{"title":"Hubblo","subtitle":"Website of Hubblo, a company specialized in assessing and reducing ICT environmental impacts (LCA, Carbon footprint, ...).","link":[{"@attributes":{"href":"https:\/\/hubblo.org\/atom.xml","rel":"self","type":"application\/atom+xml"}},{"@attributes":{"href":"https:\/\/hubblo.org"}}],"generator":"Zola","updated":"2024-04-15T00:00:00+00:00","id":"https:\/\/hubblo.org\/atom.xml","entry":[{"title":"Counting environmental impacts using attributional and consequential approaches","published":"2024-04-15T00:00:00+00:00","updated":"2024-04-15T00:00:00+00:00","author":{"name":"Unknown"},"link":{"@attributes":{"rel":"alternate","href":"https:\/\/hubblo.org\/blog\/attributional-vs-consequential\/","type":"text\/html"}},"id":"https:\/\/hubblo.org\/blog\/attributional-vs-consequential\/","content":"

Counting environmental impacts using attributional and consequential approaches<\/h1>\n
\n \"Cover\n<\/figure>\n

Author : David Ekchajzer<\/em><\/p>\n

Reviewers : Jacques Combaz and Hubblo's team<\/em><\/p>\n

Acknowledgments : Adeline Agut, Bruno Thomas<\/em><\/p>\n

Introduction<\/h2>\n

Environmental impacts are physical phenomena taking place within the biosphere. They can be localized to particular areas (land use, air pollution, etc.) or global (contribution to global warming, depletion of abiotic resources, etc.). These environmental impacts can be assessed using physical measuring instruments (with a carbon dioxide sensor, for example). This is the case for soil, air or water pollution, when directly measured on ecosystems. These impact measurements enable us to understand past and present environmental and physical constraints.<\/p>\n

However, by characterizing only phenomena that take place inside the biosphere, they make it difficult to manage consumption, production or public policies, which are socio-economic phenomena that take place within the technosphere.<\/p>\n

\n

The biosphere corresponds to all terrestrial ecosystems present on the lithosphere (earth), atmosphere (air) and hydrosphere (sea). The technosphere corresponds to the part of the biosphere modified by human activities.<\/p>\n<\/blockquote>\n

This is where environmental accounting comes in. It makes it possible to match socio-economic realities (a product, a service, a unit of currency, an action, a policy, etc.) with a physical materiality characterized by environmental impacts.<\/p>\n

This materiality is expressed in physical units: kgCO2eq. for contribution to global warming, m3 for water depletion or kg for land transformation (see PEF1<\/a><\/sup>). This suggests that the values produced by environmental accounting are of the same nature as those produced by physical measuring instruments such as a CO2 sensor, a graduated container to evaluate m3 or a weighing scale to evaluate kg.<\/p>\n

However, when used in the context of environmental accounting, these units are intended to describe not only physical realities, but also socio-economic ones. Indeed, associating environmental impacts with socio-economic realities is not a neutral approach, but rather one of accounting that follows established technical rules that are part of modeling paradigms (logical and political principles). It is these principles that define the way in which human activities in the technosphere and environmental impacts in the biosphere are linked.<\/p>\n

\"Drawing<\/p>\n

\nEnvironmental accounting associates an activity in the technosphere with impacts that take place in the biosphere (resources consumed or pollution in the air, water and soil throughout the life cycle).\n<\/div>\n\n

Several paradigms exist to establish this link. Each paradigm has its own usefulness, and is based on its own methodological principles. In this article, we present three major modeling paradigms: attributional, short-term consequential and long-term consequential.<\/p>\n

This article was written as part of the life cycle assessment of Iroco<\/a>, an eco-designed e-mail service. The environmental impact of e-mail is a recurring topic of conversation in the field of digital responsibility, to the point where it sometimes irritates environmental assessment practitioners. While its impact is probably overestimated by the public, its fundamental nature in our digital uses makes it an excellent case study for understanding how to change them. This is the approach taken by Iroco. After proposing an eco-designed mail service based on a number of green software good practices, they decided to go beyond efficiency and propose functionalities that would modify usage, encouraging users to adopt more sustainable practices. To understand the relevance of the imagined levers, they decided to carry out an environmental impacts study. The complete study can be downloaded here (in french<\/a>). Over the coming weeks, you'll find a series of articles on Iroco's blog<\/a> detailing the implementation and results of the study. What's special about this study is that it uses the three approaches mentioned above to provide the most comprehensive answer to Iroco's questions. This article uses this study to illustrate the three paradigms mentioned above.<\/p>\n

In Life Cycle Assessment (an environmental accounting method), the activities evaluated are described by a functional unit (FU). For the sake of clarity, in this article we will refer to the activity evaluated in the context of environmental accounting as a FU.<\/p>\n

\n

The functional unit is the unit of measurement used to assess the service provided by the product or service in question. In the same way that a consumer compares the price of two fruits on a per kilo basis, to compare the environmental impacts of two products, the impacts are reduced to a common unit of measurement.<\/p>\n<\/blockquote>\n

Attributional paradigm<\/h2>\n

Attributional analysis aims to answer the question: "What share of the total impacts of my system can be attributed<\/span><\/strong> to the Functional Unit?". The aim here is to characterize the impacts of the FU by attributing to it a share of the overall impacts of a system considered in a status quo (i.e. frozen) situation. In an attributional method, the sum of the impacts of the functions provided by a system must be equal to the system's impact. For example, to assess the impact of e-mails, we associate them with a share of the impact of the mail service, so that the sum of the impacts of the e-mails is equal to the impact of the mail service.<\/p>\n

\nA_LCA(SYSTEM) = SUM(A_LCA(FU))\n<\/p>\n

The attributional paradigm is the one used in the vast majority of environmental assessments, particularly in studies relating to digital services. It is also the basis for GHG Protocol, which aims to allocate greenhouse gas emissions to entities in a value chain, or Attributional LCA (A-LCA), which aims to allocate environmental impacts to a product or service according to several impact categories. It was used in a study published by ADEME in 2016, which concluded that the lifecycle impact of a 1 MB e-mail was 19 gCO2eq<\/strong>.2<\/a><\/sup><\/p>\n

\"Perimeter<\/p>\n

\nEkvall 2019 [3]<\/a>, based on Weidema 2003 [4]<\/a>.\n

The pie chart represents all the impacts of a system. An attribution method associates a share of these impacts with the functional unit under consideration. In a status quo situation, the circle is not modified by the FU.<\/p>\n<\/div>\n

3<\/a><\/sup>\n4<\/a><\/sup><\/p>\n\n

To determine the share of system impacts to be associated with the FU, we follow the physical links (energy and material) required to implement the FU until we arrive at environmental impacts. In other words, we include the impact of a resource if it is "physically" mobilized as part of the life cycle of the product or service being evaluated. In the case of e-mail, for example, this means starting with the terminals (TIER 1), network (TIER 2) and datacenters (TIER 3) mobilized for sending and e-mail. Then, working backwards and forwards, we include the physical links implied by each of these resources to arrive at the environmental impacts. In practice, to avoid describing all the physical flows exhaustively, we use impact factors to factorize the environmental materiality of a resource.<\/p>\n

\"Flow<\/p>\n

\nExample of a flow diagram describing the process of sending an e-mail and the flows required to implement the function. The aim is to draw the flows to arrive at the environmental impacts in red.\n<\/div>\n\n

Most of the systems involved in the life cycle of a product or service serve other products or services. They therefore produce several functions which are sometimes not commensurable (i.e., their quality cannot be directly qualified by the same unit of measurement). This type of system is known as multifunctional. Digital services are particularly well-suited to multifunctional systems, thanks to the high degree of mutualization of infrastructures and equipment. The Tier 3 mobilized to deliver an e-mail are used to deliver other e-mails, but also for countless other services that are not commensurable with each other (for example, a payment service is not comparable to a streaming service). In this case, the attribution paradigm involves assigning a fraction of the system's impacts to the FU under consideration. To partition these impacts between the different functions provided by a multifunctional system, we use allocation keys.<\/p>\n

\n

An allocation key is used to distribute the environmental impacts of a system involving multiple functions.<\/p>\n

The allocation key can be physical: weight, volume, time, etc.\nThe allocation key can be socio-economic: price, symbolic value, etc.<\/p>\n<\/blockquote>\n

Although the justifications for the use of certain allocation rules are partly objectivable, particularly where physical criteria are concerned, they are very often a matter of subjective or even political choice, whether explicit or implicit. Indeed, allocation rules reflect, in particular, the way in which stakeholders wish to distribute environmental responsibilities within a value chain. In the case of mail, for example, how should network impacts be partitioned? There are several possibilities: depending on the quantity of data transmitted, considering only the number of e-mails, or the importance of usage. A major limitation lies in the very great sensitivity to the choice of allocation rule (this idea will be the subject of a future article) and in the fact that, in many cases, different rules may be justified.<\/p>\n

The advantage of the attributional approach is that it makes it possible to associate an environmental materiality with the entire technosphere, while assigning responsibilities to all the resulting impacts. It therefore makes it possible to define budgets or to identify the entities who are most dependent on environmental impacts in a value chain, the degree of dependence being partly determined by the allocation rules. However, this approach does not fully identify the physical and socio-economic mechanisms induced by the implementation of the FU, since it requires reasoning in a frozen system. Nor does it take into account changes in the technosphere (changes in quantities produced and\/or consumed, production processes, etc.).<\/p>\n

Following an attributional approach, and with the assumptions retained, the Iroco study evaluates the greenhouse gas emissions attributable to one week's use of a mailbox at 63.2 gCO2eq.<\/p>\n

Consequential paradigm<\/h2>\n

In contrast to the attributional approach, the consequential paradigm identifies the impacts resulting from the changes induced by the FU. It allows us to answer the question "What is the environmental impact induced<\/span><\/strong> by the implementation of the FU?". In other words, it differentiates between a world in which FU has been implemented and a hypothetical world in which FU has not. In this approach, we are only interested in the post-implementation effects of the FU5<\/a><\/sup> , whereas the attributional paradigm will also be interested in the impacts of the resources that were necessary for its implementation and that took place prior to it.<\/p>\n

Theoretically, this paradigm is supposed to describe the physical and socio-economic consequences induced by the implementation of an additional FU. It can therefore be used to answer questions relating to an action (for example, what is the impact of charging an electric vehicle at 4pm, or more generally, what is the impact of electrifying 80% of the vehicle fleet by 2040).<\/p>\n

\"Illustration<\/p>\n

\nEkvall 2019 [6]<\/a>, based on Weidema 2003 [7]<\/a>.\n

The pie chart represents all the impacts of the system at a given time. A consequential method is used to determine the changes in impacts, represented here by the arcs of the circle (decrease or increase in impacts).<\/p>\n<\/div>\n

6<\/a><\/sup>\n7<\/a><\/sup><\/p>\n\n

In practice, the aim is to follow the consequences of FU implementation step by step, until we arrive at environmental consequences. In other words, an impact is included in the inventory if it had not occurred without the FU.<\/p>\n

\"Consequential<\/p>\n

\nExample of a consequence graph to characterize the sending of an e-mail. Only the long-term consequential approach takes gray consequences into account.\n<\/div>\n\n

As with the attributional method, it is possible to use consequential impact factors that characterize the environmental consequences of an action. There are considerably fewer consequential impact factors available, particularly in the digital sector, where no database provides sector-specific factors. This is one of the reasons why this paradigm is rarely used, even to answer questions relating to the evaluation of a change and which therefore fall within the consequential paradigm. The attribution approach is therefore often used as a substitute, either consciously or unconsciously, with no guarantee of reliability (see section particular case).<\/p>\n

By definition, the consequential paradigm does not take into account impacts linked to the implementation of existing infrastructures, since only post-FU consequences are considered. This approach therefore does not allow us to reason about past environmental impacts, but only about future ones. It is therefore not suitable for defining environmental responsibilities, but rather as a steering tool for achieving environmental objectives.<\/p>\n

There are two forms of consequential approach: short-term consequential (or "marginal approach") and long-term consequential. These two forms are opposed when it comes to taking into account the change in production capacity induced by the FU. In practice, however, the two forms can be combined.<\/p>\n

Short-term consequential paradigm<\/h3>\n

The short-term consequential or marginal approach looks at the environmental impacts directly induced by a marginal change in consumption or production (for example, the impacts of an additional unit produced). In this approach, we look at the "short-term" consequences of implementing the FU (over-consumption of energy, materials, etc.), in the sense that, as there is no time to adapt to this change, infrastructures are considered to be constant.<\/p>\n

Let's look at the consequence graph again. In this approach, only marginal consequences are considered (in black). For this service, it's mainly the energy consumption of the equipment mobilized when an e-mail is sent:<\/p>\n