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Buildings and construction are major driver of anthropogenic environmental effects. While energy use and CO2 emissions of buildings and construction have been quantified, their water footprint remains understudied from an economy-wide perspective. We use environmentally-extended multi-regional input-output analysis to quantify the water, energy and carbon (dioxide) footprints associated with the construction sector of India, Italy, South Africa, and the UK, disaggregating the supply chains driving these environmental effects by using structural path analysis. Comparisons are made in terms of contributions by country, by sector, by stage of the supply chain and in terms of actual supply chain pathways. Results show that Italy and the UK have more disaggregated and international supply chains compared to India and South Africa. Total (i.e. direct + indirect) water footprints of construction sectors vary from 11.8 to 14.8 L/USD for all countries, except India at 78.1 L/USD. There was no notable correlation between water and energy and carbon dioxide footprints in terms of sectoral contributions, even if the latter two are correlated. More developed economies exhibit a higher share of international WF than developing economies. The current focus on energy and carbon dioxide footprints might therefore miss out on significant water impacts caused by construction activities, globally.

The construction and operation of buildings is a major contributor to global energy demand, greenhouse gases emissions, resource depletion, waste generation, and associated environmental effects, such as climate change, pollution and habitat destruction. Despite its wide relevance, research on building-related environmental effects often fails to achieve global visibility and attention, particularly in premiere interdisciplinary journals – thus representing a major gap in the research these journals offer. In this article we review and reflect on the factors that are likely causing this lack of visibility for such a prominent research topic and emphasise the need to reconcile the construction and operational phases into the physical unity of a building, to contribute to the global environmental discourse using a lifecycle-based approach. This article also aims to act as a call for action and to raise awareness of this important gap. The evidence contained in the article can support institutional policies to improve the status quo and provide a practical help to researchers in the field to bring their work to wide interdisciplinary audiences.

The application of the Life Cycle Assessment (LCA) technique to a building requires the collection and organization of a large amount of data over its life cycle. The systematic decomposition method can be used to classify building components, elements and materials, overcome specific difficulties that are encountered when attempting to complete the life cycle inventory and increase the reliability and transparency of results. In this paper, which was developed in the context of the research project IEA EBC Annex 72, we demonstrate the implications of taking such approach and describe the results of a comparison among different national standards/guidelines that are used to conduct LCA for building decomposition. Methods: We initially identified the main characteristics of the standards/guidelines used by Annex participant countries. The "be2226" reference office building was used as a reference to apply the different national standards/guidelines related to building decomposition. It served as a basis of comparison, allowing us to identify the implications of using different systems/standards in the LCA practice, in terms of how these differences affect the LCI structures, LCA databases and the methods used to communicate results. We also analyzed the implications of integrating these standards/guidelines into Building Information Modelling (BIM) to support LCA. Results: Twelve national classification systems/standards/guidelines for the building decomposition were compared. Differences were identified among the levels of decomposition and grouping principles, as well as the consequences of these differences that were related to the LCI organization. In addition, differences were observed among the LCA databases and the structures of the results. Conclusions: The findings of this study summarize and provide an overview of the most relevant aspects of using a standardized building decomposition structure to conduct LCA. Recommendations are formulated on the basis of

Introduction: The international research project IEA EBC Annex 72 investigates the life cycle related environmental impacts caused by buildings. The project aims inter alia to harmonise LCA approaches on buildings. Methods: To identify major commonalities and discrepancies among national LCA approaches, reference buildings were defined to present and compare the national approaches. A residential high-rise building located in Tianjin, China, was selected as one of the reference buildings. The main construction elements are reinforced concrete shear walls, beams and floor slabs. The building has an energy reference area of 4566 m2 and an operational heating energy demand of 250 MJ/m2a. An expert team provided information on the quantities of building materials and elements required for the construction, established a BIM model and quantified the operational energy demand. Results: The greenhouse gas emissions and environmental impacts of the building were quantified using 17 country-specific national assessment methods and LCA databases. Comparisons of the results are shown on the level of building elements as well as the complete life cycle of the building. Conclusions: The results of these assessments show that the main differences lie in the LCA background data used, the scope of the assessment and the reference study period applied. Despite the variability in the greenhouse gas emissions determined with the 17 national methods, the individual results are relevant in the respective national context of the method, data, tool and benchmark used. It is important that environmental benchmarks correspond to the particular LCA approach and database of a country in which the benchmark is applied. Furthermore, the results imply to include building technologies as their contribution to the overall environmental impacts is not negligible. Grant support: The authors thank the IEA for its organizational support and the funding organizations in the participating countries for, QC 20210407

Introduction: The international research project IEA EBC Annex 72 investigates the life cycle related environmental impacts caused by buildings. The project aims inter alia to harmonise LCA approaches on buildings. Methods: To identify major commonalities and discrepancies among national LCA approaches, reference buildings were defined to present and compare the national approaches. A residential high-rise building located in Tianjin, China, was selected as one of the reference buildings. The main construction elements are reinforced concrete shear walls, beams and floor slabs. The building has an energy reference area of 4566 m2 and an operational heating energy demand of 250 MJ/m2 a. An expert team provided information on the quantities of building materials and elements required for the construction, established a BIM model and quantified the operational energy demand. Results: The greenhouse gas emissions and environmental impacts of the building were quantified using 17 country-specific national assessment methods and LCA databases. Comparisons of the results are shown on the level of building elements as well as the complete life cycle of the building. Conclusions: The results of these assessments show that the main differences lie in the LCA background data used, the scope of the assessment and the reference study period applied. Despite the variability in the greenhouse gas emissions determined with the 17 national methods, the individual results are relevant in the respective national context of the method, data, tool and benchmark used. It is important that environmental benchmarks correspond to the particular LCA approach and database of a country in which the benchmark is applied. Furthermore, the results imply to include building technologies as their contribution to the overall environmental impacts is not negligible

The IEA EBC Annex 72 focuses on the assessment of the primary energy demand, greenhouse gas emissions and environmental impacts of buildings during production, construction, use (including repair and replacement) and end of life (dismantling), i.e. during the entire life cycle of buildings. In one of its activities, reference buildings (size, materialisation, operational energy demand, etc.) were defined on which the existing national assessment methods are applied using national (if available) databases and (national/regional) approaches. The "be2226" office building in Lustenau, Austria was selected as one of the reference buildings. TU Graz established a BIM model and quantified the amount of building elements as well as construction materials required and the operational energy demand. The building assessment was carried out using the same material and energy demand but applying the LCA approach used in the different countries represented by the participating Annex experts. The results of these assessments are compared in view of identifying major discrepancies. Preliminary findings show that the greenhouse gas emissions per kg of building material differ up to a factor of two and more. Major differences in the building assessments are observed in the transports to the construction site (imports) and the construction activities as well as in the greenhouse gas emissions of the operational energy demand (electricity). The experts document their practical difficulties and how they overcame them. The results of this activity are used to better target harmonisation efforts., QC 20200417

The IEA EBC Annex 72 focuses on the assessment of the primary energy demand, greenhouse gas emissions and environmental impacts of buildings during production, construction, use (including repair and replacement) and end of life (dismantling), i.e. during the entire life cycle of buildings. In one of its activities, reference buildings (size, materialisation, operational energy demand, etc.) were defined on which the existing national assessment methods are applied using national (if available) databases and (national/regional) approaches. The "be2226" office building in Lustenau, Austria was selected as one of the reference buildings. TU Graz established a BIM model and quantified the amount of building elements as well as construction materials required and the operational energy demand. The building assessment was carried out using the same material and energy demand but applying the LCA approach used in the different countries represented by the participating Annex experts. The results of these assessments are compared in view of identifying major discrepancies. Preliminary findings show that the greenhouse gas emissions per kg of building material differ up to a factor of two and more. Major differences in the building assessments are observed in the transports to the construction site (imports) and the construction activities as well as in the greenhouse gas emissions of the operational energy demand (electricity). The experts document their practical difficulties and how they overcame them. The results of this activity are used to better target harmonisation efforts.

Introduction: The application of the Life Cycle Assessment (LCA) technique to a building requires the collection and organization of a large amount of data over its life cycle. The systematic decomposition method can be used to classify building components, elements and materials, overcome specific difficulties that are encountered when attempting to complete the life cycle inventory and increase the reliability and transparency of results. In this paper, which was developed in the context of the research project IEA EBC Annex 72, we demonstrate the implications of taking such approach and describe the results of a comparison among different national standards/guidelines that are used to conduct LCA for building decomposition. Methods: We initially identified the main characteristics of the standards/guidelines used by Annex participant countries. The “be2226” reference office building was used as a reference to apply the different national standards/guidelines related to building decomposition. It served as a basis of comparison, allowing us to identify the implications of using different systems/standards in the LCA practice, in terms of how these differences affect the LCI structures, LCA databases and the methods used to communicate results. We also analyzed the implications of integrating these standards/guidelines into Building Information Modelling (BIM) to support LCA. Results: Twelve national classification systems/standards/guidelines for the building decomposition were compared. Differences were identified among the levels of decomposition and grouping principles, as well as the consequences of these differences that were related to the LCI organization. In addition, differences were observed among the LCA databases and the structures of the results. Conclusions: The findings of this study summarize and provide an overview of the most relevant aspects of using a standardized building decomposition stru

Life Cycle Assessment (LCA) is increasingly used as an early-stage design-decision tool to support choices of structural system. However LCA modellers must first make numerous methodological decisions, and the resultant wide variations in approach are often inadequately described by the modellers. This paper identifies, and quantifies, the three major areas of methodological variation. These are: temporal differences in the stages considered; spatial differences in the material boundaries; and physical disparities in the data coefficients. The effects are then demonstrated through a case study of a student residential building in Cambridge. The cross-laminated timber (CLT) structure is compared with concrete frame, steel frame and load-bearing masonry, considering the influence that varying the temporal boundaries, the data coefficients, and the spatial boundaries has on the choice. While for this building CLT is confirmed as the lowest impact material, the paper demonstrates that varying the methodological choices can change the results by an alarming factor of 10 or even more. The findings confirm the need for the utmost clarity and transparency with all LCA calculations. Making wider industry or policy decisions based on LCA results should be undertaken with extreme caution.

Embodied and whole life carbon of buildings are increasingly gaining attention. However, embodied carbon calculation is still far from being common practice for sustainability assessment of buildings. Some of its greatest difficulties lie with the long life lifespan of buildings which implies a great unpredictability of future scenarios and high uncertainty of data. To help understand which life cycle stages should get the most attention when considering a building project, this paper proposes a new visualisation method based on Sankey diagrams for whole life carbon that allows one to cluster the carbon emitted in each of the life cycle stages as identified in current BS 15978 standards. With the proposed method, the carbon figures can be further broken down to account for building assemblies and components. Additionally, the method is equally suitable to account for physical quantities of what is embedded in buildings and their components. As such it can supplement some units of existing assessment methods (e.g. metal depletion measured in mass units of Feeq) and turn it into mass units of embodied steel. With such new metric, a life cycle assessment would include knowledge on flows as well as quantities. Such information could then be linked to the building permanently and smartly to be updated when necessary as the building evolves, changes, and gets upgraded, building on the theoretical foundations of the shearing layers of buildings. As such, this information could be embedded within BIM which is fully suitable to store parametric details for each building component.

Embodied and whole life carbon of buildings are increasingly gaining attention. However, embodied carbon calculation is still far from being common practice for sustainability assessment of buildings. Some of its greatest difficulties lie with the long life lifespan of buildings which implies a great unpredictability of future scenarios and high uncertainty of data. To help understand which life cycle stages should get the most attention when considering a building project, this paper proposes a new visualisation method based on Sankey diagrams for whole life carbon that allows one to cluster the carbon emitted in each of the life cycle stages as identified in current BS 15978 standards. With the proposed method, the carbon figures can be further broken down to account for building assemblies and components. Additionally, the method is equally suitable to account for physical quantities of what is embedded in buildings and their components. As such it can supplement some units of existing assessment methods (e.g. metal depletion measured in mass units of Feeq) and turn it into mass units of embodied steel. With such new metric, a life cycle assessment would include knowledge on flows as well as quantities. Such information could then be linked to the building permanently and smartly to be updated when necessary as the building evolves, changes, and gets upgraded, building on the theoretical foundations of the shearing layers of buildings. As such, this information could be embedded within BIM which is fully suitable to store parametric details for each building component.

Life Cycle Assessment (LCA) is increasingly used as an early-stage design-decision tool to support choices of structural system. However LCA modellers must first make numerous methodological decisions, and the resultant wide variations in approach are often inadequately described by the modellers. This paper identifies, and quantifies, the three major areas of methodological variation. These are: temporal differences in the stages considered; spatial differences in the material boundaries; and physical disparities in the data coefficients. The effects are then demonstrated through a case study of a student residential building in Cambridge. The cross-laminated timber (CLT) structure is compared with concrete frame, steel frame and load-bearing masonry, considering the influence that varying the temporal boundaries, the data coefficients, and the spatial boundaries has on the choice. While for this building CLT is confirmed as the lowest impact material, the paper demonstrates that varying the methodological choices can change the results by an alarming factor of 10 or even more. The findings confirm the need for the utmost clarity and transparency with all LCA calculations. Making wider industry or policy decisions based on LCA results should be undertaken with extreme caution.

Introduction: The application of the Life Cycle Assessment (LCA) technique to a building requires the collection and organization of a large amount of data over its life cycle. The systematic decomposition method can be used to classify building components, elements and materials, overcome specific difficulties that are encountered when attempting to complete the life cycle inventory and increase the reliability and transparency of results. In this paper, which was developed in the context of the research project IEA EBC Annex 72, we demonstrate the implications of taking such approach and describe the results of a comparison among different national standards/guidelines that are used to conduct LCA for building decomposition. Methods: We initially identified the main characteristics of the standards/guidelines used by Annex participant countries. The “be2226” reference office building was used as a reference to apply the different national standards/guidelines related to building decomposition. It served as a basis of comparison, allowing us to identify the implications of using different systems/standards in the LCA practice, in terms of how these differences affect the LCI structures, LCA databases and the methods used to communicate results. We also analyzed the implications of integrating these standards/guidelines into Building Information Modelling (BIM) to support LCA. Results: Twelve national classification systems/standards/guidelines for the building decomposition were compared. Differences were identified among the levels of decomposition and grouping principles, as well as the consequences of these differences that were related to the LCI organization. In addition, differences were observed among the LCA databases and the structures of the results. Conclusions: The findings of this study summarize and provide an overview of the most relevant aspects of using a standardized building decomposition stru