Calculation of life cycle assessment of construction products with nanoparticles

Chapter 7 Calculation of Life Cycle Assessment of Construction Products with Nanoparticles Marco Antonio Sánchez-Burgos, Paula Porras-Pereira, and Pilar Mercader-Moyano Abstract This chapter meticulously undertakes a comprehensive Life Cycle Assessment of a product infused with nanoparticles. Each section within this chapter aligns with distinct phases of the methodology, encompassing the definition of study objectives and scope, development of an inventory detailing consumption and emissions, selection and quantification of environmental impact categories, and the subsequent interpretation of obtained results. The chapter concludes with the synthesis of findings, coupled with formulated recommendations for enhancing the integration of nanoparticles in the construction sector. In general, nanoparticles are included in composite elements, and the same nanoparticle can be associated to different elements, to form different composite elements. In addition to this, nanoparticles properties mostly depend on the shape of the particle, so their characteristics are different to the bulk material [1]. The same way, the behaviour of nanoparticles released to the environment, or adsorbed by humans is different to the corresponding bulk material. Due to their size and shape, these particles react with the environment and tissues different to the corresponding bulk substance, and currently these processes have not been adequately addressed by scientific research [1]. Consequently, nowadays it is challenging to define the risk assessment of most nanoparticles [2]. Present Address: M. A. Sánchez-Burgos ·P. Porras-Pereira (B)·P. Mercader-Moyano Department of Building Construction I, Higher Technical School of Architecture, University of Seville, Seville, Spain e-mail: [email protected] M. A. Sánchez-Burgos e-mail: [email protected] P. Mercader-Moyano e-mail: [email protected] © The Author(s) 2025 P. Mercader-Moyano and P. Porras-Pereira (eds.), Life Cycle Analysis Based on Nanoparticles Applied to the Construction Industry, https://doi.org/10.1007/978-3-031-79115-4_7 111 112 M. A. Sánchez-Burgos et al. Currently there are available sources that help to conduct the risk assessment of nanoparticles, such as EUNON Nano Data, which is an EU-funded project. These databases are an important source of information to assess the volume of the emissions, the characterisation, and the risk assessment of most used nanoparticles. Regarding risk assessment, EUNON Nano Data include data on psycho-chemical characterisation, toxicological and ecotoxicological assessment of commercial nanomaterials in the European market [2]. Nanomaterials are produced used and disposed of; therefore, life cycle approach can be applied [3]. Furthermore, LCA methodology is considered the best approach to evaluate the potential impacts of engineered nanomaterials alongside their complete life cycle [4,5]. However, as stated above, significant gaps remain regarding the long-term fate of nanoparticles’ environmental emissions and their effects on human health and ecosystem quality, making LCA application to nanoparticles challenging [1]. Life cycle assessment has already been applied to a wide range of products including nanoparticles [6,4]. These studies results have been assessed and general conclusions regarding this question have been established. Consequently, there are available guidelines to apply LCA methodology to nanomaterials. A reliable example is the Guidance for applying Life Cycle Assessment to nanomaterials by REACHnano Consortium, a guidance document that is aimed at helping manufacturers and downstream users of engineered nanomaterials to perform a complete risk and environmental assessment taking into account all life cycles and considerations of nanomaterials [5]. Finally, it has to be stressed that, currently the potential impacts of the released nanomaterials in the categories of Human health and Environmental Toxicity are not included in LCA methods, therefore uncertainties and data gaps exist [4–6]. 1 Definition of Objectives and Scope of the Study The initial phase of the Life Cycle Assessment (LCA) methodology involves defining the goal, which encompasses specifying the intended application, study objectives, target audience, and any adopted constraints and assumptions. The scope of the LCA study provides a detailed description of the system under assessment and its associated analytical parameters. This scope must align with the previously defined goal and includes identifying the Life Cycle stages incorporated into the study. Following the goal and scope definition, the next steps involve establishing the functional unit, reference flow, and system boundaries. The functional unit represents the service rendered by the products under evaluation, with all resource consumption and emissions quantities referenced to the production of this functional unit. When conducting comparative LCAs between different products or processes, comparisons are made based on the amount of product required to deliver the functional unit. 7 Calculation of Life Cycle Assessment of Construction Products … 113 The reference flow denotes the quantity of product necessary to deliver the functional unit, while system boundaries delineate which flows, such as emissions and resource consumption, are considered within the LCA study. These flows must be necessary for providing the functional unit. In conjunction with defining the system boundaries, cut-off criteria and allocation rules are established. Cut-off criteria determine which flows are deemed significant for assessing the potential impacts of the product, including considerations of resulting secondary raw materials and the end-of-life stage for the product. Allocation rules come into play when there are multiple co-products resulting from the assessed system, determining the allocation of impacts to each co-product. For a thorough and precise evaluation of nanomaterials through LCA, adherence to the following procedures is advised to guarantee comprehensive and precise assessments [5]: •Taking into account that releases and emissions of nanoparticles occur mostly during use phase and end-of-product stage, and they depend on how nanoproducts are managed, the associated potential impacts will be associated to each nanoproduct Life Cycle. Therefore, LCA studies should be focused in nanoproducts instead of nanoparticles [5]. •Nanomaterials provide us with improved products that can develop enhanced or new functions. In most cases the use of nanomaterials enables the reduction in energy, raw materials and emissions. In that sense, it is important to define an adequate functional unit that cover all these advantages [5]. •Environmental and toxicological impacts for nanomaterials occur during all Life Cycle stages, therefore it is advised to extend LCA studies to “cradle to grave” scope for these products [5]. •For stages with little information, it is advised to consider different scenarios in order to conduct a sensitivity analysis [5]. 2 Development of an Inventory of Consumption and Emissions The inventory analysis, encompassing the gathering of all input and output flows within the evaluated product system, constitutes the Life Cycle Inventory (LCI). Clear establishment of system boundaries is essential for accurately computing input (consumption) and output (emission) flows. Typically, for data collection, employing primary data for core processes and secondary data for ancillary processes is recommended. Primary data is derived from modelling or monitoring of the processes, while secondary data is sourced from existing databases like Ecoinvent, Gabi, or ELCD. Presently, Life Cycle Inventories (LCIs) for nanomaterials encounter the following challenges [5]: 114 M. A. Sánchez-Burgos et al. •Data corresponding to nanomaterials are not included in existing LCA databases. Therefore, these gaps need to be completed, specifically for each study. Otherwise, the study results will not represent the complete process [5]. It advised to prioritise data taken from real measures of assessed processes. •The information regarding nanomaterials production is often confidential. Furthermore, this is a fast-evolving field of technology. As a consequence, available data is scarce, and it is needed to make estimations in some processes. This leads to some degree of uncertainty that has to be assessed [5]. Each nanoparticle synthesis method assessed has to be studied to obtain consumption and emission flows. For estimations, different scenarios must be evaluated, and discussed [5]. •Regarding emissions of nanoparticles, in most cases a critical step is the incorporation of nanoparticles in the form of powder, to the material. In these cases, the exposition of workers to nanoparticles emissions during production has to be included in the LCA study. •LCA studies for nanomaterials should encompass all life cycle stages, from production to disposal, adhering to the “cradle to grave” approach. •In general, there is no information about the released quantities of nanoparticles and their fate in the long term, for each stage of their Life Cycle. Furthermore, there is no consensus about how to measure these emissions. This data must be gathered on a process-specific basis. It is imperative to acquire extensive information regarding the assessed process to compile a comprehensive set of emission data. The emissions of nanoparticles throughout all stages of the process’s life cycle must be incorporated into the resulting LCI. •Uncertainty must be assessed. •It is advised to gather information regarding emissions using templates. In detail, the following data should be addressed: •Production stage: – Inputs and outputs during production stage; consumption and emission associated. – Emissions of nanoparticles during production stage, exposition of workers. – Releases during production stage, compartment of the emission. – Transformation of the particle after the emission •Use stage: – Lifespan and services obtained from the product. – Inputs and outputs produced during use; maintenance, cleaning, consumption and emission associated to use. – Emissions of nanoparticles during production stage, exposition of workers. – Releases during production stage, compartment of the emission. Transformation of the particle after the emission – Possibility of nanoparticles emissions during use. Environmental compartment of the emission. Transformation of the particle after the emission 7 Calculation of Life Cycle Assessment of Construction Products … 115 •End-of-life stage. – Characteristics of nanoproducts wastes generated at the end-of-life stage. – Treatment and final disposal of nanoproducts wastes. – Recycling: Type of recycling process. Emissions of nanoparticles during recycling. Quantity of nanoparticles in recycled products. – Disposed to landfill: Degradation or transformation of nanoproducts. Environmental compartment for the final fate of nanoproducts waste. – Incineration: transformation of nanoparticles after incineration. Nanoparticles included in resulting ashes. Environmental compartment for the final fate of nanoproducts included in resulting ashes. An example of check-list template for LCI data gathering is included (Table 1) [4,7]. 3 Selection and Quantification of Environmental Impact Categories This phase encompasses four sequential steps: •Classification: Assignation of each consumption and emission to the relevant impact category. •Characterisation: Calculation of impact contribution for each emission and consumption, and aggregation of contributions related to each impact. •Normalisation (this step is optional): Impact scores al multiplied by normalization factors, which relate the obtained impact for each category to the global impact produced in social group (European, national, global). This allows to inform of the relative relevance of the impacts obtained. •Weighting (this step is optional): This is a rather controversial step. It consists of multiplying obtained impact scores to enable comparison between impact categories. It has to be stressed that according LCA methodology, scores corresponding to different impact categories cannot be aggregated. Various methods exist for converting emissions and consumptions of substances into impact scores for different environmental categories. Presently, midpoint impact category methods are well-established, offering robust and meaningful results albeit with challenging interpretation. Examples of these established methods include CML and ReCiPe. Alternatively, endpoint impact category methods are easier to interpret, yet lack scientific consensus, resulting in limited usage. These methods are not widely adopted due to their less-established nature. Environmental impact category methods employ scientifically developed models that quantify the relationship between material consumption or substance emissions and the generated impacts. 116 M. A. Sánchez-Burgos et al. Table 1 Check-list template for LCI data gathering [7] Type of information Data requested Process description General description of the process (Ex. Synthesis of LFP nanoportides) Productive process Typology of process/route of production Partner/company responsible Resulting material/product description. Flow reference: Material produced Type of material synthesized. For ENMS, specify the format of the final product (powder, dilution,..,) Quantity (g) Co-products (If any) Quantity (g), use of co-product Process description Phases of the process Duration (hours) Equipment used Process scale Scale (lab, pilot, industrial,…) Production capacity (kg/year) Inventory of INPUTS Energy consumption (Electricity) Source/origin Quantity (kWh) Function/use (phase, equipment used,…) Energy consumption (heat) Source/origin Quantity (MJ) Function/use (phase, equipment used,…) Water consumption Source/origin Quantity (1) Function/use (process water or cleaning water,…} Raw Materials (precursors, gases, solvents, others…] Other materials/substances used within the process, including ancillary materials (cleaning,...) Name/source Quantity (g) Funetion/use (precursor, solvent,..,) Origin: geographical (km), synthesis process,… Other information (supplier, % recycled content…,) Packaging Packaging material (type), weight (g),… Size and capacity of packaging (continued) 7 Calculation of Life Cycle Assessment of Construction Products … 117 Table 1 (continued) Type of information Data requested Transport processes inputs Distance (km), type of vehicle Inventory OUTPUTS Direct emissions to air (including ENMs emissions) Name/type of emission Quantity (g) Process origin Treatment/filtration (% of elimination of ENMs in filtration) Emissions to water [including ENMs emissions) Pollutants, % of ENMs, type of effluent Wastewater produced Type of wastewater (characterisation, pollutants) Origin process (cleaning„.) Potential content of ENMs (%of ENMs) Treatment/Final Destination (% of degradation of ENMs, elimination and release of ENMs) Solid waste Name/Type Classification/code Content of ENMs Origin process Quantity [g] Treatment/Destination (ENMs degradation and liberation) Liquid waste Name Classification/code Content of ENMs Origin process Quantity [g] Treatment/Destination [ENMs degradation and liberation) Other outputs (scraps, subproducts, co-products,.) It’s important to note that current impact category calculation methods do not include nanomaterials. Consequently, there are no defined characterization factors to assess nanoparticle emissions, leading to their exclusion from resulting impact scores. 118 M. A. Sánchez-Burgos et al. In general, nanoparticle emissions impact Human Toxicity and Environmental Toxicity categories. However, these categories cannot be adequately addressed for nanoparticle emissions using current impact calculation methods. Given these considerations, recommendations for nanomaterials LCA should include: •Utilizing impact methods recommended at the European level, such as those outlined in the ILCD handbook. •Including relevant categories for nanoparticles, such as Human Toxicity and Ecosystems Toxicity. •Deriving characterization factors for assessed emissions using prospective approaches based on consensus models aligned with the characteristics of releases and fate of the corresponding process. To achieve this, it is recommended to collaborate with a diverse team of experts specializing in risk assessment from various fields. If calculating characterization factors proves to be impractical, it is advised to employ a precautionary approach. This involves utilizing characterization factors for analogous substances, such as the corresponding bulk material, while carefully considering potential disparities in final fate behaviour. 3.1 Recommended Impact Category Calculation Methods The Table (Table 2) features the recommended methods outlined in the ILCD Handbook. Notably, impacts such as Water Depletion and Land Transformation are deemed insignificant for nanoparticle studies and thus are advised to be omitted. However, for other methods, it is imperative to incorporate the specific risks associated with nanoparticles in LCA studies. It is important to note that none of these methods encompass flows or characterization factors tailored to evaluate the specific damages caused by nanoparticles. Hence, the assessment of this risk must be conducted separately [7]. The pertinent impact categories concerning nanoparticles are as follows: •Ecotoxicity for aquatic fresh water. For Soil Ecotoxicity and Marine Ecosystems Toxicity, there is insufficient consensus, hence they are not considered. The only method recommended by the ILCD for evaluating Ecotoxicity in Freshwater is the midpoint USEtox. Currently, no ecotoxicity impact calculation method (including USEtox) incorporates characterization factors for nanoparticles. USEtox includes characterization factors for bulk material emissions to air, water, and soil. To assess the effects of nanoparticle emissions, new characterization factors must be established. It’s important to note that the USEtox tool calculates fate factors for emissions based on the behaviour of soluble compounds, thus nanoparticles are not adequately represented in 7 Calculation of Life Cycle Assessment of Construction Products … 119 Table 2 ILCD Handbook recommended impact categories [7] PEF impact categories ILCD recommended Impact assessment model Classification of recommended impact method (ILCD) Significant for LCA of nanoproduets Relevant for released Nanopartfcles 1. Climate change Bern model—Global Warming Potentials (GWP) over a 100 year time horizon I (recommended and satisfactory) Potentially significant during all life cycle, especially manufacturing No 2. Ozone depletion EDIP model based on ODPs of the World Meteorological Organization (WMO) I (recommended and satisfactory) Potentially significant during ail life cycle No 3. Ecotoxicity for aquatic fresh water U5Etox model [8] II (recommended but in need of same improvements)/ III (recommended, but to be applied with caution) Potentially significant during all life cycle, especially end-of-llife Yes 4. Human toxicity—cancer effects USEtox model [8] II (recommended but in need of some improvements)/ III (recommended, but to be applied with caution) Potentially significant during all life cycle, especially end-of-life Yes 5. Human toxicity—oon-cancer effects U5Etox model [8] II (recommended but in need of some improvements)/ III (recommended, but to be applied with caution) Potentially significant during all life cycle, especially end-of-life Yes (continued)