzes the embodied carbon emission flow of the global nickel industry chain from the perspective of network. The results show that the embodied carbon emission flow network (ECEFN) of all links of the global nickel industry chain presents small world nature. Some economies in the network have more flow relations, and the main flows carry 50.5 % to 92.2 % of the total embodied carbon emissions in each link. The ECEFN of the whole industrial chain is divided into four plates, of which plate C has the most significant spillover effect on the entire network. Key economies are identified through centrality and weight indicators, with China playing the most crucial role. Plate members should strengthen cooperation to achieve collaborative emission reduction. Differentiated and targeted mitigation measures are needed for key economies and main flow relationships.

Differences in carbon emissions between the digital economy sectors in China and the USA.

In an era of rapid development of digital technologies and dramatic global climate change, digital economy is crucial to achieving the 'carbon peak' and 'carbon neutral' goals. However, less research has been done in the area of indirect carbon emissions in the digital economy sector. Therefore, this study uses an input-output model to calculate the embodied carbon emissions of the ICT (information and communication technology) industry in China and the USA in 2005, 2010 and 2016 from the production and consumption sides. Moreover, a comparative analysis is conducted in terms of the driving factors of carbon emissions and the relationship between emissions and economic benefits in the two countries. The results reveal that emissions are larger on the production side in the USA and on the consumption side in China. For both countries, electricity is the largest upstream sector in terms of emissions. ICT in the USA causes sectoral emissions mainly in manufacturing and services. While China mainly causes sectoral emissions in manufacturing. The US ICT sector is more economically efficient for the same emissions. Regarding drivers, the primary driver of the fall in emissions is a reduction in emission intensity. The increase in emissions driven by final demand is greater in China than in the USA. Finally, the results of the two countries are extended to other developed countries and emerging economies, providing recommendations for reducing carbon emissions in the ICT sector.

Examining Carbon Emissions in Building Materials: A Case Study of Government Buildings in Pokhara Metropolitan City

Numerous studies placed particular emphasis on reducing carbon emissions from operations, often ignoring the importance of embodied carbon emissions. To evaluate the embodied carbon emissions associated with government buildings in Pokhara Metropolitan City, a systematic process-based approach was used to estimate the total embodied carbon over the lifetime of these structures. The research findings reveal that the cumulative embodied carbon emissions stemming from these buildings contributed a total of1281.56 metric tons (Mt) and 12504540.5 MJ of embodied energy. Furthermore, the study explored the potential for reducing these emissions by adopting alternative construction materials. In particular, the inclusion of AAC (Autoclaved Aerated Concrete) blocks, hollow cement concrete blocks, and stabilized soil blocks (8% cement)in the same building demonstrated reductions in total emissions by 5.56%, 4.38%, and 5.16%, respectively. It is crucial to acknowledge that this study primarily focuses on the construction stage of the building and exclusively considers civil construction materials. It did not encompass elements such as sanitary and electrical fixtures or other stages in the building's lifecycle, including operation and maintenance and eventual demolition. Consequently, it is recommended that future research endeavors undertake a more comprehensive analysis, encompassing electrical and sanitary fixtures, as well as all phases of a building's lifecycle, to gain a more holistic understanding of embodied carbon emissions in government buildings

Environmentally sustainable construction by mitigating embodied carbon emissions of large-scale projects: a study on off-site practices on high-rise buildings

Environmentally sustainable construction by mitigating embodied carbon emissions of large-scale projects: a study on off-site practices on high-rise buildings

Characteristics of embodied carbon emissions for high-rise building construction: A statistical study on 403 residential buildings in China

High-rise residential buildings are prevalent in Chinese cities and have considerable impacts on the sustainable construction industry. Although individual case studies have assessed the embodied carbon emissions, there is still a need to explore the general characteristics and driving factors. This study established a dataset containing 403 buildings and assessed the statistics and distribution of relevant embodied carbon intensities using a cradle-to-site system boundary. An average embodied carbon intensity of 424.1 kgCO2e/m2 was obtained, with 2/3 of the carbon emissions attributed to structural materials including steel, concrete, and prefabricated members. Based on contribution analyses and significance tests, the influences of driving factors encompassing building height, structural form, seismic design grade, delivery type, and building investment were examined, and carbon reduction strategies were discussed. The results indicated a potential 28.8% reduction in the embodied carbon intensity considering a cascaded strategy of substituting low-carbon materials, optimizing material use, and using local materials.

RELATIONSHIPS BETWEEN EMBODIED, OPERATIONAL, AND LIFE CYCLE CARBON IN PASSIVE HOUSE MULTIFAMILY RESIDENTIAL BUILDINGS

ABSTRACT The building sector is responsible for a significant portion of global CO2 emissions and any attempt to meet global climate change mitigation goals requires dramatic reductions in CO2 emissions from building construction and use. Among the many green building certification programs intended to reduce the environmental impact of buildings, the passive house standards are one of the most stringent certifications with respect to reducing operational energy. While there is significant research demonstrating the reductions in operational energy use in passive house and passive house inspired buildings, there is comparatively little research into the embodied energy and embodied carbon emissions associated with these buildings. The aim of this research was to evaluate the relationship between embodied carbon emissions, operational carbon emissions, and overall carbon use intensity in passive house certified residential buildings, using a recently completed, multifamily passive house as a case study. First, the case study building was defined, and a partial life cycle assessment (LCA) was performed to evaluate the embodied and operational carbon emissions associated with this base case. Second, a catalog of alternative wall and roof assemblies were defined and the LCA of the case study was updated for each alternative assembly to assess the impact on the embodied carbon, operational carbon, and overall carbon use intensity. The results of this analysis indicate that the material composition of the exterior envelope assemblies can have significant impact on the overall, cumulative carbon impact of a particular building. Moreover, the results also indicate that there are clear scenarios in which operational energy efficiency should be sacrificed in favor of reducing upfront embodied carbon emissions, particularly when evaluated over critical time spans. Based on these results, this study recommends that green building standards and certifications, including passive house but also USGBC LEED, Living Building Challenge, and others, should place greater emphasis on embodied carbon and holistic carbon accounting in addition to operational efficiency.

Analysis of China's steel response ways to EU CBAM policy based on embodied carbon intensity prediction

The EU Carbon Border Adjustment Mechanism (CBAM) has decided to impose carbon tariffs on some imported goods after 2026 based on their embodied carbon emissions. And China, as the fourth largest steel importer in the EU, its foreign trade in steel will undoubtedly be affected. The Multi-regional Input-output and Single-regional Input-Output models were used to calculate the embodied carbon in China's steel exports to the EU from 2000 to 2020. Under the current development scenario, the EU carbon tariff rate in 2034 will reach about 5.5%, exceeding the average profitability of steel in recent years. In order to reduce carbon tariffs, a strategy to accelerate the development of carbon reduction capacity is proposed from the perspective of reducing embodied carbon. Meanwhile, considering the development trend of the tradable green certificate system and the controversial nature of CBAM in the WTO framework, a countermeasure to promote green certificates offsetting carbon tariffs is proposed from the policy perspective, and the cost increase rate generated by this measure is calculated with the scenario settings, and the cost increase rate is only 1.1% under the best situation.

Influencing mechanisms and decoupling effects of embodied carbon emissions: An analysis based on China's industrial sector

Carbon emission reduction in industrial sectors is an important link to achieve green sustainability development. In this paper, non-competitive input-output model and structural decomposition model are constructed for measuring embodied carbon emissions of 28 industrial sectors and their decomposition factor effects in China. Additionally, the decoupling state between embodied carbon and economic growth is explored using the decoupling model. On this basis, key industrial sectors' decoupling influencing factors are analyzed. The results show that the embodied carbon emissions from the industrial sector grow at an average annual rate of 7.743 % during 2005–2020. Investment demand and urban consumption are the primary sources of embodied carbon emissions, and demand size can also significantly drive carbon emissions. However, energy efficiency is crucial to reducing carbon emissions. According to embodied carbon flows and network centrality size, six key industry sectors were identified. The number of industrial sectors achieving strong decoupling increased significantly in 2005–2020, but the key industrial sectors were dominated by expansionary negative decoupling. Further analysis showed that energy efficiency contributed to the strong decoupling, whereas demand scale would inhibit decoupling more significantly. These findings are valuable for proposing targeted strategies to reduce emissions, improve industrial efficiency and resilience for sustainable development.

Embodied Carbon Accounting for Forest Industry Trade in BRICS Countries: An MRIO Modeling Approach

A multi-regional input-output (MRIO) model was constructed to measure and compare the trade-induced carbon emissions within the forest industry among the BRICS countries: Brazil, Russia, India, China, and South Africa. The results indicate the following: (1) The primary source of import/export-related carbon emissions from the forest industry in BRICS countries is the trade of paper products, with the exception of Russia, where wood products significantly contribute to its export-related carbon emissions. (2) The net carbon emissions from forest industry trade in BRICS countries underwent varying degrees of volatility during the period from 2008 to 2013. (3) China and Russia exhibited notably higher levels of trade-induced carbon emissions in their forest industries compared to other BRICS nations, while the scale of embodied carbon emissions from international trade in the forest industry of South Africa, Brazil, and India remained relatively similar. (4) The trade-induced carbon emissions of the forest industry in BRICS countries were predominantly export-oriented between 1995 and 2018. Therefore, it is recommended that BRICS nations prioritize addressing carbon emissions within the forest industry’s trade sector. Collaborative efforts should be intensified to promote cleaner development pathways, foster sustainable economic growth, and take a more proactive stance in global climate change negotiations.

Sector aggregation effect on embodied carbon emission based on city-centric global multi-region input-output (CCG-MRIO) model

Sector aggregation under the input-output framework may lead to deviation in results and the lack of detailed sectoral information, which hinder the targeted implementation of accurate sectoral adjustment policies. This paper explores the effects of sector aggregation on the embodied carbon emission of the residential consumptions of Beijing and Shanghai based on the city-centric global multi-region input-output (CCG-MRIO) model. Integrating with structural path analysis and structural decomposition analysis, the impacts of sector aggregation on the identifying of critical emission transmission paths and driving forces are also revealed. Three sector aggregation datasets are discussed to track the sector aggregation effect in 2012 and 2017. The findings show that the carbon emission results at 8 sector level better align with the results at the 22 sector level than those at 32 sector level. Moreover, sector aggregation will lead to the absence of some critical carbon transmission paths, some factor contributions on carbon emission also changed their directions at different sector levels. On the basis of clarifying the sector aggregation effect on embodied carbon emission, the research results provide a reference for similar studies to select the appropriate level of sector aggregation, to realize the goal of simplifying the calculation or gaining more detailed sectoral emission information.

Measurement and driving factors of carbon productivity in China's provinces: From the perspective of embodied carbon emissions.

Carbon productivity incorporates economic development and carbon emissions within a unified framework for measuring the economic value per unit carbon emissions. In the context of climate change, improving carbon productivity is of great value for promoting low-carbon development in a country or region. From the perspective of embodied carbon emissions, this study constructs an embodied carbon productivity (ECP) index and uses the Logarithmic Mean Divisia Index decomposition method to study the evolution trends and driving factors of ECP in China's provinces based on China Interregional Input-Output Tables for 2002, 2007, 2012, and 2017. The following results were obtained: First, China's overall ECP showed a continuously increasing trend during the entire period, with the energy efficiency factor playing the largest role among all driving factors. Second, the ECP in 19 of the 30 Chinese provinces continued to increase and the contributions of energy emission ratio, ECP per capita, and population size factors to the increase in ECP presented evident disparities among different provinces. Third, the ECP in three major regions ranged from high to low in the order of East, Central, and West, with the largest growth in the Central, followed by the West, with the smallest in the East. Based on the analysis of research results, we proposed relevant policy recommendations to further improve China's ECP and achieve low-carbon economy.

Material Requirements, Circularity Potential and Embodied Emissions Associated with Wind Energy

Wind energy, which is often posited as a key decarbonisation option, represents one of the fastest-growing energy sources globally in recent years. Research on the material requirements for transitioning to a low-carbon electricity system at national levels, as well as research exploring the potential of the electricity system to serve as a source of secondary materials remains underexplored. We address these gaps in the knowledge by analysing the stocks and flows in a wind power system towards 2050 using Sweden as a case study, including the demands for bulk (concrete and steel) and critical materials (neodymium and dysprosium), through a dynamic material flow analysis based on policy-relevant scenarios. We demonstrate that some of the investigated scenarios generate substantial increases in the stocks and flows of bulk and critical materials. We show that, after 2045, the year by which Sweden has committed to reducing greenhouse gas emissions to net-zero, the inflows show a decreasing trend while the outflows show an increasing trend, suggesting the beginning of the closing of the material loops, provided untapped circularity potentials transform into actual capacities. For wind power to comply with emissions targets, the steel and concrete production processes will need to be decarbonised at a rate in line with the climate targets. We show that the adoption of mitigation measures to decarbonise the concrete and steel industries aligned with Sweden's climate change mitigation agenda, has the potential to reduce embodied carbon emissions for wind power infrastructure in 2045 from corresponding to around 4 % of current total national emissions in the absence of measures to practically negligible levels. National policies need to focus on promoting the implementation of circularity strategies and decarbonising the entire value chain of the involved materials.

Adopting cross-laminated timber in architectural design to reduce embodied carbon emission in China based on the diffusion of innovation theory

ABSTRACT Cross-Laminated Timber (CLT) is a quasi-rigid composite engineered timber product that can assist the building industry in reducing embodied carbon emissions. The adoption of CLT in architectural design is of great importance to help to achieve China’s dual carbon goals. This study aims to understand the factors and their effects on influencing architects’ intentions to adopt this low-carbon building technology. It applied the theory of diffusion of innovation (DOI), incorporated architects’ innovativeness and material properties of cross-laminated timber and used partial least squares structural equation modelling (PLS-SEM) to construct an adoption model. The adoption of CLT was found to depend on architects’ novelty seeking and independent judgement making as well as the trialability, observability, relative advantage and riskiness. Observability had the most significant impact on the intention to use cross-laminated timber, followed by trialability, riskiness and relative advantage. It is imperative to increase the extent to which CLT can be observed and experienced by design professionals, to increase the publicity of its benefits, and to address barriers to uptake. Significant differences were found between architects with different years of work experience, which will help to develop tailored strategies for better promoting cross-laminated timber in China.

Analysis of embodied carbon emissions and carbon sequestration in Tibetan Plateau-Case study of Tibet and Qinghai

The Tibetan Plateau is one of the most important carbon sinks, while it is facing with huge pressure of carbon emission in the process of urbanization, and the inter-regional trade activities lead to the carbon emission structure to be more complex. To facilitate the realization of carbon neutrality, it is required to figure out the carbon sequestration capacity and the carbon emissions caused by socio-economic activities of the Tibetan Plateau. This study adopted the net primary productivity (NPP) remote estimation model to evaluate carbon sequestration capacity and utilized a multi-regional input–output analysis framework combined with a structural decomposition analysis model for embodied carbon emission evaluation of Tibet and Qinghai to identify the carbon emission characteristics in 2012 and 2017. The results reflect that Tibet had great potential for carbon neutrality, but Qinghai had a slight carbon deficit from both the production and consumption perspectives. The carbon emission flow patterns shown that Tibet was basically a net emission importer, and Qinghai mainly imported net emissions from northern China like Inner Mongolia, Henan, and Hebei, and exported emissions to southern China like Shanghai, Zhejiang, and Guangdong. The energy production and supply industries were the largest carbon emission sources and the major contributors of emission growth for Tibet and Qinghai. The gross capital formation have induced about 75% of the consumption-based emissions in plateau in both 2012 and 2017. The increased emissions were mainly driven by changes in average consumption structure, which promoted the emissions increased by 34.70% and 23.21% for Tibet and Qinghai, respectively. It can be concluded that the main task to achieve the target of carbon reduction is to change the energy structure of the Tibetan Plateau into a cleaner structure to reduce dependence on high-carbon products from other provinces and promote green development all over the country.

District cradle to grave LCA including the development of a localized embodied carbon database and a detailed end-of-life carbon emission workflow

The building industry is one of the main contributors to greenhouse gas (GHG) emissions in today's world. To measure the environmental impacts of GHG emissions, life cycle assessment (LCA) has been increasingly utilized in recent years, and building LCA tries to evaluate the GHG emissions in three main phases including embodied carbon (EC), operational carbon (OC), and End-of-life carbon (EOLC).Most of the studies in this field have dealt with individual buildings as the scope of their research. The literature review showed a significant gap regarding the implementation of the LCA on a wider district-level scale rather than just one building. In addition, most of the studies have only considered landfilling of the waste materials and emissions related to this activity for the whole disposal phase emissions. Therefore, a more detailed analysis regarding the EOLC emission has been carried out to recognize the actual share of this section in the whole building’s LCA.To fill the mentioned gaps, this research has done a cradle-to-grave LCA by utilizing localized building materials' EC emission data, besides an OC emission assessment followed by a detailed EOLC emission analysis for a district in Montreal's downtown. Furthermore, a sensitivity analysis regarding the selection of the best building materials according to their environmental performance has been implemented.The results of this study show that for different retrofitting scenarios of the buildings in a district, among the main building components for renovations (walls, roofs, and floors), walls are responsible for the most significant share of the GHG emissions and between various components of the walls, insulation layers have the most impact on the total embodied, operational and EOLC emissions. Detailed EOLC emission analysis revealed that even after implementing a detailed examination of the end-of-life phase, the share of EOLC emissions within the building's life cycle remains below 10%. Finally, the sensitivity analysis among the insulation layers has illustrated that buildings using foam glass for their insulation layer have the most GHG emissions, and buildings with glass wool have the least amount of emissions.