Embodied Carbon Emissions Research Articles

Integration of BIM and LCA: a system to predict and optimise embodied carbon for prefabricated buildings

This paper presents the development of a system for automatically predicting and optimising embodied carbon of prefabricated buildings during the design phase. Building information modelling (BIM) is selected as the working environment from data input to results display, highly improving the automation level of carbon assessment. Besides, automatic carbon assessment for on-site installation is achieved by developing a component-oriented on-site emission factor database from a Chinese code. This system also supports optimising embodied carbon by providing various low-carbon alternatives from the perspectives of selecting construction materials, transportation modes, and installation methods. This system is applied to a ten-storey office building for demonstration. It is found that the system can accurately estimate and efficiently reduce the embodied carbon emissions of prefabricated buildings

An approach for measuring and analyzing embodied carbon in the construction industry chain based on emergy accounting

This study proposes a comprehensive approach to analyze the embodied carbon in China’s construction industry by integrating carbon emission factors and an input–output model. The analysis covers the whole construction industry chain, including both direct and indirect carbon emissions. Moreover, this study introduces an emergy index system that incorporates the ternary diagram of materials science for environmental assessments, assessing resource allocation, development effectiveness, efficiency, and sustainability. The research measures the embodied carbon emissions for seven regions in China’s construction industry, and compares the results from the perspective of the whole industry chain. The study reveals that indirect carbon emissions contribute significantly to the embodied carbon emissions in China’s construction industry, and the central region exhibits the highest environmental loading rate among all regions. Additionally, the northern region shows the highest emergy yield rate, whereas the eastern and northeastern regions exhibit better sustainability in the development of the construction industry.

The path to global climate justice: From the perspective of regional discrepancy in embodied carbon emissions

Achieving climate justice is an important goal and basic principle of global climate governance. This paper evaluates the progress of achieving global climate justice by quantitatively depicting the evolution characteristics, group differences and driving factors of global embodied carbon emissions. The results indicate that the phenomenon of embodied carbon inequality is more obvious. Furthermore, a data-driven clustering algorithm is adopted to divide the world's major economies into four convergence clubs based on the embodied carbon emissions levels. We find that the embodied carbon emissions gap between different clubs has widened since 2008, which may be related to the re-industrialization of developed countries. The results of SDA analysis indicate that the embodied carbon emissions of developed countries, such as the United States, are more driven by per capita end-use. On the contrary, unclean consumption and investment structure is the main driving force for the increase of embodied carbon emissions in developing countries such as China. Therefore, efforts should be made in developing countries on the clean adjustment of consumption and investment structure to promote the convergence of embodied carbon emissions with developed countries.

Digital Data Management Practices for Effective Embodied Carbon Estimation: A Systematic Evaluation of Barriers for Adoption in the Building Sector

The pervasive impact of industrialisation on our daily existence has precipitated carbon emissions that demand critical attention. Although international conventions and scholarly research have scrutinised carbon emission sources and reduction strategies, the integration of digital tools and databases for estimating embodied carbon emissions remains in an incipient phase. Consequently, this review study aims to seek to optimise opportunities for digital transformation and sustainable practices while addressing the digital carbon footprint in the building sector. Employing the PRISMA guidelines, we systematically analysed 59 publications amassed from Scopus and Web of Science databases. The study’s search parameters encompassed the analytical dimensions of “embodied carbon”, “emission data”, and “barriers to digital transformation”. Through this rigorous process, 32 salient challenges and barriers were synthesised, encapsulated within four overarching parameters: traceability, accuracy, auditability, and efficiency. At its core, this study’s primary objective resides in the evaluation of existing barriers and challenges within the realm of carbon emission estimation. By doing so, it aspires to proffer a cogent knowledge model capable of catalysing the development of digital methodologies and models that can, with a high degree of accuracy, assess the burgeoning digital carbon footprint within the expansive domain of the building sector.

Assessing the circular re-design of prefabricated building envelope elements for carbon neutral renovation

Buildings and the construction industry at large are significant contributors to the catastrophic climate breakdown. The built environment is responsible for 37% of the total global carbon emission, of which about a third arises from the energy used to produce building and construction materials, usually referred to as embodied carbon. One of the key strategies to reduce the environmental impact of buildings is to significantly improve their energy efficiency, which is referred to as deep renovation. Prefabricated building envelope elements intended to prevent heat loss through the building envelope are considered a key deep-renovation technology. Connecting prefabricated elements to a building reflects a potential stream of waste if applied linearly with severe negative environmental impact in terms of natural resource depletion and exposure to pollutants. This article reports on a quantitative Design for Disassembly (Dfd) indicator to assess future recovery potential and, subsequently, its impact on embodied carbon emission of the circular redesign of three different prefabricated building envelope elements. Although none of the redesigned elements are yet considered 100% circular, the development of these three prefabricated building envelope elements showcases that the environmental impact can be substantially reduced following a well-structured and dedicated innovation process. The reduction of the environmental impact is indicated by lower quantities of embodied carbon up to 50% and an improved design for disassembly, reflecting a higher reuse potential of building materials and components. Several limitations and directions for further research were identified to advance the development of circular, prefabricated deep-renovation building envelope elements.

The fairness of shared responsibility for embodied carbon emission: a case study of the Yellow River Basin, China.

Under the dual constraints of China's carbon peaking and carbon neutrality goals, as well as ecological protection and high-quality development of the Yellow River Basin, clarifying the embodied carbon emissions and responsibility sharing of inter-provincial trade is crucial to the carbon reduction strategy of the Yellow River Basin. This paper uses the MRIO (multi-regional input-output) model to measure the production-side and consumption-side responsibility sharing of nine provinces in the Yellow River Basin in 2012 and 2017, revealing the amount and direction of the embodied carbon transfer between provinces, and finally introduces the share of provincial value added as the responsibility sharing factor to compare and analyze the differences between the three responsibility sharing methods. The results show the following: (1) The embodied carbon emissions on the production side in most provinces of the Yellow River Basin were larger than that on the consumption side, with the most significant differences in Shanxi, Inner Mongolia, and Shandong, among which local demand carbon emissions and intermediate product transfer out of carbon emissions were the main causes of production-side carbon emissions. (2) In general, all provinces except Shaanxi were net carbon transfer-in regions, and the embodied carbon was mainly transferred to Beijing, Jiangsu, Guangdong, Zhejiang, and Hebei. (3) Shared responsibility for carbon emissions was jointly determined by the volume of embodied carbon trade and the ability to obtain value added, which lay between production and consumption side responsibility shares. (4) The Yellow River Basin had a large responsibility-sharing factor and embodied carbon trade, and thus needs to take more responsibility for emission reduction. This study is expected to provide scientific support for the strategy of differentiated emission reduction in the Yellow River Basin and enrich the regional carbon accounting methods.

Use of SCM in Manufacturing the Compressed Brick Optimizing Embodied Energy and Carbon Emission

Brick is one of the most used building materials in masonry construction. Conventionally burnt clay bricks are used. These bricks are manufactured from clay and burnt in a kiln at a higher temperature. This results in a very high amount of CO2 emission and has high embodied energy, which highly affects the environment. Compressed bricks are one of the sustainable solutions to overcome these issues of high CO2 emission and embodied energy. Adopting sustainable alter- natives, such as compressed bricks incorporating supplementary cementitious materials or envi- ronmentally friendly brick manufacturing processes, can help mitigate these issues and promote more sustainable construction practices. In this study, attempts have been made to manufacture and test the bricks with different proportions of the soil, i.e., the mix of locally available soil with sand, cement as the cementitious materials, and SCMs like fly ash & GGBS. The research methodology involves the formulation of different mixtures with varying proportions of SCMs. The specimens were then prepared using a compression molding technique and cured under controlled conditions. This research paper aims to investigate the effects of incorporating sup- plementary cementitious materials (SCMs) on the properties of compressed bricks. The study focuses on evaluating the density, compressive strength, water absorption, and efflorescence, as well as calculating the embodied energy and carbon dioxide emissions associated with the pro- duction of these bricks. Furthermore, the paper comprehensively analyzes the embodied energy and CO2 emissions associated with producing compressed bricks. These calculations consider the energy consumed and CO2 emitted in manufacturing, including raw material extraction, transportation, and brick fabrication. The study's results demonstrate the influence of SCMs on the properties of the compressed bricks. The analysis of embodied energy and CO2 emissions provided valuable insights into the environmental sustainability of the brick production process.

Network causal effects of deepening global trade agreements on embodied carbon emissions

With the deepening vertical specialization of production networks and value chains among countries, the problem of global embodied carbon emission leakage under multilateral trade agreement cooperation is becoming increasingly prominent. This study measures the index of “World Trade Organization+" and “World Trade Organization-X,” finds the complex impact of the two types of deep integration of trade agreements on embodied carbon emissions from the network perspective, and compares them to draw conclusions and suggestions. First, the global trade-embodied carbon transfer link spontaneously diversifies, with most countries moving from the network's perimeter to its center. Second, more trade agreements can help carbon-absorbing, and carbon-spillover countries narrow the “production side” and “consumption side” divide. Third, “World Trade Organization+" and “World Trade Organization-X" deep integration influence embodied carbon emission linkages differently for countries with different embodied carbon emission attributes, with “World Trade Organization-X" having a more significant impact. At the policy level, free trade agreements have deepened to a certain extent to provide a consistent and synergistic path for trade governance and climate globalization. Countries should actively introduce relevant provisions based on the governance of trade-embodied carbon emission reductions in “World Trade Organization+" and “World Trade Organization-X", especially in “World Trade Organization-X", and some of the relevant policy provisions can be appropriately weighted in favor of developing countries.

Managing Carbon Efficiency and Carbon Equity

China has committed to achieving carbon neutrality by 2060, primarily focusing on reducing carbon intensity. Understanding the regional embodied carbon emissions is critical for managing carbon efficiency and carbon equity in this process. Using the input-output and SBM-DEA models, this article first calculates China's regional embodied carbon emissions. The results reveal substantial carbon transfers between China's different regions. Therefore, designing reduction pathways solely based on production-based carbon emissions raises fairness concerns. To address this, this article employs the SBM-DEA model to calculate the regional reduction potential and marginal abatement costs using the regional embodied carbon emissions and optimize China's pathways of regional carbon emission reduction. The new pathways consider consumption-based reduction potential, marginal abatement cost, and reduction equity, and are all in line with China's carbon reduction target. These schemes are of practical significance for China to develop a more efficient and equitable regional emission reduction plan.

Towards net zero carbon buildings: Accounting the building embodied carbon and life cycle-based policy design for Greater Bay Area, China

Carbon mitigation of buildings is critical to promote a net-zero society. The international society has vigorously promoted “Net Zero Carbon Buildings” across the globe, and accounting for building carbon emissions is critical to support this initiative. Embodied carbon, which represents carbon emissions from the entire lifecycle of the buildings, is fundamental for realizing the idea of zero carbon. However, only limited studies have been conducted so far that take into account the city scale. This paper aimed to act as a first try to account for the embodied carbon emissions in buildings in 2020 for the Guangdong-Hong Kong Macau Greater Bay Area in China (GBA). We integrated remote sensing techniques such as night-time light data (NLT) and building material flows analysis to calculate and spatialize the newly generated building material stocks (MS). Based on the MS data, we further applied life cycle assessment (LCA) to assess the embodied carbon in the buildings. The results highlighted that over 163 million tons of embodied carbon in buildings of GBA are expected to be generated, from 497 million tons of newly generated building MS in 2020. The embodied carbon in each life cycle stage is valuable for further lifecycle-based policy designs for: (i) supporting the updating of the green building certification system with consideration of the embodied carbon; (ii) promoting the green building material application and certification; and (iii) reducing the embodied carbon intensity from compact urban planning policy, such as the urban agglomeration policies in GBA. The goal of this paper was to shed a light on reducing carbon emissions from the perspective of the entire lifecycle and promote the development of net zero carbon buildings in China and Asia-Pacific.

Embodied energy and carbon assessment of existing affordable apartments in Indonesia

ABSTRACT The Indonesian government is making a tremendous effort in the provision of affordable public apartments (Rusunawa) across the country. Rusunawa buildings were designed and built considering urban planning, environmental impact, architecture, strength, safety, health, comfort, and accessibility requirements. However, in terms of climate change mitigation, there is little analysis of the building type’s embodied energy and carbon emissions. In this study, we investigated the Rusunawa buildings built by the central government, local government, and state-owned housing company considering the typical layout of the existing Rusunawa to identify the building’s embodied energy and carbon emissions using the cradle to end of use boundary. Rusunawa documents were collected and selected based on the required bill of quantity and drawings to quantify the building materials. The impacts of typical building materials on the embodied energy and carbon emissions of the roof, exterior wall, and partition wall were identified. The results showed that the building’s structural systems influenced the resultant embodied energy and carbon footprints the most, followed by walls, roof, painting, ceiling, doors and windows, and flooring. Among these structural systems, the precast concrete had a lower impact than the conventional reinforced concrete on these footprints. Overall, the Rusunawa buildings had an average embodied energy of 3950 to 8766 MJ/m2 and an average embodied carbon emissions of 328 to 871 kgCO2/m2. In particular, Rusunawa clusters, 1BR2 and 2BR1 had the smallest embodied energy and carbon emissions for the one- and two-bedroom apartment types. A high-rise Rusunawa had the smallest embodied energy and carbon emissions per floor area compared to those of low- and mid-rise. Several embodied energy and carbon values were proposed to be the baselines for the future lower-carbon Rusunawa design. These results could be adopted and developed for the central government’s regulations and guidelines to determine the current energy intensity and carbon emission of the existing Rusunawa and also to verify the future Rusunawa design.

Low-carbon design optimization of reinforced concrete building structures using genetic algorithm

ABSTRACT Embodied carbon emissions are getting increased attention to realize low-carbon buildings. Low-carbon designs have been explored by conducting both member-level and structure-level analyses for concrete structures. However, methods for combining two-tiered research need to be further developed to reduce the cost of design optimization. This study aims to propose a hybrid iterative approach for the low-carbon optimization of concrete framed structures. Accordingly, the integrated structural analysis was applied to design the initial scheme, subproject-based emission assessment was applied to identify the carbon-intensive structural components, and a genetic algorithm was applied to optimize the desired components subjected to relevant design constraints. A case study was made on a residential building to verify the feasibility of the proposed approach. The optimization results indicated that a potential 18.3% and 4.2% reduction in the embodied emissions from the beams and the building main body were achieved, respectively. A further discussion also proposed that an optimized scheme for interior walls using lightweight panels resulted in a 12% reduction in carbon emissions compared to the initial scheme using masonry walls. The proposed method and results can facilitate understanding the low-carbon design optimization of reinforced concrete structures and, therefore, contribute to carbon reduction of the construction industry.

Thin shell foundations: Quantification of embodied carbon reduction through materially efficient geometry

AbstractBuilding foundation systems are a significant but understudied contributor to embodied carbon emissions of the built environment, and typically use excess material in prismatic, bending-dominated typologies. This paper identifies and characterizes a promising pathway for reducing the embodied carbon associated with reinforced concrete shallow foundations through an alternative typology, thin shell foundations. The main focus is a quantification and comparison of the environmental impact of typical spread footings and materially efficient shell foundations. Validated analytical engineering equations are applied in a parametric design workflow for the same design load and soil bearing capacity. By iterating through this workflow systematically, insights are gained regarding the applicability of shell foundations to various building typologies and site conditions. Results show that for small column loads and weak soils, shells reduce embodied carbon by about half compared to spread footings. For high applied loads, shells significantly outperform their prismatic counterparts, reducing the environmental impact by almost two-thirds. Foundations are then considered within the context of a whole building structural frame to determine the potential downstream savings when multiple systems are optimized to reduce material use and mass. When floor slabs are shape-optimized in addition to using shell foundations, a building structural system can be constructed for nearly one-quarter of the embodied carbon of a typical system. To take advantage of these potential savings, a method for fabricating thin shell foundations, where earth is compacted and milled to create the formwork, is presented following a review of digital fabrication methods.

Embodied carbon assessment on road tunnels using integrated digital model: Methodology and case-study insights

With the constant increasing road tunnel construction in China, embodied carbon emissions of tunnels play an important role in addressing the issue of the low-carbon construction. This study determined the carbon emission boundary based on the characteristics of road tunnels and proposed a digital model based framework for evaluating embodied carbon emissions in road tunnels, thus realizing the rapid calculation and visualization of tunnel carbon emissions. Through two typical region cases of road tunnels in different regions, the usability and universality of this framework are verified. Based on the carbon emission calculation results of the tunnels, a systematic analysis was conducted on the proportion of carbon emissions in each stage of the tunnel and the carbon emission characteristics of the whole construction process. The results show that the material production stage of road tunnel has the largest carbon emissions proportion, accounting for about 79%-87%, among which the carbon emissions contribution of concrete is the highest, followed by steel. Concrete and steel together account for about 90% of carbon emissions during the tunnel material production stage. The carbon emissions of road tunnel increase with the deterioration of the surrounding rock. The embodied carbon in the secondary support step of road tunnel contributes the most to the total embodied carbon, and the carbon emissions difference of different tunnels is mainly reflected in the two steps of primary support and secondary support of road tunnel. The visual presentation of embodied carbon in road tunnel by digital model can help to achieve the purpose of reducing carbon emissions in tunnels.

Flexibility assessment of power-hydrogen-power (P2H2P) system in multi-energy districts

Climate change mitigation plans and recent tension over gas supply generate significant incentives for reducing reliance on fossil fuels in the built-environment, with an increase in installing renewables and in electrifying the heating sector. However, the seasonal imbalance of energy supply and demand is expected to increase further. Sector coupling enabled through power-to-hydrogen-to-power (P2H2P) systems that include seasonal storage can partially mitigate this issue. In this work, a hydrogen-based multi-energy system is modelled with a mixed-integer linear programming based Ehub optimization tool. While results show that the P2H2P system is technically and spatially feasible and more flexible, its large hydrogen storage is associated with high costs and embodied carbon emissions. Finally, an outlook for P2H2P systems for integration into renewable-based systems is presented.

Embodied carbon emissions of buildings and how to tame them

Embodied carbon emissions of buildings and how to tame them

Cluster characteristics of embodied carbon emissions in the international trade of metals: a sectoral-regional modeling perspective.

To be able to formulate any plausible strategies for sustainability, it is critical to establish a clear understanding of the international metals trade system complexity and the consequences in emergent embodied carbon emissions (ECE). For this purpose, we proposed a two-layer framework based on the multi-regional input-output model for calculating ECE: the intermediate production and final consumption trade layers. The proposed framework model combines the construction of a clustering index system and conducting cluster analysis from both the regional and sectoral dimensions. It is shown that developed regions transfer carbon emissions to developing regions via metals trading. This happens especially in the intermediate production stage at a level of 1.35 times higher than the final consumption stage. Furthermore, the metal sector suffers the most from carbon transfers from manufacturing, with the most carbon emissions transferred to mining. Moreover, considering environmental and technological factors to cluster regions and sectors into four and three clusters. China and Russia are in a cluster under greater pressure to reduce emissions as compared to other nations. Also, the construction and manufacturing form a cluster that their reduction of carbon emissions will effectively reduce the ECE of the metal sector. As a result, policy implications for reducing carbon emissions are investigated for each cluster in the international trade of metals contributing to the ultimate goal of global sustainable development.

Multi-objective optimization of embodied and operational energy and carbon emission of a building envelope

Buildings significantly contribute to global annual energy consumption and carbon footprint in their operation and initial construction. Coming up with an eco-friendly and energy-efficient building design requires a comprehensive yet complicated optimization that involves a large domain of design measures and indicators due to operational-embodied energy and carbon emissions-energy trade-offs. This paper proposes a multi-phase and multi-objective genetic based framework that couples EnergyPlus to the embodied energy and embodied carbon databases to jointly assess and optimize both the operational and embodied energy and carbon emissions. It determines the most optimal building configuration by adjusting design measures, which encompass geometrical parameters like window-to-wall ratio and building orientation and envelope-related variables such as the construction materials in external walls and window glazing type. This framework is applied to an ASHRAE benchmark model of a small office building located in College Station, Texas, which falls in climate zone 2A. ASHRAE standards 90.1 is considered for creating the initial baseline design. The building is optimized in two phases. In the first phase, the building is optimized for operational and embodied energy to understand potential tradeoffs. In the second phase, the building is optimized to reduce operational and embodied energy as well as carbon emissions simultaneously. This two-phase optimization culminated into two different Pareto front solutions. The results of the first stage of the optimization lead to a 9.73% and a 37.29% reduction in the building's total operational and embodied energy, respectively from the initial baseline design. In the second phase, the building's operational Energy, embodied energy, operational carbon emissions and embodied carbon emissions are reduced by 9.51%, 37.44%, 17.43%, and 35.67%, respectively in comparison with the baseline model.

How does conceptual design impact the cost and carbon footprint of structures?

Making sustainable conceptual design decisions is the key to reduce the environmental impact of the construction industry. Such early decisions, which must be given in a short timeframe, have the largest impact on a project’s quality, cost and embodied carbon. This study showed how much the conceptual design decisions affect the cost and carbon footprint of a building’s structure using our Non-dominated Sorted Genetic Algorithm II tool. First, we tested the tool’s reliability by comparing its solutions with three case studies from literature. Then, we showed that by quickly examining various conceptual design solutions on a Pareto graph (which spotlights cost and CO2-optimized options), more sustainable design alternatives can be identified. Then, using the tool, we analyzed 36 buildingconfigurations, providing a spectrum of embodied carbon emissions (including the life cycle assessment steps A1, A2, A3, A4, A5, C2, C3, C4) ranging between 60 and 360kgCO2e/m2. By comparing 25 material types from 15 databases (EPDs and ICE), we concluded that the geometry decisions (span length, height and shape) have the largest influence, material type (steel, timber, reinforced concrete), recycling and reuse of steel are crucial, and the embodied carbon calculations are highly sensitive to the supplier data and location. Overall, this study showed that architects and engineers possess the ability to significantly reduce the embodied carbon of structural systems by selecting the appropriate materials and structural system at the conceptual design stage.

Decoupling economic growth from building embodied carbon emissions in China: A nighttime light data-based innovation approach

The contribution of the construction sector is indispensable for the realization of China's carbon peaking and carbon neutrality goals. However, existing studies have focused on the decoupling relationship between GDP and building life cycle carbon emissions, neglecting the utilization of Night Time Light data (NTL). The research question of this research is how to describe the decoupling relationship between Economic Growth (EG) and Building Embodied Carbon emissions (BECs) by introducing NTL. To tackle this question, the carbon emission coefficient approach is used to calculate BECs first. Then, both GDP and NTL are selected to reflect EG. The Tapio model is utilized to examine the regional and temporal evolution of China's inter-provincial decoupling performance. The main findings are as follows: 1) the number of provinces that achieved decoupling status in China is increasing, and progress has been made in BECs reduction. 2) There are significant regional differences in the decoupling of China's BECs. Particularly, most of the provinces in the south of the Hu Huanyong line show a negative decoupling for the year 2020 due to the impact of COVID-19. 3) The long-term decoupling results of GDP and NTL are consistent, while the short-term decoupling results obtained via NTL are more accurate. The study can enrich the application of NTL in the field of BECs, and provide a basis for the Government to set effective carbon reduction targets and pathways.