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Wood and bio-based construction products are perceived as a way to use renewable resources, to save energy and to mitigate greenhouse gas (GHG)-emissions during production and to store carbon during the entire service life of the building. This article compares the carbon footprint per kilogram of wood products (softwood beams, plywood, oriented strand board panel, and fibre board) from the perspective of the life cycle assessment methodology for greenhouse gas (GHG) emissions of practitioners from 16 countries participating in the IEA Annex 72. These materials are used in PAL6 softwood structure multi-residential building. This article aims at comparing the carbon footprint accounting methods from 16 countries for PAL6 multi-residential building. Each national team applied the reference study period (RSP), life cycle modules covered, modelling rules, the geographical scope of inventory data as well as the LCA database according to its specific national method. The results show that there are three types of methodology to assess a building with biogenic content (0/0, -1/+1, -1/+1*). The results were more variable plywood, oriented strand board, and fibreboard than the softwood beams due to the variability in the wood transformation processes among the countries. A net negative carbon balance was obtained for the softwood beam for the countries using -1/+1* with a clear assumption of the fraction of the carbon permanently stored at the end-of-life (EoL). The carbon storage is only possible if it is secured at the EoL. Participating countries apply different definitions of permanence and EoL scenarios. Guideline on assessing, monitoring, and legally reporting carbon storage at the EoL are needed, based on concertation between standard, life cycle assessment, wood industry, and climate experts.

Wood and bio-based construction products are perceived as a way to use renewable resources, to save energy and to mitigate greenhouse gas (GHG)-emissions during production and to store carbon during the entire service life of the building. This article compares the carbon footprint per kilogram of wood products (softwood beams, plywood, oriented strand board panel, and fibre board) from the perspective of the life cycle assessment methodology for greenhouse gas (GHG) emissions of practitioners from 16 countries participating in the IEA Annex 72. These materials are used in PAL6 softwood structure multi-residential building. This article aims at comparing the carbon footprint accounting methods from 16 countries for PAL6 multi-residential building. Each national team applied the reference study period (RSP), life cycle modules covered, modelling rules, the geographical scope of inventory data as well as the LCA database according to its specific national method. The results show that there are three types of methodology to assess a building with biogenic content (0/0, -1/+1, -1/+1*). The results were more variable plywood, oriented strand board, and fibreboard than the softwood beams due to the variability in the wood transformation processes among the countries. A net negative carbon balance was obtained for the softwood beam for the countries using -1/+1* with a clear assumption of the fraction of the carbon permanently stored at the end-of-life (EoL). The carbon storage is only possible if it is secured at the EoL. Participating countries apply different definitions of permanence and EoL scenarios. Guideline on assessing, monitoring, and legally reporting carbon storage at the EoL are needed, based on concertation between standard, life cycle assessment, wood industry, and climate experts.

Life cycle assessment (LCA) is increasingly being used as a tool by the building industry and actors to assess the global warming potential (GWP) of building activities. In several countries, life cycle based requirements on GWP are currently being incorporated into building regulations. After the establishment of general calculation rules for building LCA, a crucial next step is to evaluate the performance of the specific building design. For this, reference values or benchmarks are needed, but there are several approaches to defining these. This study presents an overview of existing benchmark systems documented in seventeen cases from the IEA EBC Annex 72 project on LCA of buildings. The study characterizes their different types of methodological background and displays the reported values. Full life cycle target values for residential and non-residential buildings are found around 10-20 kg CO2e/m2/y, whereas reference values are found between 20-80 kg CO2e/m2/y. Possible embodied target- and reference values are found between 1-12 kg CO2e/m2/y for both residential and non-residential buildings. Benchmark stakeholders can use the insights from this study to understand the justifications of the background methodological choices and to gain an overview of the level of GWP performance across benchmark systems., QC 20230706

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

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

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