Substitution is not consistent with attributional life cycle assessment – reply to Provost-Savard and Majeau-Bettez (2024)

Substitution is not consistent with attributional life cycle assessment – reply to Provost-Savard and Majeau-Bettez (2024) | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Method Article Substitution is not consistent with attributional life cycle assessment – reply to Provost-Savard and Majeau-Bettez (2024) Matthew Brander This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8947729/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract There is a lack of clear consensus on the use of ‘substitution’ within attributional life cycle assessment (ALCA). A number of academic articles have previously argued that substitution is not consistent with ALCA, but a more recent article by Provost-Savard and Majeau-Bettez in the Journal of Industrial Ecology argues that it can be coherently used. In reply, this article contends that in order to resolve methodological disputes it is necessary to have a clear conceptualisation of what the method in question is intended to represent. To this end, the article clarifies that ALCA represents the processes physically used in the life cycle of the product that is studied, and also represents shares of total absolute anthropogenic impacts. A worked example for corn ethanol is used to show that substitution is fundamentally inconsistent with these features of ALCA, and to analyse what is right and wrong in Provost-Savard and Majeau-Bettez’s article. It is hoped that clarifying the reasons for why substitution is not appropriate in ALCA will help to build consensus on this issue. It is strongly recommended that standards and guidance for ALCA should clearly state that substitution should not be used. Figures Figure 1 1. Introduction Substitution is a technique for addressing instances of multifunctionality, e.g. multiple co-products from a single process within a life cycle. 1 In order to identify the flows/impacts associated with only one of the co-products, the life cycle flows/impacts up to and including the multifunctional process either need to be allocated between the different co-products, or the multifunctionality problem needs to be avoided in some other way. Substitution is intended to avoid allocation by identifying the products that are substituted by the co-products of the main product that is studied, then quantifying the environmental burdens associated with those products, and crediting the avoidance of those burdens to the product that is studied. Currently there is a lack of consensus on whether substitution is an appropriate technique to use within attributional life cycle assessment (ALCA). A large number of ALCA studies have used substitution (Moretti et al. 2020), and a number of standards and guidance documents either allow its use (e.g. WBCSD/WRI (2011a), European Commission (2010)) or are somewhat ambiguous on this point (e.g. ISO 14044 (International Organization for Standardization 2006)). However, a number of previous academic articles have argued that substitution is not appropriate for ALCA (Brander and Wylie 2011; Heijungs and Guinée 2007; Majeau-Bettez et al. 2018). More recently, an article by Provost-Savard and Majeau-Bettez (2024) in the Journal of Industrial Ecology has argued in the opposite direction, and contends that substitution can be used coherently in ALCA. The present paper is written largely as a reply to Provost-Savard and Majeau-Bettez (2024), with the principal aim of explaining why substitution is not consistent with ALCA. In order to streamline the analysis the paper does not engage in a detailed exegesis or history of the existing literature, but instead focuses directly on the substance of the arguments and issues within the debate. 2. Conceptualising ALCA In order to resolve any methodological dispute it is essential to have a precise conceptualisation of what a method, e.g. ALCA, is intended to represent in order to determine whether a technique, e.g. substitution, is consistent with the method (Brander 2016). To this end, the following provides a statement of what ALCA is intended to represent: 1. The material and energy flows (and associated impacts) to/from the processes that are physically used in the life cycle of the product that is studied. 2. The share of total absolute anthropogenic impacts attributable to the product studied. Point 1 is consistent with the UNEP/SETAC definition of ALCA, which states that it is a “modelling approach in which inputs and outputs are attributed to the functional unit of a product system by linking and/or partitioning the unit processes of the system according to a normative rule” (UNEP and SETAC 2011, 132). Point 1 above provides additional precision by clarifying that the “unit processes of the system” are those that are physically used in the life cycle of the product that is studied . This fundamental feature of ALCA is often left unspecified within definitions of ALCA, possibly because it is such an intuitive or basic feature that is assumed not to require stating. 2 Put an alternative way, it is very difficult to conceive of what ALCA is intended to represent if it isn’t intended to represent the processes physically used in the life cycle of the studied product. Provost-Savard and Majeau-Bettez’s position on this fundamental feature of ALCA is discussed later. Point 2 is often explicitly stated within definitions of ALCA, e.g. Ekvall states that ALCA “estimates what share of the global environmental burdens belongs to a product” (Ekvall 2020, 41). This feature is often represented visually by a segment of a pie chart (see Fig. 1 ), indicating a share of total absolute impacts. It is this feature that gives rise to the characteristic of ‘additivity’, which is the idea that (in principle) the sum of ALCAs for all final consumption should approximate to total absolute impacts (Tillman 2000). It is also worth noting how Point 1 relates to Point 2: it is the burdens from the processes that are physically used in the life cycle of the product that are the share of global environmental burdens that belong to a product . The above statement on what ALCA is intended to represent will be used below to analyse why substitution is not consistent with ALCA, i.e. we can ask “Do the results from using substitution represent: 1. the processes physically used in the life cycle of the product that is studied; and 2. a share of absolute impacts?”. 3. Analysis of main arguments in Provost-Savard and Majeau-Bettez (2024) Provost-Savard and Majeau-Bettez (2024) focus on rebutting two arguments against the use of substitution in ALCA from the academic literature, but also discuss a third corollary issue, and a further point related to ‘functional unit expansion’. Each of these arguments/issues are discussed in turn, with the aim of explaining what is right and wrong in Provost-Savard and Majeau-Bettez’s analysis, and to clarify why substitution is inconsistent with ALCA. 3.1. Additivity Provost-Savard and Majeau-Bettez (2024) highlight that one of the arguments within the literature for rejecting substitution is that it is inconsistent with the principle of ‘additivity’. To resolve this issue Provost-Savard and Majeau-Bettez (2024) propose assigning the avoided burden (which is credited to the main product studied) to the co-products of the main product. This solution is illustrated below with a worked example for corn ethanol (the main or ‘determining’ product) and dried distillers’ grains with solubles (DDGS; the co-product). The data in Table 1 are from Brander and Wylie [2011]. 3 Although the example focuses on GHG emissions the conclusions apply equally to any impact category. In this example the corn ethanol is credited with avoiding dedicated soy meal production (as DDGS replaces soy meal animal feed) and its associated GHG emissions (3.51 tCO 2 e/t ethanol produced) 4 . These avoided emissions are subtracted from the upstream life cycle emissions for the corn ethanol and DDGS (2.18 tCO 2 e/t ethanol) to give a result of -1.33 tCO 2 e/t ethanol. In order to achieve additivity Provost-Savard and Majeau-Bettez propose that the avoided burden value of 3.51 tCO 2 e should be assigned to the DDGS, so that the sum of the assigned burdens (-1.33 plus 3.51) equals 2.18 tCO 2 e, thereby achieving additivity to total impacts. Table 1 Data and results for corn ethanol example Data Description Value Units Emissions from the production of wheat ethanol 2.18 tCO 2 e/t ethanol produced Quantity of DDGS produced per tonne of ethanol 1.03 tDDGS/t ethanol Emissions from the production of soy meal 5.78 tCO 2 e/t soy meal Substitution ratio between DDGS and soy meal 0.59 t soy meal/t DDGS Results Description Value Units Avoided emissions credited to corn ethanol -1.33 tCO 2 e/t ethanol Emissions assigned to DDGS 3.51 tCO 2 e/1.03 t DDGS Sum of assigned emissions 2.18 tCO 2 e In one sense this proposal does ‘resolve’ the additivity problem (as the sum of assigned emissions does equal total emissions), but it nevertheless creates results that are inconsistent with ALCA. The problem with Provost-Savard and Majeau-Bettez’s solution, and the use of substitution within ALCA more generally, can be analysed by returning to the defining features of ALCA, i.e. we can ask “Does the result of 3.51 tCO 2 e/1.03 t DDGS accurately represent: 1. the processes physically used in the life cycle of the DDGS?; and 2. a share of absolute impacts?”. The answer is “no” to both questions. With regard to Point 1 (i.e. processes physically used in the life cycle), the number ‘3.51’ represents the emissions from the processes physically used in the life cycle of the soy meal , and does not represent in any way the burdens associated with the processes physically used in the life cycle of the DDGS. Provost-Savard and Majeau-Bettez (2024) accept that this is an entailment from their proposed solution, but do not appear to recognise that this is a profound departure from what ALCA is generally intended to represent. It is true that, through a radical change to existing convention, we could use an alternative normative rule for assigning responsibility for impacts, but that would be a different method to the one currently denoted by the term ‘ALCA’. With regard to Point 2 (i.e. share of absolute impacts), the result of ‘3.51’ cannot represent a share of absolute impacts as it is greater than the total absolute impacts of the system (which are 2.18 tCO 2 e). Similarly, the value assigned to the main product of corn ethanol (-1.33) also cannot represent a share of absolute impacts as it is a negative number. Conceptually it is impossible to have a negative ‘share’ of anything, e.g. when dividing a pie it isn’t possible to give one person a ‘negative slice’ of the pie. A ‘share’ cannot be more than 100% or less than 0% of total impacts. Notably, Provost-Savard and Majeau-Bettez clearly state that ALCA should represent ‘shares’ of total impacts, but do not recognise that the proposed solution for additivity, and the technique of substitution more generally, creates results which do not represent shares of absolute impacts. 3.2. State-descriptive impacts or changes in impacts A second area of focus in Provost-Savard and Majeau-Bettez(2024) is countering the argument that substitution is not appropriate because ALCA describes impacts within a given state, whereas substitution is concerned with change relative to a reference state. Provost-Savard and Majeau-Bettez argue that there is no inherent contradiction as any absolute value for impacts in a given state can be expressed as the difference or change from some alternative reference value. For example, in a world with absolute emissions of 1 tCO 2 e, this absolute value could be expressed in relative terms as a change of ‘-2 tCO 2 e, relative to a reference state in which absolute emissions are 3 tCO 2 e’. However, Provost-Savard and Majeau-Bettez’s explanation for how this relates to or justifies the use of substitution in ALCA is relatively brief, and different aspects or interpretations of the argument are discernible. One possible interpretation is that the results from substitution should be viewed as relative expressions of the absolute impacts in a static state (and so are consistent with the idea that ALCA is describing a static state and not a change). However, a problem arises if we want to use the results from substitution within subsequent ALCAs for products that use the co-products as material/energy inputs. If the results from substitution are relative expressions of absolute values, and the ALCAs in which the substitution results are used are in absolute values, there will be a strange mix of relative and absolute values within the analysis. It is hard to know what such results would represent. It could be argued that the relative expressions from substitution can be translated into absolute impacts (i.e. by adding the ‘change’ and ‘reference’ values together, e.g. -2 tCO 2 e + 3 tCO 2 e = 1 tCO 2 e). But with substitution and the proposed solution for additivity, the ‘change’ number is assigned to the main product (e.g. -1.33 tCO 2 e) and the ‘reference’ number is assigned to the co-product (e.g. 3.51 tCO 2 e). This means that when the two are summed the result only shows the total impacts in the state that is described (2.18 tCO 2 e), and does not provide separate absolute values for each co-product, and we are back to needing some form of allocation between the co-products/co-functions. A different aspect within Provost-Savard and Majeau-Bettez’s argument is that the change value can be treated as a property of the state that is being described (i.e. it is a property of the state that it displaces alternative production, and the associated impacts, that otherwise would have occurred). And this property can be used as the basis for allocation “like any other property (e.g. mass or economic value)” (Provost-Savard and Majeau-Bettez 2024, 421). However, as illustrated in Section 3.1, substitution (and the proposed solution to additivity) is not the same as allocation as it is not apportioning shares of the absolute flows/impacts associated with the multifunctional process, and can create results for individual co-products that are greater than total impacts or less than zero impacts. It might be suggested that results that are greater than 100% or less than 0% of total impacts should be interpreted in some way as relative expressions rather than absolute values, but this takes us back to the problems with relative expressions, discussed above. 3.3. Marginal data A third issue discussed in Provost-Savard and Majeau-Bettez (2024) is the use of marginal data for the product that is substituted by the co-products of the product that is studied. They argue that “an attributional state-descriptive multifunctional system can coherently be represented as the result of a transition from a reference technosphere” and that marginal data best represents the “market mechanism happening during this transition” (Provost-Savard and Majeau-Bettez 2024, 422). A first point to make is that no form of substitution is consistent with ALCA regardless of whether marginal or average data are used. For example, using marginal data for the emissions from soy meal rather than average data would not alter the inconsistency of the results with what ALCA is intended to represent (as discussed above). Secondly, the rationale given for using marginal data in Provost-Savard and Majeau-Bettez(2024) is effectively a consequential one, i.e. that marginal data represents the actual change that has occurred. But this is really just pursuing a consequential question about the decision to use the multifunctional process i.e. “What is the change caused by decision X?”, rather than the attributional question “What are the emissions from the processes physically used in the life cycle of the product studied?”. 3.4. Non-equivalence of substitution and system expansion A final issue to address is Provost-Savard and Majeau-Bettez’s point that substitution and an alternative technique called ‘functional unit expansion’ (also called ‘system expansion’) appear to yield the same overall results, and that because functional unit expansion is generally considered to be consistent with ALCA it must be the case that substitution is consistent too. As Provost-Savard and Majeau-Bettez concisely put it “Both cannot simultaneously be true: functional unit expansion and substitution cannot be methodologically equivalent and differ in their fundamental compatibility with ALCA” (2024, 413). The following analysis uses the corn ethanol example to briefly explain what is meant by ‘functional unit expansion’, and to show, in answer to Provost-Savard and Majeau-Bettez, that functional unit expansion is not methodologically equivalent to substitution. The technique of functional unit expansion simply expands the functional unit that is studied to include the functions provided by the co-products so that the problem of needing to allocate material/energy flows and impacts between different co-products/functions is avoided. In the case of the corn ethanol example the functional unit would become ‘1 tonne of corn ethanol and 1.03 tonnes of DDGS’. 5 It is a long-established truth that functional unit expansion and substitution yield the same overall outcomes in the context of a comparative analysis (Tillman et al. 1994). For a comparative analysis of two product systems it is necessary to ensure they provide the same functions in order to compare like-for-like. For example, when comparing corn ethanol to conventional petrol, the function of ‘animal feed’ either needs to be removed from the ethanol system (e.g. using substitution), or if functional unit expansion has been used for the ethanol and DDGS system then the ‘animal feed’ function needs to be added to the petrol system. This is illustrated in Table 2 , which shows that the results from a comparative analysis are the same, whether using substitution or functional unit expansion. 6 Table 2 Equivalence of substitution and functional unit expansion in the context of a comparative analysis Substitution Technique Ethanol System Petrol System Comparative result (ethanol system minus petrol system) Functional unit: 1 tonne ethanol 0.6 tonne petrol Emissions (tCO 2 e/functional unit): -1.33 0.49 -1.82 Functional Unit Expansion Technique Ethanol System Petrol System Comparative result (ethanol system minus petrol system) Functional unit: 1 tonne ethanol 1.03 tonnes DDGS 0.6 tonne petrol 0.6 tonne soy meal Emissions (tCO 2 e/functional unit): 2.18 0.49 3.51 -1.82 The crux of the apparent methodological equivalence between substitution and functional unit expansion is that they yield equivalent results, but only within the broader context of a comparative analysis , in which additional functions are added to the comparator system to ensure functional equivalence. However, comparative analysis is not the only context in which ALCA is used. For instance, if a company wants to use the results from an ALCA to report the embodied emissions from its procured corn ethanol (i.e. ‘scope 3, category 3’ under the GHG Protocol’s Corporate Value Chain (Scope 3) Standard (WBCSD and WRI 2011b)), it would be inappropriate to report the value of -1.33 (from substitution), as this does not represent an absolute value for the embodied emissions. Although the result of 2.18 (from functional unit expansion) is unlikely to be usable in this context, unless the reporting company happens to procure both ethanol and DDGS, using the value of 2.18 within a corporate GHG inventory would not be methodologically or conceptually inappropriate (in contrast to the result from substitution). In short, the numerical results from substitution and functional unit expansion, and their appropriate use cases, are not the same and the two are not methodologically equivalent. 4. Conclusions Provost-Savard and Majeau-Bettez’s paper is very useful for prompting a clearer articulation of why substitution is not appropriate within ALCA. Essentially, substitution is inconsistent with ALCA because it creates results that do not represent: 1. the impacts from the processes that are physically used in the life cycle of the studied product; or 2. shares of absolute impacts attributable to the product system. And 1. and 2. are precisely what ALCA is intended to represent. Brander and Wylie (2011) called for LCA standards and guidance documents to clearly state that substitution should not be used for ALCA, but 15 years later this recommendation has not been implemented, and LCA practitioners and scholars continue to use a technique that undermines the coherence of their reported results. This current paper calls again for the LCA community to recognise this problem and for existing standards to be updated. Declarations Author Contribution M.B. wrote the manuscript. Acknowledgement The author would like to acknowledge the very helpful feedback from Anders Bjørn, Arianne Provost-Savard and Guillaume Majeau-Bettez. References Brander, M. 2016. Conceptualising attributional LCA is necessary for resolving methodological issues such as the appropriate form of land use baseline. International Journal of Life Cycle Assessment 21(12). Brander, M. and C. Wylie. 2011. The use of substitution in attributional life cycle assessment. Greenhouse Gas Measurement and Management 1(3–4): 161–166. Accessed August 8, 2013. Ekvall, T. 2020. Attributional and Consequential Life Cycle Assessment. In Sustainability Assessment at the 21st Century , ed. by María José Bastante-Ceca, Jose Luis Fuentes-Bargues, Levente Hufnagel, Florin-Constantin Mihai, and Corneliu Iatu, 41–61. IntechOpen. European Commission. 2010. International Reference Life Cycle Data System (ILCD) Handbook . Publications Office. https://eplca.jrc.ec.europa.eu/uploads/ILCD-Handbook-General-guide-for-LCA-DETAILED-GUIDANCE-12March2010-ISBN-fin-v1.0-EN.pdf. Accessed January 8, 2026. Heijungs, R. and J.B. Guinée. 2007. Allocation and “what-if” scenarios in life cycle assessment of waste management systems. Waste Management 27(8): 997–1005. https://doi.org/10.1016/j.wasman.2007.02.013. Accessed January 8, 2026. International Organization for Standardization. 2006. ISO 14044 - Environmental Management - Life Cycle Assessment - Requirements and Guidelines . Geneva, Switzerland. Majeau-Bettez, G., T. Dandres, S. Pauliuk, R. Wood, E. Hertwich, R. Samson, and A.H. Strømman. 2018. Choice of allocations and constructs for attributional or consequential life cycle assessment and input-output analysis. Journal of Industrial Ecology 22(4): 656–670. Moretti, C., B. Corona, R. Edwards, M. Junginger, A. Moro, M. Rocco, and L. Shen. 2020. Reviewing ISO compliant multifunctionality practices in environmental life cycle modeling. Energies . MDPI AG, July 1. Provost-Savard, A. and G. Majeau-Bettez. 2024. Substitution modeling can coherently be used in attributional life cycle assessments. Journal of Industrial Ecology 28(3): 410–425. Tillman, A.-M. 2000. Significance of decision-making for LCA methodology. Environmental Impact Assessment Review 20(1): 113–123. Tillman, A.-M., T. Ekvall, H. Baumann, and T. Rydberg. 1994. Choice of system boundaries in life cycle assessment. Journal of Cleaner Production 2: 21–29. https://doi.org/10.1016/0959-6526(94)90021-3. Accessed January 8, 2026. UNEP and SETAC. 2011. Global Guidance Principles for Life Cycle Assessment Databases . Nairobi, Kenya. http://www.unep.org/pdf/Global-Guidance-Principles-for-LCA.pdf. WBCSD and WRI. 2011a. Product Life Cycle Accounting and Reporting Standard . Geneva, Switzerland and Washington, DC, USA. https://ghgprotocol.org/sites/default/files/standards/Product-Life-Cycle-Accounting-Reporting-Standard_041613.pdf. Accessed January 8, 2026. WBCSD and WRI. 2011b. Corporate Value Chain (Scope 3) Accounting and Reporting Standard . https://ghgprotocol.org/sites/default/files/standards/Corporate-Value-Chain-Accounting-Reporing-Standard_041613_2.pdf. Accessed January 8, 2026. Weidema, B. 2003. Market information in life cycle assessment . https://2-0-lca.com/publications/show/market-information-in-life-cycle-assessment/. Accessed January 8, 2026. Footnotes For ease of expression the text will generally refer to co-products rather than multifunctionality more generally, but the discussion applies to other forms of multifunctionality, e.g. recycling of waste materials, and not only co-production. One example of guidance where this fundamental feature is articulated is in the ILCD handbook, which states “It is the aim of LCA to reflect the existing physical reality of an existing supply chain (attributional modelling)” (European Commission 2010, 122), with ‘the existing supply chain’ clearly indicating the processes that physically supply the product that is studied. Another example is Ekvall’s explanation of the data required for ALCA, which states “When the supplier of a material or component is known, this supplier is linked to the product through contracts and through economic and physical flows resulting from contracts. Established good ALCA practice is then to use as specific data as possible” (Ekvall 2020, 45). The materials or components for which data are collected are those that are physically used in the life cycle. There is an error in the presentation of the results in Brander and Wylie (2011), and the following erratum should be noted: the units for the third column in Table 2 in that paper should be “tCO 2 e/1.03 tonnes of DDGS” rather than “tCO 2 e/t DDGS”, or alternatively the results in that column should be divided by 1.03. 1.03 (tDDGS/t ethanol) × 0.59 (t soy meal/t DDGS) × 5.78 (tCO 2 e/t soy meal) = 3.51 tCO 2 e/t ethanol. This statement of the functional unit is used for simplicity. Ideally the functional unit should be expressed in terms of the actual function provided, e.g. MJs of energy from the ethanol and grammes of protein or other nutritional value from the feed. Emissions from corn ethanol (-1.33 tCO 2 e) minus emissions from a functionally equivalent quantity of petrol (0.49 tCO 2 e) = -1.82 tCO 2 e; and emissions from corn ethanol and DDGS (2.18 tCO 2 e) minus emissions from a functionally equivalent quantity of petrol and soy meal (0.49 + 3.51) = -1.82 tCO 2 e. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8947729","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Method Article","associatedPublications":[],"authors":[{"id":603649360,"identity":"eb6e0a5d-779d-4513-8c7c-9f1cef43bb1b","order_by":0,"name":"Matthew Brander","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/klEQVRIiWNgGAWjYJACZhBhACJ4GBjkGBgSGOACODQwNiNrMSZdS2IDIS267eePPy6oOMxgLn342YM3FffS+9kTGD/8YDhsjEuL2ZlkxuYZZw4zWPalmRvOOVOcO7PnAbNkD8NhM5xaDgC18LbdZjA4w2AmzduWkLvhRgKDNAPDYRucWs4/Bmr5B9LC/k2a919Cuv2NBObfeLXcANnSANLCA7SlISHBQCKBDWQLbofdeGw4m+fYfx7LHp4yyTnHEgxnnHnYZtljkI7b++cTH3zmqUmTM+dh3ybxpiZBnr89+fCNHxXWhg249EABDxKbsQFvRI6CUTAKRsEoIAwAW4hUD3Ay7cYAAAAASUVORK5CYII=","orcid":"","institution":"University of Edinburgh","correspondingAuthor":true,"prefix":"","firstName":"Matthew","middleName":"","lastName":"Brander","suffix":""}],"badges":[],"createdAt":"2026-02-23 13:39:49","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8947729/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8947729/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104522164,"identity":"a97f2692-b139-46e7-aae0-db75df24fcf0","added_by":"auto","created_at":"2026-03-12 20:19:40","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":15598,"visible":true,"origin":"","legend":"\u003cp\u003eVisual representation/conceptualisation of ALCA (adapted from Weidema (2003))\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8947729/v1/652c17733551e63c33e973ac.png"},{"id":109209268,"identity":"976e60e8-808c-45e8-bca1-2ebb16a92e32","added_by":"auto","created_at":"2026-05-13 15:28:01","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":195203,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8947729/v1/a0d53724-abd5-475e-bee8-1ede4fae89c3.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Substitution is not consistent with attributional life cycle assessment – reply to Provost-Savard and Majeau-Bettez (2024)","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eSubstitution is a technique for addressing instances of multifunctionality, e.g. multiple co-products from a single process within a life cycle.\u003csup\u003e1\u003c/sup\u003e In order to identify the flows/impacts associated with only one of the co-products, the life cycle flows/impacts up to and including the multifunctional process either need to be allocated between the different co-products, or the multifunctionality problem needs to be avoided in some other way. Substitution is intended to avoid allocation by identifying the products that are substituted by the co-products of the main product that is studied, then quantifying the environmental burdens associated with those products, and crediting the avoidance of those burdens to the product that is studied.\u003c/p\u003e \u003cp\u003eCurrently there is a lack of consensus on whether substitution is an appropriate technique to use within attributional life cycle assessment (ALCA). A large number of ALCA studies have used substitution (Moretti et al. 2020), and a number of standards and guidance documents either allow its use (e.g. WBCSD/WRI (2011a), European Commission (2010)) or are somewhat ambiguous on this point (e.g. ISO 14044 (International Organization for Standardization 2006)). However, a number of previous academic articles have argued that substitution is not appropriate for ALCA (Brander and Wylie 2011; Heijungs and Guin\u0026eacute;e 2007; Majeau-Bettez et al. 2018). More recently, an article by Provost-Savard and Majeau-Bettez (2024) in the \u003cem\u003eJournal of Industrial Ecology\u003c/em\u003e has argued in the opposite direction, and contends that substitution can be used coherently in ALCA.\u003c/p\u003e \u003cp\u003eThe present paper is written largely as a reply to Provost-Savard and Majeau-Bettez (2024), with the principal aim of explaining why substitution is not consistent with ALCA. In order to streamline the analysis the paper does not engage in a detailed exegesis or history of the existing literature, but instead focuses directly on the substance of the arguments and issues within the debate.\u003c/p\u003e"},{"header":"2. Conceptualising ALCA","content":"\u003cp\u003eIn order to resolve any methodological dispute it is essential to have a precise conceptualisation of what a method, e.g. ALCA, is intended to represent in order to determine whether a technique, e.g. substitution, is consistent with the method (Brander 2016). To this end, the following provides a statement of what ALCA is intended to represent:\u003c/p\u003e \u003cp\u003e1. The material and energy flows (and associated impacts) to/from the processes that are \u003cem\u003ephysically used in\u003c/em\u003e the life cycle of the product that is studied.\u003c/p\u003e \u003cp\u003e2. The \u003cem\u003eshare of\u003c/em\u003e total absolute anthropogenic impacts attributable to the product studied.\u003c/p\u003e \u003cp\u003ePoint 1 is consistent with the UNEP/SETAC definition of ALCA, which states that it is a \u0026ldquo;modelling approach in which inputs and outputs are attributed to the functional unit of a product system by linking and/or partitioning the unit processes of the system according to a normative rule\u0026rdquo; (UNEP and SETAC 2011, 132). Point 1 above provides additional precision by clarifying that the \u0026ldquo;unit processes of the system\u0026rdquo; are those that are \u003cem\u003ephysically used in the life cycle of the product that is studied\u003c/em\u003e. This fundamental feature of ALCA is often left unspecified within definitions of ALCA, possibly because it is such an intuitive or basic feature that is assumed not to require stating.\u003csup\u003e2\u003c/sup\u003e Put an alternative way, it is very difficult to conceive of what ALCA is intended to represent if it \u003cem\u003eisn\u0026rsquo;t\u003c/em\u003e intended to represent the processes physically used in the life cycle of the studied product. Provost-Savard and Majeau-Bettez\u0026rsquo;s position on this fundamental feature of ALCA is discussed later.\u003c/p\u003e \u003cp\u003ePoint 2 is often explicitly stated within definitions of ALCA, e.g. Ekvall states that ALCA \u0026ldquo;estimates what share of the global environmental burdens belongs to a product\u0026rdquo; (Ekvall 2020, 41). This feature is often represented visually by a segment of a pie chart (see Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), indicating a \u003cem\u003eshare of\u003c/em\u003e total absolute impacts. It is this feature that gives rise to the characteristic of \u0026lsquo;additivity\u0026rsquo;, which is the idea that (in principle) the sum of ALCAs for all final consumption should approximate to total absolute impacts (Tillman 2000). It is also worth noting how Point 1 relates to Point 2: it is the burdens from the processes that are \u003cem\u003ephysically used in\u003c/em\u003e the life cycle of the product that are the share of global environmental burdens that \u003cem\u003ebelong to a product\u003c/em\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe above statement on what ALCA is intended to represent will be used below to analyse why substitution is not consistent with ALCA, i.e. we can ask \u0026ldquo;Do the results from using substitution represent: 1. the processes physically used in the life cycle of the product that is studied; and 2. a share of absolute impacts?\u0026rdquo;.\u003c/p\u003e"},{"header":"3. Analysis of main arguments in Provost-Savard and Majeau-Bettez (2024)","content":"\u003cp\u003eProvost-Savard and Majeau-Bettez (2024) focus on rebutting two arguments against the use of substitution in ALCA from the academic literature, but also discuss a third corollary issue, and a further point related to \u0026lsquo;functional unit expansion\u0026rsquo;. Each of these arguments/issues are discussed in turn, with the aim of explaining what is right and wrong in Provost-Savard and Majeau-Bettez\u0026rsquo;s analysis, and to clarify why substitution is inconsistent with ALCA.\u003c/p\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Additivity\u003c/h2\u003e \u003cp\u003eProvost-Savard and Majeau-Bettez (2024) highlight that one of the arguments within the literature for rejecting substitution is that it is inconsistent with the principle of \u0026lsquo;additivity\u0026rsquo;. To resolve this issue Provost-Savard and Majeau-Bettez (2024) propose assigning the avoided burden (which is credited to the main product studied) to the co-products of the main product. This solution is illustrated below with a worked example for corn ethanol (the main or \u0026lsquo;determining\u0026rsquo; product) and dried distillers\u0026rsquo; grains with solubles (DDGS; the co-product). The data in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e are from Brander and Wylie [2011].\u003csup\u003e3\u003c/sup\u003e Although the example focuses on GHG emissions the conclusions apply equally to any impact category.\u003c/p\u003e \u003cp\u003eIn this example the corn ethanol is credited with avoiding dedicated soy meal production (as DDGS replaces soy meal animal feed) and its associated GHG emissions (3.51 tCO\u003csub\u003e2\u003c/sub\u003ee/t ethanol produced)\u003csup\u003e4\u003c/sup\u003e. These avoided emissions are subtracted from the upstream life cycle emissions for the corn ethanol and DDGS (2.18 tCO\u003csub\u003e2\u003c/sub\u003ee/t ethanol) to give a result of -1.33 tCO\u003csub\u003e2\u003c/sub\u003ee/t ethanol. In order to achieve additivity Provost-Savard and Majeau-Bettez propose that the avoided burden value of 3.51 tCO\u003csub\u003e2\u003c/sub\u003ee should be assigned to the DDGS, so that the sum of the assigned burdens (-1.33 plus 3.51) equals 2.18 tCO\u003csub\u003e2\u003c/sub\u003ee, thereby achieving additivity to total impacts.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eData and results for corn ethanol example\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cp\u003eData\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDescription\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eValue\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eUnits\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEmissions from the production of wheat ethanol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003etCO\u003csub\u003e2\u003c/sub\u003ee/t ethanol produced\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eQuantity of DDGS produced per tonne of ethanol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003etDDGS/t ethanol\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEmissions from the production of soy meal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003etCO\u003csub\u003e2\u003c/sub\u003ee/t soy meal\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSubstitution ratio between DDGS and soy meal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003et soy meal/t DDGS\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eResults\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDescription\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eValue\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eUnits\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAvoided emissions credited to corn ethanol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-1.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003etCO\u003csub\u003e2\u003c/sub\u003ee/t ethanol\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEmissions assigned to DDGS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003etCO\u003csub\u003e2\u003c/sub\u003ee/1.03 t DDGS\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSum of assigned emissions\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e2.18\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003etCO\u003csub\u003e2\u003c/sub\u003ee\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn one sense this proposal does \u0026lsquo;resolve\u0026rsquo; the \u003cem\u003eadditivity\u003c/em\u003e problem (as the sum of assigned emissions does equal total emissions), but it nevertheless creates results that are inconsistent with ALCA. The problem with Provost-Savard and Majeau-Bettez\u0026rsquo;s solution, and the use of substitution within ALCA more generally, can be analysed by returning to the defining features of ALCA, i.e. we can ask \u0026ldquo;Does the result of 3.51 tCO\u003csub\u003e2\u003c/sub\u003ee/1.03 t DDGS accurately represent: 1. the processes physically used in the life cycle of the DDGS?; and 2. a share of absolute impacts?\u0026rdquo;. The answer is \u0026ldquo;no\u0026rdquo; to both questions.\u003c/p\u003e \u003cp\u003eWith regard to Point 1 (i.e. processes physically used in the life cycle), the number \u0026lsquo;3.51\u0026rsquo; represents the emissions from the processes physically used in the life cycle of the \u003cem\u003esoy meal\u003c/em\u003e, and does not represent in \u003cem\u003eany way\u003c/em\u003e the burdens associated with the processes physically used in the life cycle of the DDGS. Provost-Savard and Majeau-Bettez (2024) accept that this is an entailment from their proposed solution, but do not appear to recognise that this is a profound departure from what ALCA is generally intended to represent. It is true that, through a radical change to existing convention, we could use an alternative normative rule for assigning responsibility for impacts, but that would be a different method to the one currently denoted by the term \u0026lsquo;ALCA\u0026rsquo;.\u003c/p\u003e \u003cp\u003eWith regard to Point 2 (i.e. share of absolute impacts), the result of \u0026lsquo;3.51\u0026rsquo; cannot represent a \u003cem\u003eshare\u003c/em\u003e of absolute impacts as it is greater than the total absolute impacts of the system (which are 2.18 tCO\u003csub\u003e2\u003c/sub\u003ee). Similarly, the value assigned to the main product of corn ethanol (-1.33) also cannot represent a \u003cem\u003eshare\u003c/em\u003e of absolute impacts as it is a negative number. Conceptually it is impossible to have a negative \u0026lsquo;share\u0026rsquo; of anything, e.g. when dividing a pie it isn\u0026rsquo;t possible to give one person a \u0026lsquo;negative slice\u0026rsquo; of the pie. A \u0026lsquo;share\u0026rsquo; cannot be more than 100% or less than 0% of total impacts. Notably, Provost-Savard and Majeau-Bettez clearly state that ALCA should represent \u0026lsquo;shares\u0026rsquo; of total impacts, but do not recognise that the proposed solution for additivity, and the technique of substitution more generally, creates results which do not represent shares of absolute impacts.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e3.2. State-descriptive impacts or changes in impacts\u003c/h2\u003e \u003cp\u003eA second area of focus in Provost-Savard and Majeau-Bettez(2024) is countering the argument that substitution is not appropriate because ALCA describes impacts within a given state, whereas substitution is concerned with \u003cem\u003echange\u003c/em\u003e relative to a reference state. Provost-Savard and Majeau-Bettez argue that there is no inherent contradiction as any absolute value for impacts in a given state can be expressed as the difference or change from some alternative reference value. For example, in a world with absolute emissions of 1 tCO\u003csub\u003e2\u003c/sub\u003ee, this absolute value could be expressed in relative terms as a change of \u0026lsquo;-2 tCO\u003csub\u003e2\u003c/sub\u003ee, relative to a reference state in which absolute emissions are 3 tCO\u003csub\u003e2\u003c/sub\u003ee\u0026rsquo;. However, Provost-Savard and Majeau-Bettez\u0026rsquo;s explanation for how this relates to or justifies the use of substitution in ALCA is relatively brief, and different aspects or interpretations of the argument are discernible.\u003c/p\u003e \u003cp\u003eOne possible interpretation is that the results from substitution should be viewed as relative expressions of the absolute impacts in a static state (and so are consistent with the idea that ALCA is describing a static state and not a change). However, a problem arises if we want to use the results from substitution within subsequent ALCAs for products that use the co-products as material/energy inputs. If the results from substitution are relative expressions of absolute values, and the ALCAs in which the substitution results are used are in absolute values, there will be a strange mix of relative and absolute values within the analysis. It is hard to know what such results would represent.\u003c/p\u003e \u003cp\u003eIt could be argued that the relative expressions from substitution can be translated into absolute impacts (i.e. by adding the \u0026lsquo;change\u0026rsquo; and \u0026lsquo;reference\u0026rsquo; values together, e.g. -2 tCO\u003csub\u003e2\u003c/sub\u003ee\u0026thinsp;+\u0026thinsp;3 tCO\u003csub\u003e2\u003c/sub\u003ee\u0026thinsp;=\u0026thinsp;1 tCO\u003csub\u003e2\u003c/sub\u003ee). But with substitution and the proposed solution for additivity, the \u0026lsquo;change\u0026rsquo; number is assigned to the main product (e.g. -1.33 tCO\u003csub\u003e2\u003c/sub\u003ee) and the \u0026lsquo;reference\u0026rsquo; number is assigned to the co-product (e.g. 3.51 tCO\u003csub\u003e2\u003c/sub\u003ee). This means that when the two are summed the result only shows the \u003cem\u003etotal\u003c/em\u003e impacts in the state that is described (2.18 tCO\u003csub\u003e2\u003c/sub\u003ee), and does not provide separate absolute values for each co-product, and we are back to needing some form of allocation between the co-products/co-functions.\u003c/p\u003e \u003cp\u003eA different aspect within Provost-Savard and Majeau-Bettez\u0026rsquo;s argument is that the change value can be treated as a property of the state that is being described (i.e. it is a property of the state that it displaces alternative production, and the associated impacts, that otherwise would have occurred). And this property can be used as the basis for allocation \u0026ldquo;like any other property (e.g. mass or economic value)\u0026rdquo; (Provost-Savard and Majeau-Bettez 2024, 421). However, as illustrated in Section 3.1, substitution (and the proposed solution to additivity) is not the same as allocation as it is not apportioning shares of the absolute flows/impacts associated with the multifunctional process, and can create results for individual co-products that are greater than total impacts or less than zero impacts. It might be suggested that results that are greater than 100% or less than 0% of total impacts should be interpreted in some way as relative expressions rather than absolute values, but this takes us back to the problems with relative expressions, discussed above.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e3.3. Marginal data\u003c/h2\u003e \u003cp\u003eA third issue discussed in Provost-Savard and Majeau-Bettez (2024) is the use of marginal data for the product that is substituted by the co-products of the product that is studied. They argue that \u0026ldquo;an attributional state-descriptive multifunctional system can coherently be represented as the result of a transition from a reference technosphere\u0026rdquo; and that marginal data best represents the \u0026ldquo;market mechanism happening during this transition\u0026rdquo; (Provost-Savard and Majeau-Bettez 2024, 422).\u003c/p\u003e \u003cp\u003eA first point to make is that no form of substitution is consistent with ALCA regardless of whether marginal or average data are used. For example, using marginal data for the emissions from soy meal rather than average data would not alter the inconsistency of the results with what ALCA is intended to represent (as discussed above). Secondly, the rationale given for using marginal data in Provost-Savard and Majeau-Bettez(2024) is effectively a consequential one, i.e. that marginal data represents the actual change that has occurred. But this is really just pursuing a consequential question about the decision to use the multifunctional process i.e. \u0026ldquo;What is the change caused by decision X?\u0026rdquo;, rather than the attributional question \u0026ldquo;What are the emissions from the processes physically used in the life cycle of the product studied?\u0026rdquo;.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e3.4. Non-equivalence of substitution and system expansion\u003c/h2\u003e \u003cp\u003eA final issue to address is Provost-Savard and Majeau-Bettez\u0026rsquo;s point that substitution and an alternative technique called \u0026lsquo;functional unit expansion\u0026rsquo; (also called \u0026lsquo;system expansion\u0026rsquo;) appear to yield the same overall results, and that because functional unit expansion is generally considered to be consistent with ALCA it must be the case that substitution is consistent too. As Provost-Savard and Majeau-Bettez concisely put it \u0026ldquo;Both cannot simultaneously be true: functional unit expansion and substitution cannot be methodologically equivalent and differ in their fundamental compatibility with ALCA\u0026rdquo; (2024, 413). The following analysis uses the corn ethanol example to briefly explain what is meant by \u0026lsquo;functional unit expansion\u0026rsquo;, and to show, in answer to Provost-Savard and Majeau-Bettez, that functional unit expansion is not methodologically equivalent to substitution.\u003c/p\u003e \u003cp\u003eThe technique of functional unit expansion simply expands the functional unit that is studied to include the functions provided by the co-products so that the problem of needing to allocate material/energy flows and impacts between different co-products/functions is avoided. In the case of the corn ethanol example the functional unit would become \u0026lsquo;1 tonne of corn ethanol and 1.03 tonnes of DDGS\u0026rsquo;.\u003csup\u003e5\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eIt is a long-established truth that functional unit expansion and substitution yield the same overall outcomes \u003cem\u003ein the context of a comparative analysis\u003c/em\u003e (Tillman et al. 1994). For a comparative analysis of two product systems it is necessary to ensure they provide the same functions in order to compare like-for-like. For example, when comparing corn ethanol to conventional petrol, the function of \u0026lsquo;animal feed\u0026rsquo; either needs to be removed from the ethanol system (e.g. using substitution), or if functional unit expansion has been used for the ethanol and DDGS system then the \u0026lsquo;animal feed\u0026rsquo; function needs to be added to the petrol system. This is illustrated in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, which shows that the results from a comparative analysis are the same, whether using substitution or functional unit expansion.\u003csup\u003e6\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEquivalence of substitution and functional unit expansion in the context of a comparative analysis\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003eSubstitution Technique\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eEthanol System\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003ePetrol System\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eComparative result (ethanol system minus petrol system)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFunctional unit:\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e1 tonne ethanol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.6 tonne petrol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEmissions (tCO\u003csub\u003e2\u003c/sub\u003ee/functional unit):\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e-1.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e0.49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e-1.82\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFunctional Unit Expansion Technique\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eEthanol System\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003ePetrol System\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eComparative result (ethanol system minus petrol system)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFunctional unit:\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 tonne ethanol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.03 tonnes DDGS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.6 tonne petrol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.6 tonne soy meal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEmissions (tCO\u003csub\u003e2\u003c/sub\u003ee/functional unit):\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e2.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e-1.82\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe crux of the apparent methodological equivalence between substitution and functional unit expansion is that they yield equivalent results, but only within the \u003cem\u003ebroader context of a comparative analysis\u003c/em\u003e, in which additional functions are added to the comparator system to ensure functional equivalence. However, comparative analysis is not the only context in which ALCA is used. For instance, if a company wants to use the results from an ALCA to report the embodied emissions from its procured corn ethanol (i.e. \u0026lsquo;scope 3, category 3\u0026rsquo; under the GHG Protocol\u0026rsquo;s Corporate Value Chain (Scope 3) Standard (WBCSD and WRI 2011b)), it would be inappropriate to report the value of -1.33 (from substitution), as this does not represent an absolute value for the embodied emissions. Although the result of 2.18 (from functional unit expansion) is unlikely to be usable in this context, unless the reporting company happens to procure both ethanol and DDGS, using the value of 2.18 within a corporate GHG inventory would not be methodologically or conceptually inappropriate (in contrast to the result from substitution).\u003c/p\u003e \u003cp\u003eIn short, the numerical results from substitution and functional unit expansion, and their appropriate use cases, are not the same and the two are not methodologically equivalent.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eProvost-Savard and Majeau-Bettez\u0026rsquo;s paper is very useful for prompting a clearer articulation of why substitution is not appropriate within ALCA. Essentially, substitution is inconsistent with ALCA because it creates results that do not represent: 1. the impacts from the processes \u003cem\u003ethat are physically used in the life cycle\u003c/em\u003e of the studied product; or 2. \u003cem\u003eshares\u003c/em\u003e of absolute impacts attributable to the product system. And 1. and 2. are precisely what ALCA is intended to represent.\u003c/p\u003e \u003cp\u003eBrander and Wylie (2011) called for LCA standards and guidance documents to clearly state that substitution should not be used for ALCA, but 15 years later this recommendation has not been implemented, and LCA practitioners and scholars continue to use a technique that undermines the coherence of their reported results. This current paper calls again for the LCA community to recognise this problem and for existing standards to be updated.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eM.B. wrote the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThe author would like to acknowledge the very helpful feedback from Anders Bj\u0026oslash;rn, Arianne Provost-Savard and Guillaume Majeau-Bettez.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBrander, M. 2016. Conceptualising attributional LCA is necessary for resolving methodological issues such as the appropriate form of land use baseline. \u003cem\u003eInternational Journal of Life Cycle Assessment\u003c/em\u003e 21(12).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrander, M. and C. Wylie. 2011. The use of substitution in attributional life cycle assessment. \u003cem\u003eGreenhouse Gas Measurement and Management\u003c/em\u003e 1(3\u0026ndash;4): 161\u0026ndash;166. Accessed August 8, 2013.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEkvall, T. 2020. Attributional and Consequential Life Cycle Assessment. In \u003cem\u003eSustainability Assessment at the 21st Century\u003c/em\u003e, ed. by Mar\u0026iacute;a Jos\u0026eacute; Bastante-Ceca, Jose Luis Fuentes-Bargues, Levente Hufnagel, Florin-Constantin Mihai, and Corneliu Iatu, 41\u0026ndash;61. IntechOpen.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEuropean Commission. 2010. \u003cem\u003eInternational Reference Life Cycle Data System (ILCD) Handbook\u003c/em\u003e. Publications Office. https://eplca.jrc.ec.europa.eu/uploads/ILCD-Handbook-General-guide-for-LCA-DETAILED-GUIDANCE-12March2010-ISBN-fin-v1.0-EN.pdf. Accessed January 8, 2026.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHeijungs, R. and J.B. Guin\u0026eacute;e. 2007. Allocation and \u0026ldquo;what-if\u0026rdquo; scenarios in life cycle assessment of waste management systems. \u003cem\u003eWaste Management\u003c/em\u003e 27(8): 997\u0026ndash;1005. https://doi.org/10.1016/j.wasman.2007.02.013. Accessed January 8, 2026.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eInternational Organization for Standardization. 2006. \u003cem\u003eISO 14044 - Environmental Management - Life Cycle Assessment - Requirements and Guidelines\u003c/em\u003e. Geneva, Switzerland.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMajeau-Bettez, G., T. Dandres, S. Pauliuk, R. Wood, E. Hertwich, R. Samson, and A.H. Str\u0026oslash;mman. 2018. Choice of allocations and constructs for attributional or consequential life cycle assessment and input-output analysis. \u003cem\u003eJournal of Industrial Ecology\u003c/em\u003e 22(4): 656\u0026ndash;670.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoretti, C., B. Corona, R. Edwards, M. Junginger, A. Moro, M. Rocco, and L. Shen. 2020. Reviewing ISO compliant multifunctionality practices in environmental life cycle modeling. \u003cem\u003eEnergies\u003c/em\u003e. MDPI AG, July 1.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eProvost-Savard, A. and G. Majeau-Bettez. 2024. Substitution modeling can coherently be used in attributional life cycle assessments. \u003cem\u003eJournal of Industrial Ecology\u003c/em\u003e 28(3): 410\u0026ndash;425.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTillman, A.-M. 2000. Significance of decision-making for LCA methodology. \u003cem\u003eEnvironmental Impact Assessment Review\u003c/em\u003e 20(1): 113\u0026ndash;123.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTillman, A.-M., T. Ekvall, H. Baumann, and T. Rydberg. 1994. Choice of system boundaries in life cycle assessment. \u003cem\u003eJournal of Cleaner Production\u003c/em\u003e 2: 21\u0026ndash;29. https://doi.org/10.1016/0959-6526(94)90021-3. Accessed January 8, 2026.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUNEP and SETAC. 2011. \u003cem\u003eGlobal Guidance Principles for Life Cycle Assessment Databases\u003c/em\u003e. Nairobi, Kenya. http://www.unep.org/pdf/Global-Guidance-Principles-for-LCA.pdf.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWBCSD and WRI. 2011a. \u003cem\u003eProduct Life Cycle Accounting and Reporting Standard\u003c/em\u003e. Geneva, Switzerland and Washington, DC, USA. https://ghgprotocol.org/sites/default/files/standards/Product-Life-Cycle-Accounting-Reporting-Standard_041613.pdf. Accessed January 8, 2026.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWBCSD and WRI. 2011b. \u003cem\u003eCorporate Value Chain (Scope 3) Accounting and Reporting Standard\u003c/em\u003e. https://ghgprotocol.org/sites/default/files/standards/Corporate-Value-Chain-Accounting-Reporing-Standard_041613_2.pdf. Accessed January 8, 2026.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWeidema, B. 2003. \u003cem\u003eMarket information in life cycle assessment\u003c/em\u003e. https://2-0-lca.com/publications/show/market-information-in-life-cycle-assessment/. Accessed January 8, 2026.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Footnotes","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003e For ease of expression the text will generally refer to co-products rather than multifunctionality more generally, but the discussion applies to other forms of multifunctionality, e.g. recycling of waste materials, and not only co-production.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003e One example of guidance where this fundamental feature is articulated is in the ILCD handbook, which states \u0026ldquo;It is the aim of LCA to reflect the existing physical reality of an existing supply chain (attributional modelling)\u0026rdquo; (European Commission 2010, 122), with \u0026lsquo;the existing supply chain\u0026rsquo; clearly indicating the processes that physically supply the product that is studied. Another example is Ekvall\u0026rsquo;s explanation of the data required for ALCA, which states \u0026ldquo;When the supplier of a material or component is known, this supplier is linked to the product through contracts and through economic and physical flows resulting from contracts. Established good ALCA practice is then to use as specific data as possible\u0026rdquo; (Ekvall 2020, 45). The materials or components for which data are collected are those that are physically used in the life cycle.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003e There is an error in the presentation of the results in Brander and Wylie (2011), and the following erratum should be noted: the units for the third column in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e in that paper should be \u0026ldquo;tCO\u003csub\u003e2\u003c/sub\u003ee/1.03 tonnes of DDGS\u0026rdquo; rather than \u0026ldquo;tCO\u003csub\u003e2\u003c/sub\u003ee/t DDGS\u0026rdquo;, or alternatively the results in that column should be divided by 1.03.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003e 1.03 (tDDGS/t ethanol) \u0026times; 0.59 (t soy meal/t DDGS) \u0026times; 5.78 (tCO\u003csub\u003e2\u003c/sub\u003ee/t soy meal)\u0026thinsp;=\u0026thinsp;3.51 tCO\u003csub\u003e2\u003c/sub\u003ee/t ethanol.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003e This statement of the functional unit is used for simplicity. Ideally the functional unit should be expressed in terms of the actual function provided, e.g. MJs of energy from the ethanol and grammes of protein or other nutritional value from the feed.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003e Emissions from corn ethanol (-1.33 tCO\u003csub\u003e2\u003c/sub\u003ee) minus emissions from a functionally equivalent quantity of petrol (0.49 tCO\u003csub\u003e2\u003c/sub\u003ee) = -1.82 tCO\u003csub\u003e2\u003c/sub\u003ee; and emissions from corn ethanol and DDGS (2.18 tCO\u003csub\u003e2\u003c/sub\u003ee) minus emissions from a functionally equivalent quantity of petrol and soy meal (0.49\u0026thinsp;+\u0026thinsp;3.51) = -1.82 tCO\u003csub\u003e2\u003c/sub\u003ee.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8947729/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8947729/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThere is a lack of clear consensus on the use of \u0026lsquo;substitution\u0026rsquo; within attributional life cycle assessment (ALCA). A number of academic articles have previously argued that substitution is not consistent with ALCA, but a more recent article by Provost-Savard and Majeau-Bettez in the \u003cem\u003eJournal of Industrial Ecology\u003c/em\u003e argues that it can be coherently used. In reply, this article contends that in order to resolve methodological disputes it is necessary to have a clear conceptualisation of what the method in question is intended to represent. To this end, the article clarifies that ALCA represents the processes physically used in the life cycle of the product that is studied, and also represents shares of total absolute anthropogenic impacts. A worked example for corn ethanol is used to show that substitution is fundamentally inconsistent with these features of ALCA, and to analyse what is right and wrong in Provost-Savard and Majeau-Bettez\u0026rsquo;s article. It is hoped that clarifying the reasons for why substitution is not appropriate in ALCA will help to build consensus on this issue. It is strongly recommended that standards and guidance for ALCA should clearly state that substitution should not be used.\u003c/p\u003e","manuscriptTitle":"Substitution is not consistent with attributional life cycle assessment – reply to Provost-Savard and Majeau-Bettez (2024)","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-12 20:19:35","doi":"10.21203/rs.3.rs-8947729/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"66966637-5613-4cbe-9115-01d8a1bf99a2","owner":[],"postedDate":"March 12th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-05-13T15:20:58+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-12 20:19:35","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8947729","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8947729","identity":"rs-8947729","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}