The assessment of the environmental performance of buildings is now commonly using a life cycle approach, based on a growing number of databases and methods in Life Cycle Assessment (LCA). Recent ...studies have, however, highlighted the problems related to uncertainties in the LCA results. The aim of this study is to assess the sensitivity of construction materials to the different modelling choices in order to highlight their consequences at the building scale. In particular, we focused on the different modelling options in terms of database choices, system boundary definitions and replacement scenarios of building materials during the whole service life of the buildings. The assessment of uncertainties was conducted at two levels: the material or element level and the building level. The results clearly show the importance of these modelling choices. Variations on the overall assessment of buildings are significant, but the details at the material scale show that not all materials are similarly sensitive to these choices. We identified those materials that have a large contribution to the environmental impact of the buildings and which are also sensitive to different modelling choices. This can help for a better understanding of these modelling choices and can be used in upcoming regulations or public policies.
•Impact of materials used during the building's life cycle have been assessed.•We considered the different uncertainties related with the calculation method.•Concrete has the main contribution to GWP but a low uncertainty in the calculation.•Other materials are much more sensitive to calculation hypothesis.•A particular attention should be taken on insulation and wooden materials.
•A framework is proposed for assessing the embodied energy during the design stage.•Assessment covers the impact of materials supply chain based on the suppliers’ EPD.•ETL technology is integrated ...into the BIM process to facilitate the assessment.•A prototype of the proposed framework is developed.•The prototype is finally used to test the framework’s applicability in a case study.
Assessment of the embodied energy associated with the production and transportation of materials during the design phase of building provides great potential to profoundly affect the building’s energy use and sustainability performance. While Building Information Modeling (BIM) gives opportunities to incorporate sustainability performance indicators in the building design process, it lacks interoperability with the conventional Life Cycle Assessment (LCA) tools used to analyse the environmental footprints of materials in building design. Additionally, many LCA tools use databases based on industry-average values and thus cannot account for differences in the embodied impacts of specific materials from individual suppliers. To address these issues, this paper presents a framework that supports design decisions and enables assessment of the embodied energy associated with building materials supply chain based on suppliers’ Environmental Product Declarations (EPDs). The framework also integrates Extract Transform Load (ETL) technology into the BIM to ensure BIM-LCA interoperability, enabling an automated or semi-automated assessment process. The applicability of the framework is tested by developing a prototype and using it in a case study, which shows that a building’s energy use and carbon footprint can be significantly reduced during the design phase by accounting the impact of individual material in the supply chain.
Water footprinting has emerged as an important approach to assess water use related effects from consumption of goods and services. Assessment methods are proposed by two different communities, the ...Water Footprint Network (WFN) and the Life Cycle Assessment (LCA) community. The proposed methods are broadly similar and encompass both the computation of water use and its impacts, but differ in communication of a water footprint result. In this paper, we explain the role and goal of LCA and ISO-compatible water footprinting and resolve the six issues raised by Hoekstra (2016) in “A critique on the water-scarcity weighted water footprint in LCA”. By clarifying the concerns, we identify both the overlapping goals in the WFN and LCA water footprint assessments and discrepancies between them. The main differing perspective between the WFN and LCA-based approach seems to relate to the fact that LCA aims to account for environmental impacts, while the WFN aims to account for water productivity of global fresh water as a limited resource. We conclude that there is potential to use synergies in research for the two approaches and highlight the need for proper declaration of the methods applied.
In this study, the environmental impact of each material is proposed to enable effective greenhouse gas reduction design. Therefore, 6 major environmental impacts were analyzed for 29 buildings of ...school facilities using the self-developed building life cycle evaluation tool. As a result of the analysis, in the production stage of the six major environmental impacts, the top five materials consisting of structural materials such as concrete, cement, and rebar accounted for GWP 83.3%, ODP 94.4%, ADP 91.6%, AP 77.9%, EP 76.3%, and POCP 93.9%. In addition, as a result of evaluating the potential for reducing environmental impact by replacing voluntarily with concrete, cement, and insulation materials that have been voluntarily certified by the Environmental Product Declaration or low-carbon certification by companies, GWP was analyzed to be reduced by 11.9%, ODP 38.96%, ADP 13.21%, AP 1.18%, EP 5.53%, and POCP 50.61%.". Through this study, it shows the effect of material selection on greenhouse gas and suggests that designers' material selection ability can be an efficient alternative for eco-friendly design for global carbon neutrality.
•In this paper, the life cycle evaluation of school facilities was conducted.•The environmental impact of each stage was compared.•A list of materials with a large environmental impact was derived at the production stage.•The extracted materials were analyzed by replacing them with EPD or low-carbon certified materials.
•Global warming potential and primary energy as impact categories are analyzed.•The case study demonstrated the total environmental impact.•The sources of CO2e emissions for this single-family house ...is investigated.•Using wood-based building materials result in low CO2e emissions.
To understand the reasons behind the large environmental impact from buildings the whole life cycle needs to be considered. Therefore, this study evaluates the carbon dioxide emissions in all stages of a single-family house in Sweden from the production of building materials, followed by construction and user stages until the end-of-life of the building in a life cycle assessment (LCA). The methodology applied is attributional life cycle assessment (LCA) based on ‘One Click LCA’ tool and a calculated life span of 100 years. Global warming potential (GWP) and primary energy (PE) are calculated by using specific data from the case study, furthermore the data regarding building materials are based on Environmental Product Declarations (EPDs). The results show that the selection of wood-based materials has a significantly lower impact on the carbon dioxide emissions in comparison with non-wood based materials. The total emissions for this single-family house in Sweden are 6 kg CO2e/m2/year. The production stage of building materials, including building systems and installations represent 30% of the total carbon dioxide equivalent emissions, while the maintenance and replacement part represents 37%. However, energy use during the in-use stage of the house recorded lower environmental impact (21%) due to the Swedish electricity mix that is mostly based on energy sources with low carbon dioxide emissions. The water consumption, construction and the end-of-life stages have shown minor contribution to the buildings total greenhouse gas (GHG) emissions (12%). The primary energy indicator shows the largest share in the operational phase of the house.
The increasing pressure to reduce greenhouse gas emissions from buildings has motivated specialists to develop low-carbon products incorporating bio-based materials. The impact of these materials is ...often evaluated through life-cycle assessment (LCA), but there is no clear consensus on how to model the biogenic carbon released or absorbed during their life-cycle. This study investigates and compares existing methods used for biogenic carbon assessment. The most common approaches were identified through an extensive literature review. The possible discrepancies between the results obtained when adopting different methods are made evident through an LCA study of a timber building. Results identified that land-use and land-use-change (LULUC) impacts and carbon-storage credits are not included in most existing methods. In addition, when limiting the system boundary to certain life-cycle stages, methods using the –1/+1 criterion can lead to net negative results for the global warming (GW) score, failing to provide accurate data to inform decision-making. Deviation between the results obtained from different methods was 16% at the building scale and between 35% and 200% at the component scale. Of all the methods studied, the dynamic approach of evaluating biogenic carbon uptake is the most robust and transparent. 'Practice relevance' This critical review identified key methodological differences between the most commonly used methods and recommended standards for biogenic carbon accounting in buildings. This indicates a lack of consensus and guidance for conducting LCAs of bio-based construction products and buildings using bio-based materials. A case study applying four different LCA approaches on a timber building identified the inability to compare results and create proper benchmarks. Moreover, different methods lead designers to pursue different strategies to reduce a building’s carbon footprint. Regulators, the construction industry and the construction products industry are directly affected by this lack of comparability. This research highlights the flaws and benefits of commonly used methods. A clear and grounded recommendation is for practitioners to adopt dynamic biogenic carbon accounting for future assessments of bio-based materials and buildings.
Appropriate selection of construction materials plays a major role in a building's sustainable profile. The study sets out a comparative life cycle assessment of indoor flooring systems of different ...nature. The flooring systems consisted of coverings and, where required, bonding material and/or impact soundproofing material. The following coverings were assessed: inorganic (natural stone and ceramic tiles), polymer (carpeting and PVC), and wood-based (laminate and parquet) coverings. The life cycle assessment scope was defined cradle to cradle, i.e. product stage, transport to the construction site, installation of all construction elements, use, and valorisation by recycling, as end-of-life transition scenario towards a circular economy. In the use stage, three scenarios were defined as a function of pedestrian traffic intensity, which determined maintenance, repair, and replacement operations and frequencies. The environmental impacts of the coverings product stage were taken from previously assessed and selected Environmental Product Declarations (EPDs), as these are standardised public documents devised to provide environmental life cycle information. The method adopted in the study suggests that, though the use of EPDs as information source is interesting, erroneous conclusions may be drawn if the EPDs are not comparable and/or if the comparison is not made in the building context. The results indicate that the flooring systems with inorganic coverings performed best in the global warming, acidification, eutrophication, photochemical ozone creation, and abiotic depletion for fossil resources impact categories, whereas laminates performed best in the abiotic depletion for non-fossil resources and ozone layer depletion impact categories. The carpet flooring system performed worst in every impact category except photochemical ozone creation potential.
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•Six indoor flooring systems were compared through Life Cycle Assessment, considering three pedestrian traffic intensity scenarios in the use stage.•149 EPDs were analysed as starting point in the comparative study.•The importance of considering the whole life cycle vs. just the product stage was evidenced on comparing different alternative construction solutions.•Cradle-to-cradle scope was considered, based on a transition to the circular economy.•Floor systems with inorganic coverings (natural stone and ceramics) performed best in most’ of the environmental impact categories studied.
More environmental product declarations (EPDs) have been published in recent years, but type III declarations still have limitations, for example regarding comparability. According to ISO 14027, a ...comparative disclaimer addresses the equivalence between a given product and a competing product that performs the same function. ISO 14025 states that EPDs developed under the same rules can be compared, but previous research has found that even EPDs developed using the same rules cannot be used for comparison. This paper evaluates the rates of comparability between EPDs developed within the scope of the same product categories and their respective product category rules (PCRs), sub-PCRs, and program operators. For the initial analysis, the International EPD System (IES) and the Institute Bauen und Umwelt e.V. (IBU) were selected and two product categories defined from each program for a total of four categories: boards and thermal insulation from IES, and floor covering and thermal insulation from IBU. Then, the completeness of the reported information according to the requirements from ISO 14025 was assessed. The final step compared EPDs developed using the same rules and calculated the rate of comparability between documents. Comparability between two EPDs was classified into three levels (fully comparable, comparable with caution, and cannot be compared). From the four product categories, 436 EPDs were selected, each based on one PCR/sub-PCR. Only 5.04% of the EPDs presented all the mandatory information required; this lack of information affected comparability, since items that are not reported cannot be compared. This, together with flexible definitions of some elements (such as functional/declared units, allocation procedures, and cut-off rules) in the PCRs led to low rates of comparability. Of all the potential comparisons, 8.06% of the documents could not be compared in any aspect, 89.15% were considered incomparable, 2.75% could be compared with caution, and only 0.04% were comparable.
Cement is responsible for 7% of global greenhouse gas emissions, and is predicted to grow with increasing development. The majority is used in concrete, globally the most common material in ...buildings. Reducing emissions from the use of cement and concrete in buildings is therefore critical in order to limit global warming. However there remain multiple gaps in knowledge about the extent of these emissions. This paper is the first output of a project that aims to understand better the embodied impacts from the use of concrete in buildings, in order to inform and advise policy-makers and industry practitioners, and to provide clear evidence for the path forwards. In order to do so, the project collates, analyses and critiques evidence from multiple sources, reported over three papers. This first paper focuses on the basic data on materials impacts. Over the last few years, several hundred individual Environmental Product Declarations (EPD) have been published for cements, aggregates and concrete mixes, but no publication offers a comparison or overview. Therefore understanding the range and opportunities for the reduction of impacts from concrete remains very limited. This paper provides the first detailed analysis of the EPD for concrete and its constituents. 'Practice relevance' The graphs developed in this paper can be used by designers and manufacturers to understand and reduce the impacts from cement and concrete. Designers will have a better idea of an appropriate coefficient to use at the early design stage before more details are known. As the design progresses, they will be able to use the graphs presented to choose a lower impact cement or concrete with the same performance, as well as to check the likely validity of any EPD. The graphs also provide an incentive to manufacturers to reduce impacts, since they will now be able to compare their products with others. Finally, for those involved in producing EPD, the paper demonstrates the necessity of more detailed rules for consistency, and in the meantime the necessity of full transparency in EPD reports.
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